96
9.4 Checking Out the Power Modules with Input Power Off
Use the following procedure to check the drive's Power Module circuitry with power off:
DANGER
DC BUS CAPACITORS RETAIN HAZARDOUS VOLTAGES AFTER INPUT POWER HAS BEEN
DISCONNECTED. AFTER DISCONNECTING INPUT POWER, WAIT FIVE (5) MINUTES FOR THE DC
BUS CAPACITORS TO DISCHARGE AND THEN CHECK THE VOLTAGE WITH A VOLTMETER TO
ENSURE THE DC BUS CAPACITORS ARE DISCHARGED BEFORE TOUCHING ANY INTERNAL
COMPONENTS. FAILURE TO OBSERVE THIS PRECAUTION COULD RESULT IN SEVERE BODILY
INJURY OR LOSS OF LIFE.
Step 1. Turn off and lock out input power. Wait five minutes.
Step 2. Remove the drive's cover.
Step 3. Verify that there is no voltage at the drive's input power terminals.
Step 4. Check the DC bus potential with a voltmeter as described in section 9.3 to ensure that the
DC bus capacitors are discharged.
Step 5. Disconnect the motor from the drive.
Step 6. Check all AC line and DC bus fuses.
Step 7. If a fuse is blown, use a multimeter to check the input diodes and output IGBTs. See table
9.1.
Note that 110HP drives do not have replaceable transistor modules: the entire drive must
be replaced if a transistor malfunctions. Intelligent Power Modules (IPM) may be replaced if
they fail in a 60150HP drive.
Step 8. Reconnect the motor to the drive.
Step 9. Reattach the drive's cover.
Step 10. Reapply input power.
Table 9.1 Resistance Checks
160HP Drives
Input
Diode
No.
Meter
Connection
(+)
(-)
Component is OK if
resistance (R) is:
Component is defective if:
1
*
R/L1
50 < R < 10 Megohm
Continuity (short circuit) or open when the meter is
connected with reversed polarity
2
*
S/L2
connected with reversed polarity
3
*
T/L3
4
R/L1
**
5
S/L2
**
6
T/L3
**
* (+) DC Bus Volts power terminal
** (-) DC Bus Volts power terminal
StockCheck.com
Downloaded from StockCheck.com