Current Leakage at 95% SCR Phase Control in Vacuum Sintering Press Process

[FrankieAugust]

Hi all,

I am facing power source tripped due to current leakage in my Vacuum Sinter Press machine. The scenerio is below:

Incoming power: 3 Phase 415, 800A, no neutral
Rectifier: 500kVA to convert the AC to DC 4.6V
Rectifier frame is connected to ground.

The SCR control mode is phase control. Everything is normal at the beginning. Thing goes wrong when the SCR generate 95% output, we heard some noise from the rectifier and detected current leakage to earth and cause the power source tripped.

Wonder the root cause is from the SCR or transformer. And advices?

 

[LionelHutz]

95% should be well past the point where the SCRs are passing peak voltage which means a voltage breakdown should have been happening before that point.

A clamp meter around various ground wires might help detect where the problem is occurring.