Megger BM80/2 Series, User Manual

Page: 8 / 89

Operation
Insulation Tests (M
Ω
)
Insulation tests operate only when the TEST
button is pressed. (See the separate
instructions for fitting the TEST button). These
tests produce high voltages at the terminals
and are initiated when the TEST button is
pressed. When the TEST button is released,
the reading will be held for a few seconds, the
item under test will automatically be
discharged, and the capacitive charge decay
shown on the Live Circuit Warning voltmeter.
When the 1 kV range has been selected
(
BM80/2 & BM82/2 only) and the TEST
button pressed, there will be a safety delay of
3 seconds and ‘1000 V’ will flash before the
test voltage is applied. This delay only occurs
as a warning the first time that the button is
pressed after the range has been selected.
The delay will not occur on subsequent tests.
1. Set the selector switch to the test
voltage required.
2. Connect the test leads, first to the
instrument, and then to the isolated
item under test.
3. Press the TEST button to activate the test
voltage.
4. Release the TEST button at the end of the
test. The reading will hold for a few
seconds.
5. Any capacitive circuits charged during a
test will automatically discharge. If
significant voltage remains the voltage
warning will occur.
6. Remove the test leads only when no
voltage is indicated.
Polarization Index Testing
Polarization Index (PI) is the term applied to
the Dielectric Absorption Ratio when
resistance values are measured after 1 minute
and again after 10 minutes. Polarization Index
is then the resistance value after 10 minutes
divided by the resistance value after 1 minute.
The test can be run at any voltage.
More detailed information on PI Testing and
value assessment can be found in Megger
Limited publications listed in the Accessories
page.
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