MI 3201 TeraOhm 5 kV Plus Measurements
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and reaches the final test voltage with a slope that keeps the charging current under the
limit of the current threshold. The test duration normally takes 1 min.
Withstanding voltage test or dielectric test is usually applied for:
- Type (acceptance) tests when a new product is being prepared for manufacture,
- Routine (production) tests for the verification of safety on each product,
- Maintenance and after service tests for any equipment where insulation system can
be exposed to degradation.
Some examples for DC withstanding test voltage values:
Standard (only sample values) Voltage
EN/IEC 61010-1 CAT II 300 V basic insulation 1970 V
EN/IEC 61010-1 CAT II 300 V double insulation 3150 V
IEC 60439-1 (clearance between live parts…), withstanding impulse
voltage 4 kV, 500 m
4700 V
IEC 60598-1 2120 V
Humidity and insulation resistance measurements
When testing outside the reference ambient conditions, the quality of the insulation
resistance measurements can be affected by humidity. Humidity adds leakage paths
onto the surface of the complete measuring system, (i.e. the insulator under test, the
test leads, the measuring instrument etc). The influence of humidity reduces accuracy
especially when testing very high resistances (i.e. tera ohms). The worst conditions
arise in environments containing high condensation, which can also reduce safety. In
the case of high humidity, it is recommended to ventilate the test areas before and
during the measurements. In the case of condensed humidity the measuring system
must dry and it can take several hours or even few days to recover.
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