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4 insulation resistance test using megger, 5 dielectric strength test, Protective functions – MITSUBISHI ELECTRIC FR-A500L User Manual

Page 46: Daily and periodic inspection

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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

1

>

S

2

>

T

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

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

1

, L

2

,

L

3,

U, V, W>, and

ground terminal
with megger.

(2) Re-tighten.
(3) Visual check.

(1) 5M

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