lastmanstanding
Member
It's been a while since i've tasked this board with my problems, but this one's a bit of a doozy so I thought i'd come crawling back.
My theatre has three CD80 with 24- 2.4Kw channels each, dmx dimmer racks supplied by single phase, 240V 200A fuses (2-200 amp, 120V "legs"). Recently we've had a problem with all three racks simultaneously losing power under show conditions.
First we assumed that the legs had been overloaded, so we simply replaced the fuses and reduced the intensity of the cue that triggered the power failure. Upon purchasing an ampmeter, we discovered that we had not been overloading the legs, leading us to believe that a supply voltage drop, old fuses, or some other external gremlin had caused this isolated incident.
That would be that, except it has continued to happen. Often it will fail during curtain call, but sometimes even during very low light cues. A consultant was hired in, who was a bit stumped, but recommended we do a better job balancing the two legs of power. Now the real twist: Most of the fuses haven't been blown. All but the first fuses (which really did blow) have tested as having continuity, and have worked when replaced in the company switch.
The other pertinent fact is that we have redundant fuses, one set lives in the company switch (2-200A, 120/240V) the other near the electrical service entrance to the building (also 2-200A, 120/240V). Now, when the dimmers lose power (which has happened TWICE this weekend) we switch off both switches, turn them back on, and power is restored to the dimmers. When this has happened while myself or the technical director has been in the building, we've metered the load end of both switches and found no voltage. What we haven't check yet is whether there's voltage at the supply side of the fuses near the building's electrical service entrance.
Any ideas,
learned peers?
Rick
My theatre has three CD80 with 24- 2.4Kw channels each, dmx dimmer racks supplied by single phase, 240V 200A fuses (2-200 amp, 120V "legs"). Recently we've had a problem with all three racks simultaneously losing power under show conditions.
First we assumed that the legs had been overloaded, so we simply replaced the fuses and reduced the intensity of the cue that triggered the power failure. Upon purchasing an ampmeter, we discovered that we had not been overloading the legs, leading us to believe that a supply voltage drop, old fuses, or some other external gremlin had caused this isolated incident.
That would be that, except it has continued to happen. Often it will fail during curtain call, but sometimes even during very low light cues. A consultant was hired in, who was a bit stumped, but recommended we do a better job balancing the two legs of power. Now the real twist: Most of the fuses haven't been blown. All but the first fuses (which really did blow) have tested as having continuity, and have worked when replaced in the company switch.
The other pertinent fact is that we have redundant fuses, one set lives in the company switch (2-200A, 120/240V) the other near the electrical service entrance to the building (also 2-200A, 120/240V). Now, when the dimmers lose power (which has happened TWICE this weekend) we switch off both switches, turn them back on, and power is restored to the dimmers. When this has happened while myself or the technical director has been in the building, we've metered the load end of both switches and found no voltage. What we haven't check yet is whether there's voltage at the supply side of the fuses near the building's electrical service entrance.
Any ideas,
learned peers?
Rick
