Toshiba VF010H05 Benutzerhandbuch

32. The gate and cathode leads are the white wires on the gate drive 

board in the medium voltage cabinet. See drawing below.

33. If waveform is inverted, swap Oscilloscope connections for proper 

polarity. Close the temporary Start switch and allow the test motor to 

reach full speed.

34. Then verify all gating signals to each SCR (two gating signals on 

every gate drive board). See drawing below for correct waveform.

35. Once the bad signal(s) are found; write down the location and call 

the factory for further guidance.

Waveform is

the gating signal as

measured with an

ungrounded oscilloscope

at the gate to cathode

of the SCR. The

waveform should be 1.7 

to 2msec off time and 

approximately 1.5 to

3 Vdc. This signal is only 

present at full conduction

or the motor is at speed.

Each SCR gating signal

should be checked

in accordance with the

low voltage test procedure.