Hi,
I know this is a plc forum, so this is a bit off-topic. However I know there are lot of smart electrical engineers here, so I will give it a shot :
We have a motor starter that feeds a 690 VAC async motor. The motor runs a mud pump.
The motor was initially made for 480 VAC, but it got rewinded when the vendor found out they had delivered for wrong voltage.
Now one of the breakers in the starter cabinet burned, due to something that looks like high temperature, which should mean high current. It was running with water through the pump.
We have been troubleshooting while running the pump on water only, after changing the breaker.
The motor is a 300 horsepower motor, and while running on water it is running on very low load. However, the current is very high. We have been measuring on all three phases, and the current is almost three times as high as expected.
The rpm has barely dropped, so that also indicates that the load is low, since slip is somewhere around 5 - 6 % on full load.
Do any of you know what can be the reason for the high current ?
We have also checked temperature with heat gun, and motor does not seem to get hot, only that the current is high.
Motor has been meggertested with approved values.
This is a star / delta starter, and the connections have also been checked.
During start up the star / delta sequence works well, it is only the steady state current while running that ends up too high. It lands at around 150 amp, but should be at around 50 - 60 amp.
Thanks for any contributions
I know this is a plc forum, so this is a bit off-topic. However I know there are lot of smart electrical engineers here, so I will give it a shot :
We have a motor starter that feeds a 690 VAC async motor. The motor runs a mud pump.
The motor was initially made for 480 VAC, but it got rewinded when the vendor found out they had delivered for wrong voltage.
Now one of the breakers in the starter cabinet burned, due to something that looks like high temperature, which should mean high current. It was running with water through the pump.
We have been troubleshooting while running the pump on water only, after changing the breaker.
The motor is a 300 horsepower motor, and while running on water it is running on very low load. However, the current is very high. We have been measuring on all three phases, and the current is almost three times as high as expected.
The rpm has barely dropped, so that also indicates that the load is low, since slip is somewhere around 5 - 6 % on full load.
Do any of you know what can be the reason for the high current ?
We have also checked temperature with heat gun, and motor does not seem to get hot, only that the current is high.
Motor has been meggertested with approved values.
This is a star / delta starter, and the connections have also been checked.
During start up the star / delta sequence works well, it is only the steady state current while running that ends up too high. It lands at around 150 amp, but should be at around 50 - 60 amp.
Thanks for any contributions