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5.2.13 Fan Tests
The fan control circuit is made up of the fan transformer and
the control circuitry located on the power card along with
control signals for ON, OFF, and speed control from the control
card. Since the fans do not necessarily run at all times, see
the description of cooling fans operation under sequence of
operation in Section 2.
5.2.13.1 Supply Voltage
Supply voltage for the fans is from the soft charge card to
power card connector MK106. First verify the supply voltage
is present as follows.
1. With a voltmeter, measure AC phase to phase
voltage at R, S, and T of power card connector
MK106. It should equal main supply voltage
applied to drive.
2. If voltage is not present, ensure proper line
voltage is applied to drive. Conduct Input Voltage
test (5.2.1.1).
3. If line voltage is present at input of drive but not
at MK106 of power card, conduct static test of
soft charge fuses (5.1.1).
4. If voltage is present at MK106, check voltage at
fan transformer read from connector CN2
located near transformer. With a volt meter, read
AC voltage at CN2 pins 1 and 3. Voltage should
correspond to main AC line voltage applied to
drive.
5. If voltage is not present, ensure jumpers are in
place at power card connector FK103.
Otherwise connect an external source of power
to terminal FK103 for fan supply voltage.
If the jumpers are in place or an auxiliary supply is connected
and powered but no voltage is present at the fan transformer
connector CN2, the power card is likely defective. Replace
the power card in accordance with the disassembly instructions
in Section 6 or 7.
5.2.13.2 Transformer Output
If the appropriate voltage is present at CN2 pins 1 and 3, next
check the output of the transformer. Prior to making this test,
ensure the fan transformer fuse is good.
1. With a volt meter, measure AC voltage from
CN2 terminal 1 to terminal 2. Voltage should
equal 66% of main AC supply voltage (48% for
drives 525-600/690 VAC) applied to drive (or that
of auxiliary supply). If voltage is incorrect, replace
fan transformer.
2. If voltage is correct, check fan voltage being
supplied to fans themselves. Voltage can be
read at power card connector MK107 pins 8
and 11 with respect to pin 1. Voltage at pins 8
and 11 correspond to fan's commanded speed:
200 VAC for low speed and 230 VAC for high
speed.
If the correct voltage is available but the fan is not running,
that fan is defective. If no voltage is available, verify that the
fans should be running. If so, the power card is defective.
Replace the fan or power card in accordance with the
disassembly instructions in Section 6 or 7.
5.2.13.3 Fan Control Circuit
To verify that the fan control circuit is receiving appropriate
commands from the control card, the signal test board can
be used to verify those signals.
1. Remove power from drive and allow DC bus to
fully discharge.
2. Install signal test board into interface connector
MK104.
3. Reapply power to drive.
4. Connect negative (-) meter lead of a voltmeter
to signal board terminal 4 (common).
5. With positive (+) meter lead check signal at
terminal 6 of signal board. Meter should read
zero (0) volts with fans commanded to run, 5
VDC if control card commands fans off.
6. Verify cooling fans sequence of operation to
ensure they should be running. In addition, signal
board contains a fan test switch. When
switched on fans should start and run at high
speed.
The signals at terminals 5 and 10 of the signal board determine
fan speed. See Section 8 for more on those signals. In addition,
if a heat sink overtemperature trip has occurred, the fans will
automatically be switched to high speed.
Given the fact that the fans should be running, if the signal at
terminal 6 is correct and the fan test switch activates the fan,
the control card is defective. Otherwise the power card is
defective. Replace the appropriate assembly in accordance
with the disassembly instructions in Section 6 or 7.
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