Allen-Bradley 1391B Series, Instruction Manual

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Troubleshooting
Chapter 10
10-64
Table 10.A
LED Descriptions and Fault Diagnosis (Continued)
LED
UNDERVOLTAGE
(Continued)
Potential Cause
The logic supplies have dropped 10% below their nominal value
1. The input line voltage is out of tolerance.
2. The transformer auxiliary logic supply winding is open.
3. The logic supply (
±
12V DC, +5V DC) circuits have malfunctioned (fuse
blown etc.) or the AC input at TB4-19, 20, 21 is incorrectly wired.
LED Description
CURRENT FOLDBACK LED is illuminated
The logic supply (
±
12V DC) circuits have malfunctioned (fuse blown etc.)
or the AC input at TB4-19, 20, 21 is incorrectly wired.
The output current is exceeding its time-current rating
1. The acceleration/deceleration command from the position controller is
requiring peak current for an excessive amount of time.
2. The Gain pot is set too high causing excessive peak currents.
3. The machine friction, inertial load and/or viscous loading is excessive.
4. The servomotor has been improperly sized.
5. A short circuit exists across the controller output terminals.
The CURRENT FOLDBACK
LED illuminates when the
Current Foldback circuitry is
operating. CURRENT FOLD-
BACK
(YELLOW)
RUN ENABLE
(GREEN) ENABLE LED is NOT Illuminated
1. The position controller has not enabled the controller.
2. The Enable wiring to the controller is open.
3. The position controller Enable relay/switch has malfunctioned.
4. The position controller has detected a machine system malfunction that
will not allow the controllers to be Enabled.
5. Power has not been applied to input transformer.
6. The logic supply (
±
12V DC) circuits have malfunctioned (fuse blown
etc.) or the AC input at TB4-19, 20, 21 is incorrectly wired.
ENABLE LED is Illuminated, but Controller does not Enable
1. A controller malfunction has occurred but is not annunciated by the LED
indicators. Check the status of the Drive OK output (DROK) relay.
2. A component malfunction exists in the Enable circuit.
3. The circuit breaker (MCB) is tripped.
4. The power contactor has not been energized or has malfunctioned.
The controller logic supplies are not operational
1. The logic supply fuses are blown
2. Logic supply AC voltage is missing
3. A controller malfunction has occurred but is not annunciated by the LED
indicators (check the status of the Drive OK contacts).
The application of an Enable
signal by the machine position
controller will cause the RUN
ENABLE LED to illuminate.
DRIVE READY LED is NOT illuminated
1. System fault has occurred.
DRIVE READY
(GREEN) This LED is continuously
illuminated until a system fault
occurs.