Rectifier Module - Danfoss VLT HVAC Drive FC100 Service Manual

Test Procedures
The temperature sensor is an NTC (negative temperature
coefficient) device. As a result, high resistance means low
temperature. As temperature decreases, resistance
increases. Each IGBT module has a temperature sensor
mounted internally. The sensor is wired from the IGBT
module to the gate drive card connector MK100. The
centre IGBT module is used.
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 undertem-
perature conditions.
Use ohmmeter set to read Ω.
1.
6 6
2. Unplug connector MK100 on the gate drive card
and measure the resistance across the cable
leads.
The relationship between temperature and resistance is
nonlinear. At 25°C, the resistance will be approximately 5k
Ω. At 0° C, the resistance will be approximately 13.7k Ω. At
60° C, the resistance will be approximately 1.5k Ω. The
higher the temperature, the lower the resistance.

6.4.2 Rectifier Module

Heatsink Temperature Sensor Test
Remove the rectifier module from the drive in accordance
with disassembly procedures.
The temperature sensor is an NTC (negative temperature
coefficient) device. As a result, high resistance means low
temperature. As temperature decreases, resistance
increases. The power card reads the resistance of the NTC
sensor to regulate fan speed and to monitor for over
temperature conditions.
Use ohmmeter set to read Ω.
1.
2. Unplug connector MK103 on power card and
measure across cable leads.
The full range of the sensor is 787 Ω to 10K Ω where 10K
Ω equals 25°C and 787 Ω equals 95°C. The higher the
temperature, the lower the resistance.
Soft Charge Rectifier Test
1. Remove the rectifier module from the drive in
accordance with disassembly procedures.
2. Remove the power card mounting plate in
accordance with disassembly procedures.
3. Disconnect the connector MK3 from each soft
charge card.
100
High Power Service Manual for Modular F Frame Drives
Since the rectifier test requires the soft charge resistor to
be in the circuit, verify the resistor is good before
proceeding.
1.
Should the resistor be defective and a replacement not
readily available, the remainder of the tests can be carried
out by disconnecting the cable at connector MK4 on the
soft charge card and placing a temporary jumper across
pins A and B. This provides a path for continuity for the
remaining tests. Ensure any temporary jumpers are
removed at the conclusion of the tests. For the following
tests, set the meter to diode check or Rx100 scale.
2.
3.
4.
5.
Incorrect Reading
An incorrect reading here indicates the soft charge rectifier
is faulty. The rectifier is not serviced as a component.
Replace the entire soft charge card in accordance with the
disassembly procedures. Reconnect the MK3 on the soft
charge card after these tests.
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MG90K202 - VLT is a registered Danfoss trademark
Measure the resistance between pins A and B of
connector MK4 on the soft charge card. It should
read 27 Ω (±10%) for 380–500 V frequency
converters or 68 Ω (±10%) for 525–690 V
frequency converters. A reading outside this
range indicates a defective soft charge resistor.
Replace the resistor according to the disassembly
procedures. Continue tests.
Connect the negative (-) meter lead to the
positive (+) MK3 (A) (DC output to DC bus), and
connect the positive (+) meter lead to MK1
terminals R, S, and T in sequence. Each reading
should show a diode drop.
Reverse meter leads with the positive (+) meter
lead to the positive (+) MK3 (A). Connect the
negative (-) lead to MK1 terminals R, S, and T in
sequence. Each reading should show open.
Connect the positive (+) meter lead to the
negative (-) MK3 (C). Connect the negative (-)
meter lead to MK1 terminals R, S, and T in
sequence. Each reading should show a diode
drop.
Reverse the meter leads with the negative (-)
meter lead to the negative (-) MK3 (C). Connect
the positive (+) meter lead to MK1 terminals R, S,
and T in sequence. Each reading should show
open.