Allen-Bradley PowerFlex 20P, Hardware Service Manual, Page: 28 / 134

28 Rockwell Automation Publication 20P-TG001C-EN-P - February 2018
Chapter 2 Component Test Procedures
Power Component Test
Procedures Follow the applicable procedure for the affected power components.
Check the Armature SCR Modules
The frame A PowerFlex DC drive armature supply consists of three (non-
regenerative drives) or six (regenerative drives) SCR modules that are mounted
on the main heat sink. One of the following can indicate a malfunction of any
of these modules:
• An Overcurrent fault (F13)
• Blown or tripped incoming protection devices
• Erratic motor operation
If an armature bridge component malfunction is suspected, follow these steps.
1. Read the General Safety Precautions on page 10 .
2. Remove power from the drive (see page 46 ).
3. Verify that contactor power (if used) is removed.
4. Verify that power to an external field supply (if used) is removed.
5. Check the anode to cathode junction of each SCR. With a digital
multimeter set to Ohms, measure the resistance across the SCRs (lead
orientation is not critical).
• For regenerative drives, see
Table 2 on page 29 and Figure 6 on
page 29 .
• For non-regenerative drives, see Table 3 on page 30 and Figure 7 on
page 30 .
If a low resistance is detected, determine which SCR module is damaged
based on
Table 2 or Table 3 and replace that module (see SCR Module
Replacement on page 96 ).