drbond24
Senior Member
- Location
- Barboursville, West Virginia
All:
What would cause a spike in the running current of a 3 phase motor? The motor in question is 5000 hp, 4 kV and powers a fan. It will be running along just fine pulling around 570 amps, then suddenly spike to about 630 amps for a second or two, then return to normal for hours before doing it again. Once last week, one of the motor's differential relays engaged during one of these spikes and tripped the fan. For that to happen there would have to be disparity between phase currents. The ammeter that is recording the spikes is on phase 2 and I do not have an indication on either of the other two phases. So, perhaps my real question is: what would cause a spike in amps on only one or two phases of a running motor?
I checked our amp trends for all other running equipment fed from the same buss and did not see similar current spikes, but I am not entirely sure which phase(s) are being monitored on all of the other equipment. I can find out, but I haven't invested the time to do that as of yet.
Can anyone suggest something else I can check?
This motor/fan is one of three identical units and the other two do not have this problem, but each of them is fed from a separate buss.
What would cause a spike in the running current of a 3 phase motor? The motor in question is 5000 hp, 4 kV and powers a fan. It will be running along just fine pulling around 570 amps, then suddenly spike to about 630 amps for a second or two, then return to normal for hours before doing it again. Once last week, one of the motor's differential relays engaged during one of these spikes and tripped the fan. For that to happen there would have to be disparity between phase currents. The ammeter that is recording the spikes is on phase 2 and I do not have an indication on either of the other two phases. So, perhaps my real question is: what would cause a spike in amps on only one or two phases of a running motor?
I checked our amp trends for all other running equipment fed from the same buss and did not see similar current spikes, but I am not entirely sure which phase(s) are being monitored on all of the other equipment. I can find out, but I haven't invested the time to do that as of yet.
Can anyone suggest something else I can check?
This motor/fan is one of three identical units and the other two do not have this problem, but each of them is fed from a separate buss.