Going over-voltage on a distro

[DayOne]

Hey folks,
Long time since I've been around. I was recently out on a gig and we were using a CAT generator with a motionlabs power distro. I asked the generator owner if the unit was set for 208v 3ph and he grunted and looked annoyed that I would insult his intelligence. I tied in and powered up only to find that he was set to 480v 3ph. After shutting down, reconfiguring and retesting my voltage, I noticed my motionlabs voltage/current meter in the top of the unit wasn't powering on. The distro still worked fine and I got power to all of my devices, but nothing would show up on the motionlabs meter. I had trouble in the past with the unit reading current poorly, but it always powered on at least.

So, question time. Did I permanently fry my motionlabs meter? Is there a protection device inside that is easily reset or replaced? Or do I need to just suck it up and buy a new meter?

Thanks!

 

[soundman]

Your best bet is to call Motion Labs, (914) 788-8877. They are great people and have been helpful to me when ever I have had an issue.

 

[RonaldBeal]

Hey folks,
Long time since I've been around. I was recently out on a gig and we were using a CAT generator with a motionlabs power distro. I asked the generator owner if the unit was set for 208v 3ph and he grunted and looked annoyed that I would insult his intelligence. I tied in and powered up only to find that he was set to 480v 3ph. After shutting down, reconfiguring and retesting my voltage, I noticed my motionlabs voltage/current meter in the top of the unit wasn't powering on. The distro still worked fine and I got power to all of my devices, but nothing would show up on the motionlabs meter. I had trouble in the past with the unit reading current poorly, but it always powered on at least.

So, question time. Did I permanently fry my motionlabs meter? Is there a protection device inside that is easily reset or replaced? Or do I need to just suck it up and buy a new meter?

Thanks!

It's possible you fried it, it is also possible you just blew an internal fuse.
The above advice about contacting ML is good advice, they will better know what is likely to have failed.

On a separate note, an admonishment: Always meter your power before connecting it to your equipment, especially if from a questionable source.

RB

 

[DayOne]

It's possible you fried it, it is also possible you just blew an internal fuse.
The above advice about contacting ML is good advice, they will better know what is likely to have failed.

On a separate note, an admonishment: Always meter your power before connecting it to your equipment, especially if from a questionable source.

RB

Yeah, I'll call them now.

On the admonishment: My test points are right next to my cams for my handheld meter. The breaker was off on the distro, and I never flip the breaker before metering the power. I guess the MotionLabs meter is hooked up before the breaker. Now I know to check at the genny next time. Never gonna make that mistake twice :-D

 

[derekleffew]

it is also possible you just blew an internal fuse.

Do fuses blow in an over-voltage situation when no load is attached (he said the main breaker was off)?

http://www.learningaboutelectronics.com/Articles/Overvoltage-protection-circuit.php

 

[Wood4321]

You need to meter before plugging into the power in question. You should also notice that you likely burned out your phase lights, (or their fuses) as well.

That being said, normally the meter on motion labs stuff is post breaker if I remember correctly. So I am surprised that the meter powered up at all, much less being blown. Are you 100% sure the main breaker was off?

 

[epimetheus]

Do fuses blow in an over-voltage situation when no load is attached (he said the main breaker was off)?

http://www.learningaboutelectronics.com/Articles/Overvoltage-protection-circuit.php

The fuse wouldn't blow directly due to over voltage, but the over voltage can cause a flashover or short after the fuse that will draw enough current to blow the fuse. Also, in this case the load is the meter and the fuses on the meter's input should be rated pretty low, on the order of 3A or so.

 

[MikeJ]

There may be an MOV on the meter board that burned up. This is common in an over voltage protection circuit. It a sacrificial device that protects the rest of the electronics. Or it could be completely toasted, but are you sure it was working properly to begin with? This is used in motion labs motor controllers, not sure about the meters though. Give them a call, you can talk directly to the person who designed it.

On generators, even if your tails are already tied in, you can leave the main breaker off, and meter from one of the courtesy outlets. Usually there is a L21-20 so you can check all three phases. Plus the panel meters on the gennie will at least show you the ballpark voltage. You should then meter at your distro, and make fine adjustments to the voltage if necessary.

 

[RonaldBeal]

On generators, even if your tails are already tied in, you can leave the main breaker off, and meter from one of the courtesy outlets. Usually there is a L21-20 so you can check all three phases. Plus the panel meters on the gennie will at least show you the ballpark voltage. You should then meter at your distro, and make fine adjustments to the voltage if necessary.

While this method may work, it doesn't confirm that the tails are tied in correctly, or something hasn't been cross plugged between the genny and your racks. I recommend ALWAYS meter cams just before they plug in to your racks. I have seen too many times where a hot and ground or hot and neutral have been crossed. In bad lighting, blue and green can look similar, and a careless electrician may swap them. I have also seen where tails have acquired extra tape on their ends, that get mistaken for the color codes.

As a crew chief, If something fails with the lighting system, I am responsible. Not being thorough with feeder is a fireable offense on my crews.