75HP water pump has a Submonitor connected. Owner has raised imbalance trip to 10% to keep motor on line. Utility voltage measurements have been hovering around 3%+ between any two legs at meter socket. This motor has run for 2 months without a trip caused by imbalance.
Served 480/277. When I checked control today with motor running, there was a 5c difference in lug temperatures at the main breaker. Amps were 84,88,92. Voltage at main in control was what I call 1%. 475,476,480.
I have not been able to get a no load voltage check. Does anyone think the temperature difference is great enough to trip control out on voltage imbalance? The ambient temperatures lately have been running 0c-30c. Lug temps at 125 amp main today were as high as 80c.
I checked across the breaker , line to load, and each leg measure 250 millivolts.
Motor tripped once Saturday and once Sunday. Has run for two days no problem.
Served 480/277. When I checked control today with motor running, there was a 5c difference in lug temperatures at the main breaker. Amps were 84,88,92. Voltage at main in control was what I call 1%. 475,476,480.
I have not been able to get a no load voltage check. Does anyone think the temperature difference is great enough to trip control out on voltage imbalance? The ambient temperatures lately have been running 0c-30c. Lug temps at 125 amp main today were as high as 80c.
I checked across the breaker , line to load, and each leg measure 250 millivolts.
Motor tripped once Saturday and once Sunday. Has run for two days no problem.