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PROTECTIVE FUNCTIONS
143
Interval
Periodic*
Area of
Inspection
Inspection
Item
Description
Daily
1 year
2 years
Method Criterion Instrument
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 there is
no fault in
protective or
display circuits.
'
'
(1) Measure voltage
across inverter
output terminals
U-V-W.
(2) Simulate
connection of
inverter
protective circuit
output terminals.
(1) Phase-to-
phase
voltage
balance
within 4V for
200V.
(2) Fault must
occur
because of
sequence.
Digital
multimeter,
rectifier
type
voltmeter
Cooling
system
Cooling fan
(1) Check for unusual
vibration and
noise.
(2) Check for loose
connection.
'
'
(1) Turn by hand
with power off.
(2) Visual check.
No unusual
vibration and
unusual noise.
Display
(1) Check for LED
lamp blown.
(2) Clean.
'
'
(1) Lamps indicate
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 overheat,
damage, etc.
(1), (2) No fault.
Motor
Insulation
resistance
Check with megger
(across terminals and
ground terminal).
'
Disconnect cables
from U, V, W,
including motor
cables.
5M
Ω
or more. 500V
megger
* For periodic inspection, contact you nearest Mitsubishi sales representative.