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Test Procedures
Illustration 6.10 Output waveform graphic
6
6
Incorrect reading
Indicates that an IGBT or gate driver card is defective.
Check all IGBT modules for signs of damage. If no damage
is found, replace gate driver card.
6.3.11 Current Sensor Test
1.
Apply power to the unit.
2.
Ensure that motor check, pre-magnetizing, DC
hold, DC brake, or other parameter setups are
disabled that create a holding torque while at
zero speed. Current displayed will exceed 1 to 2
amps if such parameters are not disabled.
3.
Run drive with a zero speed reference.
4.
Read the output current in the display. It should
indicate approximately 1 to 2 amps.
Incorrect reading
If the current is greater than 1 to 2 amps and a current
producing parameter is not active, test the current sensor
with the motor leads disconnected as described next.
1.
Remove power from drive.
2.
Ensure the DC bus is fully discharged.
3.
Remove output motor bus bars from each
inverter module.
4.
Apply power to drive.
5.
Run drive with a zero speed reference.
6.
Read the output current in the display. The
display should indicate less than 1 amp.
Incorrect reading
If an incorrect reading was obtained from the above tests,
further tests of the current feedback signals are required
98
High Power Service Manual for Modular F Frame Drives
using the signal test board. See Testing Current Feedback
with the Signal Test Board.
6.3.12 Testing Current Feedback with the
If the control card parameters are setup to provide holding
torque while at zero speed, the current displayed will be
greater than expected. To make this test, disable such
parameters.
1.
2.
3.
4.
5.
6.
7.
8.
Incorrect reading
A current sensor feedback signal at this point in the circuit
should read approximately 400mv at 100% drive load.
Therefore, any reading above 15mv while the drive is at
zero speed has a negative effect on the way the drive
interprets the feedback signal. Replace the corresponding
current sensor if the reading is greater than 15mv. See the
disassembly instructions.
6.3.13 Input Terminal Signal Test
The presence of signals on either the digital or analog
input terminals of the drive can be verified on the drive
display. Digital or analog input status can be selected in
the display using the [DISPLAY MODE] key and the [+] and
[-] keys on the keypad.
Digital inputs
With digital inputs displayed, control terminals 16-33 are
shown left to right, with a 1 indicating the presence of a
signal.
®
MG90K202 - VLT
is a registered Danfoss trademark
Signal Test Board
Remove power to drive.
Ensure DC bus is fully discharged.
Install signal test board into the 30 pin test
connector socket in inverter one.
Apply power to the drive.
Using a DVM, connect negative (-) meter lead to
terminal 4 (common) of signal test board.
Run drive with a zero speed reference.
In turn measure AC voltage at terminals 1, 2, and
3 of signal test board. These terminals correspond
with current sensor outputs U, V, and W, respec-
tively. Expect a reading near zero volts but no
greater than 15mv.
Repeat the procedure for each inverter module in
the drive.
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