Fuse Replacement; Insulation Testing - Megger MJ10 Guide De L'utilisateur

Note:- With the BM12 the reading is taken after
pressing the 'Test' button, there is no other control to
operate.
Connect the test lead clips together, press the 'Test' button
and turn the generator handle (MJ10 only) again. The
meter should read zero. If it indicates infinity or a high
resistance value the leads may be open circuit and should
be inspected further. Replace them if necessary. (Shorting
the leads together and obtaining a zero reading also shows
that the instrument is working).
Note:- To avoid creating leakage paths when
insulation testing, it is advisable not to allow the leads to
twist together nor trail across metalwork etc. more than is
really necessary.
To check that the fuse in the continuity circuit is intact,
disconnect the test leads and set the rotary selector switch
to the 'Ω+' position. Press the 'Test' button and keep it
pressed whilst turning the generator handle (MJ10 only).
The reading obtained should be beyond full scale. If the
reading is approx. zero on the continuity resistance range
the fuse has ruptured and should be replaced.

Fuse Replacement

The fuse is held in a screw type holder situated in the base
of the instrument. To change a fuse, use a screwdriver to
release the centre part of the holder containing the fuse.
Replace with a 1 A 600 V 32 mm x 6 mm ceramic HBC fuse
(see 'Specification').

Insulation Testing

After connecting the test leads to the instrument and
carrying out the Preliminary Checks as detailed above, set
the selector switch to the voltage required. Having isolated
the circuit to be tested connect the test leads as follows:-
(a) For insulation tests to earth:-
Connect the '+' test lead to earth (ground) or frame of the
equipment, and the '–' lead to that part of the circuit to
be tested.
(b) For insulation tests between wires:-
Connect a lead to the core of each of the wires.
Press the 'Test' button and whilst keeping it pressed turn
the generator handle (MJ10 only). The meter pointer will
indicate the value of insulation resistance on the 'MΩ'
scale. If a capacitive circuit is tested the pointer will initially
deflect towards zero and then gradually rise to its final
steady value as the capacitance is charged up to the output
voltage of the tester.
If several successive readings of '∞' are obtained, connect
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