Protecting PCB in ATS from lightning

[PetrosA]

On a large farm, customer has multiple generator backup systems. Most recently installed has four Kohler ATSs controlling one generator, three located together on one wall (two tenant houses and a garage/shop), the fourth in a remote stable. Three of the four PCBs have burned out in the last four months from nearby lightning strikes (no direct hits), causing the generator to run non-stop. Per board replacement cost is about $500 and as these are the only ones blowing, customer is not happy. Any ideas on how to minimize the damage to the PCBs during strikes?

 

[mxslick]

Here's a few idears:

1: Install TVSS at ALL ATS locations, on BOTH Utility and generator sides;
2: Check integrity and proper installation of grounds and generator bonds;
3: Install supplemental ground rods in a Code-Compliant manner.

Try to get detailed information on the board failures from Kohler, they should be able to help pinpoint how the boards are failing and possible fault current path(s).

 

[zog]

On a large farm, customer has multiple generator backup systems. Most recently installed has four Kohler ATSs controlling one generator, three located together on one wall (two tenant houses and a garage/shop), the fourth in a remote stable. Three of the four PCBs have burned out in the last four months from nearby lightning strikes (no direct hits), causing the generator to run non-stop. Per board replacement cost is about $500 and as these are the only ones blowing, customer is not happy. Any ideas on how to minimize the damage to the PCBs during strikes?

PCB's? There is only one thing PCB is an acronym for and I don't think it makes sense here, what do you mean by PCB's?

 

[zbang]

Printed Circuit Board

 

[PetrosA]

Here's a few idears:

1: Install TVSS at ALL ATS locations, on BOTH Utility and generator sides;
2: Check integrity and proper installation of grounds and generator bonds;
3: Install supplemental ground rods in a Code-Compliant manner.

Try to get detailed information on the board failures from Kohler, they should be able to help pinpoint how the boards are failing and possible fault current path(s).

Grounding and bonding is code-compliant for sure. We'll send the boards in and see what they can tell us. Do you have any recommendations for TVSS units?

Thanks!

 

[bphgravity]

I would agree that using coordinated cascading surge protection would be the best fit for this particular case. It may also be advisable to install some other forms of lightning protection to mitigate some of the effects of near and direct strikes. Isolation of the equipment would seem to be an appropriate action.

 

[catchtwentytwo]

Are the ATSs networked or do they have any common control interconnections? If yes, don't rule out that being the "entry point" of the surge.

 

[zog]

Printed Circuit Board

Thanks, to me it is Polychlorinated biphenyl

 

[PetrosA]

I would agree that using coordinated cascading surge protection would be the best fit for this particular case. It may also be advisable to install some other forms of lightning protection to mitigate some of the effects of near and direct strikes. Isolation of the equipment would seem to be an appropriate action.

What other forms of protection do you have in mind? I'm new to this kind of protection so I'll need a little hand holding. I'm also not sure what you mean by isolation - I'm guessing you're not talking about installing isolating transformers for each service...

Are the ATSs networked or do they have any common control interconnections? If yes, don't rule out that being the "entry point" of the surge.

Each ATS can independently control the generator so if any one building loses power it's back online asap. I haven't opened the connections at the generator, but I'm guessing that the generator is designed for networked ATSs.

 

[hurk27]

What other forms of protection do you have in mind? I'm new to this kind of protection so I'll need a little hand holding. I'm also not sure what you mean by isolation - I'm guessing you're not talking about installing isolating transformers for each service...



Each ATS can independently control the generator so if any one building loses power it's back online asap. I haven't opened the connections at the generator, but I'm guessing that the generator is designed for networked ATSs.

There can be issues if your LV control conductors are run away from the other power cables, also try enclosing them in a metal raceway (LV control only) effectively bonded at each end, try running a EGC with the control cables also in the same conduit bonding it also at each end of the conduit and to the ATS and generator.

Near field strike are hard to stop but can be brought to a minimum when routing these conductors in the same path as the others, keeping all conductors close together as possible between any two points, and providing a parallel conductor such as a EGC that exceeds the size of the control conductors with proper bonding. for long runs a #4 short runs a #6

 

[PetrosA]

Okay, I've gotten some more info from the installer in the meantime, and will have to do a fuller analysis on site. Some of the services may not be grounded in per 2008 code (some were existing), but I won't know for sure till I get there. The ATSs are all hooked up to the same run control, not networked. There is also a possibility that a large loop exists between the generator, transformer and horse stables. The three buildings fed off of a common transformer (same location as three of the ATSs) are about 800' away from the horse stables. The transformer at the stable is fed thru from the first one and the primary is probably 80 or so feet away from the feeds and control wires going from the transformer to the stables.

I should be able to get there this week and do the analysis of the grounding system to see what can be improved. In the meantime, it would be helpful for some more detailed guidance and recommendations for the surge suppression. The only kind I've worked with have been the ones that go into a 1/2" KO and get hooked up to a breaker, but they don't sound sophisticated enough for this application.

Thanks!

 

[mxslick]

Peter, sorry I didn't answer back sooner, but the TVSS you have worked with in the past will do just fine for this app...I just can't recall the brands I've run into but what you described in your last post are the type I was thinking of.

Look for the lowest "let-through" or "clamping" voltage rating compatible with the system voltage. The ones I recall had a a rating of 330 volts for the "clamp" spec.

 

[weressl]

Thanks, to me it is Polychlorinated biphenyl

Welcome to the 20th Century. :grin:

 

[hurk27]

Peter, sorry I didn't answer back sooner, but the TVSS you have worked with in the past will do just fine for this app...I just can't recall the brands I've run into but what you described in your last post are the type I was thinking of.

Look for the lowest "let-through" or "clamping" voltage rating compatible with the system voltage. The ones I recall had a a rating of 330 volts for the "clamp" spec.

If he is having circuit boards being damaged, I think the voltage surge is coming in on the 12 volt low voltage control system, if this is the case then maybe SPD's rated with a 30 volt clamp would work across the control conductors to the grounding system at each termination point could help, but the leads would have to be kept short as possible to be of any use.

I'm not familiar with Kohler type ATSs, so I'm not sure of the control voltage.

are these control conductors in there own conduit? separately from the power conductors?

 

[kenq]

Ever heard of Pacific Coast Breakers, Pre-Cast Buildings, or PentaChloroBenzole.

Or maybe Printed Circuit Board, you are well versed...........


Hey.you're the breaker guy, maybe only on the other coast.