Farnell L30A - Page 4

SECTION
I
INTRODUCTION
This
manual
covers
the
MK
II
L30 series
of
D.C.
stabilised
voltage/current
supply
units.
The
circuit
diagram
contained
in
the
manual is
for the
particular
unit type
supplied.
Twin
units
are
designated
L30
-/T and
consist of
two appro-
priate
L30
units
mounted
in the
one case.
The
two
outputs
are
completely
independent.
They
may be
used
as
separate
supplies
or
alternatively
may be
connected
in
series or
parallel, to
provide
higher
output
voltages
or
currents
than
can be
obtained
from
a
single L30
supply.
The
semiconductor
complement
of
these
supplies is
silicon
throughout,
permitting
operation
to 45"C
ambient
at full
specified
output.
The
output
voltage
is
adjusted
by
means
of
two
controls
on
the
front
panrl
marked
"
COARSE
"
and
"
FINE."
The
o-itput
voltage or
current is
monitored
by a
switched
voltmeter/ammeter.
Overload
protection
is
provided
to
protect
the
power
unit
and
apparatus,
being
supplied by
limiting
the output
current to
a set
valup.
This
value is
adjustable
from
zero
to the
maximum
current
of
the
unit by
means of
a
control
on the
front panel
marked
"
CURRENT
LIMIT."
The circuit
will
automatically
reset
when
the
overload is
removed.
The
instrument
will operate
from
mains supplies
of 210, 220,
230
and
240v. A.C.
at
50/60
Hz.
(An
alternative
instrument
is
manufactured
for use
with
mains
supplies
of
105—
120v.).
Certain
units
in the
range
are
fitted
with
internal
overvoltage
protection
(see
Section
IV)
when
the unit
output
exceeds
a level
set by
means
of
a
front
panel
control,
the
unit output is
clamped
to
a
low
value by
means of a
thyristor
crowbar
circuit.
'