OPERATION
GENERAL
The meter is intended for
use
horizontally.
If
the pointer
is not on
zero,
it
may
be
set by using the screw head on
the
panel.
The leads fitted with Long
Reach
Safety Clips Mark 2
or
clips,
as
required, should be connected to the lower pair
of
meter terminals except when measuring voltages over
1
OOOV
. Long Reach Safety Clips are
not
suitable for high
current.
When measuring current
or
voltage, ensure that
the
instru-
ment is set to either ac or
de
as
appropriate and a suitable
range before connecting up to the circuit under test. When
in
doubt, always switch to the highest range and work
downwards, there is
no
necessity
to
disconnect the leads
as
the
switch position is changed.
Do not switch o
ff
by rotating
ei
th
er
of
the knobs to a
blank position.
The instrument is fl
ash
tested at 7000V ac but
if
used
with
accessories on circuits in excess
of
3000V,
it
should be
kept at the
low
potential end
of
the circuit {near earth
potential) or other suitable safeguards must be applied. .
CURRENT
MEASUREMENT
To measure current, the instrument should
be
set to a
suitable ac or de range and then connected in series
with
the
circuit under test.
The voltage drop
at
the meter terminals is 400mV on the
1
OA
de range dropping to 1
OOmV
on the 50 microamp
range.
In the
case
of
ac ranges it is
less
than 450mV.
on all ranges. Standard meter leads have a resistance
of
0.02 ohm per pair. Ensure th
at
the circu
it
is 'dead' before
breaking into
it
to make current measurements.
VOLTAGE
MEASUREMENT
When measuring voltage,
it
is necessary to set the appro-
priate range of 'ac' or 'de' and connect the leads across the
source of voltage to be
me
as
ured.
If
the voltage is
un-
known, set
the
instrum
en
t to its highest range, connect
up
and
if
below 1
OOOV,
decrease the ranges step by step
until the most suitable range
has
been
selected.
If
the
voltage should exceed 1
OOOV,
the instrument should be
set to measure
1000\/
as
described above, but the positive
lead should
be
transfe
rr
ed
to the
ap
propr
ia
te 3000V
terminal.
Great care must
be
exercised when making connections
to a live circuit and the procedure should be entirely avoided
if
possible.
3
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