GE Industrial Solutions AF-600 FP High Power (460V_575V 150HP and above) - Manual (Page 98)

If an incorrect reading was obtained from the above tests, further tests of the current feedback signals are required using the signal test board.
Testing current feedback with the signal test board.
8. Remove power to frequency converter. Make sure the DC bus is fully discharged.
9. Install the signal test board into power card connector MK104.
10. Using a DVM, measure the resistance between terminals 1 and 4, 2 and 4, and 3 and 4 of the signal test board. Resistance should be the same for
all three readings. Table 6-2 shows approximate resistance readings based on frequency converter power and voltage rating. Note that values listed
are values at the current scaling card. When measuring with a signal test board, the actual reading may be higher due to meter lead resistance. Absence
of resistance indicates a missing scaling card.
11. Reapply power to the frequency converter.
12. Using a DVM, connect the negative (-) meter lead to terminal 4 (common) of the signal test board.
13. Run the frequency converter with a zero speed reference.
14. Measure the AC voltage at terminals 1, 2, and 3 of the signal test board in sequence. These terminals correspond with current sensor outputs U, V,
and W, respectively. Expect a reading near zero volts but no greater than 15 mv.
If the control card parameters are set up to provide holding torque while at zero speed, the current displayed will be greater than expected. To perform this test,
disable such parameters.
The current sensor feedback signal at this point in the circuit will read approximately 400 mv at a 100% frequency converter load so any reading above 15 mv
while the frequency converter is at zero speed has a negative effect on the way the frequency converter interprets the feedback signal.
A reading of greater than 15 mv suggests that the corresponding current sensor be replaced. See the disassembly instructions in Section 7 or 8.
Voltage (AC) AF-600 FP AF-650 GP Resistance (Ohms)
380-480 150 125 4.5
380-480 200 150 3.8
380-480 250 200 3.1
380-480 300 250 2.6
380-480 350 300 5.1
380-480 450 350 4.2
380-480 500 450 2.6
380-480 550 500 2.6
380-480 600 550 2.3
525-690 125 5.9
525-690 150 150 5.9
525-690 200 200 4.5
525-690 250 250 3.1
525-690 300 300 3.1
525-690 350 350 2.6
525-690 400 400 5.1
525-690 450 450 4.5
525-690 500 500 4.5
525-690 600 600 3.8
525-690 650 650 2.6
Table 6.3: Scaling Card Resistance Values
AF-600 FP only up to 600 V
6.3.15 Fan Tests
The fan control circuit is made up of the fan transformer and the control circuitry located on the power card along with control signals for ON, OFF, and speed
control from the control card. Since the fans do not necessarily run at all times, see the description for cooling fan operation under sequence of operation in
Section 3.3.5.
AF-650 GP and AF-600 FP High Power Service Manual
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