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.
8.4.4 Intermediate Section Tests
NOTICE
PARALLEL MODULE ISOLATION
Before performing these tests in a parallel drive system,
isolate the individual module to be tested. To isolate the
module, remove the:
•
DC link connection.
•
Motor busbar/cable links.
•
Input busbar/cable links.
The intermediate section of the drive is composed of the:
•
DC bus capacitors.
•
DC coils.
•
Balance circuit for the capacitors.
Intermediate section test
1. Test for short circuits with the ohmmeter set to
Rx100 scale. If using 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 with low ohms and then moves
toward innity as the meter charges the
capacitors.
4. Reverse the meter leads so that the (-) meter lead
is connected to the positive DC(+) and the
positive (+) meter lead is connected to the
negative DC(-).
5. The meter pegs at 0 while the meter discharges
the capacitors. The meter then begins moving
slowly toward 2 diode drops as the meter charges
the capacitors in the reverse direction. Although
the test does not ensure that the capacitors are
fully functional, it ensures that no short circuits
exist in the DC link.
Incorrect reading
A short in the rectier or inverter section could cause a
short circuit reading. Ensure that the tests for these circuits
have already been performed successfully. A failure in 1 of
these sections could be read in the intermediate section
since they are all routed via the DC bus.
If a short circuit is present, and the unit is equipped with a
brake, perform the brake IGBT test next.
The only other likely cause for failure would be a defective
capacitor.
There is not an eîš‚ective test of the capacitor bank when it
is fully assembled. It is unlikely that a physically damaged
capacitor would indicate a failure within the capacitor
bank. If a failure is suspected, all the capacitors must be
replaced. Replace the capacitors in accordance with
chapter 10.2.20 Standard DC Capacitors,
chapter 11.2.20 Standard DC Capacitors, or
chapter 13.2.20 Twistlock DC Capacitors.
Further static tests could require some disassembly. See
chapter 10 D1h/D3h/D5h/D6h/J8 Drive Disassembly and
Assembly to chapter 13 E1h–E4h Drive Disassembly and
Assembly.
8.4.5 IGBT Temperature Sensor Test
The temperature sensor is an NTC (negative temperature
coeîš„cient) device. As a result, high resistance means low
temperature. As the temperature increases, resistance
decreases. Each IGBT module has a temperature sensor
mounted internally. The sensor is wired from each IGBT
module to the gate drive card connector MK100.
On the gate drive card, the resistance signal is converted
to a frequency signal. The frequency signal is sent to the
power card for processing. The temperature data is used to
regulate fan speed and to monitor for over and under
temperature conditions. In D-sized drives, there are 3
sensors, 1 in each IGBT module. In E-sized drives, there are
6 IGBT modules; the left IGBT of each phase is monitored.
In E-sized drives, individual IGBT module temperatures can
be viewed in parameter 43-00 Component Temp:
•
Parameter 43-10 Heat Sink Phase U Temp ID shows
U-phase temperature.
•
Parameter 43-11 Heat Sink Phase V Temp ID shows
V-phase temperature.
•
Parameter 43-12 Heat Sink Phase W Temp ID shows
W-phase temperature.
IGBT section test
1. Use ohmmeter set to read ohms.
2. Unplug connector MK100 on the gate drive card
(see Illustration 8.8) and measure the resistance
across each black and white pair.
Test Procedures
VLT
®
FC Series, D1h–D8h, Da2/Db2/Da4/Db4, E1h–E4h, J8/J9
102 Danfoss A/S © 02/2019 All rights reserved. MG94A502
88
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