4 Troubleshooting
4.1 Troubleshooting Tips
Before repairing an adjustable frequency drive, read and
understand the following instructions.
1.
Note all warnings concerning voltages present in
the adjustable frequency drive. Always verify the
presence of AC input voltage and DC bus voltage
before working on the unit. Some points in the
adjustable frequency drive are referenced to the
negative DC bus. They are at bus potential even
though it sometimes appears on diagrams to be
a neutral reference.
CAUTION
Voltage can be present for as long as 20 minutes on
adjustable frequency drives after removing power from
the unit. See the label on the front of the adjustable
frequency drive door for the specific discharge time.
2.
Never apply power to a unit that is suspected of
being faulty. Many faulty components within the
adjustable frequency drive can damage other
components when power is applied. Always
perform the procedure for testing the unit after
repair as described in
.
3.
Never attempt to defeat any fault protection
circuitry within the adjustable frequency drive, as
this results in unnecessary component damage
and can cause personal injury.
4.
Always use factory approved replacement parts.
The adjustable frequency drive is designed to
operate within certain specifications. Incorrect
parts can affect tolerances and result in further
damage to the unit.
5.
Read the instruction manual. A thorough
understanding of the unit is the best approach. If
ever in doubt, consult the factory or authorized
repair center for assistance.
4.2 Exterior Fault Troubleshooting
Servicing an adjustable frequency drive that has been
operational for an extended period will be slightly different
from a new installation. When using proper trouble-
shooting procedures on a long-term installation, do not
assume that a motor is wired properly, possibly
overlooking issues such as loose connections, improper
programming, or added equipment. It is best to develop a
detailed approach, beginning with a physical inspection of
the system. See
for items to examine.
4.3 Fault Symptom Troubleshooting
This troubleshooting section is organized based on the
symptom being experienced.
provides a visual
inspection checklist. Often, wrong installation or wiring of
the adjustable frequency drive causes the problem. The
checklist provides guidance through various items to
inspect during any adjustable frequency drive service
process.
The following symptoms can suggest problems to
investigate further:
•
An unrecognizable display on the LCP
•
Problems with motor operation
•
A warning or alarm displayed by the adjustable
frequency drive
The adjustable frequency drive processor monitors inputs
and outputs as well as internal adjustable frequency drive
functions. Thus, an alarm or warning does not necessarily
indicate a problem within the adjustable frequency drive
itself.
Each incident has further descriptions on how to
troubleshoot that particular symptom. When necessary,
further referrals are made to other parts of the manual for
more procedures.
Chapter 4.3 Fault Symptom Trouble-
presents detailed discussions on areas of
adjustable frequency drive and system troubleshooting
that an experienced repair technician must understand for
effective analysis.
Troubleshooting
Service Manual
46
Danfoss A/S © Rev. 2014-02-10 All rights reserved.
MG94A222
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