3ph 600v input line reactor with audible noise one side


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I have done a lot of research on the web about input line reactors, but cannot find anything about faults or symptoms before failure.

I have a 3ph 600v Morelco 3% input line reactor that is making a very noticeable noise on one side of it beginning sometime in the last 60 to 90 days. Scematic-wise, after the input line reactor, I have a SCR rectifier and a Yaskawa VFD with a brake chopper in between.

We use assignment contactors to switch the load between two GE750 1150hp motors - one for a top drive and one in our drawworks (has three motors, but two of them have their own VFD). They are identical so no need for different drive parameters. The assignment contactors allow a degree of freedom and allow for troubleshooting, ect between four VFD's. I mention this, because the fault occurs for either drawworks or top drive assignment. In particular, the noise occurs whether the drawworks is hoisting or paying out (brake chopper works just fine...)

In any case, if any are familiar with line reactors I would very much appreciate any input.

I am wondering if it is going resonant.

- strangepeade
Strangepeade... several questions, to start:

1) Does the intensity, and/or frequency vary with load?

2) Does the temperature seem unusually high?

3) Do the temperatures of the three coils differ?

4) Has the load appreciably changed in the last 60-90 days?

5) Do you have phase-current measurements?

Regards, Phil Corso