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Author Topic: Generator power problems  (Read 5879 times)

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


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