Farnell L30A - Page 8

Output
Current
Variation
for
10%
Mains
Change
(Accurate
Constant
Current
Operation)
Less than
.01
%
or 1mA whichever
is the
greater—
short term.
Less
than
.02%
or
2mA whichever
is the
greater
—long term.
Output
Current
Variation
for
Zero
Resistance
to
Max. Resistance
Change (Accurate
Constant
Current Operation)
Less
than
.01%—short term.
Less than
.02%—long
term.
Output
Current
Variation
for 10%
Mains
Change
(Approximate
Constant
Current
Operation)
Less
than 1
%—short term.
Less than
2%—long
term.
Output
Current
Variation
for
Zero
Res.
—
Max.
Res. Change
(Rough
Constant Current
Operation).
Less than
2%—short
term.
Less
than
3%—
long term.
Ripple
Voltage
at Full
Load
Less than
ImV peak to
peak.
Ripple
Current
at Full
Load
Less than
ImA
peak
to peak.
Overload
Protection
Current
Limiting.
Overvoltage
Protection
Thyristor
"crowbar" trip.
Trip level adjustment
approx. 3.2V.
to 14V., temp,
coefficient of trip
level
0.04%
/°C. typical.
Max. Operating
Temperature
45°C.
Temperature
Coefficient
±0.02%
per °C. Typical.
Output
Impedance
See Fig.
(2).
8
SECTION
V
INTERNAL
ADJUSTMENT
Units
are
set up
before
leaving
the factory,
but in
the
event
of
future
mis-alignment
the
setting-up
procedure
is
as follows
:—
VOLTAGE
ADJUSTMENTS
(1)
An
accurate
voltmeter
is
connected
between
the
"O/P—
"
and
"O/P
\-"
terminals,
with
an
f.s.d.
compatible
with
the
specified
maximum
output
voltage
of
the
unit.
With
the unit
switched
on,
the link
on the
bottom
of
the unit
set
to
"CV"
and
the
"VOLTAGE
ADJUST"
controls
fully
clockwise,
TI,
on
the
circuit
board,
is
adjusted
to
give
the
specified
maximum
output
voltage.
(2)
With the
meter
switch
set to
"VOLTS",
T3
is
now
adjusted
so
that
the front
panel
meter
reads
full
scale.
CURRENT
ADJUSTMENTS
(1)
An
accurate
ammeter with
an
f.s.d.
compatible
with
the
specified
maximum
output
current
of
the
unit,
is
connected
in
series
with
a
variable
load
between
the
"0/P+"
and
"O/P—
"
terminals.
With
the
unit
switched
on,
the link
on the
bottom
of the unit
set to
"CV" and
the
"CURRENT
LIMIT"
control
fully
clock-
wise,
the
load
is
adjusted
to
give
10%
in
excess of
the
specified
maximum
output
current.
T2
is then
adjusted
until
the current
just starts
to fall.
{2)
With
the meter
switch
set to
"AMPS",
the
load
is
re-adjusted
to give
the
specified
maximum
output
current
and
T4
is
adjusted
so
that the
front
panel
meter
reads
full scale.
9