ABB UNITROL 1020 - Chapter 8 - Troubleshooting; General; Safety Regulations; List of Possible Faults

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UNITROL 1020 User Manual 3BHS335648 E82 167
Chapter 8 - Troubleshooting
8.1 General
Chapter 8 - Troubleshooting provides instructions to assist in localizing a
fault within the excitation system as a whole. However, it is not possible to
deal with all eventualities in full.
8.2 Safety Regulations
Before working on the excitation system the general safety instructions in
Chapter 2 - Safety Instructions must be read and understood.
8.3 List of Possible Faults
Possible causes
Checks, action
Machine is not excited
Check operation of AVR, green LED must be
blinking and yellow LED must be on
Field circuit interrupted
Field circuit-breaker does not close
Check wiring for break
Check field circuit-breaker
Shunt supply:
Field flashing does not work
Check field flashing circuit
No electronic supply UAUX
Measure auxiliary supply UAUX
Check for tripped protective circuit-breaker
No control element supply UPWR
Measure power electronics supply UPWR
Check for tripped protective circuit-breaker
Shunt supply:
Machine is only excited to the value supplied by the
field flashing
Machine is first excited then discharges again
Measure auxiliary supply UAUX,
Measure power electronics supply UPWR
Check field flashing Off level
Check operating mode. For field flashing Auto is
normally used
Check field flashing Off level
Check setpoint
Measure power electronics supply UPWR
If all supplies and setpoints are correct, then
change the unit
Setpoint error
Check operating mode. For field flashing normally
Auto is used
Check setpoint
Regulator error
Measure output voltage at terminals 8, 9 (Osc.) ->
positive
Measure voltage UPWM (CMT1000, Monitor)
-> positive rising