GE Industrial Solutions AF-600 FP High Power (460V_575V 150HP and above) - Manual (Page 77)

6.2.3 Soft Charge and Rectifier Circuits Test: 5x-frame sizes
For 5x-frame size frequency converters, the rectifier and soft charge circuits are tested separately. The soft charge circuit is made up of the soft charge rectifier,
fuses and the soft charge resistor. The rectifier circuit is made up of the SCR and diode modules. The soft charge resistor limits the inrush current when power is
applied to the frequency converter. The soft charge circuit card also provides snubbing for the SCRs.
It is important to pay close attention to the polarity of the meter leads to ensure identification of a faulty component should an incorrect reading appear.
Prior to performing the test, it is necessary to ensure the soft charge fuses, F1, F2, and F3, located on the soft charge card, are good. An open fuse could indicate
a problem in the soft charge circuit. Continue test procedures.
Illustration 6-6 shows the soft charge card and the location of the fuses. It is for reference only. It is not necessary to remove the card to perform the tests.
Disconnect the MK3 from the soft charge card and leave disconnected until completion of soft charge and rectifier tests.
Soft charge fuse test
Use a digital ohmmeter to test continuity on rectifier fuses F1, F2, and F3 on the soft charge card.
1. Measure F1 across fuse. Open reading indicates open (blown) fuse.
2. Measure F2 across fuse. Open reading indicates open (blown) fuse.
3. Measure F3 across fuse. Open reading indicates open (blown) fuse.
A measurement of 0 ohms indicates good continuity. Replace any open fuse (infinite resistance).
130BX78.10
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Illustration 6.8: Soft Charge Card Fuse Location
380–480V: Blue MOV and 8 PTCs. 525–690V: Red MOV and 6 PTCs.
1 Fuses F1, F2 and F3 2 MK3 (disconnect for soft charge and rectifier tests)
AF-650 GP and AF-600 FP High Power Service Manual
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