Episode 276. CO2 Experts: Bitzer Compressors - Varistep Capacity Control with Tobias Fuhrer and Manuel Reichle

Welcome to another CO2 experts live. Super excited that you're here today and thank you for continuing to come and learn a little bit about CO2,

today. We have some special guests. Experts from Bitzer, Tobias and Manuel, these guys, if you have any questions and you're listening to this on the podcast or YouTube, put it in the comments. This is how we can get back to you. Ask questions that you need to know that really will help you develop your skills as well as you're here today in the live session.

today. We have some special guests. Experts from Bitzer, Tobias and Manuel, these guys, if you have any questions and you're listening to this on the podcast or YouTube, put it in the comments. This is how we can get back to you. Ask questions that you need to know that really will help you develop your skills as well as you're here today in the live session.

Shoot it in the chat, ask the questions. Have you been working on these before? And I'd love to see that in the chat as well as where you. You're listening in from throw that in the chat as well, because we know their compressors are all around the world and we know we see them. I see them consistently more and more in racks.

When I was at Chilventa there a few months back, I seen it on a ton of different manufacturers rack. And this is the stuff that you want to dive into and learn about to find out. Capacity control is on every CO2 rack out there. You need, you know, it's either the very speed or the very step, but today we're going to be getting into the capacity control, the mechanical uh, design of the very step.

Tobias, Manuel, welcome to CO2 experts. How are you guys doing? Good morning, Trevor. Yeah, we are very excited to give you and all the people online the insights of the VARI step, why it makes sense. My name is Tobias Fuhrer. I'm meanwhile the head of center of expertise for the commercial refrigeration and I'm here with my nice colleague, Manuel Reichle.

Tobias, Manuel, welcome to CO2 experts. How are you guys doing? Good morning, Trevor. Yeah, we are very excited to give you and all the people online the insights of the VARI step, why it makes sense. My name is Tobias Fuhrer. I'm meanwhile the head of center of expertise for the commercial refrigeration and I'm here with my nice colleague, Manuel Reichle.

Pleasure to be here. Trevor, thanks for having us. Yeah. I'm the product manager for our reciprocating compressors. Really great to be here on your show. Awesome. Well, these are the experts. So make sure you ask the questions. Like I said, leave, leave a comment, reach out to me because these guys have been doing it.

They've been working with the manufacturers all around the world, all the different countries, all they were working with the technicians and contractors. So they've seen it all. Like they've seen it and we were talking about it. They're like, Hey, Trevor, we get compressive back where we seen gloves in the suction builder.

So this stuff happens. Right. So we have to make sure that we're doing the things right. Doing the setup. Right. And this is what we're going to dive into today. Set up and troubleshooting. All right, so before really going into the deep dive into the technical topics, a brief look onto a bits or as a company, you have mentioned that Trevor, we are worldwide active and represented in many, many countries around the globe with 75.

So this stuff happens. Right. So we have to make sure that we're doing the things right. Doing the setup. Right. And this is what we're going to dive into today. Set up and troubleshooting. All right, so before really going into the deep dive into the technical topics, a brief look onto a bits or as a company, you have mentioned that Trevor, we are worldwide active and represented in many, many countries around the globe with 75.

Sites in 40 countries and have 21 production sites reached 1 billion in turnover last year, right? And the family, the bits of family growth, we have 4, 300 employees around the globe and invest also, that's a Also, the message here, we invest quite some money in R& D, not only for Varistep or for capacity control, of course, but that is a major topic for us also.

So when we talk about reciprocating compressors, what are the, the main, you know, manufacturing facilities that we have made in Germany, reciprocating compressors means factory Schoeditz. That is close to Leipzig with approximately 800 people there. And there's also the competence center that means main R& D really for reciprocating compressors.

And when we talk about made in the U. S. flowery branch in in Atlanta, Georgia, with close to 300 people where most really the majority of our reciprocating compressors are produced and assembled for the North American and also South American market. Okay. What compressors do we, do we have? I mean, that is well known.

And when we talk about made in the U. S. flowery branch in in Atlanta, Georgia, with close to 300 people where most really the majority of our reciprocating compressors are produced and assembled for the North American and also South American market. Okay. What compressors do we, do we have? I mean, that is well known.

Also, we talked about it before the session. Everyone knows our compressors on the left hand side. That's for HFC, HFO, our Ecoline series. But and what we want to focus on today is really CO2. So the Ecoline CO2 compressor series for sub and transcritical CO2. Applications and those come as two, four, six and eight cylinder models, and pretty much all of them can have the barry step.

So mechanical capacity control or unloading what some people call that to really. You know, give a good balance between the system and the suction groups. Also, we want to focus really on refrigeration, you know, with the two cylinders and the smaller compressors. That's more like convenience stores, you know, smaller capacities and then going up to supermarkets, hypermarkets.

So mechanical capacity control or unloading what some people call that to really. You know, give a good balance between the system and the suction groups. Also, we want to focus really on refrigeration, you know, with the two cylinders and the smaller compressors. That's more like convenience stores, you know, smaller capacities and then going up to supermarkets, hypermarkets.

Also, you know, industrial applications like storages, ice rings is a good example. And what is common for all those applications, whatever it is, you know, smaller, bigger, industrial, commercial, but it's common for all of them. They need capacity regulation. They need to be able to go down quite low. In in part load and and that background is now explained better by to be asked why that is needed.

Thanks, Manuel. Because, yeah we brought the example here of the scale, what we, what we can see, the scale should be always balanced in the middle. So if the scale is balanced, we can run a stable evaporating temperature, a stable suction pressure. Thank you. But you know the, the weights between evaporator and compressor and so on is influenced by, by a lot of things around.

Thanks, Manuel. Because, yeah we brought the example here of the scale, what we, what we can see, the scale should be always balanced in the middle. So if the scale is balanced, we can run a stable evaporating temperature, a stable suction pressure. Thank you. But you know the, the weights between evaporator and compressor and so on is influenced by, by a lot of things around.

So the ambient temperature outside where the gas cooler is, have a big influence on the compressor capacity, the hotter it is. The compressor performance will be a little bit reduced, whereas in subcritical, for example, the compressor has much more mass flow and therefore much more power. But also the capacity control method, for example, is, is on the, on the left side.

Very important. If I don't have various step or variable speed, I can manage it by on and off, but then it will always dance like this. With a frequency inverter, I can really run it let's say quite stable within the range of the frequency inverter. And with the Varistep, I can basically do the same like with the inverter, but with a wider range.

Very important. If I don't have various step or variable speed, I can manage it by on and off, but then it will always dance like this. With a frequency inverter, I can really run it let's say quite stable within the range of the frequency inverter. And with the Varistep, I can basically do the same like with the inverter, but with a wider range.

We will have some examples there in the later slides. The system design itself has also quite an influence on the compressors. If it's a flash gas bypass system, the MT compressor have to deal with the evaporator mass flow plus the flash gas mass flow. So and, and they have to balance the, the changing requests by the high pressure, but also by the, by the suction pressure.

If it's a booster system, the, the LT stage has an influence if this is bringing more and. Capacity inside or less, it can be seen as an additional evaporator, but it's bringing also let's say the scale into into a movement parallel compression, then we basically have to see it as two scales.

So the empty compressor has an own scale and the parallel compressor have an own scale, of course. That the influencing is always a little bit the evaporator load plus the ambient for example. So try to have both scales balanced is, is the, is the challenge. The ejector brings the scales again into movement.

So the empty compressor has an own scale and the parallel compressor have an own scale, of course. That the influencing is always a little bit the evaporator load plus the ambient for example. So try to have both scales balanced is, is the, is the challenge. The ejector brings the scales again into movement.

So how accurate I can adjust. The capacity and I should do it without having any jumps in between. This is then the point for the rack systems where we'll have later some, some further slides. Operating method, if it's suction pressure control, cold room temperature control, have an influence. On the other side, also the EVA operators, how much EVA operators I have installed is there big size differences in the operator evaporates.

The smallest evaporator have an influence because in the best case, I can cover with my capacity regulated compressor, the smallest evaporator load in my system, which is not always possible, but we go later on when we talk about the supermarket application. Into one one example, then the operation. Is it a supermarket?

Is it a cold storage if there is forklifts? That the load for the rack system in the supermarket is is quite different between opening times and closing times So when the temperature in the supermarket is reduced during the night that the evaporator capacity or the demanded evaporator capacity is lower than they put the The fence is down or they have closed anyhow already.

Is it a cold storage if there is forklifts? That the load for the rack system in the supermarket is is quite different between opening times and closing times So when the temperature in the supermarket is reduced during the night that the evaporator capacity or the demanded evaporator capacity is lower than they put the The fence is down or they have closed anyhow already.

The people don't open or don't bring any additional heat inside as big influence on, on that. The challenge, I have a question on that because this is one of the things that for CO2 was everyone was like worried about the ambience being so warm. You know what I mean? It's always hot out in the hot ambience that CO2 doesn't work as well in, in hot climates.

We know now with parallel compression, you talked about, we talked about ejectors. It can be all around the world, but when I first started learning CO2, no one really talked about the issues on low load situations. I'm seeing more and more of that being an issue where all of a sudden it's minus 40 out or minus 30, where systems are running into more problems.

We know now with parallel compression, you talked about, we talked about ejectors. It can be all around the world, but when I first started learning CO2, no one really talked about the issues on low load situations. I'm seeing more and more of that being an issue where all of a sudden it's minus 40 out or minus 30, where systems are running into more problems.

And then you just said it, you got curtains pulled down. It's in the middle of the night. Everything is satisfied. This is where capacity control comes in huge. But have you ever seen it with some of the manufacturers that you may have worked with where they have to add something to keep the rack running?

Because even with just the Varistep running at minimum, it's the load is still too low. Have you ever seen that? With the Varistep Not so far because we can really go quite low in capacity with with frequency, inverted driven compressor selection. We, we have been, we had challenges with a high number of starts and stops because if the compressor is too big, it starts and stops quite often.

If it cannot address the minimum load. And therefore, we have had some examples where we did also retrofits. We replaced Varistep against the frequency inverter. The situation with the frequency inverter in the wintertime was the compressor started, it went to 25 hertz, and after one or two minutes it stopped again.

If it cannot address the minimum load. And therefore, we have had some examples where we did also retrofits. We replaced Varistep against the frequency inverter. The situation with the frequency inverter in the wintertime was the compressor started, it went to 25 hertz, and after one or two minutes it stopped again.

Which was running fine for a couple of, of, of weeks or months. At the end of the day, the, the oil separator is not separating 100 percent of oil always. So there's always a little bit oil going into the system, which was not coming back because there was no running time. And the service technician was then called for lack of oil.

In the, in the compressor because of the oil management system they could not feed back the oil. So what they did is then they refilled oil and the system was running. When we implemented the Varistep technology, then we have, we added also our Bitsaw OLM IQ. That's our oil management system, which works in combination with the IQ module.

This oil management system can. Record the oil level in the compressor. It's not only a device that feeds back, it's also a digital side glass. You can see, and you can see the side glass history in the data log over two weeks. And we We upgraded the system and we investigated the data log after some time of operation.

This oil management system can. Record the oil level in the compressor. It's not only a device that feeds back, it's also a digital side glass. You can see, and you can see the side glass history in the data log over two weeks. And we We upgraded the system and we investigated the data log after some time of operation.

And we found out that the oil injection never called for oil, and we have seen the oil level up to 100%, which means the compressor was really full with oil coming from the suction side. We went back because it was a field test case to the service guy. And we asked them, Hey, could, can you look to the maintenance log?

Did you put oil, additional oil to the system? Yeah. And then they find out different service technicians did three times we feel oil. So it was massive overfilled with oil causing the next. Challenge for the compressor because it's running as an oil pump. It's not going good for for for the long term With that measure we could adjust the system and since then we follow this online now it's connected to a warm controller and We could see that it had two stops over one year.

Did you put oil, additional oil to the system? Yeah. And then they find out different service technicians did three times we feel oil. So it was massive overfilled with oil causing the next. Challenge for the compressor because it's running as an oil pump. It's not going good for for for the long term With that measure we could adjust the system and since then we follow this online now it's connected to a warm controller and We could see that it had two stops over one year.

So it's running Basically all the time between 30 and 100%. Sometimes we see 20 percent or 10 percent compressor capacity, but then it must be really a short period during the nighttime. And this is a question I've got over the years all the time. Well, when should I use a frequency inverter or when should I use mechanical capacity control?

And, and Tobias just said it there, you know, if you need a higher turndown rate, that's when you're going to want to probably go with the. The very step versus a frequency inverters. Is that correct? Yeah, that's correct. I, we have later some nice pictures. Personally, I would prefer the frequency inverter, but I show you on the next slides then.

Yeah. Yeah. Going back to the presentation you said it, the system gets a little bit more complex by parallel compression ejectors and so on. But also the integrated systems where you do refrigeration, air conditioning and heating. in one system brings additional complex complexity. The target of bits or is or how we tackle these solutions is we, therefore we brought our IQ modules, a lot of things which, which are complicated to run safely around the compressor.

Yeah. Yeah. Going back to the presentation you said it, the system gets a little bit more complex by parallel compression ejectors and so on. But also the integrated systems where you do refrigeration, air conditioning and heating. in one system brings additional complex complexity. The target of bits or is or how we tackle these solutions is we, therefore we brought our IQ modules, a lot of things which, which are complicated to run safely around the compressor.

We put this operating functions to our IQ module. For the rack controller, it is the same interface like to a frequency inverter. You give us the zero to 10 volt signal and we give you the capacity you want to have. Secondly, we have some monitoring of the operation parameters, so the sensor values and so on we have in our data log as well.

So you can communicate with the compressor, which makes it also a little bit easier. Secondly, when we speak about efficiency of the compressors, we, we want we try to make energy efficiency increases very easy. Therefore, in 2016 at the Chaventa, we first time launched the so called Ecoline Plus range.

So you can communicate with the compressor, which makes it also a little bit easier. Secondly, when we speak about efficiency of the compressors, we, we want we try to make energy efficiency increases very easy. Therefore, in 2016 at the Chaventa, we first time launched the so called Ecoline Plus range.

So the L. S. P. M. Line start permanent magnet motors what you can use directly online without any electronics and you have a more efficient compressor. Secondly, in Europe, we have to worry Park frequency inverters, which is very easy to configure and also to select because you get the perfect match to your compressor.

And at the end of the day, you have only to put in Yeah, This is my compressor type. This is my frequency inverter type. And then all the parameters which is needed to operate it are automatically set. So you don't need to go into deep frequency inverter values to, to, to do an optimized setting. So if you select the compressor, all the settings.

Are optimized. Yeah. And then what we want to achieve is when we speak about a capacity regulation on the left side we see the mechanical capacity regulation, we are versus the on off operation, for example. So in on, off, we always start the compressor. It goes down. When it reaches a certain set point, we stop it and then we restart it.

Are optimized. Yeah. And then what we want to achieve is when we speak about a capacity regulation on the left side we see the mechanical capacity regulation, we are versus the on off operation, for example. So in on, off, we always start the compressor. It goes down. When it reaches a certain set point, we stop it and then we restart it.

So in average, the suction pressure is lower than if we can control the capacity. So a wide capacity modulation is, is always good to cover the minimum loads. And then we talk about the control factor later. Again, I'm going to explain it. The control factor. Describes the capacity steps between the variable capacity compressor and the fixed speed compressor.

This is an important value where we have a deeper slides on it. If you have a perfect capacity regulation, you have lower operating cost therefore reduced carbon footprint and a higher system availability because your system is running without any, let's say problems. You don't create any additional problems by too high starts and stops.

This is an important value where we have a deeper slides on it. If you have a perfect capacity regulation, you have lower operating cost therefore reduced carbon footprint and a higher system availability because your system is running without any, let's say problems. You don't create any additional problems by too high starts and stops.

You don't have running time on the compressors and these kinds of things. So the systems are running really. All the time and, and yeah, with less troubles and Manuel is going to explain us a little bit more. What is the possibilities and what is the ranges between the different options? So, yeah, first of all, what are the options?

And I don't think there is a clear, you know, There's advantages disadvantages for using inverters, there's advantages disadvantages possibly for using Varistep with being able to go down to 10 percent is a clear advantage, of course, and option three what we show here also is a combination of both and that is also coming next year I guess the best of both, both worlds, right, mechanical capacity control in combination with the inverter that is also something that I So now we're seeing that cause we know the compressor can go down.

I think 25 Hertz. Most there's different, depending on the model and stuff, you always have to go in and check the application engineering or go to bits or their web software and look at, cause different compressors do different ranges, but you're, and this one, for an example, it would go to 25 Hertz and then potentially use unloaders.

I think 25 Hertz. Most there's different, depending on the model and stuff, you always have to go in and check the application engineering or go to bits or their web software and look at, cause different compressors do different ranges, but you're, and this one, for an example, it would go to 25 Hertz and then potentially use unloaders.

Or do one or the other. This is pretty cool. I've been seeing this. This is definitely making me intrigued. And I have so many questions already on that one. We have to have a separate session. That's for sure. In the end, in my mind, it's also giving options. And in some cases, it's also a matter of philosophy where customers feel the most comfortable, you know, using one or the other, or in future, even both combined, you know, combining.

Combining those, those great advantages that we have here, and you have mentioned it, there is, if we just look at inverter control, depending on the compressor size, maybe compressor type, there's a certain frequency range with the two cylinders, 30 to 75 Hertz, right, which then percentage wise goes down to 34%, and four and six cylinder, if we talk CO2, 25 to 70 Hertz, which also gives them the minimum of 34%.

Combining those, those great advantages that we have here, and you have mentioned it, there is, if we just look at inverter control, depending on the compressor size, maybe compressor type, there's a certain frequency range with the two cylinders, 30 to 75 Hertz, right, which then percentage wise goes down to 34%, and four and six cylinder, if we talk CO2, 25 to 70 Hertz, which also gives them the minimum of 34%.

Whereas, using Really vary step here with two unloaders on a four cylinder compressor. Excuse me, first of all, option three, the combination, I will come back to option two, because that's the focus today. . And that is really for, for the lowest, for the greatest range, really, if you have on a four cylinder, if you have two unloaders, right? And then of course it gives you 10 to 100%. So that is really for minimum, to cover minimum part load operation and for six cylinder compressors.

And then with two unloaders installed, right, that's 33 to 100%. So, and that is really what we want to highlight and, and focus on today. Now, how does, how does it work when you look on a compressor from the outside? All you see is the cylinder head and there's a solenoid coil and a solenoid valve on the outside.

So let's Let's take a more detailed look how it looks like and how it works on the inside. First of all, the cutoff view on top and below that we can really see the inside also with a solenoid coil on top and then the internal parts, mainly the control piston, which is then when activated. It's moving and then that really unloads the cylinder bank and when unloaded, of course, it doesn't contribute to the to the cooling capacity.

So let's Let's take a more detailed look how it looks like and how it works on the inside. First of all, the cutoff view on top and below that we can really see the inside also with a solenoid coil on top and then the internal parts, mainly the control piston, which is then when activated. It's moving and then that really unloads the cylinder bank and when unloaded, of course, it doesn't contribute to the to the cooling capacity.

There's no more mass flow rate coming out of that cylinder bank. And when it is unloaded. Yes, please. So when that's energized. I just looking at there's a little drill hole that goes up. Is that high pressure that goes in underneath that control piston and pushes it down? So the, exactly the gas pressure.

So the flows are pressure differences are used to move the control piston and that then internally connects high pressure and low pressure side, right? So that the, the cylinders basically no longer compress. And what you then want to avoid is that you have a, like a reverse flow from the system, from the, you know, the gas, the high pressure side of the system, basically.

So the flows are pressure differences are used to move the control piston and that then internally connects high pressure and low pressure side, right? So that the, the cylinders basically no longer compress. And what you then want to avoid is that you have a, like a reverse flow from the system, from the, you know, the gas, the high pressure side of the system, basically.

So there has to be, and there is a check valve really on the valve plates or inside the cylinder head to prevent the moment it's unloaded to prevent any flow, you know, coming back, coming back inside from the high pressure side, because one cylinder, the other one. Cylinder bank could still be operating, so that's the basic principle here of unloading and that is not really the block suction as, as we do on HFC or HFO compressors, that's a bit different principle here for CO2.

Okay, so I got a question on this now. So when I do a lot of training, I talk about compression ratio is very important and you, and we know if you get too low of a compression ratio, that causes an issue with the compressors. So if you have really low compression ratio, what will happen with that same thing happen to using a very step versus a fixed compressor, because my understanding on a compressor, when you get really short, small compression ratio or pressure ratio that the reads will not open or close properly. Or could they could flap and then that causes the degradation and then they fail. If you have too low a compression ratio, what would happen with the Berry stuff? Yeah, that is something I will come back to later on where we also our application limits.

Okay, so I got a question on this now. So when I do a lot of training, I talk about compression ratio is very important and you, and we know if you get too low of a compression ratio, that causes an issue with the compressors. So if you have really low compression ratio, what will happen with that same thing happen to using a very step versus a fixed compressor, because my understanding on a compressor, when you get really short, small compression ratio or pressure ratio that the reads will not open or close properly. Or could they could flap and then that causes the degradation and then they fail. If you have too low a compression ratio, what would happen with the Berry stuff? Yeah, that is something I will come back to later on where we also our application limits.

I mean, within what we published, this is tested and, and that is verified, but you are completely right. I mean, At lower pressure ratios at some point the valve plates no longer function properly I mean a compressor is not a pump being able to do really, you know, really low pressure ratios and the same thing So that is why we also publish right where it can be used and where it should not be used.

I love it Okay, sorry I'll come back It's a good point. And we, we paid attention on this when we developed the wealth plate, the wealth plate for, for the Marie step is for the moment, still different from the standard wealth plate. So we paid attention that we that, that we avoid this flapping situation if there's no no pressure difference.

I love it Okay, sorry I'll come back It's a good point. And we, we paid attention on this when we developed the wealth plate, the wealth plate for, for the Marie step is for the moment, still different from the standard wealth plate. So we paid attention that we that, that we avoid this flapping situation if there's no no pressure difference.

Secondly is because we, we run it, let's say in this internal loop, there's not really. A big mass flow. So in a lot of cases. Well, we'll maybe not move really. So when it unloaded, we have really also, because this is also important for the efficiency later on when it's unloaded, it's really only the mechanical rear of the drive. There's not really compression work done. Also,

good. Now, real quick, there's suction and discharge, right? And if the compressor is operated at 100%, there's 100 percent mass flow, so both cylinder banks would be active. So if we go to 50%, that's also relatively easy. One cylinder bank is completely, you know, deactivated. One is active, giving you 50%. So if you now want to operate anywhere between 50 and 100%, so that means one on here, the right hand side cylinder bank would be active and the left hand side one would be cycling.

good. Now, real quick, there's suction and discharge, right? And if the compressor is operated at 100%, there's 100 percent mass flow, so both cylinder banks would be active. So if we go to 50%, that's also relatively easy. One cylinder bank is completely, you know, deactivated. One is active, giving you 50%. So if you now want to operate anywhere between 50 and 100%, so that means one on here, the right hand side cylinder bank would be active and the left hand side one would be cycling.

That means, you know, being activated, deactivated in order to achieve anything, any percentage number between 50 and 100%, say 65, 79, and so on. Anything below 50%, so 10 to 50%, So the right hand side cylinder bank would be off and then left hand side would be cycling. So making one off is already 50 percent and then with the remaining cylinder bank, cycling, and then any number between 10 and 50 percent is achieved.

So would it be the same with this? So I know in a lot of your documentation on your fixed compressors, they want to, you, we want technicians to check the cylinder temperatures, right? So one cylinder versus the other, because one could be damaged. So if they're all closer to the temperature, is that, are they going to do the same check on the very speed I set up very sorry, very step set up checking the discharge gas temperature with the very step is a little bit more challenging, especially when we go below 50 percent of operation because we don't see a constant mass flow and therefore we will always see a peak and so on.

So would it be the same with this? So I know in a lot of your documentation on your fixed compressors, they want to, you, we want technicians to check the cylinder temperatures, right? So one cylinder versus the other, because one could be damaged. So if they're all closer to the temperature, is that, are they going to do the same check on the very speed I set up very sorry, very step set up checking the discharge gas temperature with the very step is a little bit more challenging, especially when we go below 50 percent of operation because we don't see a constant mass flow and therefore we will always see a peak and so on.

Therefore, we have this on the latest slides also we, we, it is mandatory to have the IQ module to operate the very step. Because since we, we cannot simply cut off at 140 or 150 degrees Celsius, sorry for speaking in Celsius because I don't know the value in Fahrenheit. 284 Fahrenheit. 284. Simply stop the compressor because the sensor cannot measure it because the cycling rate, doesn't allow it.

We had to to implement an intelligent function to to have a cross reading of what is the real temperature now versus the measured temperature. And for how long time we can, let's say, accept the high temperature. And because everything is overheating, if 10 percent constantly, The oil will get too hot because there's no suction gas flow enough coming to cool it down.

We had to to implement an intelligent function to to have a cross reading of what is the real temperature now versus the measured temperature. And for how long time we can, let's say, accept the high temperature. And because everything is overheating, if 10 percent constantly, The oil will get too hot because there's no suction gas flow enough coming to cool it down.

There is the discharge gas temperature can be exceeding the 284 and we will not see it. So therefore, the IQ module. Has a special function to, to monitor all this situation and when after a certain time, this is depending on did I operate the compressor at 100% before, at 30%? What was the, the situation before?

The time is always different. How much I can run it at 10%, but if the IQ module is then detecting. That the compressor gets too hot and if we need a cooling, it will override the signal and it will say, okay I run the compressor, I run it with 20, and then it increases up the steps, step by step.

The time is always different. How much I can run it at 10%, but if the IQ module is then detecting. That the compressor gets too hot and if we need a cooling, it will override the signal and it will say, okay I run the compressor, I run it with 20, and then it increases up the steps, step by step.

With this measure, we force direct controller for a reaction. If we don't do this, we will end up in a broken compressor or in a compressor that at some point will show a discharge gas temperature far away from 284, 300, 350, easily possible. So. Therefore we, we increased the speed or the capacity of the compressor, and then the rec controller identifies, I have too much capacity in the system.

I need to stop either this compressor, if it's the only one which is active, or if we have a compound system, it stops compressor number two, compressor number one will automatically run then at 80, 90 or 100 percent and, and gets the full mass flow is cooling down again. Everything is fine. We don't create any alarm.

or any unnecessary stop of the compressor, we brought the compressor out of that critical situation without making any trouble. Let's say this is a function which we tested 2017. And since that we didn't hear any problems with, with that function, because nobody is really going to recognize it, that we are let's say overriding the signal.

or any unnecessary stop of the compressor, we brought the compressor out of that critical situation without making any trouble. Let's say this is a function which we tested 2017. And since that we didn't hear any problems with, with that function, because nobody is really going to recognize it, that we are let's say overriding the signal.

Speaking about efficiency because this is always let's say a big topic. And it's not possible to calculate it at the moment in the bits of software. It's also something where we work on, we, we have a quite long list of what we want to do with the software, but maybe at some point we can have it.

Therefore we did the, the calculation now by ourself. So we have here flash gas bypass system. The values for the compressors you can see on the top line. The important things is on the right side we have to compressor. It's a four J T E with variable speed, which is the bright green line.

Therefore we did the, the calculation now by ourself. So we have here flash gas bypass system. The values for the compressors you can see on the top line. The important things is on the right side we have to compressor. It's a four J T E with variable speed, which is the bright green line.

It can go from 25 to 70 Hertz, which is 37 KBTU per hour. And in the top it's 115, whereas we selected one size bigger, Varistep compressor from the displacement wise, because we don't have to. Capability to go to 70 hertz. So it's calculated with 60 hertz. Then we have to select the four HTE, which is one size bigger this compressor is doing then 118 KBTU at 100% and roughly 15 KBTU at 10%.

So it's a much wider range. So if we focus now on the range where I can compare these two compressors, the comparable range is between 29 percent and 69%. At 29 percent because also the compressor loses some efficiency if we run it with lower speed in CO2 in this operating condition, the COP of the VARISTEP is around 7 percent in favor.

So it's a much wider range. So if we focus now on the range where I can compare these two compressors, the comparable range is between 29 percent and 69%. At 29 percent because also the compressor loses some efficiency if we run it with lower speed in CO2 in this operating condition, the COP of the VARISTEP is around 7 percent in favor.

So it's, it's better in, in COP versus the frequency inverter combination. And the higher we go, so at around 50 percent for the Varistep compressor, which is then around 40 to 45 Hertz, we still have, let's say 5%. Efficiency increase versus the, the, the various variable speed compressor. And if the the CO2 compressor is running at 70 Hertz, the variable speed, we have a flat situation.

So, of course, this is now a transcritical operating point in subcritical. It looks a little bit different, but in average, depending on what you calculate, if you compare the VARISTEP, And the frequency inverter in the comparable area with comparable, let's say displacements, then the VARISTEP and the frequency inverter are from the efficiency wise always on the same level with a small tendency that in the range, the VARISTEP has a slight benefits of one or 2 percent in average over all the families.

So, of course, this is now a transcritical operating point in subcritical. It looks a little bit different, but in average, depending on what you calculate, if you compare the VARISTEP, And the frequency inverter in the comparable area with comparable, let's say displacements, then the VARISTEP and the frequency inverter are from the efficiency wise always on the same level with a small tendency that in the range, the VARISTEP has a slight benefits of one or 2 percent in average over all the families.

And, but if you would ask me, I would say efficiency in the comparable area is good. Yeah. So we can cope with, with that. Yeah. And I think that's a big thing for, that's more on the manufacturer side versus the technician and contractor side. But if you are building with these compressors, you want, you, you need to go through each one of these steps and get into that bits or software or reach out to your bits of rep to walk you through that, to see what is going to work, because both of them, as the technology starts to evolve.

We're making it easier and easier to work on this equipment with the IQ modules and the way the manufacturer set up, but you're going to have to reach out to them to, to just double check that, like, is this one or 2 percent worth it? Versus the complexity potential. You know, so, and who, who's going to work on it afterwards, depending on what part of the world you're in, do you have someone that can go out and service something that's a frequency inverters or something that's a mechanical control?

We're making it easier and easier to work on this equipment with the IQ modules and the way the manufacturer set up, but you're going to have to reach out to them to, to just double check that, like, is this one or 2 percent worth it? Versus the complexity potential. You know, so, and who, who's going to work on it afterwards, depending on what part of the world you're in, do you have someone that can go out and service something that's a frequency inverters or something that's a mechanical control?

You know, it all comes back to the controls, but that's what you got to think about before, you know, designing a system. Yeah. Varistep is a, let's say universal solution. You don't have power electronics involved in these kinds of things. You don't have EMC topics with the cables and so on. So it's, it's.

And it's efficiency wise from, from the capacity regulation point of view, equal to the variable speed compressor. So now coming to the system design, we spoke about the CF factor earlier. The CF factor is not an invention of bits. So it's coming from the so-called Ascom, which is the Association of European refrigeration component manufacturers.

Bitso is part of it. All the other compressor manufacturers are also joining this. And together in this group, there were guidelines for multiple compressor rack system using frequency inverters. At that time they did this recommendation, what you have to consider if you do this this kind of systems out of that, this, this we highlight here because they explained this CF factor.

Bitso is part of it. All the other compressor manufacturers are also joining this. And together in this group, there were guidelines for multiple compressor rack system using frequency inverters. At that time they did this recommendation, what you have to consider if you do this this kind of systems out of that, this, this we highlight here because they explained this CF factor.

It comes out of this document, BITSO used it also in its own documentation, the AT. 744. It's a technical advice, I would say where we have a little bit more holistic approach also with the LT stage. For, for this time, it makes it too complicated. But out of this other com guideline, the CF factor is describing it's the calculation.

What we can see, this is the capacity of the variable. Speed or variable capacity compressor, maximum minus minimum divided by the capacity of the fixed speed compressor. So if this range is, is bigger than the fixed speed compressor, we get an CF factor of 100, which is ideal. It's perfect. And it's very easy to, to do it with, with the VARISTEP.

What we can see, this is the capacity of the variable. Speed or variable capacity compressor, maximum minus minimum divided by the capacity of the fixed speed compressor. So if this range is, is bigger than the fixed speed compressor, we get an CF factor of 100, which is ideal. It's perfect. And it's very easy to, to do it with, with the VARISTEP.

It's more critical with the frequency inverters. But more on that on the next slides. If you have achieved a factor of 80%, it's still okay. But you have, you start to be below 100%. You start to have gaps where your compressor combination can not fulfill the demand from the evaporator. You either.

Offer too much capacity or too few capacity. And this brings your system into an imbalanced situation. If you stay in this area, you will also always have a stop and stop of the compressor. The point is, how big is this gap? If we speak about 500 of one kbtu or two kbtu, it's maybe not so dramatic. If we speak about 20, 50, KBTU the, the situation gets, gets more worse.

Offer too much capacity or too few capacity. And this brings your system into an imbalanced situation. If you stay in this area, you will also always have a stop and stop of the compressor. The point is, how big is this gap? If we speak about 500 of one kbtu or two kbtu, it's maybe not so dramatic. If we speak about 20, 50, KBTU the, the situation gets, gets more worse.

And the, the, the bigger the gap is the, the, the, the, the, the lower the factories, the bits of recommendation is because of the green color, try to make it over 100%. If we look to the supermarket, we have again, our scale of the evaporators now changed to the left side and the compressors on the right side.

We have to design the system for the summer conditions, which is defining our maximum load and the winter conditions, which is defining our minimum load. For the whole set up, then we have installed a number of operators in the supermarket. So out of that, so we have cooling furniture with 20 KBTU, some with 10 KBTU.

So depending on the amount you can also calculate how much furniture is equal at the same time active. It's also a question what you assume there for my example now, I assume that I have to go with, with, with, with 40 K BTU out of that situation, which means that only two furniture of the big furnitures are off or on, or so in total we have installed 360 K BTU in this, in this combination here.

So depending on the amount you can also calculate how much furniture is equal at the same time active. It's also a question what you assume there for my example now, I assume that I have to go with, with, with, with 40 K BTU out of that situation, which means that only two furniture of the big furnitures are off or on, or so in total we have installed 360 K BTU in this, in this combination here.

So 440 kbtu is what we have to, what we try to achieve in the winter conditions. So my target is that my rec combination in the summer conditions can do around 345 kbtu. And in the winter operating conditions I should achieve the 40, then I can cover the demand of two big furnitures or four small furnitures or, or, or three two small and one big as a calculation.

We used 104 Fahrenheit as the gas cooler outlet temperature, 18 Fahrenheit evaporating temperature for the summer conditions. And in the winter condition, the system is running subcritical. Then we we calculate with a 60 Fahrenheit condensing, which has an influence on the, on the, on the lead compressor, because this is defining the minimum capacity in the winter conditions.

We used 104 Fahrenheit as the gas cooler outlet temperature, 18 Fahrenheit evaporating temperature for the summer conditions. And in the winter condition, the system is running subcritical. Then we we calculate with a 60 Fahrenheit condensing, which has an influence on the, on the, on the lead compressor, because this is defining the minimum capacity in the winter conditions.

If I look now to a first selection done in Europe, in some supermarkets, because the challenge is I want to have 345 kBTU, but I don't want to spend more, the space for more than three compressors. And in this case and they also tried to pay an attention that the winter capacity is not so far away from the 40.

So. They, they put in a small variable speed compressor with 25 to 70 Hertz. The problem is the next compressor is in the fifth or 60 Hertz. Volumetric volume as double as big. As the first one, which, which gives us a big a big jump in in here when the second compressor is starting.

So. They, they put in a small variable speed compressor with 25 to 70 Hertz. The problem is the next compressor is in the fifth or 60 Hertz. Volumetric volume as double as big. As the first one, which, which gives us a big a big jump in in here when the second compressor is starting.

So in this point, the, the lead compressor, this one is running with 70 Hertz. Here it is running. With 25 Hertz and then when this is at 70 Hertz and the combination is restarting, the lead compressor goes back to 25 Hertz and the second compressor is then on with 100%. Then I have a big jump and all the evaporator request in that area cannot be covered.

So I either have too low capacity or too high capacity, and then I have a high number of starts and stops. The situation gets even worse because to achieve the summer capacity, I had to select a compressor that's roughly 2. 5 bigger than the first one. So the jump here is quite even bigger. Okay. The controller could also address this because he could stop this compressor and then start This compressor first, then he would have a different scenario here which make it a little bit better.

So I either have too low capacity or too high capacity, and then I have a high number of starts and stops. The situation gets even worse because to achieve the summer capacity, I had to select a compressor that's roughly 2. 5 bigger than the first one. So the jump here is quite even bigger. Okay. The controller could also address this because he could stop this compressor and then start This compressor first, then he would have a different scenario here which make it a little bit better.

But from the CF factor itself, it does not make a big difference. We have areas where we cannot cover the evaporator load, which is not so good. If you have such a system and the winter capacity is more or less acceptable. Because you have enough evaporator power in the winter, you can update that systems by replacing for the moment the second compressor with a fixed very step.

This means you run the compressor 50 or 100%, then you can start the second compressor with 50% first, and you don't offer too much capacity and you have a well. balance system at the end of the day. However in the winter, the system is not perfect now because you can not go down below 52 kbtu. In this example, if you want to have a system with a, with one variable speed drive that can manage the below 40 kbtu, you have to select the MTE.

This means you run the compressor 50 or 100%, then you can start the second compressor with 50% first, and you don't offer too much capacity and you have a well. balance system at the end of the day. However in the winter, the system is not perfect now because you can not go down below 52 kbtu. In this example, if you want to have a system with a, with one variable speed drive that can manage the below 40 kbtu, you have to select the MTE.

Compressor, which is roughly, you know, not completely the half displacement of the compressor lead compressor before, but three quarter of that. So we have, and if we go with equal compressors now in this scenario, we would have to install eight compressors to, to have, to have it, we would have a perfect capacity regulation.

And a perfect gear up, but we would need to install eight compressors. And I'm in sales a bit. So I like this solution because we could sell much more compressors per supermarket, but it's not a solution that is really practical. So therefore just to show, if you want to go to the 40, it is not so easy with the variable speed drive.

And a perfect gear up, but we would need to install eight compressors. And I'm in sales a bit. So I like this solution because we could sell much more compressors per supermarket, but it's not a solution that is really practical. So therefore just to show, if you want to go to the 40, it is not so easy with the variable speed drive.

If you do it with the worry step. And an easy execution, you can have the 40 KBTU or below 40 KBTU by selecting the biggest configuration, the biggest compressor in the configuration is now with the Varistep the lead compressor. It's not the smallest anymore. It's the biggest. In this example, it is not the most perfect example, but it's the easiest execution with three compressors.

So 10 to 100% with a four DTEU, or you can also use a DTE. The DTU is the LSPM configuration for a little bit higher efficiency or for higher efficiency. And then you can gear up with the GTEs. easily and you don't have any let's say areas of no coverage. It is perfectly running by only having three compressors installed.

So 10 to 100% with a four DTEU, or you can also use a DTE. The DTU is the LSPM configuration for a little bit higher efficiency or for higher efficiency. And then you can gear up with the GTEs. easily and you don't have any let's say areas of no coverage. It is perfectly running by only having three compressors installed.

If there is no space available, we don't recommend it really to do such big systems with a two compressor execution for smaller capacities. It is. to have only two empty compressors now with the Varistep, but even you can do it with two compressors, whereas with variable speed drive, you would need eight with two compressors, one 10 to 100%.

The other one with a 50 to 100 equal displacements installed in this case. You, you can go down from 33 to 334 kbtu with only two compressors versus in the other case, the eight. Our recommendation to do thing is a little bit similar to the to the to the variable speed. Drive. And I see I have one issue on the slide.

Here should be the H T E and 10 to 100 percent followed by an F T E with 50 to 100 percent and for D T E 100 percent you can go down to 50 K B T U. You will have approximately T E. Hurts a 30 percent capacity at 40 KBTU. So the efficiency is, is very good in the low load situation. And you can gear up until 334 KBTU with only three compressors and you can cover very, very large range with three compressors installed.

Here should be the H T E and 10 to 100 percent followed by an F T E with 50 to 100 percent and for D T E 100 percent you can go down to 50 K B T U. You will have approximately T E. Hurts a 30 percent capacity at 40 KBTU. So the efficiency is, is very good in the low load situation. And you can gear up until 334 KBTU with only three compressors and you can cover very, very large range with three compressors installed.

So this is this is a quite nice situation. So balancing the system between maximum load and minimum load gets very easy with the VARI step due to the range of the 10 to 100 percent of the lead. Yeah. And this is going to be a balance for the manufacturer too, because, and the end user, because now eight compressors cost way too much.

You're not going to go do that. And then only two compressors, like you mentioned, one fails and you're really. You don't get anything to hold you, help you out. But if you have three or four, that's in between, if something happens, a valve plate damages or something that you still can keep the system going.

You're not going to go do that. And then only two compressors, like you mentioned, one fails and you're really. You don't get anything to hold you, help you out. But if you have three or four, that's in between, if something happens, a valve plate damages or something that you still can keep the system going.

So, so that's something you want to talk about with your customer. If you're a designer or engineering firm out there, you want to have a good understanding. And most do most do today. The most manufacturers I work with, man, they're, they're real smart. So they're understanding the differences on that, but that's something you look at as a.

You should think about any rack or any parallel system is like, why did they put this many compressors here? What is the capacity of it? And the biggest thing is the gaps as well. Like you said earlier if you have a big gap and it's real low, low in the middle of winter, a compressor bangs on, bangs off, bangs on, bangs off.

Then you get oil issues. And then lots of other, not a good quality of cooling. So, and it, it definitely makes sense. Okay. Manuel, we'll take over now. All right. And talk a little bit about how the VARISTEP can be then controlled from the electrical side. What I have to do there. Yes. And I'm not sure Trevor, how much, how much more time you allow us.

Then you get oil issues. And then lots of other, not a good quality of cooling. So, and it, it definitely makes sense. Okay. Manuel, we'll take over now. All right. And talk a little bit about how the VARISTEP can be then controlled from the electrical side. What I have to do there. Yes. And I'm not sure Trevor, how much, how much more time you allow us.

I'll try to be, to be quick and then show that the rest of information that we have here, how to integrate it really, and to control the VARISTEP that is done by the IQ module that has now mentioned, been mentioned a couple of times. And that could be done in combination with extension board CMIOA, on which you then just provide a control signal from the system controller, right?

The capacity signal, 0 to 10 volts, which then activates and deactivates the various step accordingly, depending on what capacity is really needed on, on a given compressor. And to monitor and also to supervise the discharge gas temperature, there is here. Connection possible to integrate the discharge gas temperature and also you have mentioned it earlier when you turn down, you know, the capacity too much and the mass flow rate at some point motor cooling could become a topic, right.

So that's why the discharge gas temperature is measured. And if a certain limit or threshold is exceeded, then the capacity by the module itself. It's increased for a certain amount of time in order to, to cool down the compressor, again, the motor, and to bring down the discharge gas temperature in the end.

So that's why the discharge gas temperature is measured. And if a certain limit or threshold is exceeded, then the capacity by the module itself. It's increased for a certain amount of time in order to, to cool down the compressor, again, the motor, and to bring down the discharge gas temperature in the end.

So is that a specific sensor? Is it a 10 K and 86 K? Is it a specific one for that one? Just say one fails in the field. They check the resistance. What, what would the replacement be for that sensor? And does that come with it? Because I think I tell every technician, you gotta be putting discharge protections on your compressors because if you get overheat, the compressor's gonna die and it costs a lot more money than a 20 or $30 sensor or whatever it costs, you know what I mean?

But is it a specific discharge gas temperature sensor? That's a PT 1000 And I mean, you can find it on, on, on E parts, on on bits or bit.com and find the part number there. It's a special sensor in this case because it's measuring in the discharge gas flow. So it's not on the tube. It's inside of our compressor.

Screwed in. So there's an NPT thread to re screw it into the housing to measure the inside the gas flow. Even better. So it is a, a specific one. So you just order it out. It's just a PT 1000 sensor, but it is one that goes inside the, the compressor. Does it go in the in the head of the compressor? Is that where it would go on the right side or what side In the common discharge flow, let's say.

Screwed in. So there's an NPT thread to re screw it into the housing to measure the inside the gas flow. Even better. So it is a, a specific one. So you just order it out. It's just a PT 1000 sensor, but it is one that goes inside the, the compressor. Does it go in the in the head of the compressor? Is that where it would go on the right side or what side In the common discharge flow, let's say.

So after, after the, the cylinder head, but in, in, in some cases, like on before the discharge cut off valve. Yep, makes sense. Good. That would be this. And how to access, how to access the IQ module that can be done with a laptop, can be done with a, with a cell phone via Bluetooth, right? Using the best software, bits of electronic service tool that is also then used to set up to choose certain configuration. How many various steps do you have installed?

And also afterwards to look at the operating. You know, profile and how the, whether there was any alarms and you know, the, the, the operation basically of, of the system and off the compressor. And that was a question earlier, where to operate and to avoid anything too low pressure ratio down here. So this is then given by the application envelope by the application limits.

And also afterwards to look at the operating. You know, profile and how the, whether there was any alarms and you know, the, the, the operation basically of, of the system and off the compressor. And that was a question earlier, where to operate and to avoid anything too low pressure ratio down here. So this is then given by the application envelope by the application limits.

So the, this is a little bit misunderstood. You can run this also in this area. We don't expect any interference of our of our IQ module to the, to the capacity of the compressor. If you run here in that area, it might be that in some time the IQ module will start to increase the speed. And on there, it says you need a 10 K.

So in the gray area, that's not green. So that says that you need a 10 K or 18 degree Fahrenheit superheat at the suction, right? Yeah, that's correct, but that is that for whether Every step or not. Yeah. Yeah, exactly. And is that for both transcritical and subcritical or is that just for the transcritical compressor on?

So in the gray area, that's not green. So that says that you need a 10 K or 18 degree Fahrenheit superheat at the suction, right? Yeah, that's correct, but that is that for whether Every step or not. Yeah. Yeah, exactly. And is that for both transcritical and subcritical or is that just for the transcritical compressor on?

On the transcritical ones we state the application limits for 10k correct and for subcritical compressors We state that for 20 kelvin and those really Usually require a bit higher superheat due to the operating condition. They run a bit colder. So you wanna Run them a bit warmer in order to have a certain oil temperature in order not to have that much CO2 being solved in the oil.

That's the background on, on the subcritical machines on the subcritical conditions. Yeah. And this doesn't matter if it's very step or capacity control, this is compressors in general, even their fixed compressors. So you've got to really watch that. You got to check this on all the compressors when you're out there is check the soup read on all of them to make sure it is above that.

Perfect. Very correct. One, one, one number we want also to highlight. We have the VariStep since seven years now, so, and we, we have 4, 100 supermarkets running with the VariStep as lead compressor, 4, 000, 4, 100. Okay. Wow. Then if it is used in stepped, so basically 50 or a hundred percent, you will also find the application limits in the bits of software where there is just slight, let's say restrictions on the thermal limits.

Perfect. Very correct. One, one, one number we want also to highlight. We have the VariStep since seven years now, so, and we, we have 4, 100 supermarkets running with the VariStep as lead compressor, 4, 000, 4, 100. Okay. Wow. Then if it is used in stepped, so basically 50 or a hundred percent, you will also find the application limits in the bits of software where there is just slight, let's say restrictions on the thermal limits.

So that's the top left hand side corner of the compressor. We are in typical, you know, cooling and in freezing applications, you don't operate the compressor anyways. So something for heat pumps. The IQ module will, if it. In this configuration, it's possible to run it also without the IQ module in the 50 or 100 percent execution.

But for the, the, the area of stepless control, the IQ module is mandatory to protect. And this is so important as a technician to understand because a lot of people like they hear about operation envelopes and, you know, Permissional area, but when you're in the field, you don't, you're not always looking it up.

But for the, the, the area of stepless control, the IQ module is mandatory to protect. And this is so important as a technician to understand because a lot of people like they hear about operation envelopes and, you know, Permissional area, but when you're in the field, you don't, you're not always looking it up.

This is why I keep saying you got to go into that specific compressor because this operation envelope they're showing. Multiple operation envelopes here for different compressors are going to have different envelopes and you got to stay inside that this has all been tested by them and they know if you're running a high discharge pressure and a low evaporator pressure, you're outside that that envelope, which is going to cause damage to the compressor.

It might not fail right away. But this reduces the lifetime of that compressor. So when you're there and you got your, your gauges on, or you see the pressures, or you're looking at the, the best software, you got to look at these trend graphs to get a better understanding of why this is happening. So you understand when you're servicing the compressor.

Yes. So now I try to, to win some time. Because we, we, we, we already connected. Now you could see it in the video during, it was talking to the IQ module. We connect by the Bluetooth. If you go on site and you think that your system is not running. So for the troubleshooting you have an issue with the VARI step and you want to control the VARI step.

Yes. So now I try to, to win some time. Because we, we, we, we already connected. Now you could see it in the video during, it was talking to the IQ module. We connect by the Bluetooth. If you go on site and you think that your system is not running. So for the troubleshooting you have an issue with the VARI step and you want to control the VARI step.

The first thing is what we recommend is. to connect to the module to download the data log. And then it takes a little bit time to process this data log because it's quite a high number of data and you can see the the circle is still running. When you, when you have connected to it, you will, you will get, of course, all the alarms, all the, the warnings you can see in the operational graph, but also you can see it in the alarm history.

So, you know, what was going on with this compressor. And if you open the counter and statistics area of the of the best software. And you will see a compressor that is looking like this one, for example, in this case, the compressor running statistics show that the compressor was running in average for zero to four minutes.

So, you know, what was going on with this compressor. And if you open the counter and statistics area of the of the best software. And you will see a compressor that is looking like this one, for example, in this case, the compressor running statistics show that the compressor was running in average for zero to four minutes.

So it was starting running maximum four minutes in average, something like two, two minutes. And then it stopped again. Also, the number of starts per hour is an indication 15 to 19 starts per hour is quite a lot. So the system cannot control the capacity properly. Something is wrong. If you see these statistics, it is really important to To to check the various step, if it's functioning, if the solenoid valve is okay, and these kinds of things.

Also, what you can do is, for example, if you have a controller that can give you the number of starts and stops of the compressor per day. If the compressor is starting more than 120, 130 times per day it is might be on at the, maybe at the time to pay the system a visit. And to check because something is wrong because you have a high number of starts and stops in a good balance system.

Also, what you can do is, for example, if you have a controller that can give you the number of starts and stops of the compressor per day. If the compressor is starting more than 120, 130 times per day it is might be on at the, maybe at the time to pay the system a visit. And to check because something is wrong because you have a high number of starts and stops in a good balance system.

We will see in the next data log. So when the system is running good and good balance, we have an average operating between more than five hours. So it is not stopping. And zero to one stop per hour. Basically all the time. So this compressor had in 54 days, 23 starts. So this is not really a lot. Of course at some point you reach the limits of the compressor and then it has to start to stop, but 23 starts in in more than one month is acceptable.

It's less than I think in the service guide, it says you guys, it's on average, you want six an hour, less than six an hour. Is that right? Yeah. On just your standard compressor. So once again, there's more than one compressor guide to read. You know, so there's a lot of they got a lot of different types of compressors.

So when you get in there, they'll have the i've read a lot of them But you'll read their main guide for their fixed compressors And then you'll have the capacity control guide for how the capacity control works then you'll have the co2 guide there may be information from that very first guide that relates to the The co2 compressor because once again Refrigeration is refrigeration.

So when you get in there, they'll have the i've read a lot of them But you'll read their main guide for their fixed compressors And then you'll have the capacity control guide for how the capacity control works then you'll have the co2 guide there may be information from that very first guide that relates to the The co2 compressor because once again Refrigeration is refrigeration.

It carries over. We do not want liquid to go into the compressors We do not want the discharge to run really high and this is why the more manuals you read the better Information you'll have when you're doing the troubleshooting just like reading those trend graphs. It's so important in this one that you have here Yeah, so this is now an operational graph.

I told you earlier we replaced one very step. We take off the variable speed compressor. And in this case, we can see how on the lower black graph, we can see the reference signal from rec controller, which capacity we should drive. In this point, the green line is the oil level. This is the digital side glass.

So we have some something 58%. So there's still coming a little bit oil from the, from the suction line. But it's not critical at all. We have always the site class in the minimum, but the, the thing is in this three hours, what we see here on the graph, we didn't need to inject. Oil. So the oils, the oil management system is useless.

So we have some something 58%. So there's still coming a little bit oil from the, from the suction line. But it's not critical at all. We have always the site class in the minimum, but the, the thing is in this three hours, what we see here on the graph, we didn't need to inject. Oil. So the oils, the oil management system is useless.

This shows also the Varistep compressors have a very low, low oil carryover rate. They, they don't, in this case, it didn't call for oil. It lived with the oil that it got from the suction line. So this is also with the Ecoline, quite a good achievement what BITSO made. Then we can see the suction pressure, which is always around the 23 Fahrenheit was, which is, we expect the set point of the controller, of course.

But we can see there is different load situations because the load of the compressor is going up and down. So the evaporators call more capacity, less capacity, but the system can control this. Quite good. Of course, the condensing is going a little bit, or high pressure is going a little bit up and down.

But we can see there is different load situations because the load of the compressor is going up and down. So the evaporators call more capacity, less capacity, but the system can control this. Quite good. Of course, the condensing is going a little bit, or high pressure is going a little bit up and down.

Of course, because the, the condenser or gas cooler is charged with more or less capacity. This is clear. This, this, this part of the system is also to react on it. But when once this is made, it really, you can have a system that is close to run. With a flat signal. This is quite, quite good. For the troubleshooting we have the KW 234 maintenance instruction.

You can find this in the BITSA software. So when you go to the area documentation for the transcritical compressors, there we have a very good description. Also, we have a maintenance manual. If you want to replace a valve, then there is a video instruction, what you have to do, what you have to pay attention when you exchange the valve.

You can find this in the BITSA software. So when you go to the area documentation for the transcritical compressors, there we have a very good description. Also, we have a maintenance manual. If you want to replace a valve, then there is a video instruction, what you have to do, what you have to pay attention when you exchange the valve.

And, and also there's a guideline of, of troubleshooting, how how you can identify if the cylinder bank is working or not. I think Trevor, you read it already. Yeah, no, I definitely I read as much as I can so I I can ask good questions And I understand when i'm training people on these compressors.

So I do have a definitely a few questions, for them, so If a technician doesn't have say the phone their phone's not working You know what I mean? Their phone is dead. What are like what? Maybe three or four things that they can check on one of these compressors to really help let them know what's going on.

For an example, these are an unloading compressors when you're 100 percent capacity and you're on your amps. And you have, you're checking the amps, amps are going to be the highest it is, depending on those conditions, your suction and your discharge. But when it unloads, all of a sudden, you're going to notice those amps drop off.

There's no, there's no linear relationship with this because it all depends on conditions of your suction and your discharge. Do you want to talk about four or five things that they can go and check to, to verify that that compressor is running operation properly? So I would bring the system into kind of stable conditions, a little bit higher suction pressure is, is maybe better than, than too low.

There's no, there's no linear relationship with this because it all depends on conditions of your suction and your discharge. Do you want to talk about four or five things that they can go and check to, to verify that that compressor is running operation properly? So I would bring the system into kind of stable conditions, a little bit higher suction pressure is, is maybe better than, than too low.

So if I run the system at, at stable conditions, I would take off the solenoid coils from the compressor. Of course we, we discussed this earlier before the call, we should take care that we don't overheat the coil, so we should put a screwdriver in or, or disconnect the coils from the plug. If I have done this I can come with a permanent magnet coil and then I would check if I, I would measure the s in full condition and I would measure the S at 50% operation.

First at the left side bank of the compressor and then I checked the 50 percent of the, of the other side. So left side for me is from the motor side is the side glass side and the other side is the opposite of the side glass and then measure it both offloaded. And then you can also, let's say.

First at the left side bank of the compressor and then I checked the 50 percent of the, of the other side. So left side for me is from the motor side is the side glass side and the other side is the opposite of the side glass and then measure it both offloaded. And then you can also, let's say.

Check your your suction and high pressure and you can put the values to the software and you can calculate the 50 percent values as well that this way you know that mechanically the capacity regulation is working. If if you put it back and it is not working so well, the second thing is what you can pay attention is do Does the module get the 0 to 10 volt capacity request signal correctly?

Because if this is going, let's say, from 5 volts to 10 volts, and it's dancing up and down, jumping, then the, the controller can also not react, or the IQ module cannot react perfectly on this, because It also needs a stable signal and I'm not saying I need 70 percent I need 10 percent I need 100 percent So checking the zero to 10 point signal is a is also Important thing then the IQ module have also led a side glass with with three leds The green one is if there's no, there's power then we have, if, if it's green, it is okay.

Because if this is going, let's say, from 5 volts to 10 volts, and it's dancing up and down, jumping, then the, the controller can also not react, or the IQ module cannot react perfectly on this, because It also needs a stable signal and I'm not saying I need 70 percent I need 10 percent I need 100 percent So checking the zero to 10 point signal is a is also Important thing then the IQ module have also led a side glass with with three leds The green one is if there's no, there's power then we have, if, if it's green, it is okay.

If it's yellow, there is a warning. We are in a condition. This is not so nice, but it's not critical. There's no demand to stop the compressor. And if it's red, the compressor has an alarm and it's stopped. And if you want to read out what alarm is, you need to recharge your phone. Yeah, no, no, definitely.

And so for example, if someone never came up to one of these capacity control compressors, when they, when they put the solenoid on or when they unload. The sound changes. So can you talk a little bit about that? Cause that's a pretty important, the first time I've ever seen a capacity control, even block suction compressor, you could hear a change.

And if you've never seen that before, it kind of gives you a, maybe there's something wrong with the compressor. Do you want to talk a little bit about that when it's loading and unloading? Yeah, the sound changes because we go from basically a four cylinder operation. To to, to a two cylinder operation.

And if you've never seen that before, it kind of gives you a, maybe there's something wrong with the compressor. Do you want to talk a little bit about that when it's loading and unloading? Yeah, the sound changes because we go from basically a four cylinder operation. To to, to a two cylinder operation.

So the system gets a little bit the compressor configuration gets a little bit imbalanced. We try to, to make it as balanced as possible also for the unloaded situation. But the reaction of the compressor from its vibration to the system is changing. And therefore, you can have also noises, of course.

And then by, by, by, of course, the whole load situation for the machine is also changing. And therefore because of the frequency, the output frequency is now two cylinders versus four cylinders. The sound itself changes, but this is not, not critical for the compressors. No, but what is important though, is that all of a sudden, if it's calling to unload or unload and the sound doesn't change.

Then you will want to look into that because now maybe that solenoid coil is not working properly You're not getting the output of the 24 volts to it. Load and unload Maybe that's your the 10 volts is not working like you talked about already so these are some of the things that you really want to go and it's all in the maintenance guy and in the Destruction, but these are some of the things that you have to check, you know Especially if you haven't worked on them before One of the biggest things is that we'll have to do another one just on the wiring diagram because that's so important Their understanding of what to check physically in the IQ module.

Then you will want to look into that because now maybe that solenoid coil is not working properly You're not getting the output of the 24 volts to it. Load and unload Maybe that's your the 10 volts is not working like you talked about already so these are some of the things that you really want to go and it's all in the maintenance guy and in the Destruction, but these are some of the things that you have to check, you know Especially if you haven't worked on them before One of the biggest things is that we'll have to do another one just on the wiring diagram because that's so important Their understanding of what to check physically in the IQ module.

Yes, you have the best software and all this stuff is great, but you have to understand it mechanically. So this is using your meter. Does the compressor have the proper voltage? Does the IQ module have proper voltage? Does the solenoid output voltage going out to it, getting the proper voltage, because there could be wires that are pulled, they could not be connected properly.

So there's lots of these things that we need to check as technicians. In the field. But that, this is awesome. Definitely get out, out, out to the, to the manual the maintenance instructions for sure. Or get out to manual to the manual instruction into manual. All right. And I think it's, I agree. It's a good, good idea to do, to do another webinar on the, on the, you know, the do's and don'ts and, and, and really.

So there's lots of these things that we need to check as technicians. In the field. But that, this is awesome. Definitely get out, out, out to the, to the manual the maintenance instructions for sure. Or get out to manual to the manual instruction into manual. All right. And I think it's, I agree. It's a good, good idea to do, to do another webinar on the, on the, you know, the do's and don'ts and, and, and really.

Troubleshooting and then maybe we can also prepare some videos or on a, on a live demo or something. I could even imagine that like on a compressor and connect something or measure something for today. I think it was, it was really great to be able to, to talk about our virus step, how it works. And I think we all agree how important it is to have good capacity control.

And then to have a certain range and also not to forget about efficiency and and not to forget about the amount of of compressors where sometimes there is really on site there is restrictions so that you need relatively large compressors and then it's even more important to be able to to unload those.

And in the next step, I mean, as the systems become a bit more complex, like with ejectors, adiabatic gas coolers, additional air conditioning load, possibly, you know, or heat recovery, additionally in winter time. So all this then adds up to, we need good capacity control for different operating conditions for summer, winter, as Tobias pointed out here and explained.

And in the next step, I mean, as the systems become a bit more complex, like with ejectors, adiabatic gas coolers, additional air conditioning load, possibly, you know, or heat recovery, additionally in winter time. So all this then adds up to, we need good capacity control for different operating conditions for summer, winter, as Tobias pointed out here and explained.

So in the end, in a nutshell, less trouble and highly efficient systems. Of course that is the goal. That is what we want to achieve. We are worried that is really a great technology to accomplish that. Yeah. Okay. Let's dive into some questions before we finish up here. So you can put you can skip to the next slide so everybody can see your contact info if they want to call you at 10 o'clock in the morning when you're troubleshooting a CO2 system.

Can you advise advantage of CO2 refrigeration pack over ammonia pack? That's We're seeing this go. You guys do both. You've got compressors for ammonia, you've got compressors for CO2. We're seeing the transition in big, large industrial CO2. It's just, it's a very efficient refrigerant. So is ammonia.

Now, both of these refrigerants are going to stay. This is just, this is my opinion. We're going to see a different application, but you're going to see CO2 more and more in industrial applications just because a lot of the advantages, what are your thoughts on CO2 in larger applications? That is, that is coming more and more, and I think there's again, there's pros and cons.

Now, both of these refrigerants are going to stay. This is just, this is my opinion. We're going to see a different application, but you're going to see CO2 more and more in industrial applications just because a lot of the advantages, what are your thoughts on CO2 in larger applications? That is, that is coming more and more, and I think there's again, there's pros and cons.

I mean, some people really think that ammonia is, is, is a bit more difficult for service, you know, due to the properties of ammonia. But we do see CO2 really more and more. But I could even think about a combination of both, right? I mean, I could see ammonia in the, in the medium term stage and CO2 in, in the freezer stage, like in a cascade configuration.

Oh, yeah. But also a nice combination. But yeah, for example, high and I, and I thought, sorry, go ahead. Ice rinks, right? Using ammonia with glycol is one thing, using CO2 even underneath the ice, for example, having that uniform temperature distribution, that is another example, right? And then not having the temperature difference in the cascade or glycol heat exchange and so on.

So there's, there's certain advantages of CO2. Oh, for sure. I've seen it too. Like, and I talked to industrial technicians all the time. They're like, I don't want to work on CO2. And then I talked with CO2 guys. I don't want to work on ammonia. And so it's, you know what I mean? It's refrigeration, you know, it's what you're comfortable with.

So there's, there's certain advantages of CO2. Oh, for sure. I've seen it too. Like, and I talked to industrial technicians all the time. They're like, I don't want to work on CO2. And then I talked with CO2 guys. I don't want to work on ammonia. And so it's, you know what I mean? It's refrigeration, you know, it's what you're comfortable with.

And both of them are good solutions for sure. Definitely. Definitely. So also, you know, when, when, when you want to build a bigger system and it's close to, to the city or even inside of the city So then, then it's a little bit difficult for ammonia to get the higher charges. Then I see if there is restrictions from the, not from the system itself, but, but from the, the refrigerant ammonia to, to get the release to operate it in a dense area.

It's, it's more complicated than reducing the charge is one thing, but. Then also CO2 is easier applicable in this kind of applications when we are more in the industrial outside big slaughterhouse and so on. And the charge limit is, is not really a big topic. And Then you can operate CO2.

It's, it's more complicated than reducing the charge is one thing, but. Then also CO2 is easier applicable in this kind of applications when we are more in the industrial outside big slaughterhouse and so on. And the charge limit is, is not really a big topic. And Then you can operate CO2.

Sorry, ammonia easier. Then, then it's also good. And it's also, we see also that some countries have a different approach. We have countries, they stick more to, to ammonia in large sinks. They don't want to touch CO2. In, in, in these areas other countries, they, they go very strong with CO2 because.

They they don't have the focus so much on ammonia, but to, to tell really what is better. Also there, we don't have a recipe in BITSO because we, we try to, to provide the best solutions for, for both applications. We are good in two compressors with ammonia and with ammonia packs, definitely, but we also have, and sorry for that, the best CO2 compressors on the market.

So we also try to push these as well. So and we see a lot of nice installations with our products and we are very proud of that also. Yeah, you should be. There's another one here. So you're going to have to add Ireland to your map. Somebody mentioned that it's missed there. A good friend, the BL can, can IQ module communicate with system managers, like the SM 800A, the boss E3 or E2 or Corel can they communicate?

So we also try to push these as well. So and we see a lot of nice installations with our products and we are very proud of that also. Yeah, you should be. There's another one here. So you're going to have to add Ireland to your map. Somebody mentioned that it's missed there. A good friend, the BL can, can IQ module communicate with system managers, like the SM 800A, the boss E3 or E2 or Corel can they communicate?

The IQ module itself can communicate if the protocol of the IQ module is available in the system manager. So that would be like the map, the map of the IQ module. Is that something you, you would the contractor could give to their programmer and install that. Is that what you mean? Like those parameters.

Okay. And so they got to reach out to you to get those that information or how does that work? For example, it's they have to get in contact with us, but also more important to get in contact with the provider of the. of the system. We, we don't hide anything. So our protocol is open. We have been the best software, all the, you can read out every temperature, you can eat out every alarm warning, everything.

Okay. And so they got to reach out to you to get those that information or how does that work? For example, it's they have to get in contact with us, but also more important to get in contact with the provider of the. of the system. We, we don't hide anything. So our protocol is open. We have been the best software, all the, you can read out every temperature, you can eat out every alarm warning, everything.

You can send us also the capacity reference and these kinds of things. Once this protocol is implemented. So we have rec controllers that are able to read our IQ module. Danfoss have, have one, one platform where they can read it. VOM for sure. They, they, they can read it also. It's, it's our controller brand.

So, and, and also others are working on it. There is one from RDM that is also able to read our Modbus and the plant managers, if they can read it, they can transfer all the information they would like to have. Another question. How can we use CO2 system with high ambient like 40 degrees Celsius?

Well great question. CO2 is in every, every part of the world even above 40 Celsius. I've seen CO2 system. So you just have to, it has to be designed correctly with the right high ambient strategies. Next question was answered. I do LSP motors need a speed drive. Well, I think earlier you said you have very step with LSP motors, right?

Well great question. CO2 is in every, every part of the world even above 40 Celsius. I've seen CO2 system. So you just have to, it has to be designed correctly with the right high ambient strategies. Next question was answered. I do LSP motors need a speed drive. Well, I think earlier you said you have very step with LSP motors, right?

LSPM, Line Start Permanent Magnet Motors. They can use a frequency inverter, but they don't have to. They can also run, you know, for 60 volts, 60 Hertz direct online. Perfect. Is Varistep now available for all two cylinder and four cylinder CO2 compressors? Four cylinder and six cylinder and eight cylinder.

In eight cylinder, we only run the staged configuration, but it is available there. Two cylinders transcritical possible on request. We should talk a little bit about the application before we release it. It's there if you want to order it, 25 to 100 percent is possible but since with the small system and stopping and starting the mass flow we should little bit talk first if it's a condensing unit and you have a high suction line behind it long suction line with volume, it is okay to use the VARI step in these executions, but if you have a compact chiller, let's say with a praise plate heat exchanger directly after the compressor with couple of inches suction line.

In eight cylinder, we only run the staged configuration, but it is available there. Two cylinders transcritical possible on request. We should talk a little bit about the application before we release it. It's there if you want to order it, 25 to 100 percent is possible but since with the small system and stopping and starting the mass flow we should little bit talk first if it's a condensing unit and you have a high suction line behind it long suction line with volume, it is okay to use the VARI step in these executions, but if you have a compact chiller, let's say with a praise plate heat exchanger directly after the compressor with couple of inches suction line.

So then the stopping and starting the mass flow is not the best idea. This is why for the two cylinders and the smaller capacities, we, we always try to get in contact with our customers, but it's possible. On subcritical or we get also hearing their requests and we look into that together with our OEM customers to, to offer a solution here in the future.

Somebody asks us where the people can find more information about that combination. 2025. I think that's the very step in a very speed or frequency inverter. Do you have information yet out there or no? There is more to come. That is a bit also looking into the future. So we ask for a, for a bit, a bit of patience.

Somebody asks us where the people can find more information about that combination. 2025. I think that's the very step in a very speed or frequency inverter. Do you have information yet out there or no? There is more to come. That is a bit also looking into the future. So we ask for a, for a bit, a bit of patience.

And once it's time, then of course there will be information on, on the homepage. And we also then send out the information via email. Also, if you have an interesting project we are send an email to Manuel or me. We can look into that because the software is ready. We have it in, in field trials.

So contact us and we check what is, what is possible. Of course we try to do a webinar. On that also, and, and publish more information by 2025. Yeah. Amazing. A couple more here, . Thank you so much for your time. So the question is, what is the cycle time for the pulse of it? Or is there a cycle time on loading and unloading?

It's not a fixed cycle time in the IQ module but in ever, in average, the cycle time is around 30 seconds. 30 seconds. Okay. Cause that's dynamic. I think you could talked about that already. It's cause now it's not really coming from the, say the Dan Foss controller, the E3 controller, whatever it's coming from the IQ module, that's actually cycling it.

It's not a fixed cycle time in the IQ module but in ever, in average, the cycle time is around 30 seconds. 30 seconds. Okay. Cause that's dynamic. I think you could talked about that already. It's cause now it's not really coming from the, say the Dan Foss controller, the E3 controller, whatever it's coming from the IQ module, that's actually cycling it.

I think that's it guys. This has been amazing. I learned a ton. Where can people learn more about you guys learn more about these compressors or find out more? Yeah, we have several seminars in BITSO in our academy. So there you can check out the BITSO homepage, the academy homepage, for example.

Manu and I, we are very often in exhibitions actually. So talk directly to us if you see us. So normally we are friendly. I love it. I want to thank you. I want to thank you guys so much for taking the time to, to share some of this knowledge with us and just teaches a few things. I appreciate it and look forward to seeing you guys at another CO2 experts.

Manu and I, we are very often in exhibitions actually. So talk directly to us if you see us. So normally we are friendly. I love it. I want to thank you. I want to thank you guys so much for taking the time to, to share some of this knowledge with us and just teaches a few things. I appreciate it and look forward to seeing you guys at another CO2 experts.