GE SPM Series, Instruction Manual

Page: 81 / 126

GE Power Management SPM Synchronous Motor Protection & Control 7-
7
7 TESTING AND TROUBLESHOOTING 7.4 TROUBLESHOOTING
7
Motor starts and
synchronizes but
shuts down
immediately upon
application of
excitation.
TRIP PF
setting too high. Reduce
TRIP PF
value (address 01) to no higher than –0.8.
FCX DELAY
setting too low. Increase
FCX DELAY
setting to 3 seconds minimum.
Current/voltage inputs are
incorrectly wired or are from
incorrect phases. Check and correct wiring as required.
No excitation voltage. Check for available DC excitation voltage. If a rotating exciter
driven by a motor shaft is used, the exciter field should be forced
(rheo is shorted out) during acceleration to cause exciter to build
up its output as quickly as possible.
No excitation current, open
circuit at motor field, brushes,
or leads. Correct discontinuity in field circuit.
Wiring to terminal points is
missing or loose. Connect or tighten missing or loose wires to proper points on the
rear of the unit.
Shutdown occurs
during normal
running (after
successful
synchronization) Motor has pulled out of step
from excessive overload (
PF
TRIP or PULL-OUT TRIP is
displayed)
Check condition of load bearing and other mechanical situations
at drives. Push any key to reset the SPM and restart.
Loss of excitation Check exciter, exciter fuse, and connections to field.
Transient power factor change
occurring during system power
disturbance. Increase
PF DELAY
setting.
Motor is unloaded and power
factor regulator reference
setpoint at or near unity
resulting in instability. Increase
REG FLOOR
setpoint to override regulator to maintain
stability during light-load condition.
Wiring to terminal points on
rear of unit missing or loose. Connect or tighten missing or loose wires to proper terminal
points on rear of unit.
Motor starts,
applies DC to
field and then
immediately
removes DC from
field Exciter voltage too low causing
SPM to attempt
resynchronization. Adjust exciter transformer tap or exciter adjustment potentiometer
to obtain higher exciter voltage output.
Field contactor closing too
soon. Motor cannot pull-in to
step since slip too high. Reset
SYNC SLIP
to lower value.
Excessive shaft load greater
than the motor’s capability to
pull into step. Reduce load or unload motor during start. Apply load after motor
has synchronized and stabilized.
Wiring to terminal points on
rear of unit missing or loose. Connect or tighten missing or loose wires to proper terminal
points on rear of unit.
Display frozen,
garbled, incorrect,
or unreadable Loose electrical connections or
CPU failure. Momentarily interrupt control power to unit and then re-energize. If
still displaying incorrectly, replace unit OR check ribbon connector
between faceplate assemble and top of cradle. It must not be
loose, shifted, or skewed.
Contrast needs adjustment. Open lower flip door on faceplate assembly and rotate the
contrast adjustment to obtain clear display.
Table 7–1: SPM TROUBLESHOOTING (Sheet 2 of 2)
SYMPTOM POSSIBLE CAUSE CORRECTIVE ACTION