Inverter test part II
1.
Reverse the meter leads by connecting the
negative (-) meter lead to the positive (+) DC bus.
2.
Connect the positive (+) meter lead to U, V, and
W in sequence.
A diode drop indicates a correct reading.
Inverter test part III
1.
Connect the positive (+) meter lead to the
negative (-) DC bus.
2.
Connect the negative (-) meter lead to terminals
U, V, and W in sequence.
A diode drop indicates a correct reading.
Inverter test part IV
1.
Reverse the meter leads by connecting the
negative (-) meter lead to the negative (-) DC bus.
2.
Connect the positive (+) meter lead to U, V, and
W in sequence.
Infinity is a correct reading. The meter starts at a low value
and slowly climb toward infinity due to the meter charging
capacitance within the adjustable frequency drive.
Incorrect reading
An incorrect reading in any inverter test indicates a failed
IGBT module. Replace the IGBT module according to
chapter 7 Disassembly and Assembly Instructions
. Following
an IGBT failure, it is important to verify that the gate drive
signals are present and the wave form is correct. See
chapter 6.4.11 IGBT Gate Drive Signals Test
6.3.4 Brake IGBT Test
This test can only be carried out on units equipped with a
dynamic brake option. If a brake resistor is connected to
terminals R-(81) and R+(82), disconnect it before
proceeding. Use an ohmmeter set on diode check or
Rx100 scale.
Brake IGBT test part I
1.
Connect the positive (+) meter lead to the brake
resistor terminal 82 (R+).
2.
Connect the negative (-) meter lead to the brake
resistor terminal 81 (R-).
Infinity is a correct reading. The meter may start out at a
value and climb toward infinity as capacitance is charged
within the adjustable frequency drive.
Brake IGBT test part II
1.
Connect the positive (+) meter lead to the brake
resistor terminal 81 (R-).
2.
Connect the negative (-) meter lead to the brake
resistor terminal 82 (R+).
A diode drop indicates a correct reading.
Brake IGBT test part III
1.
Connect the positive (+) meter lead to the brake
resistor terminal 81 (R-).
2.
Connect the negative (-) meter lead to the
negative (-) DC bus.
Infinity is a correct reading. The meter may start out at a
value and climb toward infinity as capacitance is charged
within the adjustable frequency drive.
Brake IGBT test part IV
1.
Connect the negative (-) meter lead to the brake
resistor 81 (R-).
2.
Connect the positive (+) meter lead to the
negative (-) DC bus.
A diode drop indicates a correct reading.
Incorrect reading
An incorrect reading on any of these tests indicates that
the brake IGBT is defective. Replace the brake IGBT
module.
6.3.5 Intermediate Section Tests
The intermediate section of the adjustable frequency drive
is made up of the DC bus capacitors, the DC coils, and the
balance circuit for the capacitors.
1.
Test for short circuits with the ohmmeter set on
Rx100 scale or, for a digital meter, select diode.
2.
Connect the positive (+) meter lead to the (+) DC
and the negative (-) meter lead to the negative (-)
DC.
3.
The meter starts out with low ohms and then
move towards infinity as the meter charges the
capacitors.
4.
Reverse the meter leads such that the (-) meter
lead is connected to the positive (+) DC and the
positive (+) meter lead is connected to the
negative (-) DC.
Test Procedures
Service Manual
74
Danfoss A/S © Rev. 2014-02-10 All rights reserved.
MG94A222
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Summary of Contents for VLT FC 103
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