Rockwell Automation 1336T FORCE Series B User Manual

Page 237

Chapter 6
Troubleshooting

6–25

The motor inductance measuring routine contains several special faults.
If the drive trips during the inductance test, check bits 0 through 5 of
Motor Inductance Test Errors (parameter 295):

If this bit
is set (1):

Then:

Motor Not at Zero Speed
The motor is not at zero speed. Generally, this bit is set in two cases:

•

If the motor rotates during this test, an improper result is likely. Make
sure the motor (decoupled from load or process) is not rotating just
before or during the test.

•

If the motor is not rotating during this test, then investigate electrical
noise creating encoder transitions. Improper encoder grounding or a
noisy encoder power supply could cause noise.

This fault cannot be determined for encoderless applications. You must
visually check for this condition on encoderless systems.
If your motor does rotate during this test, consult the factory.

Sign Error
A sign error fault occurs when the average voltage is negative. If you
receive a sign error, you need to:

1. Run the test again.
2. Consider replacing the circuit boards.

Zero Current
If this bit is set, you need to:

1. Set the rated motor current in Nameplate Amps (parameter 4) to the

correct value.

2. Run the test again.
3. Consider replacing the control board.

A/D Overflow at Min gain
The motor terminal voltage measuring circuit is not working properly.
You need to:

1. Determine if the motor is connected.
2. Check cable connections between the gate drive and control boards.
3. Consider replacing the circuit boards.
4. Investigate any noise problems.

Enable Dropout
The drive enable was lost during the inductance test. Consider running
the test again and monitor the drive enable (bit 9 of Inverter Status
(parameter 54) and/or the Inv En LED on the main control board.

Sign error / Overflow
The calculated inductance is negative
1. Run the test again
2. Consider replacing the circuit boards