AVO AVOMETER 8 Руководство по эксплуатации - Страница 5

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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
off
by rotating
eith
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
that
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
measured. If
the
voltage
is
un-
known,
set
the instrument to
its highest
range,
connect
up
and
if
below 1 OOOV, decrease the
ranges
step
by step
until
the
most suitable
rang
e
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 transferred
to the
appropriate
3000V
terminal.
Great care must be
exercised
when making connections
to a live circuit
and the procedure should
be
entirely
avoided
if possible.
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