mrsparky
14-12-2007, 12:19 PM
I have a 700HP 480V refrigeration motor that is controlled by a ABB soft starter interfaced with a RAM controller. One of the B phase SCRs shorted anode to cathode but it twin did not. The system has six months run time but two years ago there was a phase to phase short in the motor peckerhead soon after installation. Is it reasonable to think that the old short weakened this SCR? If that is true then should I replace all of the SCRs or would it be good practice to only replace the one bad SCR? There are no mitigating observable causes for this SCR short. Thanks for any and all responses. Robert