104. Idea: Low and Medium Voltage Applications Transcript

Mike: 00:00

Yeah, this is a funny topic and it really depends on who you’re talking to. Especially in our environment, we deal with so many different manufacturers and customers and this conversation, or at least the terms are understood very differently.

Whether you’re talking to somebody that’s used to working with power equipment or somebody that’s maybe more associated PLCs. I think there’s really a primary definition. That’s based upon ANSI instruction. And then obviously the OEMs that manufacturer equipment that play within the low voltage and medium voltage. 

Chris: 00:32

Welcome to EECO Asks Why. A podcast that dives into industrial manufacturing topics and spotlights the heroes to keep America running. I’m your host, Chris Grainger, and on this podcast, we have not covered the latest features and benefits on products that come to market. Instead, we focus on advice and insight from the top minds of industry because people and ideas will be how America remains number one in manufacturing in the world. 

All right. Welcome to this episode of EECO Asks Why. So today we’re going to be digging into the topic of what to consider when looking at low voltage or medium voltage applications. And why is that important? So today we have with us, Mr. Mike Rathbun, and Mike is going to be helping us explore this topic together. So Mike, let’s just start by defining what it’s meant when we hear the terms low voltage or medium voltage. 

Mike: 01:26

Yeah, this is a funny topic and it really depends on who you’re talking to. Especially in our environment, we deal with so many different manufacturers and customers and this conversation, or at least the terms are understood very differently.

Whether you’re talking to somebody that’s used to working with power equipment or somebody that’s maybe more associated PLCs. I think there’s really a primary definition. That’s based upon ANSI instruction. And then obviously the OEMs that manufacturer equipment that play within the low voltage and medium voltage.

So to start with, from our perspective we consider low voltage, basically anything up to a thousand volts. Above thousand volts, we would consider medium voltage up to a certain point, which is typically at the transmission and generation at the utility level. I see commonly what we see and what from the manufacturers, when we’re talking low voltage and medium voltage is in general, low voltage electrical equipment is typically designed up to 600 volts. Okay. that’s the general category. And then as we’re talking about, 

Chris: 02:35

That’s what I’d always considered up to 600 volts for at low voltage, right? 

Mike: 02:39

Yeah. If you’re looking at a power panel or a motor controller, or, those typical types of electrical apparatus that you see around a plant, they’re rated up to 600 volts and almost all cases, at least here in America.

As we go beyond that, to the typical medium voltage range, that we’re used to seeing in industrial environment, we’re looking at equipment that is in kind of two primary categories and that’s a thousand to 5,000 volts capability. And then 5,000 up to 15,000. Now there’s many levels within that, within those areas that are quote unquote standard medium voltages.

I think what’s most common that we probably deal with most of our customers is, in terms of medium voltage is a 4160. 4,160 volts. Is a lot of your distribution. You see that utilized in a lot of your large motor applications. Beyond that as we step a little bit from typically could be on the line side, or even on the low side of the of a utility transformer or a substation would be  your 12,000 and 13,000 volt range. 

Chris: 03:55

We’ve seen a lot of 2300 volt motors and industry just curious never even thought about this path, if you’ve crossed that threshold of a thousand volts and you’re in the medium voltage range, why stop at 2300 and not get the, the 41 60 volts?  There’s current savings when you go to that voltage? I’ve never thought about that. 

Mike: 04:19

I think when you’re having this conversation, at least from potentially from a design standpoint, I think what you’re touching upon is when, or why would you use four 80 volts or 2300 volts or 41 60 or 12 7, right? You have all of these, what’s really behind the thought process there? And to me, it boils down to two primary areas. Really they all anchor back down is at the end of the day, it’s gonna be cost.

No matter where you go in your design of a distribution or controlling system, there’s going to be, advantages and disadvantages in terms of cost. From a basic standpoint, if I’m looking between low voltage, let’s consider we’re talking force 460 volts, which is a typical three-phase voltage for an industrial environment.

If I’m looking between that 480 volts and the consideration of a medium voltage of 4,160, the length of the distribution runs, which we’re talking about, the cables, right? That’s a big consideration there. At what point does one make sense over the other? So understand this, the longer cable is the more copper, the more costs associated with copper, right? Copper is never cheap in any form. 

Chris: 05:43


Mike: 05:44

So that really builds into a project costs. But what that means is at 480 volts or the lower voltages, right over a long extended run, a couple of things are going to happen. We’re going to have a voltage drop as that run gets further and further. A 2% voltage drop at a low voltage or 480 is a little bit different when we’re starting from 4,160.

So I think what we do in terms of design and distribution, we weight a couple of things. Is the distribution going to be spread out over a wide physical area. Multiple buildings, large, extremely large warehouses, where the length of the runs, where it would make sense to go to a higher voltage. The other factor that comes into play here is the loads. 

Industrial manufacturer, we have a lot of motors if we’ve already talked about in some of the other conversations, but. Utilizing the higher voltage for your higher or your larger motors equals a great decrease in the amount of current being consumed. So let, let’s walk that through a little bit. If we have on a particular application, a 500 horsepower motor is what’s required.

To drive that application, right? We could power that motor, or we could design that motor or purchase it being a 480 volt motor. It could be a 2300 volt motor could be a 41 60 volt motor on up. Could give you a sense of the comparison of that. Just using some basic specifications, a 480 volt motor, at 500 horsepower, you’re looking at a current draw of somewhere between 550-600 amps. 

We take a 500 horsepower motor that is designed to operate on 4,160 volts, that current draw is going to be somewhere between 60 and 70 amps. So it’s a significant difference in current consumption. So what does that mean to us?

If I’ve got to have cabling that supports that 500 to 600 amp of current draw through it, you could imagine that’s very large cable and multiple conductors in parallel to handle that. Whereas if I only have to transmit 60, 70 amps at 4,160 volts, yes, I have to have a 5,000 volt rated cable, but that cable is much smaller, right?

So that copper cost goes way down in comparison to the two, right? Another factor that plays into this whole game of offsetting costs and fitting the application is low-voltage gear, such as motor controllers, distribution centers, all of those in a 480 volt type of gear is going to have a smaller footprint.

As compared to a piece of distribution or motor control gear, that’s rated for 4,000 volts or 5,000 volts. So there are a lot of trade-offs here, but I think you start from the basis of the size or the coverage area of the distribution system. And then look at the loads. If the loads are at such a level, that it makes sense, to save costs associated with copper and manage the current to a greater degree than meeting voltage really comes into play. 

Chris: 09:07

And from a cost standpoint, when you make that shift to medium voltage, yes, that cabling potentially would go down, but typically that medium voltage equipment and the motors themselves that’s at a higher price point, correct?

Mike: 09:21

You’re absolutely right. So this is really a trade-off. It becomes to some degree  from a designer’s perspective, it’s a knife edge, right? So they’ll really look at, have to have a big picture, look at this as you start adding in the factors to a design of a facility or a building.

And at some point, you’re, you’re gonna, you’re going to leverage to one side of the other. So it’s just saying, going to medium voltage type of distribution system, because we don’t have to have anywhere near as much copper associated with cabling to save costs. It’s not that simple, right? There’s a lot more to the equation. 

Chris: 09:58

How did the local utility factor in, or does it into these types of decisions from a plant standpoint? 

Mike: 10:05

To a great degree, your utilities trap is providing you a transmission level voltage. Okay. So we’re at the very high end of that medium voltage scale, typically right. Now, unless there’s a consideration with your utility, that they are going to own or lease you a substation.

That’s going to take those high transmission level voltages down to a usable voltage that you could use in a plant, whether that’s a medium voltage or low voltage. So the utility may come into play into that conversation. Quite often, a utility could provide some sort of a contract with an industrial plant that they would provide, not only the transformer to support voltage  transmission, but, maintain ownership and the maintenance and the liability of that equipment. 

So when we’re having that conversation, if the utility is going to own and maintain that equipment, they probably will drive a little bit more that conversation around what’s the best or the most applicable medium voltage or low voltage scenario that would work for that facility.

Chris: 11:14

Okay. That helps. Also think about resources. When I  speak resources, I’m talking about personnel. And a lot of times we been in many situations where people are typically comfortable that at 600 volt or below gear. Cause they’ve had some training there when things shift up to the medium voltage, I’ve flat out heard ENI techs and technicians just say, I’m not going in there.

I’m not dealing with that. So does that factor in, when you start looking at these types of applications and making decisions from your resource standpoint? 

Mike: 11:48

I think at this day and time, it’s probably a huge one. This is common for me too.  Working onsite in customers’ plants, I run into this all the time and I have to tell you, as well as I tell customers in my scenario, because I have a long background in electrical equipment and, hands on yeah. Working with his gear throughout my career. If I walk into a customer’s environment that I know nothing about. Really, and I’m helping them, I’m typically more comfortable working on their medium voltage gear.

Why is that? Because of the scenario you just described. Most traditional technicians in the industrial area in industrial base are not comfortable working on at higher voltage stuff. So what you end up with is a lot less hands right in that where, a traditional low voltage control center, motor control center, distribution gear, anybody from a maintenance technician to an electrician and anywhere in between, kind of gets  involved in, operating, maybe troubleshooting and tweaking that gear. And you don’t see a lot of that at the medium voltage levels. 

Chris: 12:58

Right. If you’re running a plant right now, you run a team, a crew Eni techs, and you want to elevate them. Part of EECO Asks Why, we’re trying to educate, help people get better. More confident in their abilities, just further their career paths.

What would you recommend for the technician that wants to, Hey, I’m not comfortable today, but a year from now, I want to be comfortable. What would that path at training look like? 

Mike: 13:25

I think  that’s why, we have the ask EECO. Start there. No really? It really starts from the facility ownership and management right. The guidelines are there. First to work from. I think, people need to start with the basics from NFPA70E. 

Chris: 13:43

That’s where training could start with that. I didn’t know if we were thinking more or if you were thinking, rather manufacturer specific training or is there just general medium voltage industrial knowledge, how would how would you gain that?

Mike: 13:58

That’s why I say I would start with NFPA70E because it, it crosses beyond low voltage, medium voltage, right? It’s practical, foundational electrical safety, and knowledge of how to engage with electrical equipment regardless of the voltage. And it walks you through those differences. How they apply, what are the risk factors and how do you associate them?

Not only to, arc flash situations, but to the level of voltage that is utilized on that equipment, right? That guidance is there for great foundation. Beyond that you touch on a good subject. OEMs manufacturers of this equipment is a great resource. So that’s where you could get a more detailed understanding or engagement around , as we look inside a medium voltage enclosure or compared to a low voltage, what are the things that I’m looking at? And get that level of understanding. I think we have to rely in this day and age on OEMs for a lot of that. 

The days of having constructed courses that really speak to the higher voltages and the type of distribution gear that we’re, that we’re  talking about are limited at best throughout the country. Right. 

So at that, and that’s what I did is I started learning. I really leaned on the OEMs, the manufacturers of the, of this equipment. So I could get that basic understanding of what are the pieces and parts, let’s start with there. So that I’ve always worked from the aspect of when I open a cabinet,  prior to opening that cabinet, if I don’t have an understanding that I know what’s inside of it.

And can understand what I’m looking at and it’d be understanding what’s what are the areas that I can interact with and that I shouldn’t. And what are the practices involved? That’s the ball game right there. Right. I think in this day and age, you really have to look to people, like that’s a lot of what I do, in, in work with our customers is help that education process. And we incorporate the OEMs that we work with in that process as well. 

Chris: 16:01

Absolutely. Mike, when you’re looking at a project. Maybe it’s a Greenfield, maybe it’s an expansion. At what point do you investigate or evaluate the voltages? Where would that come in? Would, is it just automatically defaulted to, Hey, this is we’re going to go low voltage here. We need to look at medium voltage for this particular application. Just curious for the listeners, when that evaluation process would occur on a project. Very early I’m imagining. 

Mike: 16:30

Obviously it’s got to be early, right? Prior to making any purchasing decisions it’s really getting to play. We talked  initially about how there’s a big trade off. There can be cost savings associated with this decision around do I build an application around low voltage or medium voltage or there may not. It could go both ways. Having that understanding and looking at the application, and basing it upon what resources are available, what infrastructure is currently in play. 

If we’re talking about you commonly see, in an industrial plant that they’re adding a new piece of the process, or they’re adding additional capacity, which is a new machine or a bigger machine, to carry out a greater productive capacity is we’re gonna have to supply power to that. So in that case, it, I think the same approach from a Greenfield design level needs to be applied here. So we look at that additional piece of information that’s going to come into play now is we already have an infrastructure.

So how can we best utilize existing infrastructure and add to the existing infrastructure and balanced costs and that measure, and still get the most efficient use of power and current for that particular application. 

Chris: 17:49


Mike: 17:49

I’ll give you a scenario on that aspect.  Initially we talked about, if you’ve got a large 750 horsepower motor thousand horsepower motor, it really makes sense for that motor to be a medium voltage motor. But if I’m a facility that has my entire infrastructure from the substation down is all 480 volts, right? 

Chris: 18:09


Mike: 18:09

That may not make sense. Cause now we’re talking about the gear associated with that, right? The substation that would convert to that medium voltage all the way down to a specific application. Once again, looking at what’s the nature of the load and the power consumed there, what are the lengths of the runs and the distance we have to travel and imbalance that against the existing infrastructure. 

Chris: 18:33

That’s great. In preparing for this, you mentioned in a previous life, low voltage and medium voltage ment very different things. So you want to walk us through that story a little bit? 

Mike: 18:42

My first entrance to this, I started my career in the Navy. We had a great process. I thought it was a great process at the time, which is nowhere. We didn’t have an NFPA70E back then, by the way. But the Navy was very good at recognizing and understanding risk and in mitigating those risks. 

But basically in Naval ships or Naval environment, we had two classes of voltage. We had low voltage and high voltage. What I think is interesting about what, how they derive those classifications was not so much the voltage level, even though there is a voltage level that applies to these stations, what was more pronounced was how we engage with these.

So here’s an example. We would define and on a Navy ship that low-voltage was 48 volts and below anything above that was considered high voltage. What that truly meant and how we went about doing our jobs is we could work live on low voltage. 

High voltage. The Navy was actually very ahead of the game. Some of the things that you see associated with arc flash and electrical safety that are very apparent now we were utilizing back then. So basically anything over 48 volts, we would suit up. We’d have safety observers. All of these practices would be in place if we were going to be working live on that type of voltage. So that was really the distinction is how we approached it from a low voltage to a high voltage level. 

Chris: 20:14

That’s great. It’s PPE and  that’s what we deal with now. The different PPE levels associated with the plants, with the art rating of the gear and equipment. 

Mike: 20:22

Absolutely. Absolutely 

Chris: 20:25

Good stuff. Anything else Mike, that you would offer up? We talked about things to consider. Great things driven load. That’s a big one. The resources, the personnel. Obviously cost budgeting, somebody got paid for this stuff, right? Any other points that you’d offer our listeners up  around what to consider when looking at low voltage or medium voltage applications?

Mike: 20:48

I would just add one, one area. We really didn’t touch upon, but it’s underlying in this conversation. As we talk about these long cable runs and high current loads, really what comes into play there as voltage drop. All right. If we have an extremely long run of cable and we start out at 460 volts, by the time we get to the other end of that cable, we’ve lost either through connections or just a natural impedance of that type of cable.

We lose some of that voltage, we could potentially start out at 480 volts and they end up at 455 at the other end. The reality of that is, any industrial environment, this has a much greater impact I think, than people truly understand. So I’d like to touch on that and it really comes more into play with motors.

And as we’ve already discussed, motors are your predominant loads in industrial manufacturing plant, right? So what happens with a motor and a voltage drop scenario? If you look for some guidance in this, the national electric code will recommend it basically on any feeder and or branch circuit combination that the voltage drop should be less than 5%.

And it’s a good rule of thumb. Once again, I said, NEC makes that a recommendation. That’s not a code within NEC, but it is a recommendation, but here’s how that works out. If we take a motor that is designed to operate a 460 volts, There’s an expectation within that design that it will perform it will deliver whatever horsepower, whatever torque that it’s designed to provide.

Assuming it is operated at 460 volts. Okay. There is some fluff within that within design and motors and the NEMA organization really defines those standards. And one that’s, I think it’s overlooked is a NEMA based motor is only designed to perform to its design levels. If the voltage applied to it is within 5% of the rating that is stamped on a nameplate, so what happens? 

I commonly see, as I go throughout plants of voltages all over the place. And you can appreciate what the comfort with a customer, there may not be a lot that they can do at any given point. This may go all the way back to you, utility to a substation. Some of these things that are driving these voltages, not necessarily just a length of a cable run, but here’s what happens if we take a motor and it’s operating to is design rating and delivering 500 horsepower at a certain level of torque. But it’s doing that on a voltage that’s, let’s say 10% less than what a traded at the motor doesn’t know. 

The motors had a dumb animal. It’s going to reach its speed. It’s going to deliver what it’s designed to do. Where’s the trade-off. The trade-off is in heat. So motor operating at that lower voltage is still going to deliver, but it’s going to be operating at a much higher temperature. And if the motor cannot manage that temperature, what’s going to happen to that motor? The life of that motor becomes greatly shortened to the point of failure and service.

So those are that’s. I want them to connect that dot to applying the right voltage, thinking that through and how the voltage drop comes into that equation and how it impacts your traditional motor loads. 

Chris: 24:21

Absolutely. Mike, thank you for such great insight to this . We hope that this brings a lot of value to our listeners.  We’re trying to connect the dots, let the people that are listening really understand and hopefully get some value when considering low voltage or medium voltage applications. Again, thank you for your time today, Mike. 

Mike: 24:41

You got it, Chris, and go Navy.