100 amp breaker tripped 1

[DTrump]

We have a 50 HP motor at 480 v that is serviced through a 100 amp CB and VFD controlled. It runs a large fan that exhausts fumes from one department into a Regenerative Thermal Oxidizer to "cook" off the fumes before they are released to the atmosphere. I got a call from the second shift supervison that the fan had shut down because the breaker had tripped there was no damage to the motor or anywhere in the electrical pathway to the motor. Power is generated here locally in town, I suggested they had a low voltage condition causing the breaker to trip, they denied it. Am I correct in my assumption?

 

[wayne440]

I respectfully submit that you haven't provided enough information to allow a substantiated conclusion.

 

[Zogzog]

Depends on how he determined the was "no damage", any actual testing done?

 

[Overvoltage]

It seems to me you have a lot more investigation to do before you can make any realistic assessment of what happened. You say the breaker tripped. Does the VFD have any diagnostics or logging that you can review? Why did the VFD not take the motor offline, and instead it was the CB?

 

[DTrump]

There was no faults to ground in the conductors to the motor, the breaker reset with no problem and the motor ran perfectly drawing 33 amps.

 

[DTrump]

"Why did the VFD not take the motor offline, and instead it was the CB?"
That's what I'm trying to find out

 

[waross]

Look for loose connections and/or signs of heating on the breaker. The most probable cause is local heating of the breaker. This may be a loose connection of the cables, the bus connections or possible internal deterioration that is causing heating.

Bill
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"Why not the best?"
Jimmy Carter