After-Repair Tests For D-Sized And E-Sized Drives; After-Repair Tests For Parallel Drive Systems - Danfoss VLT FC Series Service Manual

Test Procedures
8.6.1 After-repair Tests for D-sized and E-
sized Drives
Following testing or repair of a unit, use these steps to
ensure that all circuitry is functioning properly before
putting the unit into operation.
1. Perform visual inspection procedures as described
in chapter 6.4 Visual Inspection.
2. Perform static test procedures to ensure that the
unit is safe to start.
3. Disconnect motor cables from output terminals
(U, V, W).
4. Apply AC power to the unit.
5. Give the unit a run command and slowly increase
reference (speed command) to approximately
40 Hz.
6. Using an analog voltmeter or a DVM capable of
measuring true RMS, measure phase-to-phase
output voltage on all 3 phases: U to V, U to W, V
to W. All voltages must be balanced within 8 V. If
unbalanced voltage is measured, refer to
chapter 8.5.2 Input Voltage Test.
7. Stop the unit and remove input power. Allow DC
capacitors to discharge fully.
8. Reconnect motor cables to the output terminals
(U, V, W).
9. Reapply power and restart the unit. Adjust the
motor speed to a nominal level.
10. Using a clamp-on style ammeter, measure output
current on each output phase. All currents must
be balanced.
8.6.2 After-repair Tests for Parallel Drive
Systems
Following testing or repair of a unit, use these steps to
ensure that all circuitry is functioning properly before
putting the unit into operation.
1. Perform visual inspection procedures as described
in chapter 6.4 Visual Inspection.
2. Perform static test on the drive as described in
chapter 8.4 Static Test Procedures.
3. Remove the 3 output motor busbars from each
module.
4. Connect a 610–800 V DC supply to the SMPS
input for each module using the test cable
(176F8766). (Preferably, use a Danfoss split bus
power supply.)
5. Apply power to the split bus power supply and
check that the LCP lights properly. The fans do
not operate when powered in this manner.
MG94A502
Service Guide
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
8.00
6.00
4.00
2.00
0.00 V
-2.00
-4.00
-6.00
-8.00
-4.0ms
Illustration 8.20 System Test Waveform: 2 V/div 100us/div Run
at 10 Hz
Danfoss A/S © 02/2019 All rights reserved.
Give the drive a run command (press [Hand on])
and slowly increase the reference (speed
command) to approximately 40 Hz.
Using the signal test board (176F8437) and an
oscilloscope, check the waveform at pins 25–30
with the scope referenced to pin 4. This
procedure must be performed on each inverter
module. Each waveform must approximate the
example in Illustration 8.20.
Connect a 24 V DC supply to the DC bus of the
drive. Preferably, use a Danfoss split bus power
supply. Connect it to the DC bus output of the
moduleor, or to the busbars connecting the top
of the DC fuses on any module.
Observe the phase-to-phase waveform on the
motor busbars of each phase of each inverter
module. Compare the waveform to the normal
output waveform of a properly operating drive.
Check that the waveforms are similar, except that
the amplitude is 24 V instead of the full output
voltage.
Press [OFF] on the LCP.
Disconnect power from both supplies and
reinstall jumper connectors to the SMPS input
plugs on all modules.
Reinstall the motor motor busbars on all modules.
Apply AC power to the drive.
Apply a start command to the drive. Adjust the
speed to a nominal level. Observe that the motor
is running properly.
Using a clamp-on style current meter, measure
the output current on each phase. All currents
must be balanced.
Input A
50Us/Div
8 8
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