Introduction; Static Test Procedures - Trane TR150 Service Manual

Test Procedures

6.2 Introduction

WARNING
DISCHARGE TIME!
Frequency converters contain DC-link capacitors that can
remain charged even when the frequency converter is
not powered. To avoid electrical hazards, disconnect AC
mains, any permanent magnet type motors, and any
remote DC-link power supplies, including battery back-
ups, UPS, and DC-link connections to other frequency
converters. Wait for the capacitors to fully discharge
before performing any service or repair work. The
amount of wait time is listed in the Table 1.1. Failure to
wait the specified time after power has been removed
before doing service or repair could result in death or
serious injury.
This section contains detailed procedures for testing
frequency converters. Previous sections of this manual
provide symptoms, alarms, and other conditions which
require additional test procedures to diagnose the
frequency converter further. The results of these tests
indicate the appropriate repair actions. Again, because the
frequency converter monitors input and output signals,
motor conditions, AC, and DC power and other functions,
the source of fault conditions may exist outside of the
frequency converter. Testing described here isolates many
of these conditions as well. Disassembly and Assembly
Instructions describes detailed procedures for removing
and replacing frequency converter components.
Frequency converter testing is divided into Static Tests, and
Dynamic Tests. Static tests are conducted without power
applied to the frequency converter. Most frequency
converter problems can be diagnosed simply with these
tests. Static tests are performed with little or no
disassembly. The purpose of static testing is to check for
shorted power components. Perform these tests on any
unit suspected of containing faulty power components
before applying power.
CAUTION
For dynamic test procedures, main input power is
required. All devices and power supplies connected to
mains are energized at rated voltage. Use extreme
caution when conducting tests on a powered frequency
converter. Contact with powered components could
result in electrical shock and personal injury.
Dynamic tests are performed with power applied to the
frequency converter. Dynamic testing traces signal circuitry
to isolate faulty components.
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Digital voltmeter/ohmmeter capable of reading
real RMS
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Analog voltmeter
BAS-SVM04B-EN
TR150 and TR170 Service Manual
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6.3 Static Test Procedures

The purpose of performing static testing is to check for
any short circuit of the power components.
For all tests, use a meter capable of testing diodes. Use a
digital Volt-Ohm Meter (VOM) set on the diode scale or an
analog ohmmeter set on Rx100 scale.
Before making any checks, disconnect all connections for:
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Ensure that the frequency converter is disconnected from
power, before performing static tests.
WARNING
SHOCK HAZARD
Disconnection of the input cable while the frequency
converter is powered could result in electrical shock
causing death or personal injury.
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6.3.1 Pre-test Precautions
Consider the following safety precautions before
performing static tests.
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02/2017 All rights reserved.
Oscilloscope
Current meter
Input.
Motor.
Brake resistor.
Do not disconnect the input cable while the
frequency converter is powered.
Prepare the work area according to the ESD
regulations.
Ground the ESD mat and wrist strap.
Ensure that the ground connection between
body, the ESD mat, and the frequency converter
is always present while performing service.
Handle disassembled electronic parts with care.
Perform the static test before powering up the
fault unit.
Perform static test after completing the repair
and assembly of the frequency converter.
Connect the frequency converter to the mains
only after completion of static tests.
Complete all necessary precautions for system
start-up, before applying power to frequency
converter.
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