Component Test Procedures 2-17
Checking the DC Bus
Capacitors
Important: This procedure requires special equipment and training. Only
qualified and trained personnel should perform these
procedures.
These tests require the recommended high voltage DC-power supply.
1. Remove power from the drive. Refer to Removing Power from the
Drive on page 3-3.
2. Remove the covers from the power structures. Refer to Removing the
Covers from the Power Structures on page 3-15.
3. Set the current limit of the DC power supply to less than 50mA.
4. On Power Structure #1, connect the power supply’s DC+ to the drive’s
DC+ terminal and the power supply’s DC- to the drive’s DC- terminal.
5. Set the power supply voltage setting to zero.
6. Switch on the external DC power supply.
7. Slowly increase the external DC power supply output voltage to the
drive’s nominal DC bus voltage (650V dc for drives with 380-500V ac
input or 775V dc for drives with 600-690V ac input).
8. Monitor the current while testing.
9. Leakage current should be less than 3mA when voltage has stabilized.
10. Abort test if current leakage is significantly higher when voltage has
stabilized.
11. Decrease the DC power supply output voltage to zero. Wait until DC
bus voltage has decreased to zero. Switch off the external DC power
supply.
12. As a precaution, use a resistor to discharge each capacitor after testing.
Use a resistor with the proper resistance and power handling capability
for the discharge current.
13. If any capacitor has failed. Replace all the capacitors in the same series
connection (See Removing the DC Bus Capacitors on page 3-40
).
14. Repeat steps 3 - 13 for Power Structure #2.
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