Allen-Bradley 23PFC, Hardware Service Manual

Page: 22 / 150

22 Rockwell Automation Publication 23PFC-TG001A-EN-P - March 2018
Chapter 2 Component Test Procedures
Power Component Test
Procedures Follow the applicable procedure for the affected power components.
Check the SCR Modules
The PowerFlex DC field controller power bridge consists of six SCR modules
that are mounted on the main heat sink. One of these conditions can indicate a
malfunction of a SCR module:
• An Overcurrent fault (F13)
• Blown or tripped incoming protection devices
• Erratic field operation.
The following procedure can be used if a power bridge component
malfunction is suspected.
1. Read the General Safety Precautions on page 10 .
2. Remove the protective covers from the device.
• For frame A devices, see page 36
• For frame B devices, see page 80
3. Verify that contactor power (if used) is removed.
4. 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 frame A devices, see
Table 3 on page 22 and Figure 3 on page 23 .
• For frame B devices, see Table 3 on page 22 and Figure 4 on page 23 .
5. If a low resistance is detected, determine which SCR modules are
damaged based on Table 3 on page 22 and replace that module.
• For frame A devices, see SCR Module Replacement on page 67 .
• For frame B devices, see SCR Modules Replacement on page 103 .
Table 3 - SCR Anode to Cathode Junction Measurements
On SCR Module SCR Measure from
Terminal To Terminal Nominal meter Reading
1 1 U C “open circuit” or “megaOhms” range
4 U D
2 2 V C
5 V D
3 3 W C
6 W D
01 01 U C
04 U D
02 02 V C
05 V D
03 03 W C
06 W D