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Troubleshooting 5-7MN894
Table 5-3 Troubleshooting Chart Continued
Symptom Cause Corrective Action
Incorrect heater size or setting. Check overload relay heater table in Appendix A.
Loose or burned heater. Tighten or replace heater.
Overload relay
trips when starting
Long starting time. (high inertia loads may
require slow trip overloads.
Evaluate the thermal capabilities of the motor
before extending the overload trip time.
t
r
i
ps
w
h
en
s
t
ar
ti
ng
Mechanical failure within the load. Check machinery for binding or excessive loading.
Single phasing or unbalanced start circuit. Refer to “Motor is noisy or vibrates when starting”.
Excessive starting time (CL too low). Increase CL (rotate CW).
Incorrect heater size or setting. Check overload relay heater table in Appendix A.
Overload relay
Loose or burned heater. Tighten or replace heater.
O
ver
l
oa
d
re
l
ay
trips when running
Mechanical failure within the load. Check machinery for binding or excessive loading.
t
r
i
ps
w
h
en
runn
i
ng
Single phasing or unbalanced start circuit. Refer to “Motor is noisy or vibrates when starting”.
Ambient temperature too high. Use ambient compensated overload relay.
Motor decelerates
too quickly
(RDD=OFF)
Ramp down time (RD) set too short. Decrease RD (rotate CW).
Motor decelerates
too slowly
(RDD=OFF)
Ramp down time (RD) set too long. Decrease RD (rotate CCW).
Erratic operation Loose connections. Check all connections.
No load attached. Connect a motor to T1, T2 and T3 terminals.
Loss of phase or low input voltage to starter. Repair the input voltage problem.
Bad or misfiring SCR. Check resistance and replace SCR if defective.
Shunt trip light
Grounded delta power source. Shunt trip is not effective.
Shunt trip light
comes ON
Note: If the MCP is tripping, remove the relay or disconnect the wires from terminals 8 and 9.
You can then determine if the MCP is tripping or if the module is opening the MCP.