GE Industrial Solutions AF-600 FP High Power (460V_575V 150HP and above) - Manual (Page 96)

12. Insert the signal test board into power card connector MK104.
13. With scope probe earth connected to terminal 4 (common) of signal board, measure six gate signals at signal board terminals 25 through 30.
14. Place the frequency converter in run at 30 Hz.
The waveform should appear as in Illustration 6-19.
Illustration 6.19: Gate Signal Waveform from Signal Test Board. IGBT Gate Signal measured with the Signal Test Board: 2 volts per division vertical
scale, 50 microseconds per division time scale. Unit running at 30 Hertz.
15. Using a DVM, again check these same signal board terminals. DVM should read 2.2 to 2.5 VDC.
An incorrect reading of a gate signal indicates either the power card is defective or the signal has been lost prior to arriving at the power card. There is no test to
verify the signals directly out of the control card. The power card would be suspect if a single gate signal is incorrect. The control card would be suspect if all six
signals are incorrect. Replace the corresponding card in accordance with the disassembly procedures in Section 7 or 8.
6.3.12 IGBT Switching Test
Using the test cable 6KAF6H8439 while the frequency converter is powered and the DC bus is disabled, a simple test can be made to determine if the IGBTs are
actually turning on.
Before proceeding, verify that the DC bus is in fact disabled.
1. Disconnect the cable from connector MK105 on the power card. With a voltmeter, measure between white lead of the cable disconnected from MK105
and output terminals U, V, and W in sequence. Switch between AC and DC scales. Voltage should read nearly zero.
2. Measure between the black lead of the same cable and the output terminals U, V, and W in sequence. Voltage should read nearly zero.
With the DC bus disabled, proceed using a DVM set on a diode scale.
1. With the frequency converter in stop mode, connect the positive (+) meter lead to the black lead of MK105 cable disconnected from the power card.
2. In sequence, connect the negative (-) meter lead to the frequency converter output terminals U, V, and W. The meter should indicate a diode drop.
3. Leave the positive meter lead connected to cable MK105, and run the frequency converter at 30 Hz.
4. In sequence, again connect the negative (-) meter lead to the frequency converter output terminals U, V, and W. The meter should effectively indicate a
short circuit or around a 0.035 diode drop which indicates lower IGBTs are turned on and shorting the meter to a negative bus.
NB!
Some voltage leakage within the unit may cause the meter to indicate a small negative voltage drop.
5. Repeat the test for positive (+) or upper IGBTs.
6. With the frequency converter in stop mode, connect the negative (-) meter lead to the white lead of MK105 cable disconnected from the power card.
AF-650 GP and AF-600 FP High Power Service Manual
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