GE Industrial Solutions AF-600 FP High Power (460V_575V 150HP and above) - Manual (Page 79)

6.2.4 Soft Charge Rectifier Test: 5x-frame size
The DC cable at connector MK3 remains disconnected for this procedure.
Since the rectifier test requires the soft charge resistor to be in the circuit, verify the resistor is good before proceeding.
1. Measure the resistance between pins A and B of connector MK4 on the soft charge card. It should read 27 ohms ( ±10%) for 380–480 V frequency
converters or 68 ohms ( ±10%) for 525–690 V frequency converters. A reading outside this range indicates a defective soft charge resistor. Replace the
resistor according to the disassembly procedures in Section 8. Continue tests.
Should the resistor be defective and a replacement not readily available, the remainder of the tests can be carried out by disconnecting the cable at connector
MK4 on the soft charge card and placing a temporary jumper across pins A and B. This provides a path for continuity for the remaining tests. Ensure any temporary
jumpers are removed at the conclusion of the tests.
For the following tests, set the meter to diode check or Rx100 scale.
2. Connect the negative (-) meter lead to the positive (+) MK3 (A) (DC output to DC bus), and connect the positive (+) meter lead to MK1 terminals R, S, and
T in sequence. Each reading should show a diode drop.
3. Reverse meter leads with the positive (+) meter lead to the positive (+) MK3 (A). Connect the negative (-) lead to MK1 terminals R, S, and T in sequence.
Each reading should show open.
4. Connect the positive (+) meter lead to the negative (-) MK3 (C). Connect the negative (-) meter lead to MK1 terminals R, S, and T in sequence. Each
reading should show a diode drop.
5. Reverse the meter leads with the negative (-) meter lead to the negative (-) MK3 (C). Connect the positive (+) meter lead to MK1 terminals R, S, and T in
sequence. Each reading should show open.
An incorrect reading here indicates the soft charge rectifier is faulty. The rectifier is not serviced as a component. Replace the entire soft charge card in accordance
with the disassembly procedures in Section 8.
Reconnect the MK3 on the soft charge card after these tests.
130BX120.10
1
2
3
4
Illustration 6.9: Soft Charge Card Connectors
380–480V: Blue MOV and 8 PTCs. 525–690V: Red MOV and 6 PTCs.
1 MK1 3 MK4
2 MK3 4 MK2
6.2.5 Inverter Section Tests
The inverter section is primarily made up of the IGBTs used for switching the DC bus voltage to create the output to the motor. IGBTs are grouped into modules
comprised of six IGBTs. Depending on the size of the unit, either one, two, or three IGBT modules are present. The frequency converter also has 3 snubber capacitors
on each IGBT module.
AF-650 GP and AF-600 FP High Power Service Manual
78
6