Came up across this situation:
I got a call that some lights flicker and some go brighter when the AC and/or other appliances go on. This is a 240 single phase system.
Anyway, after talking with the owner and after one hour of measuring voltages, turning loads on and off this is what I came up with:
1: If the loads where perfectly balanced I would get 120V to ground on each phase.
2: As soon as one phase had higher load than the other the voltage on the phase with higher load would go down while the voltage on the phase with lower load will go up.
3: So if I had A=40A and B=60A then I'd have something like A=140V and B=100V which caused the light on phase A to go brighter and the ones on phase B to go dim.
4: This was the case in reverse as well, if B had lower load than B voltage was higher and so on.
The only thing I can think of is problem with the utility transformer.
Anyone has other ideas?
Daniel Dejeu
I got a call that some lights flicker and some go brighter when the AC and/or other appliances go on. This is a 240 single phase system.
Anyway, after talking with the owner and after one hour of measuring voltages, turning loads on and off this is what I came up with:
1: If the loads where perfectly balanced I would get 120V to ground on each phase.
2: As soon as one phase had higher load than the other the voltage on the phase with higher load would go down while the voltage on the phase with lower load will go up.
3: So if I had A=40A and B=60A then I'd have something like A=140V and B=100V which caused the light on phase A to go brighter and the ones on phase B to go dim.
4: This was the case in reverse as well, if B had lower load than B voltage was higher and so on.
The only thing I can think of is problem with the utility transformer.
Anyone has other ideas?
Daniel Dejeu
