4.3 Visual Inspection
Table 4.1 lists a variety of conditions that require visual
inspection as part of any initial troubleshooting procedure.
Inspect For Description
CT feedback
and other
auxiliary
equipment
•
Check the function and installation of current
sensors that provide feedback to the active
filter.
•
Ensure that CT feedback is connected to the
AFC card correctly: MK101 (5 A), MK108 (1 A).
•
Check for auxiliary equipment, switches,
disconnects, or input fuses/circuit breakers
that may reside on the input power side of
active filter.
•
Check the jumpers on the CT terminal.
•
Examine the operation and condition of these
items for possible causes of operational
faults.
Cable routing
•
Avoid routing cables through free air. Avoid
routing power line wiring and signal wiring in
parallel. If parallel routing is unavoidable, try
to maintain a separation of 150–200 mm (6–8
in) between the cables or separate them with
a grounded conductive partition.
•
For North American installations, control
wiring and power wiring must be in separate
conduits.
Inspect For Description
Control wiring
•
Check for broken or damaged wires and
connections.
•
Ensure that the CT polarity is correct. If
summation CTs are used, ensure polarity and
sequence is correct.
•
Check that CTs have the same rating
(summation CTs as well).
•
Check the voltage source of the signals.
•
Check that the maximum CT burden is not
exceeded through long wiring or small
square section.
•
Though not always necessary depending on
the installation conditions, the use of
shielded cable or a twisted pair is always
recommended.
•
Ensure the shield is terminated correctly.
Refer to the section on grounding shielded
cables in 2 Operator Interface and Active Filter
Control.
•
For North American installations, control
wiring and power wiring must be in separate
conduits.
Cooling and
clearances
•
Make sure the bottom connector plate is
installed.
•
Check the operational status of all cooling
fans and fan direction.
•
Check the door filters.
•
Check for blockage or constrained air
passages inside the enclosure and in the back
channel.
•
Check that required top clearance of 225 mm
(9 in) is present to ensure proper air flow for
cooling.
Display
•
Warnings, alarms, filter status, fault history
and many other important items are available
via the local control panel display on the
filter.
Interior
•
The active filter must be free of dirt, metal
chips, moisture, and corrosion.
•
Check for burned or damaged power
components or carbon deposits resulting
from catastrophic component failure.
•
Check for cracks or breaks in the housings of
power semiconductors and loose pieces of
broken component housings inside the unit.
Troubleshooting VLT Advanced Active Filter AAF006 D and E Frames Service Manual
4-2 MG90Z122 - VLT
®
is a registered Danfoss trademark
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