ABB UNITROL 1020 - Page 177

 Chapter 8 - Troubleshooting
UNITROL 1020 User Manual 3BHS335648 E82 169
Possible causes
Checks, action
Irregular instability, i.e. sporadic over- or underexcitation which is not caused by grid
Droop influence of the voltage regulator ineffective or
IM2 measurement defective
Check droop/compensation setting
Check external current transformer circuit
Gen CB Closed Status not active
Machine within inadmissible operating range
(normally protected by limiters)
Bring machine into normal operating range by
adjusting the setpoint.
Check setting of limiters
Regulator fault
Measure output voltage at terminals 8, 9 (oscillos-
cope)
Measure voltage UPWM (CMT1000, Monitor)
Signals in phase opposition: unit defective
Signals in phase: disturbance possibly caused by
the driving side of the machine or by disturbances
from the grid
Operating point cannot be adjusted
Setpoint error
Check operating mode. For field flashing normally
Auto is used
Check setpoint
Limiter active
Bring machine into normal operating range by
adjusting the setpoint.
Check setting of limiters
Excitation with compounding and boost circuit:
Excitation is only supplied by the series compounding
No control element voltage
Regulator fault
Measure power electronics supply UPWR
Check for tripped protective circuit-breaker
Check operating mode. For field flashing normally
Auto is used
Check setpoint
Check parameters of Auto regulator