The shorting connector provided with most
customer-supplied external CTs should be
removed after the AFC card has been wired to
the CT and prior to operating the active filter
For safety considerations, short the secondary
side of customer-supplied external CTs anytime
the AFC card is not wired to the external CT,
even if current is not present on line power
Customer-supplied external CTs connect to the
AFC card at MK101 (5A) or MK108 (1A)
6.1.1 Tools Required for Testing
-
Digital volt/ohmmeter (must be rated for 1200 V
DC for 690 V units)
-
Analog voltmeter
-
Megohmmeter
-
Oscilloscope
-
Clamp-on style amp meter
-
Signal test board (p/n 176F8437) and extension
board (p/n 130B3147)
-
Split-bus power supply (p/n 130B3146)
-
Power quality analyses Fluke 435 (p/n
130BB3173), Dranetz 4300, 4400, or similar
6.1.2 Signal Test Board
The signal test board can be used to test circuitry within
the filter and provides easy access to test points. The test
board plugs into connector MK104 on the power card. Its
use is described in the procedures where called out. See
9.1.1 Signal Test Board (p/n 176F8437)
in
, for detailed pin descriptions.
130BX
66.10
Figure 6.2 Signal Test Board
6.2 Static Test Procedures
6.2.1 Inverter Section Tests
The inverter section is contains the IGBTs for two
functions; First, provide power to the DC line capacitors
and, second, to inject current back into the power grid.
IGBTs are grouped into modules comprised of six IGBTs.
Depending on the size of the unit, either one, two, or
three IGBT modules are present. The filter also has three
snubber capacitors on each IGBT module.
Before starting tests, ensure that meter is set to diode
scale. If removed previously, reinstall the soft charge card
and power cards. Do not disconnect the cable to
connector MK105 on the power card since the path for
continuity would be broken.
6.2.1.1 Inverter Test Part I
1.
Connect the positive (+) meter lead to the (+)
positive DC bus connector MK105 (A) on the
power card.
2.
Connect the negative (–) meter lead to LC
inductor secondary side terminals L1, L2, and L3
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 filter being charged by the meter.
6.2.1.2 Inverter Test Part II
1.
Reverse the meter leads by connecting the
negative (–) meter lead to the positive (+) DC bus
connector MK105 (A) on the power card.
2.
Connect the positive (+) meter lead to LC
inductor secondary side terminals L1, L2, and L3
in sequence.
Each reading should show a diode drop.
Incorrect reading
An incorrect reading in any inverter test indicates a failed
IGBT module. Replace the IGBT module according to the
disassembly instructions in
7 D-Frame Sizes Disassembly and
or
8 E-Frame Sizes Disassembly and
. It is further recommended for units
with two IGBT modules that both modules be replaced
even if the second module tests correctly.
Test Procedures
VLT Advanced Active Filter AAF006 D and E Frames Service Manual
6-2
MG90Z122 - VLT
®
is a registered Danfoss trademark
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