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PROTECTIVE FUNCTIONS
35
5.3.4 Insulation resistance test using megger
1) Before performing the insulation resistance test using a megger on the external circuit, disconnect the
cables from all terminals of the inverter so that the test voltage is not applied to the inverter.
2) For the continuity test of the control circuit, use a tester (high resistance range) and do not use the megger
or buzzer.
3) For the inverter, conduct the insulation resistance test on the main circuit only as shown below and do not
perform the test on the control circuit. (Use a 500VDC megger.)
R<L
1
>
S<L
2
>
T<L
3
>
U
V
M
IM
Inverter
Motor
Power
supply
DC500V
megger
Ground terminal
5.3.5 Dielectric strength test
Do not conduct a dielectric strength test. The inverter's main circuit uses semiconductors, which may be
deteriorated if a pressure test is made.
Daily and Periodic Inspection
Interval
Periodic
Area of
Inspec-
tion
Inspection
Item
Description
Daily
1
year
2
years
Method Criterion Instrument
Surrounding
environment
Check ambient
temperature, humidity,
dust, dirt, etc.
{
(Refer to page 3)
Ambient
temperature:
−
10
°
C to +40
°
C,
non-freezing.
Ambient humidity:
90% or less,
non-condensing.
Thermometer,
hygrometer,
recorder
Overall unit
Check for unusual
vibration and noise.
{
Visual and auditory
checks.
No fault.
General
Power
supply
voltage
Check that main circuit
voltage is normal.
{
Measure voltage
across inverter
terminals R-S-T
<L
1
-L
2
-L
3,
>.
Within permissible
AC voltage
fluctuation
(Refer to page 40)
Tester, digital
multimeter
General
(1) Check with megger
(across main circuit
terminals and
ground terminal).
(2) Check for loose
screws and bolts.
(3) Check for overheat-
ing of each part.
(4) Clean.
{
{
{
{
(1) Disconnect all
cables from
inverter and
measure across
terminals R, S, T,
U, V, W <L
1
, L
2
,
L
3,
U, V, W>, and
ground terminal
with megger.
(2) Re-tighten.
(3) Visual check.
(1) 5M
Ω
or more.
(2), (3) No fault.
500VDC class
megger
Conductors,
cables
(1) Check conductors
for distortion.
(2) Check cable
sheaths for
breakage.
{
{
(1), (2) Visual check. (1), (2) No fault.
Main
circuit
Terminal
block
Check for damage.
{
Visual check. No fault