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PROTECTIVE FUNCTIONS
178
Interval
Periodic
*
Area of
Inspec-
tion
Inspection
Item
Description
Daily
1
year
2
years
Method Crlterlon 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 a meter range of
100
Ω
.
(Refer to page 179) Analog 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 a meter.
(1) No fault.
(2) Error should
be within
±
10%
of indicated
resistance
value.
Meter, digital
multimeter
Control
circuit
Protec-
tive 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
4V(8V) for
200V(400V).
(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, unusual
noise.
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
Check with megger
(across terminals and
ground terminal).
$
Disconnect cables
from U, V, W,
including motor
cables.
5M
Ω
or more 500V megger
Note: Values in parentheses are those of the 400V class.
*For periodic inspection, consult Mitsubishi.
5