Operation; Precautions; Battery Condition Tests; Battery Replacement - Megger MJ10 Guide De L'utilisateur

Operation

Precautions

1. The circuit under test must be de-energized and
isolated before insulation or continuity tests are
made. The instrument's voltmeter function may be
used to verify that the circuit is 'dead'.
2. When capacitive circuits have been tested allow a
suitable time to elapse, before disconnecting the
test leads, for the circuits to discharge. Monitor the
discharge on the meter and remove the test leads,
when this voltage has fallen to zero.
3. The instrument should not be used in explosive
or inflammable environments, although there is
unlikely to be a fire hazard due to the instrument
itself. However, arcing in faulty insulation, sparking
caused when making or removing connections to
equipment that has not been properly de-energized,
or discharge of capacitance following tests, can all
lead to explosion or fire hazard.
Battery Condition Test (BM12 only)
Prior to carrying out any of the preliminary checks
or testing with the instrument, perform the battery
condition test. Press the battery condition test switch,
marked with the battery symbol, and check that the
meter indicates within the portion of the scale marked
with the battery symbol. If the meter does not indicate
the correct battery voltage level the cells must be
changed before proceeding with any checks or testing.
6
Battery Replacement (BM12 only)
The cells are housed in a battery compartment in the
base of the instrument. To change the cells, use a
screwdriver to remove the battery cover securing screw
and lift off the battery compartment cover. Replace the
cells ensuring that the polarity is as marked on the base
of the battery compartment. Replace and secure the
battery compartment cover.

Preliminary Checks

Without the test leads being connected to the
instrument, but with the rotary selector switch set to
the 1 kV range, press and hold down, the 'Test' button,
whilst turning the generator handle (MJ10 only).
The meter pointer should remain over the '∞' (infinity)
position on the scale. This establishes that there is no
leakage through the instrument itself.
Inspect the test leads to see that they have good
unbroken insulation and that they are not contaminated
with grease, oil or dirt. Connect two of the test leads to
the '+' and '–' terminals on the side of the instrument
case and ensure that their clips are not touching
anything. Press the 'Test' button again and keep it
pressed whilst turning the generator handle (MJ10 only)
and observe the meter pointer. It should rest over the
'∞' (infinity) position on the scale. If it does not, the test
leads may be faulty and should be inspected more closely
for damage. Replace them if necessary.