Marconi Instruments 2955 - Page 21

INSTALLATION
POWER
SUPPLY
REQUIREiVltN
i S
The
instnjmem
may
be
operared
from
AC mains
or
from an
external
battery
pack,
AC
power
supply
^For
AC
operation,
the
instrument
requires
105
to 120
V
or 210
to 240
V,
50
to
400
required
supply
fuses
(time
lag)
are
lA for
105 to
120
V
or
500
mA
for
--10
to
240 V.
^
^fore
switching
on,
ensure
that
the
rear
panel voltage
range
switch
is
in
Its
coirect
position
as
revealed
by the
cut-cut
in
the
locking
plate,
and
that
the
correct
value
fuses
are
fitted.
To
change
the
mains
voltage
setting,
reverse
the
locking
plate
after
setting
the
slide
switch
to
its
alternative
position.
The
AC
supply
cable
is
fitted at
one
end
with
a
female plug
which
mates
with
the
AC
connector
at
the
rear
of the
instrument.
When
fittins
a suopiy
plue,
ensure
that
the
connections
are
as
follows:-
Earth
(ground)
-
Green/Yellow
Neutral
-
Blue
Live
(phase)
-
Brown
When
attaching
the
mains
lead
to a
non-soldered
plug,
It is
recommended
that
the
unned^ends
of
the
lead
are
first
cut
off
to avoid
the
danaer of
cold
flow
resultins
in
intermittent
connection.
DC
power
supply
For
DC
operation,
a
16
V,
7
Ah
rechargeable
nickel
cadmium
battery
pack
is avail-
able^
as an
optional
accessory.
The
battery
is
protected
bv a
time-lae
6.3
A fuse. Remove
the
battery
lead
from
its
stowage
and
connect
to
the
DC
SUPPLY^
socket
on the
instru-
ment
rear
panel.
With
a
fully-charged
battery,
operating
time
is in
excess
of 1 hour.
Aternatively,
an
external
DC
supply
of
between
11
V
and 32
V
and able
to
supply
cr
^
used.
Connect
the
battery leads
to
the
rear panel
DC
SUPPLY
socket
ensuring
that
polarities
are
correct.
AC
and
DC
operation
If
both
the
DC
supply
and
the
AC supply
are
connected, the instrument automati-
cally
selects
AC
power.
If the
AC
power
is
then
removed,
the instrument switches to
DC
with
no
interruption
of
operation.
In
certain
circumstances,
the
external power supply
may
not
be
able
to
take
the
sudden
change
in load
and its
inbuilt protection,
e.g.
current
feedback
limiting,
may
switch
off the
supply.
Tnis
can normally be prevented by setting
the
DC supply
to
around
20
V.
There
should
be no
problems
with
units
able
to supply
32
V
at
approx.
4
mA.
To
protect
the
~12 V
power
supply
to board
ACl,
an in-line fuse
has been
fined
between
boards
ACl
and
ABl.
The fuse
is
1.6 A
time-lag.
Access to
it is gained
after
removal
of the
upper
half
of
the
case.
The
fuse
is
located
adjacent to
the grey
box
of the
crystal
oscillator.
46S81-622N
Apr.
83
2-3