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Troubleshooting
1 = left most inverter module.
2 = middle inverter module in F2 or F4/F12 or
F13 frequency converter.
2 = right inverter module in F1 or F3/F10 or F11
frequency converter.
3 = right inverter module in F2 or F4/F12 or F13
frequency converter.
4
4
5 = rectifier module.
WARNING 250, New spare part
A component in the frequency converter has been
replaced. Reset the frequency converter for normal
operation.
WARNING 251, New typecode
The power card or other components have been replaced
and the typecode changed. Reset to remove the warning
and resume normal operation.
4.8 After Repair Tests
Following any repair to a frequency converter or testing of
a frequency converter suspected of being faulty, the
following procedure must be followed to ensure that all
circuitry in the frequency converter is functioning properly
before putting the unit into operation.
1.
Perform visual inspection procedures as described
in the table Visual Inspection.
2.
Perform static test on the frequency converter as
described in Static Test Procedures.
3.
Remove the three output motor bus bars from
each inverter module.
4.
Connect a 610 – 800 VDC power supply to the
switch mode power supply (SMPS) input to each
module using the test cable 176F8766.
5.
Apply power to the SMPS and observe that the
display lights up properly. (The fans will not
operate when powered in this manner.)
6.
Give the frequency converter a run command
(press Hand on) and slowly increase the reference
(speed command) to approximately 40 Hz.
7.
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 should approximate the
illustration below.
8.
Connect a 24 VDC power supply to the DC bus of
the drive. This can be done on the DC bus output
of the rectifier module or the bus bars
connecting to the top side of the DC fuses on
any of the inverter modules.
74
High Power Service Manual for Modular F Frame Drives
9.
10.
11.
12.
13.
14.
8.00
6.00
4.00
2.00
0.00 V
-2.00
-4.00
-6.00
-8.00
Illustration 4.1 After repair waveform: 2v/div 100us/div run at 10
Hz
®
MG90K202 - VLT
is a registered Danfoss trademark
Observe the phase to phase waveform on the
output bus bars of each phase of each inverter
module. This waveform should appear the same
as the normal output waveform of a properly
operating drive, except that the amplitude will be
24 V instead of the full output voltage of a
normal drive.
Press the OFF key of the frequency converter,
disconnect power from both power supplies, and
reinstall jumper connectors to the SMPS input
plugs on all modules.
Reinstall the motor output bus bars on all
inverter 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
should be balanced.
Input A
-4.0ms
50Us/Div
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