Basler Electric DECS-100 - Manual (Page 81)

9287500991 Rev M DECS-100 Maintenance and Troubleshooting 6-3
If the front panel Overexcitation Limiting indicator is not lit, proceed to Step 7.
Step 7. Low generator output voltage may occur when operating in droop mode with an inductive load.
If the low voltage condition is not caused by the droop function, proceed to Step 8.
Step 8. Verify that the voltage setpoint is not being modified by application of voltage to the optional
Accessory Input.
If the low voltage condition is not caused by voltage applied to the Accessory Input, proceed to
Step 9.
Step 9. Replace the DECS-100 unit.
High Generator Output Voltage
Step 1. Verify that the voltage adjustment is not set too high.
If the voltage adjustment is too high, adjust it to the correct setpoint.
If the voltage adjustment is correct, proceed to Step 2.
Step 2. Verify that the sensing potential transformer (if used) has the correct turns ratio.
If the turns ratio of the sensing potential transformer is incorrect, replace the sensing potential
transformer with the correct one.
If the sensing potential transformer is correct, proceed to Step 3.
Step 3. High generator output voltage may occur when operating in droop mode with a capacitive load.
If the high voltage condition is not caused by the droop function, proceed to Step 4.
Step 4. Verify that the voltage setpoint is not being modified by application of voltage to the optional
Accessory Input.
If the high voltage condition is not caused by voltage applied to the Accessory Input, proceed to
Step 5.
Step 5. Replace the DECS-100 unit.
Poor Voltage Regulation
Step 1. Verify that the case of the DECS-100 is properly grounded.
If the DECS-100 is not properly grounded, connect a dedicated ground wire to the quarter-inch
fast-on connector labeled GND on the rear of the DECS-100 case.
If the DECS-100 is properly grounded, proceed to Step 2.
Step 2. Check for grounded field leads.
If the field leads are grounded, isolate them from ground.
If the field leads are not grounded, proceed to Step 3.
Step 3. If the DECS-100 is powered from a PMG, check for grounded PMG leads.
If the PMG leads are grounded, isolate them from ground.
If the PMG leads are not grounded, proceed to Step 4.
Step 4. Verify that the generator frequency is not dropping below the DECS-100 underfrequency
setpoint when load is applied to the generator.
If the generator frequency is dropping below the underfrequency setpoint, reduce the setpoint if
possible. Also check the prime mover and generator for proper sizing in relation to the applied
load.
If poor regulation is not related to DECS-100 underfrequency operation, proceed to Step 5.
Step 5. Verify that regulation is not being affected by normal droop operation.
If droop operation is not affecting regulation, proceed to Step 6.
Step 6. Replace the DECS unit.
Generator Output Unstable (Hunting)
Step 1. Verify that the governor for the prime mover is operating properly.