Mains Phase Loss Trips; Control Logic Problems; Programming Problems - Trane TR150 Service Manual

Frequency Converter and Mot...

5.1.2 Mains Phase Loss Trips

The frequency converter monitors phase loss by
monitoring the amount of ripple voltage on the DC bus.
Ripple voltage on the DC bus is a product of a phase loss
and can cause overheating in the DC-bus capacitors and
the DC coil. If the ripple voltage on the DC bus is
unchecked, the lifetime of the capacitors is drastically
reduced.
When the input voltage becomes unbalanced or a phase
disappears completely, the ripple voltage increases. This
5
5
increase causes the frequency converter to trip and issue
alarm 4, Mains Phase Loss. In addition to missing phase
voltage, a line disturbance or imbalance can cause an
increased bus ripple.
Possible sources of disturbance
•
Line notching.
•
Defective transformers.
•
Other loads that can affect the form factor of the
AC waveform.
Mains imbalances which exceed 3% cause sufficient DC-
bus ripple to initiate a trip.
Other causes of increased ripple voltage on the DC bus
are:
•
Output disturbance.
•
Missing or lower than normal output voltage on
1 phase.
Checks
When a mains imbalance trip occurs, check both the input
and output voltage of the frequency converter.
Severe imbalance of supply voltage or phase loss is
detectable with a voltmeter. View line disturbances
through an oscilloscope. Conduct tests for:
•
Input imbalance of supply voltage.
•
Input waveform.
•
Output imbalance of supply voltage.
See details in chapter 4 Troubleshooting.

5.1.3 Control Logic Problems

Problems with control logic can often be difficult to
diagnose, since there is usually no associated fault
indication. The typical complaint is that the frequency
converter does not respond to a given command. To
obtain an output, give the following 2 basic commands to
the frequency converter:
•
Start command: To execute.
•
Reference or speed command: To identify the
speed of execution.
40
The frequency converters are designed to accept various
signals. First, determine which of these signals the
frequency converter is receiving:
•
•
•
•
•
The presence of a correct reading indicates that the
microprocessor of the frequency converter has detected
the wanted signal. See chapter 2.3 Frequency Converter
Inputs and Outputs.
This data can also be read in parameter group 16-6* Inputs
and Outputs.
If there is no correct indication, check if the signal is
present at the input terminals of the frequency converter.
Use a voltmeter or oscilloscope in accordance with
chapter 6.4.7 Input Terminal Signal Tests.
•
•

5.1.4 Programming Problems

Difficulty with operation of the frequency converter can be
a result of improper programming of the frequency
converter parameters.
Three areas where programming errors can affect
frequency converter and motor operation are:
•
•
•
See chapter 2.3 Frequency Converter Inputs and Outputs.
Set up the frequency converter correctly for the motor or
motors connected to it. Parameters must have data from
the motor nameplate entered into the frequency converter.
These data enable the frequency converter processor to
match the frequency converter to power characteristics of
the motor. Inaccurate motor data can cause the motor to
draw higher than normal amounts of current when
performing a task. In such cases, setting the correct values
to these parameters and performing the AMA function
usually solves the problem.
02/2017 All rights reserved.
Digital inputs (18, 19, 27, and 29).
Analog outputs (42 and 45).
10 V output.
Analog inputs (53 and 54).
Serial communication bus (68 and 69).
If the signal is present at the terminal, the control
card is defective and must be replaced.
If the signal is not present, the problem is
external to the frequency converter. Therefore,
check the circuitry providing the signal along
with its associated wiring.
Motor settings.
References and limits.
I/O configuration.
BAS-SVM04B-EN