Danfoss calculates line imbalance per an IEC specification.
Imbalance = 0.67 X (Vmax – Vmin)/Vavg
For example, if three phase readings were taken and the
results were 500 V AC, 478.5 V AC, and 478.5 V AC; then
500 V AC is V
max
, 478.5 V AC is V
min
, and 485.7 V AC is
Vavg, resulting in an imbalance of 3%.
Although the filter can operate at higher line imbalances,
the lifetime of components, such as DC bus capacitors, will
be shortened.
Incorrect reading
CAUTION
Open (blown) input fuses or tripped circuit breakers
usually indicate a more serious problem. Before replacing
fuses or resetting breakers, perform static tests described
in
.
An incorrect reading here requires checking the line power
supply. Typical items to check would be:
•
Open (blown) input fuses or tripped circuit
breakers
•
Open disconnects or line side contactors
•
Problems with the power distribution system
If the Input Voltage Test was successful check for voltage
to the control card.
6.3.3 Control Card Basic Voltage Test
1.
Measure the control voltage at terminal 12 with
respect to terminal 20. The meter should read
between 21 and 27 V DC.
An incorrect reading could indicate the supply is loaded
down by a fault in the customer connections. Unplug the
terminal strip and repeat the test. If this test is successful,
then continue. Remember to check the customer
connections. If still unsuccessful, proceed to the Switch
Mode Power Supply (SMPS) test.
2.
Measure the 10 V DC control voltage at terminal
50 with respect to terminal 55. The meter should
read between 9.2 and 11.2 V DC.
An incorrect reading here could indicate the supply is
loaded down by a fault in the customer connections.
Unplug the terminal strip and repeat the test. If this test is
successful, then continue. Remember to check the
customer connections. If still unsuccessful, proceed to the
SMPS test.
A correct reading of both control card voltages would
indicate the LCP or the control card is defective. Replace
the LCP with a known good one. If the problem persists,
replace the control card in accordance with the
disassembly procedures in
7 D-Frame Sizes Disassembly and
or
8 E-Frame Sizes Disassembly and
6.3.4 Switch Mode Power Supply (SMPS)
Test
For this procedure, provide 650 V using the split-bus
power supply. The SMPS derives its power from the DC
bus. The first indication that the DC bus is charged is the
DC bus charge indicator light located on the power card
being lit. This LED however can be lit at a voltage still too
low to enable the power supplies.
First test for the presence of the DC bus.
1.
Insert the signal test board into the power card
connector MK104.
2.
Connect the negative (-) meter lead to terminal 4
(common) of the signal board. With a positive (+)
meter lead, check the following terminals on the
signal board.
Terminal
Supply [V]
Voltage Range [V DC]
11
+18
16.5–19.5
12
-18
-16.5–-19.5
23
+24
23–25
24
+5
4.75–5.25
Table 6.3
In addition, the signal test board contains three LED
indicators that indicate the presence of voltage as follows:
Red LED +/- 18 V DC supplies present
Yellow LED +24 V DC supply present
Green LED +5 V DC supply present
The lack of any one of these power supplies indicates the
low voltage supplies on the power card are defective. This
assumes that the proper DC bus voltage was read at
power card connector MK105 (A) and (B). Replace the
power card in accordance with the disassembly procedures
in
7 D-Frame Sizes Disassembly and Assembly Instructions
or
8 E-Frame Sizes Disassembly and Assembly Instructions
Test Procedures
VLT Advanced Active Filter AAF006 D and E Frames Service Manual
6-6
MG90Z122 - VLT
®
is a registered Danfoss trademark
6
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