this facility was engineered and installed by the electrical contractor. the soft starts have 800 amp time delay fuses in them. they are fed by 600 amp circuit breakers. other that a lighting transformer these are the only loads on the switchgear. i will try adjusting the IT setting to 5600a...
how much static head does the pump have?
i have a well site that is a constant problem in the spring that goes away during the summer months.
the cause was too much water in the hole allowing the pump too run off its curve.
once the water table dropped no more problems.'
i also tried...
after further scrutiny of the logs. there is a huge amperage imbalance happening during motor stop. at the point of trip the amps are L1- 4000 A L2 4500A L3 1500 A.
the 4500a is causing the breaker to trip on the instantaneous setting.
seimens type vl breaker
pg frame 1600 amp
right now it has a 545 lig trip unit with fixed gpf sensing and delay.
im going to replace it with a 576 lsig trip unit that is fully adjustable
max current is 1500 a trip unit is set at 1600. long time delay doesnt activate until 6x trip unit setting. instantaneous trip is set at 4600A.
attached is both recordings in power log format incase you decide to install...
number two would be correct...the softstart reduces voltage to slow the pump before dropping it out completely...this is set at 15 seconds stop time to avoid water hammer
i have alot more readings from these motors...would you like to see the 2 sets of power harmonics recordings?
i also have the complete recordings in fluke power log if you have that installed..actually i have a copy of power log you can have if it will help
the current increase is the motor stopping. each motor pulls 400A running normally. the softstarts do not fault. the fuses in the soft starts dont blow and the 600a breakers feeding the softstarts dont trip. the 1600A main trips. the instantaneous trip setting is set to 4600A. so the breaker...
there are 2 pumps both feeding into a single discharge line.
i dont see any additional loading of the pump that is still running. flow is halved and pressure drops slightly.
i see the current climb to about 1500 amps while the motor stops. motor stop time is 15 seconds.
after the current has...
since it appears no one can see the info i have from the fluke 435 lets try it this way.....
when the breaker trips the power harmonics screen is showing THD of 60%.
when the motor stops and the breaker doesn't trip THD is .4%.
why am i getting so much distortion intermittently and what can...
