Visual Inspection - Danfoss VLT Series Service Manual

Visual Inspection

The table below lists a variety of conditions that should be
inspected for visually as part of any initial troubleshooting
procedure.
Inspect For
Auxiliary
equipment
Cable routing
Control wiring
Drive cooling
Drive display
Drive interior
EMC
considerations
Environmental
conditions
Grounding
Input power
wiring
Motor
Output to motor
wiring
Programming
Proper
clearance
Vibration
3-2 VLT is a registered Danfoss trademark
Table 3-1. Visual Inspection
Look for auxiliary equipment, switches, disconnects, or input fuses/circuit
breakers that may reside on input power side of drive or output side to motor.
Examine operation and condition of these items as possible causes for
operational faults. Check function and installation of pressure sensors or
encoders (etc.) used for feedback to drive.
Avoid routing motor wiring, AC line wiring, and signal wiring in parallel. If
parallel routing is unavoidable, try to maintain a separation of 6 - 8 inches (150
– 200 mm) between the cables or separate them with a grounded conductive
partition. Avoid routing cables through free air.
Check for broken or damaged wires and connections. Check the voltage
source of the signals. Though not always necessary depending on the
installation conditions, the use of shielded cable or a twisted pair is
recommended. Ensure the shield is terminated correctly. Refer to the section
on grounding shielded cables in Section 1.
Check operational status of all cooling fans. Check door filters on NEMA 12
(IP54) units. Check for blockage or constrained air passages. Verify bottom
gland plate is installed.
Warnings, alarms, drive status, fault history and many other important items
are available through the display on the local control panel of drive.
Drive interior must be free of dirt, metal chips, moisture, and corrosion.
Check for burnt or damaged power components or carbon deposits that were
the result of a catastrophic component failure. Check for cracks or breaks in
the housings of power semiconductors, or pieces of broken component
housings loose inside the unit.
Check for proper installation with regard to electromagnetic capability. Refer to
the drive instruction manual and Section 4 of this manual for further details.
Under specific conditions these units can be operated within a maximum
ambient of 50°C (122°F). Humidity levels must be less than 95% non-
condensing. Check for harmful airborne contaminates such as sulfur based
compounds.
The drive requires a dedicated ground wire from its chassis to the building
ground. It is also suggested that the motor be grounded to the drive chassis as
well. The use of conduit or mounting of the drive to a metal surface is not
considered a suitable ground. Check for good ground connections that are tight
and free of oxidation.
Check for loose connections. Check for proper fusing. Check for blown fuses.
Check nameplate ratings of motor. Ensure that motor ratings coincide with
drives. Check that drive's motor parameters (102 – 106) are set according to
motor ratings.
Check for loose connections. Check for switching components in output circuit.
Check for faulty contacts in switch gear.
Check that drive parameter settings are correct according to motor, application,
and I/O configuration.
These drives require top and bottom clearance adequate to ensure proper air
flow for cooling in accordance with the drive size. Drives with exposed heat
sinks out the back of the drive must be mounted on a flat solid surface.
Though somewhat subjective look for an unusual amount of vibration that the
drive may be subjected to. The drive should be mounted solidly or the use of
shock mounts employed.
Description