BOOK 0958-B
TABLE 6. TROUBLESHOOTING
INDICATION | POSSIBLE CAUSE | |
|
| |
| One or more SCR‘s or Diode D1b | |
3. Controller line fuse | shorted | |
| ||
blows when a Start com- | Motor shorted or grounded | |
mand is initiated |
| |
Control board failure causing SCR’s to | ||
| ||
|
Motor overloaded
4. Controller line fuse |
| |
Loose or corroded connection. Wiring | ||
blows while the motor is | ||
running | faulty, incorrect, or grounded | |
|
| |
| Motor shorted or grounded | |
|
| |
| One or more SCR‘s or Diode D1b | |
| breaking down (shorting intermit- | |
| tently) | |
|
| |
| Control board failure causing SCR | |
| false firing or misfiring | |
|
| |
5. Minimum speed | Minimum speed not adjusted correctly | |
| ||
excessive |
| |
Motor armature grounded | ||
| ||
|
| |
| Control board failure | |
|
| |
| Maximum speed set too high | |
|
| |
6. Maximum speed | Controller not calibrated correctly | |
| ||
| ||
excessive | Open shunt field winding or wiring to | |
| the motor shunt fielda | |
|
| |
| Motor field demagnetizedb |
CORRECTIVE ACTION
Replace shorted devices or the control board.
Repair or replace the motor.
Replace the control board.
Check shunt field current.a Low shunt field current causes excessive armature current. If field current is adequate, check for a mechani cal overload. If the unloaded motor shaft does not rotate freely, check motor bearings. Also check for a shorted motor armature. Motor overload can also be caused by incorrect gear ratio. Correct accordingly.
Check all terminals, connections, and wiring between the line, controller, and motor.
Repair or replace the motor.
Replace faulty devices or the control board.
Replace the control board.
Turn the MIN SPD potentiometer counter clockwise.
Correct ground fault.
Replace the control board.
Turn the MAX SPD potentiometer counter clockwise.
Refer to Steps 4 and 5 on page 5.
Check the motor shunt field and associated circuitry for a loose connection or a broken wire. Repair accordingly.
Replace the motor.
Cont’d on next page
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