Voltage Range - Megger MJ10 Guide De L'utilisateur

The guard terminal is at the same potential as the negative
terminal. Since the leakage resistance is effectively in
parallel with the resistance to be measured, the use of the
guard causes the current flowing through surface leakage
to be diverted from the measuring circuit. The instrument
therefore reads the leakage of the insulator, ignoring
leakage across its surface.

Voltage Range

The a.c. voltage range on the instrument is effective
whenever the 'Test' button is not pressed. Therefore, as
soon as the test leads are connected to the item under test,
any a.c. voltage present will be immediately shown. Thus
indication is given that the item has not been completely
de-energized.
The instrument may be used directly as an a.c. voltmeter
with a 0 - 600 V range. It also acts as a discharge monitor
when the 'Test' button is released following an insulation
test on a capacitive item, e.g. a cable. In this case it is
important to realise that the actual voltage is not shown
(that being d.c. in nature), but the meter does indicate
when the voltage has decayed to zero and therefore when
it is safe to remove the test leads. Please note, however,
that the instrument does not indicate the presence of
negative d.c. voltages.
Note:- Users of this equipment and or their employers are
reminded that Health and Safety Legislation require them
to carry out valid risk assessments of all electrical work so
as to identify potential sources of electrical danger and risk
of electrical injury such as from inadvertent short circuits.
Where the assessments show that the risk is significant then
the use of fused test leads constructed in accordance with
the HSE guidance note GS38 'Electrical Test Equipment for
use by Electricians' should be used.
9