Chapter 6 Maintenance and Inspection
6-2
6.2 Daily and Periodic Inspections
Check the ambient temperature,
humidity, and dust.
See Section 2.1, "Installation."
The ambient temperature must be
within -10C to +50C without
congelation. The ambient humidity
must be 90% RH or less without
condensation.
Thermometer,
hygrometer,
recorder
Check for abnormal vibrations and
noise.
Check visually and by listening.
There must be no abnormality
found.
Check that the main circuit voltage is
normal.
Measure the voltage between the main
circuit terminals R, S, and T.
The measured voltage must be
within the allowable tolerance for
AC power voltage.
Tester, digital
multimeter
(1) Check the ground resistance
between the main circuit and
ground terminals with a megger.
Disconnect all input and output cables
from the inverter's main circuit terminal
block, detach the control circuit terminal
block from the inverter, and remove the
jumper for switching the inverter's internal
filter function. Subsequently, measure the
insulation resistance between the ground
terminal and the jumper connecting all the
following terminals:
R, S, T, U, V, W, P, PD, N, RB, R0, and T0
The measured ground resistance
must be 5M or more.
(2) Check screws and bolts for
loosening.
Retighten loose screws and bolts.
There must be no abnormality
found.
(3) Check each part for any trace of
overheating.
There must be no abnormality
found.
Connecting
conductors and
cables
(1) Check the conductors for
distortion.
There must be no abnormality
found.
(2) Check the cable insulations for
damage.
Check the terminal blocks for damage.
There must be no abnormality
found.
Inverter circuit and
converter circuit
(including
resistors)
Check the resistance between
terminals.
Remove all cables from the inverter's
main circuit terminal block. Use a
tester (in 1Ω range mode) to measure
the following:
- Resistance between terminals R, S,
and T and terminals P and N
- Resistance between terminals U, V,
and W and terminals P and N
See Section 6.5, "Method of
Checking the Inverter and Converter
Circuits." Standard operating life of
power module(IGBT,IPM,Diode and
Thyristor ) until replacement: 10
6
cycles of starting and stopping (*3)
(1) Check for liquid leak.
There must be no abnormality
found.
Target operating life until
replacement: 10 years
(*1) (*3)
(2) Check that the relief valve does not
protrude or swell.
(1) Check that no fluttering sound is
generated during the relay
operation.
There must be no abnormality
found.
(2) Check the contacts for damage.
There must be no abnormality
found.
Control
and
protective
circuits
(1) While performing a unit operation
of the inverter, check the balance
output voltage among the
individual phases.
Measure the voltage between the
cables connected to the main circuit
terminals U, V, and W.
The inter-phase voltage balance
must be as follows:
200 V class models: 4 V or less
400 V class models: 8 V or less
Digital multimeter,
rectifier
instrument, and
voltmeter
(2) Carry out a sequential protection
operation test, and check the
protective and display circuits for
any abnormality.
Short-circuit or open the protective
circuit outputs as a simulation.
An error must be detected
according to the sequence.
(1) Check for abnormal vibrations and
noise
Turn the fan manually during the
inverter power-off status.
The fan must rotate smoothly. There
must be no abnormality found.
Standard operating life until
replacement: 10 years
(*2) (*3)
(2) Check the joints for loosening.
The heat sink must not be clogged.
(1) Check that all LEDs light up
normally.
The LEDs must light up normally.
Clean the monitor with a rag.
Check that meter readings are normal.
Check the meter readings on the panel.
The readings must meet the
standard and control values.
(1) Check for abnormal vibrations and
noise.
Check vibrations and noise visually, by
listening, and with physical senses.
There must be no abnormality
found.
(2) Check for unusual smells.
Check for any unusual smells caused by
overheating or damage.
There must be no abnormality
found.
Check the ground resistance between
all motor terminals and the ground
terminal with a megger.
Remove the cables from the inverter's
main circuit terminals U, V, and W,
connect the motor wires (for three
phases) with one another, and
measure the ground resistance
between the motor wires and the
ground terminal.
The measured ground resistance
must be 5M or more.
*1 The operating life of the smoothing capacitor is under the influence of the ambient temperature. Refer to Section 6.6, "Smoothing-Capacitor Life Curve," as a standard for the operating life until
replacement.
*2 The operating life of the cooling fan varies depending on environmental conditions, including the ambient temperature and dust. Check the status of the cooling-fan operation during daily
inspections.
*3 The standard operating life (number of years or operation cycles) and the data described in Section 6.6, "Smoothing-Capacitor Life Curve," are based on the expected design life, but they do not
indicate the guaranteed life of any parts.
*4 When replacing to the capacitor stored for 3 years or longer, please have shakedown period as below.
Apply 80% of rated voltage for 1 hour.
Increase the voltage to 90% and keep for 1 hour.
Then apply rated voltage for 5 hours.
*5 In case fan is locked by dust or particle, it takes 5 to 10 seconds to restart even after the dust is removed.
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