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LABORATORY TEST METHOD NO. H-12
DIELECTRIC VOLTAGE BREAKDOWN
1. PURPOSE:
To verify the integrity of electrical component insulation used
in appliances through the application of a specific high voltage
to the input power circuit over a period of time. In normal
operation of the appliance, insulation breakdown (dielectric
failure) could allow electrical current to pass directly to the
user.
2. REFERENCE:
Various UL Standards
3. TEST APPARATUS AND MATERIALS:
3.1 Slaughter Model No.105-5 OW, Hi-pot tester or dielectric
strength tester or similar equipment.
4. PROCEDURE:
CAUTION: Because of the
high voltage output, the dielectric strength tester can be very
dangerous. Therefore, do not come in personal contact with the
exposed test probe lead tips when testing. Do not leave the
dielectric strength tester "ON" when not in actual use.
4.1 Allow appliance to be tested to operate until the normal
operating heat build-up has been attained.
4.2 Turn on the dielectric strength tester and set the voltage
output to the specific amount required by the applicable UL
Standard for the appliance being tested.
4.3 Touch one test probe to one prong of the bi-polar AC plug,
then touch the other test probe to an exposed "DEAD"
metal part, such as the outside case or chassis. Maintain this
contact for 60 seconds. The buzzer and light of the dielectric
tester will remain "OFF" if insulation of the appliance
being tested does not breakdown. Repeat the same procedure using
the other prong of the bi-polar AC plug. ,-
5. REPORT:
Report the result of this test in terms of whether the
appliance being tested pass or failed applicable UL Standards. In
case of failure, note the voltage at which the insulation
breakdown occurred.
_HARDLINES
TEST METHOD_
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