DECS-100 Maintenance and Troubleshooting
7-5
If the sensing potential transformer has the wrong turns ratio or is malfunctioning, replace it.
If the sensing potential transformer is correct and functioning properly, proceed to Step 4.
Step 4.
Verify that the generator output voltage is present on all phases.
If the generator is missing a phase, refer to the generator manual. Generator is defective.
If generator output voltage is balanced on all phases, proceed to Step 5.
Step 5
Replace the DECS-100.
OVEREXCITATION LIMITING Indicator is Annunciating
Step 1.
Check for generator overloading.
If the generator is operating with a larger than rated load, shed load.
If the generator is operating with a rated or less than rated load, proceed to Step 2.
Step 2.
Verify that the DECS-100 output (field) current limit is not set too low.
If the output current limit setpoint is too low, adjust for the proper setting.
If the output current limit is set properly, proceed to Step 3.
Step 3.
Verify that the generator exciter field current requirements are compatible with the DECS-100.
If the generator exciter field current requirements are not compatible with the DECS-100, contact
Basler Electric Customer Service for recommendations.
If the generator exciter field current requirements are compatible with the DECS-100, proceed to
Step 4.
Step 4.
Replace the DECS-100.
If replacing the DECS-100 does not correct the malfunction, proceed to Step 5.
Step 5.
Refer to the generator manual. Generator is defective.
UNDERFREQUENCY ACTIVE Indicator is Annunciating
Step 1.
Verify that the generator is operating at rated speed.
If the generator is not operating at rated speed, adjust the generator speed.
If the generator is operating at the rated speed, proceed to Step 2.
Step 2.
Verify that the underfrequency setpoint is correct.
If the underfrequency setpoint is incorrect, adjust it to the correct value.
No Droop
Step 1.
Verify that the DECS-100 52L/M contact input is open.
If the 52L/M contact input is not open, it must be opened to enable the droop function.
If the 52L/M contact input is open, proceed to Step 2.
Step 2.
Verify that the DECS-100 52J/K contact input (if present) is closed or the Var/PF function is
disabled via BESTCOMS. Var/PF operation must be disabled for droop operation. If Var/PF
operation is disabled, proceed to Step 3.
Step 3.
Verify that the DECS-100 droop setting is not adjusted to 0% droop.
If the droop setting is adjusted to 0% droop, increase the setpoint above 0%.
If the droop setting is adjusted to above 0%, proceed to Step 4.
Step 4.
Check for an open in the circuit connected to DECS-100 CT1 and CT2.