 |
|
| Browse | Ask | Answer | Search | Join/Login |
|
|
||||
|
Troubleshooting a 3 phase 480VAC lighting system.
We have a Large park that is lit at night by a underground 3 phase power. That lights come on via a relay that energizes at night. When I take a voltage reading of power coming into the relay, each phase to ground is 277 and phase to phase is 480Vac. But when I energize the relay turning on the lights, two of the phases to ground read 480Vac and the other only reads 3.8Vac. What's causing this? Short to ground?
|
||||
|
||||
|
I will assume the main is 277/480 volt with a grounded neutral, and the lights are 480 volts single phase connected in Delta on the 3 phase conductors.
If it was a short to ground, I would expect a fuse/CB to open. What is the OCPD? Fuses or 3 pole CB? I need to suggest that even though you see 277 phase to ground and 480 volts phase to phase, that you start at the beginning of the 480 volt system, and confirm no fuses or breakers are open, starting at the Main, and work your way through the system to this lighting contactor (relay). I would then disconnect the load wires from the contactor to confirm proper voltage at the load terminals of the contactor with no load. The odd voltages you get phase to ground on two phases and one goes to 3 volts leads me to believe the supply feeder is the issue, rather than an issue in the lighting circuit. This is a start to troubleshooting. |
||||
| Question Tools | Search this Question |
Add your answer here.
Check out some similar questions!
We have a Large park that is lit at night by a underground 3 phase power. That lights come on via a relay that energizes at night. When I take a voltage reading of power coming into the relay, each phase to ground is 277 and phase to phase is 480Vac. But when I energize the relay turning on the...
Hello, My wife bought me a stadium light to place on my Fishing Pier. Unfortunately it was 480 volts and was setup for commercial 3 phase. Can I consider this an absolute bust or is their a way to convert or retrofit to 110 or 220? Thanks in Advance
I can't seems to get the right answer and I totally don't know how to do it. Please someone help me. In Figure Q1.2, a three-phase four-wire system operating with a line voltage of 480 V is supplying a balanced motor load at 560 kVA and 0.86 power factor (pf) lagging. The motor load is...
Just a quick question.
A t8 lighting fixture with two each lighting tubes, both tubes quit working at same time. Does this mean the ballast needs to be replaced? Do I need to try to replace just one of the tubes? Thanks, Jeanne
View more questions Search
|
