Author Topic: What it means to be a professional Electrician  (Read 671 times)

BrianDzyak

  • Administrator
  • Full Member
  • *****
  • Posts: 156
    • View Profile
What it means to be a professional Electrician
« on: April 26, 2015, 10:56:42 PM »
Here's the link to the thread at cinematography.com and the first post in the thread.  I recommend stopping by and reading the entire discussion to get a better idea of what goes on behind-the-scenes to get a movie made:

http://www.cinematography.com/index.php?showtopic=50066&pid=343017&st=0&#entry343017


Quote
Did a rig this week where had a problem.

Did a rig with three Arri 18k fresnels and three Arri max 18k pars. All square wave ballasts and arri max square wave ballasts supposedly power factor corrected. 1400 amp MQ generator. 100 feet of two aught to a box powering an 18 fresnel and a arrimax unit. Then a separate 150 feet of 4 aught from the genny to a box powering another pair of 18 fresnel and and an arrimax par. Continuing past that running another 50 feet of 2 aught powering the final box and pair of 18k and arrimax.

Here's the issue. I could get 5 lights out of the six on. But could not get the 3rd arri max light to stay on. At first we thought it was that light and swapped headers and ballasts. The light would strike warm up. as it was warming up voltage would go nuts varying from 110 to 130 volts on all three legs and the light would drop. Sometimes taking out all three arri max's on the run. When that light was off and 5 lights were on, voltage was steady at 121 volts across three legs at the end of the run.

We then could get the light to burn fine with other lights off. Thats when we had the oh poop moment.

Our amperage was a little less than 350 amps per leg. So with a 1050 or so load I thought we would have been OK on a 1400 amp machine and power factored ballasts.

There was no real voltage drop as the runs were fairly short. We switched voltage regulators on the machine.

Personally I think we had a harmonics issue, but I thought power factored ballasts helped that issue or is that a mistake in my thinking?

Thanks

Tim