Basler Electric DECS-400 - Manual (Page 162)

150 9369700990 Rev R
e. Field flash dropout level
f. Generator soft start bias
g. Generator soft start time
Check the external field flashing components:
h. Field flashing contactor
i. Field flashing power source fuses
j. Field flashing current limiting resistor values
If the generator voltage still does not build, increase the soft start setting values in paragraphs d through f,
and decrease the setting for paragraph g.
Temporarily turn off the overexcitation limiter.
Generator Voltage Builds but DECS-400 Fails To Flash
Check the DECS-400 settings for the following system configurations:
a. Generator potential transformer (PT) primary voltage
b. Generator PT secondary voltage
c. Analog control output signal type
Check the DECS-400 soft start settings:
d. Maximum field flash dropout time
e. Field flash dropout level
f. Generator soft start bias
g. Generator soft start time
If the generator voltage still does not build, increase the soft start setting values in paragraphs d through f,
and decrease the setting for paragraph g.
Temporarily turn off the overexcitation limiter.
Check the exciter power circuitry: rectifier bridge, firing circuit, and power input transformer.
If the problem persists, return the unit to the factory as described in the preceding paragraphs.
Field Voltage or Current Reading on LCD Does Not Change
Check the connections between the isolation module and the DECS-400.
Check the connections between the isolation module and shunt (field current sensing) and between the
isolation module and the output of the exciter (field voltage sensing).
If the problem persists, apply a field current or voltage input signal to the DECS-400 at connector P1.
(You are simulating the output from the isolation module.) The field current signal should be applied to P1,
pin 4, and return to P1, pin 5. The field current signal should be 2.0 to 9.5 volts dc with 2.0 volts dc equal
to zero field current.) The field voltage signal should be applied to P1, pin 8, and return to P1, pin 7. The
field voltage signal should be 0.9 to 9.1 volts dc with 5.0 volts dc equal to zero field voltage. If the LCD
reading does not change, return the unit to the factory as described in the preceding paragraphs. If the
reading does change, the isolation module is defective.
Low Generator Voltage (In AVR Mode)
Check the DECS-400 for the following settings:
a. AVR voltage setpoint
b. AVR Kg loop gain (too low)
c. Generator potential transformer (PT) primary voltage
d. Generator PT secondary voltage
e. OEL is not activated
f. Accessory inputs (should be zero)
g. Var/PF and droop should be disabled
h. Cut-in underfrequency setting is below the generator operating frequency
If the problem persists, contact Basler Electric Technical Sales Support for advice.
Maintenance DECS-400