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Author Topic: Generator power problems  (Read 5870 times)

DavidTurner

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Generator power problems
« on: August 09, 2014, 05:06:08 pm »

Last night I had significant power problems running off a generator. Power metered just fine, but neither my UPS nor my surge protector liked it. Surge strip would go into protect mode and UPS would switch to battery and then shut off as well.

I had to plug the console in directly (bypassing surge surpressor and UPS) to get through the show. Any ideas why this would be? BTW, once I plugged in directly, no problems. I did not like doing this, but it was necessary. FOH on the same service through the same PD had no issues and was able to run both surge protector and UPS.

I am really puzzled.
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g'bye, Dick Rees

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Re: Generator power problems
« Reply #1 on: August 09, 2014, 05:09:13 pm »

Last night I had significant power problems running off a generator. Power metered just fine, but neither my UPS nor my surge protector liked it. Surge strip would go into protect mode and UPS would switch to battery and then shut off as well.

I had to plug the console in directly (bypassing surge surpressor and UPS) to get through the show. Any ideas why this would be? BTW, once I plugged in directly, no problems. I did not like doing this, but it was necessary. FOH on the same service through the same PD had no issues and was able to run both surge protector and UPS.

I am really puzzled.

Not enough information...
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DavidTurner

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Generator power problems
« Reply #2 on: August 09, 2014, 05:37:04 pm »

What more information do you need?

Three-phase power, my distro was teed from the local sound companies cam locks. I was using a 100 amp motion labs power distribution system. 1-20 amp circuit for monitor world, 1-20 amp circuit for front of house, 3-20 amp circuits for onstage power. Front of house and monitors were on different legs. each of the 3-20 amp circuits for the band were on different legs. Voltage from each leg to neutral measured 119 or 120, voltage between each pair of legs measured 208. There was no voltage between neutral and ground.
« Last Edit: August 09, 2014, 05:39:42 pm by DavidTurner »
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DavidTurner

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Re: Generator power problems
« Reply #3 on: August 09, 2014, 05:41:17 pm »

Number two feeder,  L5 20s on my branch circuits, 12/3 going to each of those circuits.
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DavidTurner

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Re: Generator power problems
« Reply #4 on: August 09, 2014, 05:47:27 pm »

Furman PL plus surge protector, TRIP LITE PRO UPS
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DavidTurner

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Re: Generator power problems
« Reply #5 on: August 09, 2014, 05:54:20 pm »

BTW, I tried putting monitors on same leg as house - no help.
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Art Welter

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Re: Generator power problems
« Reply #6 on: August 09, 2014, 05:54:32 pm »

Power metered just fine, but neither my UPS nor my surge protector liked it. Surge strip would go into protect mode and UPS would switch to battery and then shut off as well.

I had to plug the console in directly (bypassing surge surpressor and UPS) to get through the show. Any ideas why this would be?
Could be the surge strip is hosed, have you checked it out since?
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DavidTurner

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Re: Generator power problems
« Reply #7 on: August 09, 2014, 05:57:00 pm »

I put it all back to normal today, and all is working fine.
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DavidTurner

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Re: Generator power problems
« Reply #8 on: August 09, 2014, 05:59:50 pm »

Also tried s different UPS last night (lighting guy carries a spare) - same issue. It would shut off after a few minutes.
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DavidTurner

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Generator power problems
« Reply #9 on: August 09, 2014, 06:01:29 pm »

Sorry for the multiple posts, but I'm adding things as I remember them. I also tried a different quad box/L5 20 combination to monitor world. No help there either.
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Stephen Swaffer

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Re: Generator power problems
« Reply #10 on: August 09, 2014, 06:44:09 pm »

Not sure of the Trip Lite model.  The Furman unit monitors for an intermittent neutral and over 140 volts. Possibly a neutral/ground bonding issue?  The only reference for a intermittent neutral would be ground-via the EGC.  Really shouldn't see zero (as in 0.00 volts) between neutral and ground.
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Steve Swaffer

Guy Holt, Gaffer

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Re: Generator power problems
« Reply #11 on: August 10, 2014, 08:11:32 am »

Possibly a neutral/ground bonding issue?

Not likely since the OP states "FOH on the same service through the same PD had no issues and was able to run both surge protector and UPS." An intermittent Neutral/Ground bond in the generator would effect both the OP's equipment and FOH.

Some more questions:

Were you the furthest downstream on the service? If so, how many feet from the FOH.

Do you remember what other loads were on the service? Were they mostly switch mode devices?

Were you metering with a True RMS meter? If so, did you happen to get an amp reading on the Neutral?

Guy Holt
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Stephen Swaffer

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Re: Generator power problems
« Reply #12 on: August 10, 2014, 02:44:24 pm »

Not likely since the OP states "FOH on the same service through the same PD had no issues and was able to run both surge protector and UPS." An intermittent Neutral/Ground bond in the generator would effect both the OP's equipment and FOH.

Guy Holt

Agreed-if surge protection and UPS at FOH were the same or similar models offering the same neutral monitoring.
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Steve Swaffer

DavidTurner

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Re: Generator power problems
« Reply #13 on: August 10, 2014, 06:18:42 pm »

If by "furthest downstream" you mean "most copper between supply and console", no, FOH had about 300' of 12/3 and monitors 25'. The Foh stage rack only had about 6'. FOH stage rack has identical Furman and Tripp Lite units as monitors amd had no problems.
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DavidTurner

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Re: Generator power problems
« Reply #14 on: August 10, 2014, 06:19:51 pm »

Probably not true RMS meter and I did not measure current on the neutral.
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DavidTurner

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Generator power problems
« Reply #15 on: August 10, 2014, 06:21:53 pm »

All Lab Grupen amps, so I'm guessing they were switch mode power supplies. As far as I know, only Foh amps, lake processors for foh, our band gear, back line for opening acts, and 4 Avid Venue consoles on this service.
« Last Edit: August 10, 2014, 06:47:31 pm by DavidTurner »
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Guy Holt, Gaffer

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Re: Generator power problems
« Reply #16 on: August 10, 2014, 09:39:43 pm »

If by "furthest downstream" you mean "most copper between supply and console", no, FOH had about 300' of 12/3 and monitors 25'. The Foh stage rack only had about 6'. FOH stage rack has identical Furman and Tripp Lite units as monitors amd had no problems.

Bear with me. I'm from the motion picture lighting world and not up on all of your lingo.  Are you saying that your Furman and Tripp Lite units were much  closer to the generator than the ones on the FOH stage rack?  Or, was it the other way round. You mentioned your distro was teed from the local sound companies cam locks. How far upstream (closer to the genny) were you teed in from the FOH rack? How far were you from the genny?

Guy Holt
« Last Edit: August 10, 2014, 09:46:26 pm by Guy Holt, Gaffer »
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DavidTurner

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Re: Generator power problems
« Reply #17 on: August 11, 2014, 02:07:52 am »

Hey Guy:

Thanks for hanging with me to try to figure this out. Here is a detailed description of the situation:

A 00 or larger feeder was run about 150' from the generator to a set of tees on stage. One side of the tees fed the local sound companies' distro through 10' of 0000 I borrowed from our lighting guys. The sound co's distro supplied power for  the main PA amplifiers, the monitor system power amps, two sound consoles with associated racks and backline (guitar amps, bass amps, keyboards, etc.) for the other acts on the bill.  All the sound co's power amps were modern Lab Gruppens  - almost certainly switch mode devices. Their backline was mostly vintage tube stuff or reproductions of same.

The other side of the tees fed my 100a Motion Labs distro through 25' of #2 feeder. From one 20a circuit on my distro there was a 330' (100 meter) run of 12/3 to the front of house mixing console and its associated local rack that contained a Furman and a Tripp Lite Smart Pro UPS. The foh system includes a remote input rack, situated on stage, containing a Furman and a Tripp Lite, connected to a separate 20a circuit on my distro by the power cord from the
furman (about 6'). Monitor console and associated racks  were connected to a separate 20a circuit from the distro through 25' of 12/3.  Three more 20a circuits (two 75' and one 50' run of 12/3) from my distro powered my backline - consisting of a bass rig, a drum seat thumper, 4 guitar amps, a few pedal boards and a keyboard.

The built in meter on my distro read @ 117 - 122 from each leg to neutral and @ 208 between each pair of legs. It showed no voltage between neutral and ground. When I started having issues, I checked with an inexpensive DMM and it confirmed what the meter on the distro read.

Most of the current  would have been consumed by  the sound company's power amplifiers. My monitor rig is all  RF in ear except for the 100 w amp driving the drum seat. My backline power draw is minimal compared to the tens of  thousands of watts the pa system produces. Lighting and video were on a separate generator.

Of all these devices only the Furman and Tripp Lite units in my monitor system had issues. I had no issues at the next gig or tonight's gig - both on power company services.

I am trying to assess the situation so that, if it occurs again, I will have a game plan for a remedy.

Thanks for your help.



 
Bear with me. I'm from the motion picture lighting world and not up on all of your lingo.  Are you saying that your Furman and Tripp Lite units were much  closer to the generator than the ones on the FOH stage rack?  Or, was it the other way round. You mentioned your distro was teed from the local sound companies cam locks. How far upstream (closer to the genny) were you teed in from the FOH rack? How far were you from the genny?

Guy Holt
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Stephen Swaffer

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Re: Generator power problems
« Reply #18 on: August 11, 2014, 07:28:38 am »

A 5 amp draw on #12 wire will have a 5% (6 volt) drop at 345 feet which would leave you only 111 to 116 volts at you monitor position.

Did you check voltage there or only at distro?
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Steve Swaffer

Guy Holt, Gaffer

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Re: Generator power problems
« Reply #19 on: August 11, 2014, 09:38:50 am »

A 5 amp draw on #12 wire will have a 5% (6 volt) drop at 345 feet which would leave you only 111 to 116 volts at you monitor position.

While Stephen is correct that there would be appreciable VD over the 300' 12/3 run to the FOH, I understand
David to say that the FOH rack containing the Furman and Tripp Lite that did not experience problems was situated on the  stage,  and connected to his power distro by a 6' power cord - is that correct David? If so it would have experienced the same VD  as the Furman and Tripp Lite in his rack (VD over the 175' run to the generator.) If that is the case VD doesn't account for one set of Furman and Tripp Lites failing while another set 6' away doesn't.

Guy Holt

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Mike Sokol

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Re: Generator power problems
« Reply #20 on: August 11, 2014, 09:46:09 am »

A 5 amp draw on #12 wire will have a 5% (6 volt) drop at 345 feet which would leave you only 111 to 116 volts at you monitor position.

Did you check voltage there or only at distro?

That's a good point. Most wire gauge calculations are for 100 ft of run, so you'll have 3 times the voltage drop if you have 3 times the length of run. I've seen and measured that in a few instances, one of which was corrected by using a 10 gauge run  that happened to be in place for a 20-amp service. That reduced the voltage drop significantly and got the SSL console up and running again.

However, one would think that devices that are specifically designed to monitor and correct low-voltage conditions wouldn't crap out on the same low-voltage conditions. Digital consoles, yes... UPS boxes, no...
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DavidTurner

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Generator power problems
« Reply #21 on: August 11, 2014, 10:21:14 am »

I 'll try to clarify:

3 racks - each containing Furman and Tripp Lite:
A. 6' from pd
B. 25' from pd
C. 300' from pd

B fails, A and C do not.

BTW the consoles in this case have universal power supplies and are hapy with 100 - 240v.  50 - 60hz
« Last Edit: August 11, 2014, 10:28:09 am by DavidTurner »
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Chris Hindle

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Re: Generator power problems
« Reply #22 on: August 11, 2014, 11:12:47 am »

Possible wiring damage ??
Once had a case where power was split 4 ways backstage, from a 125K Genny.
Runs 1 and 2 were stage right/left
Run 3 was FOH
Run 4 was a stringer for concessions (Not my idea, I was there day 3 for 2nd opener - no say in anything)
Anyhoo, run #4 was fine on light loads. Someone plugged in a popcorn machine in the middle of the run, and we lost FOH power.
Well, down to 80 volts or so. Me and Lampey's UPS both start screaming for attention. Put my troubleshooter hat on, and as I am talking up and down the concession line, to see who has and doesn't, I see a tent spike pretty freakin close to the power trench. Sure nuf, they nicked the feeder. Under a light load there was no problem. No blown breakers, but all problems dissapeared after pulling the spike (with well insulated gloves and pliers)
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DavidTurner

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Re: Generator power problems
« Reply #23 on: August 12, 2014, 11:34:52 pm »

I suppose we will never know the answer to this riddle. Thank you all for your suggestions. It's all working four nights in a row now. I don't think I had any cable or equipment failure, I just think it was bad power.
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Re: Generator power problems
« Reply #23 on: August 12, 2014, 11:34:52 pm »


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