After Repair Tests - Danfoss VLT Series Service Manual

3.4 AFTER REPAIR TESTS

Following any repair to a drive or testing of a drive suspected
of being faulty, the following procedure must be followed to
ensure that all circuitry in the drive is functioning properly before
putting the unit into operation.
1. Perform visual inspection procedures as
described in Table 3-1.
2. Perform static test procedures 5.1.1., 5.1.2 and
5.1.5 for D-frame size units or 5.1.3, 5.1.4 and
5.1.5 for E-frame size units to ensure drive is
safe to start.
3. Disconnect motor leads from output terminals
(U, V, W) of drive.
4. Apply AC power to drive.
5. Give drive a run command and slowly increase
reference (speed command) to approximately 40
Hz.
6. Using an analog volt meter or a DVM capable of
measuring true RMS, measure phase-to-phase
output voltage on all three phases: U to V, U to
W, V to W. All voltages must be balanced within
8 volts. If unbalanced voltage is measured, refer
to Input Voltage Test (5.2.1.1).
7. Stop drive and remove input power. Allow 40
minutes for DC capacitors to fully discharge
for E-frame size drives or 20 minutes for D-
frame size drives.
8. Reconnect motor leads to drive output terminals
(U, V, W).
9. Reapply power and restart drive. Adjust motor
speed to a nominal level.
10. Using a clamp-on style ammeter, measure
output current on each output phase. All
currents should be balanced. If unbalanced
current is measured, refer to Current Sensor
Test (5.2.12).
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