106 Rockwell Automation Publication 8720MC-RM001K-EN-P - September 2018
Chapter 8 Troubleshoot the 8720MC-RPS Unit
Operation Flow Charts
These flow charts track the 8720MC-RPS unit power-up sequencing to make
sure that the unit has power applied and that the DC-bus is at an acceptable
voltage level.
Figure 47 - 8720MC-RPS Unit Fails to Power Up
The 8720MC-RPS unit
does not run.
Is AC power applied to the
8720MC-RPS unit?
RUN sequence
input entered?
Is Precharge
complete?
Is the main magnetic
contactor operating?
Check the following:
• Circuit breaker
•Protection fuse
• Wiring
•Power supply
The 8720MC-RPS unit is
defective. Replace the unit.
Check wiring for the sequence signals.
Check the following:
• Setting of the Precharge/Discharge Time (F.014)
• Precharge/Discharge resistor and associated wiring
Check the following:
• Wiring for sequence signals
• Wiring to main magnetic contactor coil
• Order of phases of wiring for main power supply
and control power
Yes
No
Yes
No
Yes
No
Yes
No
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