Rockwell Automation SA500 DC Bus Supply - Manual (Page 25)

Diagnostics and Troubleshooting 4-1
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Diagnostics and Troubleshooting
Use the procedures described in the following section to diagnose and troubleshoot
DC bus supply faults. If the problem cannot be corrected by following these
instructions, the DC bus supply is not user-serviceable.
4.1 DC Bus Supply Faults
Bus supply faults are indicated by the LEDs visible on the faceplate.
4.1.1 The PHASE LOSS LED Is On
Problem: At least one phase of the three-phase AC input power is missing.
Use the following procedure to correct the problem:
Step 1. Cycle the AC input power to the bus supply. If the PHASE LOSS LED
remains on, proceed to step 2.
Note that this LED may light when low AC line voltage is detected or when
line notching occurs. The LED will remain on until power is cycled.
Step 2. Using a voltmeter, verify that AC input power is reaching the DC bus supply
input terminals (L1, L2, L3).
Step 3. If AC power is not reaching the bus supply, check the incoming AC power
lines and fuses.
If AC power is reaching the bus supply and the PHASE LOSS LED remains
on, replace the DC bus supply.
4.1.2 The OVERTEMP LED Is On
Problem: The bus supply has overheated and shut down.
Allow the bus supply to cool down. Then cycle power and try running it again. The
LED will remain on until power is cycled. Typically, if the ambient temperature is above
the rated value, fan failure or air flow blockage may be the cause. If the bus supply
overheats repeatedly, it may be overloaded and should be replaced with a larger unit.
!
ATTENTION: DC bus capacitors retain hazardous voltages after input
power has been disconnected. After disconnecting input power from the
DC bus supply, wait five (5) minutes and then measure the voltage at the
POS and NEG terminals of the DC bus supply and each Power Module
to ensure the DC bus capacitors are discharged before touching any
internal components. Failure to observe this precaution could result in
severe bodily injury or loss of life.