Electric Motor Fault - "Leg Loss Fault"

[ClaytonStMarysVibe]

We have a 2000 Hp D/C motor (I will not disclose the make or model) that has been getting a strange fault that no one at our plant seems familiar with. The fault in question is a Silpac fault and is called a "leg loss fault". I have limited knowlege of Electrical problems within motors, because my background is strictly mechanical. Recently I have been monitoring vibration levels because we have linked a sort of "precursor condition" to these leg loss faults and it always includes a spike in vibration at 60 Hz(3600 CPM) and 120 Hz(7200 CPM). Everytime this Motor trips on this "Leg loss fault" it knocks down our vertical crushing mill and over the past 5 months it has taken down our mill probably somewhere in the ballpark of 70-80 times. Everytime it goes down, the electricians reset the silpac fault and the mill starts up fine and runs fine until it trips out again.

Does anyone with an Electrical Engineering background or even better an Electrical Motor background have any ideas or thoughts on tests we can try to help solve our issue. Your ideas would be much appreciated.

Thx

Clayton
Vibration Analyst, Predictive Maintenance Dept.
St Marys Cement Co., Bowmanville ON Canada.

 

[waross]

To start with, "Leg loss" is mostly associated with AC equipment. Your issue may be with your drive and/or the incoming power supply. A loss of one phase (leg loss) on the rectifier input may well cause the vibration that you are seeing. Just because the motor stops does not mean that the problem is in the motor.
If you tell us the make and model of your drive there may be someone here who has direct experience with the unit.

(I will not disclose the make or model)

My car has a hesitation and I want help, but I won't tell you what make or model or even that it is actually a pickup truck.
Not very productive.
If you want mind readers this may be the wrong web-site.

Bill
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"Why not the best?"
Jimmy Carter