GE Industrial Solutions AF-600 FP High Power Unit Sizes 6x - Manual (Page 91)

Incorrect reading
If an incorrect reading was obtained from the above tests, further tests of the current feedback signals are required using the signal test board. See Testing Current
Feedback with the Signal Test Board.
6.3.12 Testing Current Feedback with the Signal Test Board
If the control card parameters are setup to provide holding torque while at zero speed, the current displayed will be greater than expected. To make this test,
disable such parameters.
1. Remove power to drive.
2. Ensure DC bus is fully discharged.
3. Install signal test board into the 30 pin test connector socket in inverter one.
4. Apply power to the drive.
5. Using a DVM, connect negative (-) meter lead to terminal 4 (common) of signal test board.
6. Run drive with a zero speed reference.
7. In turn measure AC voltage at terminals 1, 2, and 3 of signal test board. These terminals correspond with current sensor outputs U, V, and W, respectively.
Expect a reading near zero volts but no greater than 15mv.
8. Repeat the procedure for each inverter module in the drive.
Incorrect reading
A current sensor feedback signal at this point in the circuit should read approximately 400mv at 100% drive load. Therefore, any reading above 15mv while the
drive is at zero speed has a negative effect on the way the drive interprets the feedback signal. Replace the corresponding current sensor if the reading is greater
than 15mv. See the disassembly instructions.
High Power Service Manual for Unit Sizes 6x
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