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4.3 Dielectric Strength Test
To confirm the freedom from insulation breakdown, testing should be carried out under the conditions
specified below.
1) Measuring conditions
Measuring instrument: Dielectric strength tester (The specified voltage should be maintained in the
state that a current of 10mA is carried.)
Testing point: Between the electrical circuit block and the exposed metallic block (D-SUB connector)
Note: The electrical circuit block should mean the power input block (primary side). Testing should be carried
out under the condition that both poles of the power plug are short-circuited. (Where a 3-core cord is used, the
two poles other than the earth terminal should be short-circuited.)
2) Judgment standard
The freedom from insulation breakdown should be confirmed under the condition that the applied voltage
is maintained at 1500V AC (+0 to 50V) for one minute.
Even though the result of this testing is OK, such a condition should be regarded as unacceptable if there
is a leakage (flashing) around the section where the test voltage has been applied.
If the result of insulation resistance test is found unacceptable, to be carried out after this testing,
such a condition should be regarded as that an insulation breakdown has occurred.
4.4 Leakage Current Test
A leakage current should be measured under the conditions specified below, in order to confirm that the
requirements of the judgment standard are met.
1) Measuring conditions
Measuring instrument: Leakage current meter (A 1500Ω resistor should be incorporated, together
with a bypass capacitor of 0.15µF. )
Testing point: Between the exposed metallic block (D-SUB connector) and Phases A and B of the
power source.
Condition of the set: A power cable should be connected without connecting a signal generator. The
see-saw switch on the set side should be turned ON and OFF.
2) Judgment standard
The leakage current measured should be 1.5mA or less with an input of 240V AC × 1.06 +5/-0V (60Hz).
4.5 Insulation Resistance Test
An insulation resistance should be measured under the conditions specified below, in order to confirm that the
requirements of the judgment standard are met.
1) Measuring conditions
Measuring instrument: 500V DC MEGOHM Meter
Testing point: Between the power circuit block and the exposed metallic block
(D-SUB connector)
Measured value readout: A test voltage should be applied for one minute and the resistance
value should be read out thereafter.
2) Judgment standard: 10MΩ or more
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