Latest / The Refrigeration Mentor Podcast / Episode 371. A 6-Step Process for Faster Electrical Troubleshooting

Transcript

Episode 371. A 6-Step Process for Faster Electrical Troubleshooting · The Refrigeration Mentor Podcast

• 0:00
  Trevor: Welcome to this refrigeration electrical troubleshooting session. Today, I want to dive in and teach you some of the tricks that I wish I would've known. I'm gonna teach you how to stop guessing and start proving. This is one of the most important things you want to learn in refrigeration. One of the biggest things, one of the real problems in the industry, most electrical issues are misdiagnosed, and this costs money.
• 0:01
  Now think about your safeties inside your compressor. That safety lines where you get the low pressure, high pressure, oil pressure control. You gotta understand one. Open stops everything. Loads can run independently. So remember parallel circuits, refrigeration or electrical 1 0 1. As you can see in this example, we got a crank case heater parallel with a receiver heater.
• 0:02
  Read left to right. So when you're looking at a diagram. The power source to the load. This is so, so important. As the power goes through, you're reading from left to right. Think of L and n, L two and L two on your wiring diagrams. Electrical problems fit in really one bucket. That is it. One bucket. No power, block power, or failed the load.
• 0:03
  Think about a switch. You close a switch, you put your meter across it, and it does have voltage to it. You get zero voltage, no potential across it. But now if you have voltage across it, that means it's open or potentially a bad contact. Okay. Voltage appears across it, so it's open. You get voltage, it's closed.
• 0:04
  One of the things, the safety strings, you really wanna understand one open hides in place site. Think about that time you're doing a troubleshoot. You get a call, it's on you're, you get a call and it's a proof failure or an SLA failure. This is called a compressor proof alarm. And if one of those open, one can be hiding in a plain sight.
• 0:05
  Open or if it's, if it's, if it's missing. For this example here, you see got a contact and we gotta load after it. If that's open up, we could still have voltage to ground, but that coil's not gonna pull in 'cause there's no potential to pull it In. Reading the condensing unit diagram, it looks complex, but follow the simple rules.
• 0:06
  Okay. Oil safety, this is so, so important. The differential pressure plus time. What does that mean? So if I get below my nine PSID 0.65 barg and that oil pressure control, TRO pen, danfoss, whatever, uh uh, delta PI that will. Trip, but not right away. It'll have a time, it could be 90 seconds, it could be one 20 seconds.
• 0:07
  You should be getting that voltage if you do not. You either have a fail coil or a blocked or stop voltage. Okay? The load side matters. Line power doesn't equal operation, the load side does. So if I go to the load side and I don't see any power, what is stopping? That power meter placement is so, so important.
• 0:08
  So don't miss it because we really wanna understand. Why that trip? Okay. Auxiliary context. And these are misunderstood at all. How do they really work? Okay, that con contactor coil starts up, all of a sudden this auxiliary switch opens up. One of the things you need to understand, all these electrical wiring diagrams are the de-energized position.
• 0:09
  Factory versus field wiring. There is so many times that I've seen, and I've been at site and I've talked to field startup technician, and there's wires that are still in the electrical control cabinet, a gas cooler sensor in the cabinet that needs to be there to run certain components, understand it.
• 0:10
  Okay? One thing, you want to understand what normal means, and that is the de-energized position. Controls are usually innocent, prove before replaced, and so many components are replaced on a daily basis because we're not proving what is actual the fault that root cause because readings smart readings beat more readings and this.
• 0:11
  Why am I measuring the, the line side when I know this is a control loads load side issue? I. Now let's talk about six step process. The repeatable method. When you understand how to repeat the process every time, 100% of the time, this is gonna speed you up and build your confidence. It's a repeatable method and you should have one, one, identify what loads are, how the load is.
• 0:12
  Now we're going from one to C. Now we're going across that load to see if we have power and hey, we have power. That is great. Now find a voltage drop. Where do we have, is the voltage drop? Is it shorted or is open because we got power to it, but we're not heating up? What is the issue? So what we need to do is prove the failure.