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Author Topic: Help With Tripping Dimmer Breakers  (Read 11049 times)

Don Lomonaco CFCRC

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Help With Tripping Dimmer Breakers
« on: August 04, 2014, 04:16:55 pm »

Hi all!  We have an ETC Unison DRD 12-24-120 with 10 D20 modules.  The entire Unison cabinet is wired to a dedicated 150 Amp breaker.  We're using 19 circuits on those modules in the following way:

10 circuits each with 1 ETC Source Four 750 watt fixtures and a 575 watt lamp.

9 circuits each with 4 ETC Source Four PAR EA 750 watt fixtures with 575 watt lamps.

When we turn the all 19 circuits up all the way using our ETC SmartFade console we have a tendency to trip some of the dimmer module breakers that are wired to groups of 4 par cans.  Doing the math it seems that four 575 watt lamps at 100% would require 2.3k watts on a 2.4k watt dimmer circuit.  Am I correct in thinking that this plan is just too close to the maximum power available and that's why these circuits continue to trip?
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g'bye, Dick Rees

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Re: Help With Tripping Dimmer Breakers
« Reply #1 on: August 04, 2014, 04:18:37 pm »

Wiring?
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Don Lomonaco CFCRC

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Re: Help With Tripping Dimmer Breakers
« Reply #2 on: August 04, 2014, 04:25:53 pm »

Wiring?

I'll have to look into it and report back.  What type of wiring should I be looking for?
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TJ (Tom) Cornish

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Re: Help With Tripping Dimmer Breakers
« Reply #3 on: August 04, 2014, 04:27:33 pm »

Hi all!  We have an ETC Unison DRD 12-24-120 with 10 D20 modules.  The entire Unison cabinet is wired to a dedicated 150 Amp breaker.  We're using 19 circuits on those modules in the following way:

10 circuits each with 1 ETC Source Four 750 watt fixtures and a 575 watt lamp.

9 circuits each with 4 ETC Source Four PAR EA 750 watt fixtures with 575 watt lamps.

When we turn the all 19 circuits up all the way using our ETC SmartFade console we have a tendency to trip some of the dimmer module breakers that are wired to groups of 4 par cans.  Doing the math it seems that four 575 watt lamps at 100% would require 2.3k watts on a 2.4k watt dimmer circuit.  Am I correct in thinking that this plan is just too close to the maximum power available and that's why these circuits continue to trip?
Do they trip right away, or over time?

ETC breakers are rated at 100% duty cycle, so theoretically it should be possible to run 4 575w fixtures on one circuit.  HOWEVER, the power consumption of your bulbs depends heavily on the voltage at the fixture.  Have you measured your facility voltage?  If you trend a little high - more than 120V, you may have too much voltage at your fixtures, causing your bulbs to effectively be more than 575w loads. 

If you're having trouble, make sure you're using the 120V rated bulbs instead of the 115V bulbs.

You may also want to check your lugs in your dimming equipment to make sure that all connections are tight, and that you aren't adding to the ambient temperature in your dimmer rack with heat from loose connections.
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Don Lomonaco CFCRC

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Re: Help With Tripping Dimmer Breakers
« Reply #4 on: August 04, 2014, 04:30:29 pm »

I'll have to look into it and report back.  What type of wiring should I be looking for?

It looks like the red, blue and white wires inside the dimmer box are all 10 AWG.
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Don Lomonaco CFCRC

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Re: Help With Tripping Dimmer Breakers
« Reply #5 on: August 04, 2014, 04:33:36 pm »

Do they trip right away, or over time?

ETC breakers are rated at 100% duty cycle, so theoretically it should be possible to run 4 575w fixtures on one circuit.  HOWEVER, the power consumption of your bulbs depends heavily on the voltage at the fixture.  Have you measured your facility voltage?  If you trend a little high - more than 120V, you may have too much voltage at your fixtures, causing your bulbs to effectively be more than 575w loads. 

If you're having trouble, make sure you're using the 120V rated bulbs instead of the 115V bulbs.

You may also want to check your lugs in your dimming equipment to make sure that all connections are tight, and that you aren't adding to the ambient temperature in your dimmer rack with heat from loose connections.

It takes a few minutes for them to begin to trip.  The lamps in the par cans are GE 120V.
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TJ (Tom) Cornish

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Re: Help With Tripping Dimmer Breakers
« Reply #6 on: August 04, 2014, 04:37:48 pm »

It takes a few minutes for them to begin to trip.  The lamps in the par cans are GE 120V.
Measure your facility voltage, and if you can, put a twofer at one of your fixtures, and do a voltage measurement with the light on.  This will tell you the voltage through the whole system at the fixtures.

I don't recall if there's a way to tweak max output in the Unison, but you may be able to limit the channels that are problematic to 95%, which would likely solve the issue.  You could manually do the same thing on your board by only raising the master fader to slightly less than full scale.
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Don Lomonaco CFCRC

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Re: Help With Tripping Dimmer Breakers
« Reply #7 on: August 04, 2014, 04:44:07 pm »

Measure your facility voltage, and if you can, put a twofer at one of your fixtures, and do a voltage measurement with the light on.  This will tell you the voltage through the whole system at the fixtures.

I don't recall if there's a way to tweak max output in the Unison, but you may be able to limit the channels that are problematic to 95%, which would likely solve the issue.  You could manually do the same thing on your board by only raising the master fader to slightly less than full scale.

Yeah, that's what we've been doing, only using slightly less than maximum on all the faders that control the par can circuits.  It seems to only be the same two circuits that are tripping.  It takes about 1 minute for them to go.
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TJ (Tom) Cornish

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Re: Help With Tripping Dimmer Breakers
« Reply #8 on: August 04, 2014, 04:47:02 pm »

Yeah, that's what we've been doing, only using slightly less than maximum on all the faders that control the par can circuits.  It seems to only be the same two circuits that are tripping.  It takes about 1 minute for them to go.
If they trip that fast, that suggests to me that something fairly drastic is wrong.  Are you sure you don't have a couple 750w bulbs on those circuits?  Check the tightness of screws in the dimmer panel, measure the voltage in your facility to make sure you aren't running too far above nominal - both at the dimmer and at the fixture if possible, and verify that all bulbs are 575w 120v.
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Cailen Waddell

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Re: Help With Tripping Dimmer Breakers
« Reply #9 on: August 04, 2014, 05:06:49 pm »

It's also possible you have a worn out breaker on one module and or a heat issue there.  Try moving modules around (but turn off rack power before doing so for arc flash safety).  If the problem follows the module... There ya go....
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Re: Help With Tripping Dimmer Breakers
« Reply #9 on: August 04, 2014, 05:06:49 pm »


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