Nidec 22765-01, Manual

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Page 46
WARNING: Problems left
uncorrected can result in injury or serious
damage, which can result in costly repairs
and downtime.
Troubleshooting Guide
Corrective Maintenance
Between regular preventive maintenance inspections, be alert for any
signs of trouble. Correct any trouble immediately. See Table 7 for
symptoms, causes and remedies.
Symptom Cause Remedy
No voltage Open voltage regulator,
circuit breaker, or fuses
Check. Reset the circuit breaker or replace fuses if
open
Overvoltage, under-
voltage, or overload
devices tripped (when
protective devices are
incorporated into the
circuit)
Check for the cause of the abnormal condition.
Correct any deficiencies. Reset devices. Check the
generator nameplate for nominal operating values.
Open circuit in exciter field
poles
Check continuity of shunt field and leads to voltage
control. (Use ohmmeter or Wheatstone bridge.) If
open in field coils, remove exciter field assembly and
return assembly to factory for repair.
Loss of residual
magnetism in exciter field
poles.
Restore residual magnetism or flash field. When the
voltage regulator is a model that requires flashing,
install an automatic field flashing system.
Open circuit in stator
windings
Check for continuity in the windings. Return the
generator to the factory for repair if open.
Malfunction of automatic
voltage regulator.
See Troubleshooting of voltage regulator. Correct
deficiencies.
Short-circuited generator
output leads
Clear lead to restore voltage buildup
Open in rotating rectifiers Check rotating rectifiers and replace if open
Open in generator field Check for continuity and return rotor to factor for
repair if field coils are open.
Shorted or grounded
surge protector
Check for shorts or grounds. Replace.
Shorted or grounded
rotating rectifier
Check for shorts grounds. Replace or repair.
Shorted or grounded
exciter armature
Check for shorts or grounds. Replace or repair.
Table 7 Troubleshooting