Motor/Load Problems; Internal Frequency Converter Problems; Overtemperature Faults; Current Sensor Faults - Trane TR150 Service Manual

Frequency Converter and Mot...
Any references or limits set incorrectly result in less than
acceptable frequency converter performance. For instance,
if maximum reference is set too low, the motor is unable
to reach full speed. Set these parameters according to the
requirements of the particular installation. References are
set in parameter group 3-0* Reference Limits.
Incorrectly set I/O configuration usually results in the
frequency converter not responding to the function as
commanded. Remember that for every control terminal
input or output there are corresponding parameter
settings. These settings determine how the frequency
converter responds to an input signal or the type of signal
present at that output. Utilizing an I/O function involves a
2-step process. Wire the wanted I/O terminal properly, and
set the corresponding parameter accordingly. Control
terminals are programmed in parameter group 5-0* Digital
I/O Mode and parameter group 6-0* Analog I/O Mode.

5.1.5 Motor/Load Problems

Problems with the motor, motor wiring, or mechanical load
on the motor can develop in several ways. The motor or
motor wiring can develop a phase-to-phase or phase-to-
ground short circuit resulting in an alarm indication. Check
whether the problem is in the motor wiring or the motor
itself.
A motor with unbalanced, or asymmetrical, impedances on
all 3-phases can result in uneven or rough operation, or
unbalanced output currents. For measurements, use a
clamp-on style ammeter to determine whether the current
is balanced on the 3 output phases. See
chapter 6.4.6 Output Imbalance of Motor Supply Voltage Test.
Usually, a current limit warning indicates an incorrect
mechanical load. If possible, disconnect the motor from the
load to determine if the load is incorrect.
Often, the indications of motor problems are similar to the
problems of a defect in the frequency converter itself. To
determine whether the problem is internal or external to
the frequency converter, disconnect the motor from the
frequency converter motor terminals. Perform the initial
procedure with no motor connection on all 3-phases with
an analog voltmeter, see chapter 6.4.6 Output Imbalance of
Motor Supply Voltage Test. If the 3 voltage measurements
are balanced, the frequency converter is functioning
correctly. Hence, the problem is external to the frequency
converter.
If the voltage measurements are not balanced, the
frequency converter is malfunctioning. Typically, 1 or more
output IGBTs are not functioning correctly. This problem
can be a result of a defective IGBT or gate signal.
BAS-SVM04B-EN
TR150 and TR170 Service Manual

5.2 Internal Frequency Converter Problems

5.2.1 Overtemperature Faults

If an overtemperature indication is shown, determine
whether this condition actually exists within the frequency
converter, or whether the thermal sensor is defective.

5.2.2 Current Sensor Faults

Sometimes an over-current alarm that cannot be reset,
even with the motor cables disconnected, indicates when a
current sensor fails. However, the frequency converter
experiences frequent false ground fault trips. This is due to
the DC offset failure mode of the sensors.
The simplest method of determining whether a current
sensor is defective is to disconnect the motor from the
frequency converter. Then observe the current in the
frequency converter display. With the motor disconnected,
the current should be zero. A frequency converter with a
defective current sensor indicates some current flow. An
indication of a fraction of 1 A is tolerable. However, that
value should be considerably less than 1 A. If the display
shows more than 1 A of current, there is a defective
current sensor. All 3 current sensors in TR150 and TR170
units are mounted on one circuit board (either power card,
SMPS card, or current transducer card). The repair
procedure is to replace all 3 current sensors at the same
time.
5.2.3 Signal and Power Wiring
Considerations for Electromagnetic
Compatibility
This section provides an overview of general signal and
power wiring considerations when addressing the electro-
magnetic compatibility (EMC) concerns for typical
commercial and industrial equipment. Only certain high
frequency phenomena (such as RF emissions, RF immunity)
are discussed. Low-frequency phenomena (such as
harmonics, mains voltage imbalance, notching) are not
covered.
NOTICE
Special installations or compliance to the European CE
EMC directives require strict adherence to relevant
standards and are not discussed here.
02/2017 All rights reserved.
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