someguy98457
Member
So I encountered a confusing sketchy Dimmer hook up/power supply that was blowing 200 amp fuses in a 3 phase distro box. The confusing bit comes from the leg that was blowing was the leg that should have been the least likely to blow. The sketchy bit (extremely SKETCHY) comes from the fact that some genius wired a 3 phase dimmer power into a 3 phase motor power distro box so you were missing the dedicated neutral, they had inside the box wired the grounds and neutral together. Also the power going to the motor distro box was 3 phase 200 amp, so a total of 600 amps. The amount of dimmers wired into this box was was 1 etc 24 dimmer 2.4kw sensor plus rack, and 2 dimmex 24 dimmer 1.8kw packs. So a total of 1200 amps.
The dimmer packs were not all wired to the power distro similarly either.
Leg A of the power distro powered Leg A of the two Dimmex packs, and Leg B of the Sensor Rack
Leg B of the power distro powered Leg B of the two Dimmex packs, and Leg A of the Sensor Rack
Leg C powered all the leg C's
We blew the 200 amp fuse for leg C in the power distro box, despite the fact that with the lights we were turning on we were only pulling 183 amps, Leg A had 203 amps and Leg B had 208 amps going through them.
So after this convoluted explanation I have two questions:
First, completely academic, why would the under loaded leg blow first? I know that most dimmer packs take power for the control module from their Leg A, would affect this some how? Am I missing something? I checked, double checked and triple checked the loads, cause my first thought was PEBKAC.
Second, for hooking up multiple portable dimmer packs in the future, should you stagger where you put Leg A for multiple packs so if you happen to loose Leg A, and thus the control modules, you don't loose all those packs? Is there a reason to not do this? I know for 3 phase motors order of Legs matter but I cant think of a reason this would matter in a dimmer pack.
I know that might be confusing, please let me know if something needs to be cleared up. Thanks!
The dimmer packs were not all wired to the power distro similarly either.
Leg A of the power distro powered Leg A of the two Dimmex packs, and Leg B of the Sensor Rack
Leg B of the power distro powered Leg B of the two Dimmex packs, and Leg A of the Sensor Rack
Leg C powered all the leg C's
We blew the 200 amp fuse for leg C in the power distro box, despite the fact that with the lights we were turning on we were only pulling 183 amps, Leg A had 203 amps and Leg B had 208 amps going through them.
So after this convoluted explanation I have two questions:
First, completely academic, why would the under loaded leg blow first? I know that most dimmer packs take power for the control module from their Leg A, would affect this some how? Am I missing something? I checked, double checked and triple checked the loads, cause my first thought was PEBKAC.
Second, for hooking up multiple portable dimmer packs in the future, should you stagger where you put Leg A for multiple packs so if you happen to loose Leg A, and thus the control modules, you don't loose all those packs? Is there a reason to not do this? I know for 3 phase motors order of Legs matter but I cant think of a reason this would matter in a dimmer pack.
I know that might be confusing, please let me know if something needs to be cleared up. Thanks!