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PROTECTIVE FUNCTIONS
36
Daily and Periodic Inspection
Interval
Periodic
Area of
Inspec-
tion
Inspection
Item
Description
Daily
1
year
2
years
Method
Criterion
Instrument
Inverter
module,
Converter
module
Check resistance
across terminals.
¡
Disconnect cables
from inverter and
measure across
terminals R, S, T, P, N
and U, V, W, P, N <L
1
,
L
2
, L
3,
+, -, and U, V,
W, +, -> with tester
range of 100
Ω
.
(See the following
pages)
Analog tester
Smoothing
capacitor
(1) Check for liquid
leakage.
(2) Check for safety
valve projection
and bulge.
(3) Measure
electrostatic
capacity.
¡
¡
¡
(1), (2) Visual check.
(3) Measure with
capacity meter.
(1), (2) No fault.
(3) 85% or more
of rated capacity.
Capacity
meter
Relay
(1) Check for chatter
during operation.
(2) Check for rough
surface on
contacts.
¡
¡
(1) Auditory check.
(2) Visual check.
(1) No fault.
(2) No fault.
Main
circuit
Resistor
(1) Check for crack in
resistor insulation.
(2) Check for open
cable.
¡
¡
(1) Visual check.
Cement resistor,
wire-wound
resistor.
(2) Disconnect one
end and measure
with tester.
(1) No fault.
(2) Error should
be within
±
10% of
indicated
resistance
value.
Tester, digital
multimeter
Control
circuit
Protective
circuit
Operation
check
(1) Check balance of
output voltages
across phases
with inverter
operated
independently.
(2) Perform sequence
protective operation
test to make sure of
no fault in
protective and
display circuits.
¡
¡
(1) Measure voltage
across inverter
output terminals U-
V-W.
(2) Simulatively
connect or
disconnect
inverter protective
circuit output
terminals.
(1) Phase-to-
phase voltage
balance within
8V for 400V.
(2) Fault must
occur
because of
sequence.
Digital
multimeter,
rectifier type
voltmeter
Cooling fan
(1) Check for unusual
vibration and noise.
(2) Check for loose
connection.
¡
¡
(1) Turn by hand with
power off.
(2) Re-tighten
(1) Smooth
rotation.
(2) No fault.
Cooling
system
Cooling fan
power
supply
Is the power supply's
output voltage correct?
¡
Measure with a
tester.
24V 2.4V
Tester
Display
(1) Check if LED lamp
is blown.
(2) Clean.
¡
¡
(1) Light indicator
lamps on panel.
(2) Clean with rag.
(1) Check that
lamps are lit.
Display
Meter
Check that reading is
normal.
¡
Check reading of
meters on panel.
Must satisfy
specified and
management
values.
Voltmeter,
ammeter, etc.
General
(1) Check for unusual
vibration and noise.
(2) Check for unusual
odor.
¡
¡
(1) Auditory, sensory,
visual checks.
(2) Check for unusual
odor due to
overheating,
damage, etc.
(1), (2) No fault.
Motor
Insulation
resistance
(1) Check with megger
(across terminals
and ground
terminal).
¡
(1) Disconnect cables
from U, V, W,
including motor
cables.
(1) 5M
Ω
or more
500V megger