Rockwell Automation 23P PowerFlex DC Stand Alone Regulator and Gate Amplifier - Manual (Page 67)

Rockwell Automation Publication 23P-UM001D-EN-P - July 2012 67
Power Interface and SCR Firing Order Chapter 5
If the power module is not firing properly, check the timing relative to the AC
Line, with the L1 to L3 signal acting as the reference point. Using a two channel
oscilloscope, the L1 to L3 waveform will be on channel 1 and then the gate pulse
positions relative to the AC line can be checked one at a time with channel 2.
Caution: Be certain that the oscilloscope probe is rated for the line voltage before
taking the measurement from L1 to L3.
Figure 31 below shows an actual oscilloscope image of the gate pulse output
relative to the AC Line, L1 to L3, with positive phase rotation (L1, L2, L3). With
the Alpha Test, the output of the gates can be checked by using a spare gate output
port on the Gate Amplifier along with a Gate Coupler assembly module.
Incandescent light bulbs connected in series at the output of the power module
serve as a load. Be sure that the rating of all of the incandescent bulbs connected
in series is greater than the power module maximum output voltage rating. For
the gate waveforms shown here, two diodes connected in series are connected to
each gate coupler output, with the anode connected to the “G” (Gate) pin. The
output can also be checked in an open circuit mode; the peak voltage will be 15 to
30 volts. The waveform shown in
Figure 31 was generated by using the Alpha
Test with the firing angle set at 5 Degrees (full on).
Figure 31 - Power Module Thyristor Firing Pattern, Positive Phase Rotation (L1, L2,
L3)