SAFETY FIRST! REMOVE ALL POWER PRIOR TO PERFORMING THIS TEST AND SHORT A HIGH VOLTAGE POINT USING SHORTING STICK

Question: What causes the plate breaker to trip on a plate on?

Answer: A common cause often is the failure of a High Voltage Rectifier. Plate breaker tripping may be accompanied by plate voltage start up prior to the trip. Also, a hum may be heard from the plate transformer.

To check the rectifiers disconnect the input at the center bottom and measure with an ohmmeter from center to each end. Good units will measure infinite while bad units will measure as a short.

A second cause of breaker trip is trouble in the SCR control system. See troubleshooting SCR systems.