Inverter test part IV
1.
Reverse the meter leads by connecting the
negative (–) meter lead to the negative (-) DC bus
bar.
2.
Connect the positive (+) meter lead to U, V, and
W in sequence.
Each reading should show infinity. The meter will start at a
low value and slowly climb toward infinity due to
capacitance within the frequency converter being charged
by the meter.
Incorrect reading
An incorrect reading in any inverter test indicates a failed
module. Replace the IGBT module according to the
disassembly instructions. The inverter module must be
removed to replace the IGBT module.
6.2.3 Brake IGBT Test
This test can only be carried out on units equipped with a
dynamic brake option.
1.
Remove the safety covers to access the unit.
2.
Note the position of the brake jumper bus bars
prior to removal. The tops of the bus bars are
connected to the motor lead bus bars as referred
to in the following test procedures.
3.
Remove the brake jumper bus bars
Brake IGBT test part I
1.
Connect the positive (+) meter lead to the brake
resistor terminal R+ (82).
2.
Connect the negative (-) meter lead to the brake
resistor terminal R- (81).
The reading should indicate infinity. The meter may start
out at a value and climb toward infinity as capacitance is
charged within the frequency converter.
Brake IGBT test part II
1.
Connect the positive (+) meter lead to the brake
resistor terminal R- (81).
2.
Connect the negative (-) meter lead to the brake
resistor terminal R+ (82).
The reading should indicate a diode drop.
Brake IGBT test part III
1.
Connect the positive (+) meter lead to the brake
resistor terminal R- (81).
2.
Connect the negative (-) meter lead to the
negative (-) DC bus.
The reading should indicate infinity. The meter may start
out at a value and climb toward infinity as capacitance is
charged within the frequency converter.
Incorrect reading
An incorrect reading on any of the above tests indicates
the brake IGBT is defective. Replace the brake IGBT per the
disassembly procedure. The inverter module must be
removed to replace the IGBT brake.
6.2.4 Fan Continuity Test
Make all continuity checks using an ohmmeter set to Rx1
scale. A digital or analog ohmmeter can be used. Some
instability may result when measuring resistance of a
transformer with a multimeter. This can be reduced by
turning off the auto-ranging function and setting the
measurement manually.
Control Source
Fan Location
Inverter module 2
Rectifier cabinet door
Inverter module 2
Inverter cabinet left door
Inverter module 2
Inverter cabinet right door
Inverter module 1
Rectifier heatsink
Inverter module 1
Inverter module 1 heatsink
Inverter module 2
Inverter module 2 heatsink
Inverter module 3 (if unit has 3
modules)
Inverter module 3 heatsink
Check 1: Fan Fuse Test
Check the 15 amp fan fuse on the top of each inverter
module.
An open fuse could indicate additional faults. Replace the
fuse and continue the fan checks.
Check 2: Continuity from the AC Input Terminals to Each
Inverter Module.
For the following tests, unplug the 10-pin connector on
the top of each Inverter Module. Read the terminals on the
Inverter Module side of the connector (female connector).
The 8-pin connector must be plugged into the top of the
Inverter Module. The 12-pin connector must be plugged
into the top of the Rectifier Module.
1.
Measure from L3 (T) to terminal 1. Reading of <1
Ohm should be indicated. This measurement
should be made once for each Inverter Module.
2.
Measure from L3 (S) to terminal 2. Reading of <1
Ohm should be indicated. This measurement
should be made once for each Inverter Module.
Incorrect reading
An incorrect reading could indicate a number of different
problems.
1.
Perform the Rectifier Module Soft Charge Fuse
Test. If any soft charge fuses are open, replace
the fuse and retest the fan continuity.
2.
Check the wire harness between the Rectifier
Module and each Inverter Module. At the Rectifier
Test Procedures
High Power Service Manual for Modular F Frame Drives
92
MG90K202 - VLT
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is a registered Danfoss trademark
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