Latest / The Refrigeration Mentor Podcast / Episode 257. CO2 Experts Live: Case Controllers with Kevin Mullis

Transcript

Episode 257. CO2 Experts Live: Case Controllers with Kevin Mullis · The Refrigeration Mentor Podcast

• 0:00
  Trevor: Welcome to another CO2 experts. We're going to be diving in to MPX pro and AK five fifths. He's a good friend, Kevin. We've done a couple of podcasts together already. This guy is an expert. He has helped hundreds of technicians. He've solved. Thousands of problems on CO2 systems over the years. And we wanted to talk about case controllers because we know this here is, is not new to the industry, but it's still new.
• 0:01
  And the way we troubleshoot and walk through things is very, very important to your success when you're out in the field, servicing CO2 systems. Kevin, how you doing brother?
• 0:02
  Kevin: I'm good. Good to see you again, Trevor. Thanks for having me back.
• 0:03
  Trevor: Okay. Let's, let's just dive right into it. So. How long have you been working with the Danfoss AK 550 and the Corel MPX Pro?
• 0:04
  Kevin: Wow the 550 probably all early 2010s I would say, so a good few years. The, the MPX Pro we came to a little bit later, sort of 2015 probably 2016, something like that.
• 0:05
  Both really good pieces of kit. It's a good one to talk about because neither of them are super friendly if you, if you're coming up to them for the first time, because it's buttons and item codes and all of that. So they're good ones to talk about. They've got a lot of features that don't necessarily spring to light easily.
• 0:06
  So we, we need to sort of point out the key ones, as we were saying yesterday, there is no way we will. Be able to cover everything on these controllers in this, but hopefully we can give some pointers as to common things that people are going to see common things they should be looking for and checking when they're on site.
• 0:07
  Trevor: One of the biggest things is that you need to get the manual. You need to get the wiring diagram from that manufacturer because they have wiring diagram and the manual of the controller as well. And it's not always easy to go through it. Me and Kevin were looking for some parameters on their newer controllers.
• 0:08
  Yesterday and the parameters aren't there, but they're in the controller. So this is some of the things that it happens with all manufacturers. So don't, and they're all good ones. You know, all of them out there, they all do work really hard to make good controllers. We just really need to understand them more.
• 0:09
  And when you understand the controller more, you can troubleshoot it quicker and easier. Okay. Awesome. Let's start, start with here. This is out of one of one of the sites that you used to work on. This is electrical wiring diagram. They can look different. Let's talk about some of the, what's the important things to look at, at this, for this controller here, the Danfoss one.
• 0:10
  Kevin: Yeah, so. Important things to consider the, this is the, so this is the 550A version of the controller, which was the adapted for CO2 version of it. The, the main difference between 550A that we'll be concerned about is with the, the original 550 that worked on, they had designed for Freons. You could use a coil in probe for your evaporating temperature or a transducer.
• 0:11
  With the 550A, they want you to use a transducer for your superheat calculation, you can't use the coil in probe. So, we have got a transducer on there, all your probe assignments at the top. Obviously, if anyone worked on the old precursors to this controller, you'll know that had a DC. expansion valve on it.
• 0:12
  This has got an AC expansion valve. Key when you're changing the coil on site, you know, if you've got one on the van that you've had for 10 years and it's a DC one, it ain't going to work with this. So be aware of the the differences on that. I think, yeah, the first, if it's looking at the look at the top there where your probes and your transducer is just as most people will know, every controller manufacturer likes a different order for their probes.
• 0:13
  So just make sure you know what probe goes in where, because you, what worked on, let's say a corral, the order of your probes won't be the same on this. So this likes to do your superheating probes first. So you've got the transducer, which is sensor one, your coil outlet probe, sensor two. So that's how your superheat's been calculated.
• 0:14
  That is the key thing. Then you've got your air on, then your air off, then you defrost. When we look at the MPX Pro in a bit, the order is completely different. So just make sure you know where everything is. As I say, AKV, which is your pulse valve, your expansion valve on these controllers on this controller that is tied straight into the line.
• 0:15
  And all you're doing is switching the line voltage on and off. So if you're in the UK and Europe, that's probably two 30 volts, single phase. If you're in the States, that's probably the 110, 115 volt version. But you're switching the line voltage to it. So when, when it's done, when it's dunked in water in the bottom of the cabinet, as you'll frequently find them, just be aware there's line voltage on the plug.
• 0:16
  Trevor: So the first step, let's go through the process of when you're going up to a controller and you're going to go to do a maintenance. Okay. Just say the, the system has been running fine. What are the starting point? The first thing we need to see is what's that supply voltage coming in.
• 0:17
  Do you want to walk through some other steps?
• 0:18
  Kevin: Yeah, sure. So as you've got marked, their supply voltage is going to be key to anything working on this controller. The chances are, if you've got a problem on that, that screen is going to be blank when you walk up to it. So let's say, you know, I mean, if this is, let's say a cold store with six evaporators in it.
• 0:19
  They might not notice if one of them has gone off. So, that's going to be your start point. Nothing is going to work unless you've got the 230 there. If you've got the 230 there and the display is on what you'll see on the 550 and the 550A, what you see on this controller, you can see the cooling and the fan lights are on to the left of the numbers.
• 0:20
  If it's in alarm, all four indicators, because there's the valve indicator and the defrost indicator on the side there, they'll all be flashing. That's it. If you just touch the top button on the controller, it will give you status code for what the controller is doing.
• 0:21
  And you want that to be telling you that it's in regulation or startup. If that's giving you an alarm code straight off, or it's giving you a status code saying it's stopped, then you know where to look around the rest of that controller. The assuming it's running, but let's say for some reason it's not cooling hidden underneath those probe wires right there is the plug for the AKV which is obviously Dan Foster's expansion valve.
• 0:22
  There we go. So as I said, different to the old Dan Foster controllers, all this is doing is taking the line voltage and switching it on and off through a big transistor. So you're going to want to check. that you've got a voltage going into that, and that you've got a pulse coming out of it. It's not going to be on, see 5 and 6 there, so that's going to be your supply in, and then your feed out to your valve.
• 0:23
  So you're not going to see on the output of that permanent voltage, what you're going to see is probably 3 4 seconds at the most on, and then off, and on, and then off. Standard timescale that Danfoss works on is 6 seconds, so you will get a percentage of 6 seconds on dependant on how much Valve drive it's asking for so yeah, just check you've got a voltage out to your coil if you've got a voltage out to the coil and you're still not doing any cooling Then you're gonna be at the coil end going has my coil burnt out You can take the coil off do a continuity test on the coil.
• 0:24
  It's The exact value isn't really important. It's going to depend on what voltage your coil is, but you are going to want to see some resistance between the two pins. If it's dead short, you'll probably find it's damaged the controller, but if it's open, then your coil is not going to work. And you're going to need to replace the coil.
• 0:25
  Trevor: And so you can do it from the control, but just remember you got to unplug it. And then if you do it from the controller, there's resistance in these lines. So who knows how long these lines are running, right? Yeah, absolutely. The best thing to do if you get weird resistance from here, you got to go right to the coil itself.
• 0:26
  Does that make sense?
• 0:27
  Kevin: And that can, and that can totally happen because the, the coil plug of course has a rubber seal in it, but those rubber seals get old and hardened, or somebody doesn't do the gland up on the back of the plug and very, very common to get rust in the plug. That'll either rot the connection away and you'll get no connection or you get a high resistance on it and it won't lift the valve.
• 0:28
  You won't generate enough to lift the valve. So that's, that's super important. Yeah, so that's if, if the controller thinks it's working and it's not, that is the most likely cause of you not getting any cooling. And it's the same for the other relays to the right of that. So. You know, if you've got no fans, for example, you know, all these relays are just voltage in one side and then the switch feed out the other side.
• 0:29
  So you can, that's going to be your first point. You've got no fans. The controller has got the fan symbol on, as you can see there, you know, is there actually any voltage coming out through the relay? And is that relay running the fans directly? Is it going to a contactor in the tray or something like that?
• 0:30
  Check there, make sure it's something I mentioned on a on a, I think it was a LinkedIn post the other day. People like for cost saving reasons, running things like fans directly out of the controller. And that's absolutely fine. Other than if you get a dead short on a fan and it comes to switch that fan relay.
• 0:31
  You are putting all that stress on the fan relay in the controller rather than on a contactor. Now that contactor might cost you, I dunno, 20 pounds in the uk, you know, 30, $30. The controller's probably gonna cost you several hundred. So , yeah, I really wish people would switch those with a sub relay, but they don't.
• 0:32
  So the defrost, if you've got electric defrost, you will almost certainly find through a contactor again, if you, if your case is iced up. Put it on defrost. If you push the bottom button on the controller and hold it down for four seconds, it'll go into defrost. And you should then see the defrost relay close and you can do some tests from there.
• 0:33
  Have you got an output on the defrost relay? Is it pulling in the contact or are the heaters working, et cetera. If you just touch the defrost button for like a second. it will show you the defrost sensor temperature. So you, in the Danfoss 550, you can assign which probe is a defrost probe. It might be the air off probe.
• 0:34
  If you're an off cycle cabinet, it might be defrost sensor in the coil if you're electric, but it will show you what that sensor value is. So if, for example, you push that button and it shows you, I don't know, 130 degrees, the chances are you've got manual defrost, the relay is not going to close because it's going to go, I'm too warm, I've already terminated.
• 0:35
  But you know the likelihood is that's a probe failure and actually up on the top plugs You can unplug the defrost sensor. Yeah. If there's S five in that it's probably S five. If it's air off, it'll be S four and you can do a resistance check on your probe. The Dan Foss likes PT 1000 probes. So resistance range is pretty tight on those.
• 0:36
  I think we have got a slide somewhere with the resistances for the probes on Trevor, haven't we? Yeah,
• 0:37
  Trevor: I'll show them.
• 0:38
  Kevin: But yeah, it's, you can, you can look that up in the field as well. I think there you go. On the right hand side, PT 1000 probes. It's a thousand domes at zero Celsius is your reference point for it, but it's like, you know, you're talking a really tight resistance range.
• 0:39
  If you look at the difference to the the NTC probe, the resistance change that you get for a temperature is quite small. So let's say you've got a little bit of water in the end of the probe, it is going to have a much bigger effect on the temperature. And it's the same with long cables. If you've got a really big cold store and somebody's used really skinny cables to wire your probes in, you are gonna have a built in error in that sensor.
• 0:40
  And we've actually done it in the past. If you, let's say you've got some really funny readings on your sensors, if you take the probe off at the cooler. Twist the wires together and take them out of the controller. Do a resistance test on it. See how much resistance is just in that cable. And that'll give you a guide as to how much you need to offset your probe by to get the right reading out of it.
• 0:41
  There's, there's an argument to PT 1000 isn't the best for huge cold stores, but you are kind of stuck on certain controllers with using it. So cabling. Obviously, if you've got. Quick check for you. If you haven't got the table to hand, if you, if your case is off, let's say it's all at 10 degrees C, all your probes are going to have roughly the same resistance on them.
• 0:42
  If you've got three Let's say, you know, 1040 ohms, something like that, and you've got one at 1500 or one at 3000, that probe is almost certainly going to be faulty because everything's at roughly the same temperature. They should all be saying the same thing.
• 0:43
  Trevor: Yeah.
• 0:44
  Kevin: So it's, you don't necessarily, it's like a lot of things with refrigeration, you know, it's the exact values when you're doing something like this.
• 0:45
  If you're, if you're tweaking are really important when you've got a blatant fault. You know, it doesn't, it doesn't really matter. You know, if they're, if they're all saying 1041 homes and it's 10 degrees, not a major drama, if you've got it saying 3000 domes, you know, you don't need to be looking into that in great detail to say there's something wrong with that probe, there'll be something wrong with that probe.
• 0:46
  Trevor: Yeah.
• 0:47
  Kevin: So, I mean, worth saying as well, if very, very rarely the input on the controller will go faulty. Now, Dan Foss says 180 degrees. If the probes open, but there's nothing to stop you flipping the plugs for the air on and the air off round. Let's say if you think the air off probes faulty, but you've changed the probe and the reading still looks terrible, plug it in the air up.
• 0:48
  If it then starts giving you the correct reading and you know, you've got no offset in there. The chances are that controller does have a fault on it.
• 0:49
  Trevor: That point
• 0:50
  Kevin: it's, I mean, I will say the five 50 is bulletproof. So you'd have to go some to break it. But you could actually see it on the wiring diagram for the, for the five 50.
• 0:51
  Yeah. Digital inputs one and two. Volt free up on the top left of the controller, but digital input three on the bottom right of that drawer in is a high voltage input. So that is expecting line voltage to change that status. And if you have been unfortunate enough to put the line voltage one on the vault free one, it's probably not going to be very happy.
• 0:52
  And yeah, just, just bear in mind and for testing as well. So di three, and that will be your line voltage. It doesn't matter which way around the wires are all it's looking for is. The voltage difference across it, but bear in mind, yeah, that's that is. Not gonna be a happy controller if you plug that into Di1 or Di2.
• 0:53
  I think that's why they put it on the opposite side, to make it really difficult to get the wire around. But yeah, just, just bear in mind Di1, Di2, Volt 3. And you can configure those inputs to do a whole range of, Things for stuff that's quite minor to tell in the case to run or not. So one of your key statuses is a status 10 S.
• 0:54
  So when you push that top button and it tells you the status code, it can say S 10, and that is something's told me to stop. And that'll either be your digital input is configured as a run signal or parameter, there's a software version of it as well. Parameter R12, and that is what Danfoss called main switch.
• 0:55
  If you set that up to zero. The control will stop at all. The outputs will go off. So yeah, if you've got status 10, something has told the controller to stop.
• 0:56
  Trevor: That'd be right there. Great. Makes sense. So if I wanted to test the transducer which is right up top here. What, what's the sequence of it here?
• 0:57
  Cause I know this controller, this is the older version. They got a newer version and I think it's 41, 42, 43 for their transducer, but this is 30, 31, 32. We'll walk through that.
• 0:58
  Kevin: Yeah, of course. So In this application right here, this is one controller with one transducer. So you, they're all ratio metric five volt transducers.
• 0:59
  So they need a supply, a ground, and they give you a voltage back. So 13 and 31, there is your supply and your ground, which you've got the probes on, so you should see five volts between those two dc If you go between ground and S with your probes, you will see. the proportional signal back. So that's your pressure reading effectively.
• 1:00
  And depending on what you set your transducer range to in the controller and what gas you select in the controller, it will give you your pressure and it will give you your calculated temperature from that. So if you've got, let's say for example, it's not running and you've got five volts on where you've got the probes there, that would be maxed out on the transducer.
• 1:01
  So you've either got a system that stopped and your pressure is very high. Or you've got a fault somewhere or a miswire. Now, Dan Foss is very good with transducers. So if you imagine you can use one transducer to run a whole Island of cabinets that's great. It saves you a lot of transducers. You don't need six transducers.
• 1:02
  If you've got six cabinets on an Island, the pressure is going to be close enough, especially on CO2 on all those cases and Dan Foss lets you. Daisy chain, all of that together. So all your five volts get linked up or your grounds get linked up or your signals get linked up and you will get the same reading on each controller.
• 1:03
  The beauty of that. Is if you turn any case off, the transducer still gets power. You still get your reading. When we come to corral in a little bit, you don't, you can't do that. You can only power the transducer from one controller. So if let's say somebody is doing a case clean, you turn the controller off that's powering the transducer.
• 1:04
  Everything's going to lose its evaporating temperature, but Dan Foss is really good with that. You can feed, I think it's up to 10 cases off one transducer, but yeah, check you've got your five volts coming out, check you've got a signal coming back. Things can drag it down, water in the plug will drag the five volts down.
• 1:05
  It's only got a limited amount, a very limited amount currently can put out, it'll protect itself. The chances are, you take the fault away, it'll recover. You can also take the wires out of the plug or take the plug off the transducer. If your five volts comes back, the fault is at the transducer end, not at the controller end.
• 1:06
  It's, it's quite rare to kill the output from the controller. It's much more common that something drags it down in the field.
• 1:07
  Trevor: And that's a good thing. I didn't have the slide here, but that's exactly right. Pull it off. Am I getting the five volts out? If you are, and you know, it's transducer and I've seen this countless times on CO2 systems where people are.
• 1:08
  Changing parameters, changing stuff in reality, or replacing components in reality is just a pressure transducer that is faulty.
• 1:09
  Kevin: Yeah, it's, it's more often than not something it's using to calculate the superheat or the case temperature that's gone faulty rather than the controller. The controllers are pretty good at that.
• 1:10
  solid on things like that. So we've just highlighted here, the network. There's various different networks that Danfoss supports. In UK, it's really common to use the ethernet connection. Most other places they like to use the RS 485 with the with the Danfoss front ends. So you should have. Around about two volts difference between your your A and your B line.
• 1:11
  The 485 standard is anything above a volt and a half difference, so that it can see what's going on. It's worth checking. I would say with network fault finding, And we could do hours and bore people to death probably on network fault finding. Network fault finding is, is all about using logic. If you've got a whole island off and the island next to it's on, the chances are your fault's on the cable between.
• 1:12
  If you've got one case on an island off, you know, you can sort of break down where that fault is going to be. It's worth having a look, see if you've got a voltage difference there as a little A little indicator, but network fault finding, and I've done a lot of network fault finding over the years, is, is very much an exercise in organization and logic.
• 1:13
  Look where you've got things that are talking, look where you haven't got things that are talking, and then upset the store manager by telling them you need to get in the ceiling in between them, usually. It is worth checking.
• 1:14
  Trevor: So here's some of the status codes.
• 1:15
  Kevin: So, as I say, there's very helpful status codes on the Danfoss that's going to tell you what that controller is doing.
• 1:16
  Key ones, status zero, as it says normal, status 23, 22, that are on the screen there, all normal. It's it's either starting up or it's gone into regulation. They're the ones you're going to see most of the time. You might see defrost. Every so often, you'll know if you're expecting to see defrost, it will say D on the screen.
• 1:17
  But that is a really quick way of seeing why, why is it stopped? You know, what else am I looking at here? You know, if it's high temp, you know, my first place I'm going to look is what is the controller thing? You know, before I start looking, doing my fault finding, let's see what the controller thinks is happening.
• 1:18
  And if it 10, then it's even telling you right there, where you're going to look. You know, you're going to look at the R12 parameter. Is that turned on? There was a, there was a bug. Was it with the, I think it was actually with the E2 years ago, which should have been worked out by now, where if you got the five fifties logged onto a, an E2 panel, there was a little bit of comms drama that meant occasionally it would switch R12 off remotely,
• 1:19
  Trevor: which was
• 1:20
  Kevin: not a good look.
• 1:21
  I do believe they have resolved it. I don't actually, I don't think the latest 550s even talk to an E2, but that was, that can happen. R12 can get switched off more often than not, it's a digital input. And that digital input could be a switch on the front of the tray for case clean. Simple as that. Don't, don't discount the obvious for it.
• 1:22
  So yeah, and it will, it will tell you, there's a 1 percent error there at status 20. You know, if, if you've got status 20, then you've got a sensor error.
• 1:23
  Trevor: Yeah. Okay. Let's keep going on. Let's talk about adaptive superheat. Why this is important.
• 1:24
  Kevin: Yep. Sure. So Dan Foss doesn't use a fixed superheat reference.
• 1:25
  It uses adaptive control. So you tell it what your maximum allowable is. You tell it what your minimum allowable is. 90, I know nine and 10 there. So what it does, it's uses something called MSS which is a minimum stable superheat. It will try and give you the lowest superheat. It can and still have the coil stable.
• 1:26
  There's, if you google it on Danfoss MSS, it will explain all about it. It does tell you here, like I said, I don't think, unfortunately we've got time to go through it all today. But yeah, no, it will, you will see its target super heat move up and down depending on what it can do to stabilize the coil.
• 1:27
  So you need to give it a range to work in. But don't make the, don't make the limits crazy because it won't work properly. We tended to set the maximum to eight. And let the minimum, I don't think you can set the minimum much lower than three and still have it work. You need, especially with DX stuff, you need a little bit of room because your sensors take time to react.
• 1:28
  You, if you set that really, really, really low, by the time your sensors worked out that your pipe's got too cold, you're already flooding back. But Danfoss is quite good. It will adjust the superheat to get the most out of your coil.
• 1:29
  Trevor: And this is in Calvin for, so anyone doing superheat, you would multiply that by 1.
• 1:30
  8. So three multiplied by 1. 8 would be like five degrees superheat.
• 1:31
  Kevin: Yeah, we'll just touch on that. If you're programming a lot of Danfoss cases for a startup or something like that. That saves you hours. So that programming tool, which is not super expensive, fits in the slot on the controller where your communications card fits.
• 1:32
  You pull out the communications card, which is, yeah, just under that sticker there. Carefully, preferably using the little hole in the corner, so that you don't bust that chip that's right near the top of it. And then the programming tool slides into the controller and you can either use that to extract all the settings out of a controller you know to be good, or Or you can use it to drop settings into a controller that you want to set up.
• 1:33
  And it takes like 30 seconds to go through its cycle. And you've got a fully programmed controller, even if you don't know what settings should be in that case, if you haven't got that information to hand. You can suck all that information out of the case next door. And if that case next door is working, you are pretty sure that one's going to work on those settings and it will get you going.
• 1:34
  We, it's an absolute massive labor saver. If you're setting up loads of cases, all you need to then set is a parameter called Oh, Oh three, which is the London dress, which is how the front end panel identifies it. And you can then see your parameters on the front end and that will make your life. A lot easier.
• 1:35
  EKA 183 that is you can, you can Google that and find one to buy on the internet. So what we used to do this is something I've talked about on our other podcasts. When we were doing a lot of stuff with things like the five 50 for a specific customer, we, I produced a table of all the parameters for the different cabinets that that customer had that were different to default.
• 1:36
  Because if you've got to take the Dan Foss manual, which has got a million parameters in it to every cabinet. And you're stood there typing in the numbers and this, that it's going to take you forever. And what we found was you could reduce it down to that for this customer, to that number of parameters that were different to default, because, you know, the defaults work for a lot of things.
• 1:37
  So this gave the minimum number of parameters that people need to change for any given cabinet. I just makes your life a lot easier. I mean, there's nothing to stop you doing this with one of your own cabinets that you know, to be good. You know, manually record the parameters out of it versus the list.
• 1:38
  You only need to do it once and then it saves you every time because you know what will happen. You'll get to the case, you'll have no 4g, which means you can't get the manual online or you've had to screenshot it or download it or whatever else. Sometimes it's just easier to have it. We had all our guys had this on a laminated a four.
• 1:39
  We did it specifically. So it would all fit on one sheet. And if you're doing a lot of cases, it makes your life a lot easier.
• 1:40
  Trevor: But even if you look at Kevin's parameters, you got one, two, three, four, five, six cases here, but look, they're all almost all the same in the mind, the low temp. But you get down here, there's just a couple of parameters that are just a little bit different.
• 1:41
  Most of them are still all the same afterwards. And there's one that's a little change right here, but you got, you got to save, save time doing that. And this is your base, right? Because maybe you have it in a deli or in a bakery versus back in where the meat is or back where produce is. They might have to be adjusted and you actually have it there.
• 1:42
  You have produce and you have deli. So, which is good.
• 1:43
  Kevin: Yeah. And it's, I mean, the key things are things like the defrost sensor. So your freezers which you can see on there from the control temps, they were electric defrost. So you want to set the defrost sensor to be S five. You know, it's when you've got off cycle stuff, you want to set the defrost sensor to be the air off probe.
• 1:44
  So, you know, that's, that's one of the key ones to set. A lot of them, you know, you will get away without having them exactly how they need to be, you know, things like drain down time and what have you, but things like that are going to be key and fans in defrost, things like that in day nine, the one above it.
• 1:45
  Yeah. If you've got electric defrost, a lot of the time, you're not going to want the fans on during electric defrost. Some of them you will, but you know, especially if it's a cold store, you don't want the fans on.
• 1:46
  Trevor: You don't. Cause that's when you walk into like a freezer or something and it's like, Oh, look at all these droplets on the roof on here.
• 1:47
  Yeah. Oh,
• 1:48
  Kevin: Santa's grotto. Yeah, exactly.
• 1:49
  Trevor: Let's keep going here. We're crushing it. So, so there's Danfoss. You got to get into the manuals. You got to read them. You got to use your meter. You got to go out just like Kevin said, and get your meter on on a case that is working. Remember, you got to learn how to troubleshoot on systems that are working to be able to troubleshoot a system that you, that is not working if you don't know how it's supposed to work, how are you supposed to know how to troubleshoot it?
• 1:50
  Kevin: Absolutely. Absolutely. So, yep, this is an example of the Corel. The biggest difference, really, in terms of technology is Corel really want you to use their stepper valve, what they call on the small stuff, the E2V, a big one, it's the E3V, etc, etc. So. All your good stuff about stepper valves that you've probably talked about before applies with that.
• 1:51
  It's not like an AKV pulse valve or solenoid valve. If you, if you disconnect an AKV or a solenoid valve, it will shut. If you disconnect a stepper valve, that's mid cycle, it'll stay exactly where it is because it's on a worm drive. If you disturb that valve plug and it's driving, you're going to need to reboot the controller to put the valve back to where it needs to be, or, and, or wind the valve shut with a magnet.
• 1:52
  All right. It's also sensitive to how those are wired up. So on a stepper valve, you've got two coils in the valve SATA, one and three and two and four on the terminals there. And you can, you can check if that's working with resistance. If you unplug the valve from the board, you'll have continuity and a given resistance on one and three, and you'll have continuity with a given resistance on two and four.
• 1:53
  It doesn't actually really matter exactly what that resistance is. It will change a little bit depending on what temperature the coil is and everything else. But if you've got one that's, I think, usually with Corel it sits about 19 ohms. If you've got one that's 19 ohms and one that's 1019 ohms. Either your wire's broke or your coil is dead, I'm afraid to say, so, and it won't work.
• 1:54
  What'll happen is it'll either drive open and never shut or it'll drive shut and never open. The controller will usually be able to tell you on the fault codes that will come up on Corel, it's EFS comes up on the display if it thinks the coil is faulting. It will not tell you if the valve is stuck.
• 1:55
  All it knows is what it can see electrically. It don't know if it's mechanically stuck. We talked about this last time, didn't we Trevor, on the, on the podcast. You, you will need to physically check. If the controller says it's at zero and it's not saying EFS, it's happy the stator's working and it thinks it's shut.
• 1:56
  Whether or not it is shut is a, is a different matter. The MPX Pro the big black thing, Lump on the top there is a little battery pack. So if you power the controller off, it's got a little super capacitor or whatever, and it will shut the valve for you with the charge that's remaining in the controller, as long as the valve's plugged in.
• 1:57
  Interestingly enough, if you ever need to do it, interestingly for me, at least the, the baseboard of the MPX, they do do an AKV version of the MPX Pro. You can actually use the baseboard of that controller for both the the module on top there with the battery in it unclips very carefully through a series of pins and you can if you're in a in a spot take the akv board off one And slot it onto that instead of the stepper board.
• 1:58
  And it will, it will work absolutely fine. It's, you've got to be careful. There's a load of pins come up through the bottom board. You can just see the black connector to the right of the battery there. Don't bend any of the pins, but you can do all the parameters of the same parameters. Don't change.
• 1:59
  It's you just use different parameters to drive it. That's super key on that. Trevor's just highlighted on that transducer. So again, It's the same type of transducer, 5 volt ratiometric that you would use on the Danfoss. That's your terminals for checking the supply out to the transducer. It comes back on S6 on Corel for checking the the voltage return.
• 2:00
  As I said earlier, with Corel, you only, if you're daisy chaining it to an island, You have to use the right transducer. They've got a whole range of transducers for sharing which are the S range of transducers, but you only link together the grounds and the signals you power it off one controller, which does give you an issue, obviously, if that case gets turned off for cleaning.
• 2:01
  So be aware of that. There is a parameter, which we'll talk about in a sec, that will help you out during that. But be aware if that case gets turned off, they're going to all lose the readings. That's super important. If you look at the probe order there, probe order on this, it's completely different to Danfoss.
• 2:02
  Yep, so this does air off defrost, air on, and then your suction probe, then your product probe if you've got one, then your transducer. And you've not got a ground after every probe, they share their grounds. But you see the groups. So the ground for the first four probes, it's just one pin and the ground for the second group is just one pin.
• 2:03
  That's because on Corel, they let you use different transducer ranges on different groups of probes. So you can actually have an NTC probe on your air on and your air off and use BT 1000. On your superheat and probe if you so wish to, which some, some manufacturers actually do. So just be aware of that.
• 2:04
  This is what we were saying before about the stepper valves. As I say, the controller will not know if the valve is blocked. There is. The Corel drivers do have a setting which attempts to find out if the valve's blocked. It is it's called something like Expansion Valve to Limit Switch, and it'll be a fault that comes up if the valve's sat wide open all the time and it's not cooling down the controllable thing, the valve's blocked.
• 2:05
  But that won't help you if it's stuck 20 percent open or 30 percent open and it won't know. All it knows is whether it's electrically okay or not. Worth saying on these, the, the older status, which is photographed there, the plug that plugs in with your expansion has to be the right way around. If you, you can fit the plug with a little bit of effort.
• 2:06
  180 degrees out from where it should be and if you do that the valve will drive backwards very handily so The the tail of the cable wants to point towards you can't unfortunately see it on that photo, but The, the side has got E2V written on it, this tail of the cable wants to point to the side that says V on it, and that will drive the valve in the right direction.
• 2:07
  If you've got the cable flipped 180, and it's pointing towards a bit that says E, your valve's going to go backwards, which is not going to be a good look.
• 2:08
  Okay, so MOP, really important to mention all of these controllers, and this has become much more relevant again on CO2. As people will know on TEVs, TXVs, you could get a TXV that had a limited amount of charge in the sensing bulb so that when you came off of something like a gas defrost, It didn't bang the valve to a massive huge opening and flood back before it could react or to control the pressure coming back to your plant.
• 2:09
  So what they've done on all these electronic controllers is replicate that. They're all sensing the suction pressure. So they've got a function that says if the suction pressure is above this point, don't open the valve anymore. Now you can use that to your advantage, especially on CO2 when you're trying to regulate load or stop the plant venting if there's a, if there's a problem, you know, and you can't get the suction under control, but.
• 2:10
  It can fight you as well. So you see the settings for MOP there. You can set that very carefully. Let's say you want to control load on HT. You can set that for to limit the opening at like minus one, minus two C evaporating, but if you're operating something like floating suction, that can become an issue because you can inadvertently float the suction up to a point where you've hit the MOP setting in the valve, same with Danfoss and.
• 2:11
  The valves will all start locking up and you'll be like why have all my cases stopped working? The evaporating temperature is still cold enough for them to work. So it can be your friend, it can help control your load, but just bear in mind, be very careful if using floating suction.
• 2:12
  Trevor: And definitely understand, go in, that's why we put it here, go in and read it and understand what's happening because it's going to close, it's going to limit what's going to go through that, that valve through the suction pressure.
• 2:13
  Kevin: Yeah, absolutely. And if, if so happens, you hit MOP when your valve is shut, that's the point you'll stay at. It just won't open at all. And you'll end up eventually with all the valves shut. Okay.
• 2:14
  So
• 2:15
  Trevor: we just wanted to dive into, got to get into the fault codes. Not most of the time when you come in to a call, you're probably Not all the time, but you're going to have a lot of time. There's going to be error codes, troubleshooting, get to the troubleshooting section of the man. This is the corral one, which I had a hard time to find this one on their website.
• 2:16
  I actually had to get it from one of their customers websites. And then the Dan Foss one, but get into these. If you read the codes, figure out, Oh, this is a high, high alarm, high temperature one. Well, what does that mean? Well, something caused the temperature to increase. Now us as a technician need to figure that out.
• 2:17
  Kevin: If you, if you read no other part of the manual, get the fault codes, because that's going to give you a place to start. Okay. And as I say, like, EFS is in there to say it's, it's, Steppenmotor's got something wrong with it, for example. Yeah, very common one to see. And S6 error on the Danfoss for transducer and things like that.
• 2:18
  Really common stuff to see. Yeah, just very, very quickly, because I know we're out of time. As I said earlier, with the Corel, If you turn off the master case for the transducer, you lose transducer reading. Corel have a setting for safety evaporation temperature, you can, it'll default to a reading if you lose the the transducer, but just be really careful if you, that defaults to like minus 10 on a lot of setups.
• 2:19
  If you're on a freezer. That ain't going to help you, your freezer is going to break down, so make sure that number's set right, but don't set it so low that you're going to flood back, because that'll be, it won't move at all till you switch the transducer back on, and you can very easily have it too low or too high.
• 2:20
  Trevor: And Kevin's an expert on this, and we were talking about yesterday, we had the manual, we couldn't find it very easily, so we know this is hard for you guys out there. He's been working on these for 10 15 years And then we know that but what you need to do is take the time to go through there Get a contact at one of these manufacturers Don't abuse them the relationship but use them after you understand how to use this stuff Okay And get out and ask them the questions and call them up When you do have a real problem because they want to provide you with that solution because sometimes they don't have that answer And don't blame them either They got to go in and get the control and they got to look at it and they got to call their You Experts, they're senior experts.
• 2:21
  Okay. So just utilize them when you can.
• 2:22
  Kevin: Absolutely. And yeah, you, you see it doing things that they'll rarely see it do. So they'll get the answer eventually, but you know, it's not a substitute for the things we all see in the field. You know, they see it under test conditions and they'll see a certain number of things and unless they've been about, they won't necessarily have seen the same things that you say.
• 2:23
  They do their debugging in the field. The same as we do. Well, yeah,
• 2:24
  Trevor: but, but this is how you got new product. They do their best. You know, and they test in their lab, all of them, all the manufacturers, Copeland, micro thermal, RDM, Corel, I go on the list. They're all doing their best to make the best product in this competitive market.
• 2:25
  But there's some things that there's issues that do happen. Most of the times though, most of the times, the highest percent of the time it is us as technicians or the customer. That are making the mistakes most of the time. So just, we've
• 2:26
  Kevin: just got to find them. Yep. Absolutely.
• 2:27
  Trevor: Somebody just threw in the chat.
• 2:28
  Dan Foss, cool code app is a big time saver. So it has Error codes, programming guides, troubleshooting tips. So definitely check that out. Man, this was a flash course. And we could talk about this for two days straight. I've been into many of these different trainings and this was highly, this was by far the best that I've learned as so quickly.
• 2:29
  Kevin, always. I love it. Any final thoughts on case controllers for technicians who are out there, either starting up or going to service on these case controllers or any?
• 2:30
  Kevin: They're all doing the same thing. All you need to learn is their little foibles of how to do it. What order the probes are in, what it likes to see, and fault codes.
• 2:31
  Start with the fault codes. You know, and your basics are always the same. Is it driving the valve? Can it see all its sensors? They've all got their own codes for it, their own ways of doing it, but they're all doing the same thing. They're switching the valve on, switching fans on, making something cold.
• 2:32
  You know, it's just a matter of learning. Learn It's specifics that it likes
• 2:33
  Trevor: love it kevin. Thank you so much for taking the time to come on co2 experts I I know we're going to have you on again because you're just such a wealth of knowledge and you care about the industry you care about the people in the field and that's what I love about chatting with you And learning with you thank you so much for taking the time and we'll see you at the next co2 experts
• 2:34
  Kevin: Trevor,