HP Lab Series User Manual

3-9
CONSTANT CURRENT
3-10
To
select
a
constant
current
output,
proceed
as
follows:
a.
~hortoutput
terminals.andadjust
CURRENT
controls
for
desired
output
current~
·
b.
Open
output
terminals
and
adjust
VOLTAGE
controls
for
maximum
output
voltage
allowable
·
(voltage
limit),
as
determined
by
load
conditions.
If
a
load
cbanqe
causes
the
voltage
limit
to
be
ex-
ceeded,
the
power
supply
will
automatically
cross-
over
to
ci>nstant
voltage
output
at
the
preset
volt-
age
limit
and
the
output
current
will
drop
propor-
tionately.
In
setting
the
voltage
limit,
allowance
must
be
made
for
high
peak
voltaqe.s
whlQh
can
ca!lse
unwanted
crossover,
(Refer
tO
~aragra~h:3.~48
..
)
3-11
CONNECTING
I.DAD
3-12
Each
load
shoµld
be
connected
to
the
power
supply
output
terminals
using
separate
pairs
of
connecting
wires.
This
will minimize mutual
cou-
pling
effects
between
loads
and
will
retain
full
ad-
vantage
of
the
low
output
impedance
Of
the
power
aupply.
Each
pair
of
connecting
wires
should
be
as
short
as
possible
and
twisted
or
shielded
to
reduce
noise
pickup.
(If
shield
is
used,
connect
one
end
to
power
supply
gi-Ound
terminal
and
leave
the
other
end
unconnected.)
·
3-13
If
load
considerations
require
that
the
outp1,1t
power
distribution
terminals
be
remotely
located
from
the
power
supply,
then
the
power,
supply
output
terminals
should
be
connected
to
the
remote
distri-
bution
terminals
via
a
pair
of
twisted
or
shielded
wires
and
each
load
separately
connected
to
the
remote
distribution
terminals.
For
this
case,
remote
sensing
should
be
used
(Paragraph
3-31)·.
3-14
OPERATION
BEY'OND
NORMAL
RATED
OUTPUT
3-15
The.
shaded
area
on
the
front
panel
meter
face
indicates
the
amount
of
output
voltage
or
cur-
rent
that
is
available
in
excess
of
the
normal
rated
output.
Although
the
supply
can
be
operated
in
this
shaded
region
without
being
damaged,
it
can-
not
be
guaranteed
to
meet
all
of
its
performance
specifications.
Generally
when
operating
the
sup-
ply
in
this
manner,
the
output
is
unstable
when
a
load
is
connected.
However,
if
the
line
voltage
is
maintained
above
its
nominal
value,
the
supply
will
probably
operate
within
the
specifications
above
the
rated
output.
3-16
OPTIONAL
OPERATING
MODES
3-17
REMOTE PROGRAMMING, CONSTANT
VOLTAGE
3-18
The
constant
voltage
output
of
the
power
sup-
ply
can
be
programmed (contr.olled) from a
remote
location
if
required.
Either a
resistance
or
voltage·
3-2
source
can
be
used
for
the
programming
device.
The
Wires con,neCting
the
programming
terminals
of
the
supply
to
the
remote
programming
device
should
be
twisted
or
shielded
to
reduc·e
noise
pick-up.
T'1e
VOLTAGE
control
on.
the
front
panel
is
disabled
ac-
cording
to
the
following
procedures.
3-19
Resistance
Programming (Figure
3-3)
•.
In
this
mode,
the
output
voltage
will
vary
at
a
rate
deter-
mined
by
the
programming
coefficient-
300 ohms
per
Volt
(i.e.
the.
output
voltage
will
increase
l
Volt
for
each
3 00
ohms
added
in
series
with
programming
terminals).
The programming
accuracy
is
1%
of
the
.progra,mmed
value.
If
·greater
programming
accuracy
is
required,
it
may
be
-achieved
by
cha~ging
resis-
tor·Rl3
(see
Paragraph
5-79).
·
PROGRAMMING
RL
·
RESISTOR
Figure
3-3.
Remote
Resistance
Programming
(Constant
Voltage)
3-29
The
output
voltageof
the
power
supply
should
be
zero
Volts
::1:20
millivolts
when
zero
ohms
is
con-
nected
across
the
programming
terminals.
If
a
zero
ohm
voltage
closer
than
this
is
required.
it
may
be
achieved
by
changing
resistor
R6
or
RS
as
described
in
Paragraph
5-77.
3-21
To
maintain
the
stability
and
temperature
co-
efficient
of
the
power
supply,
use
programming
re-
sistors
that
have
stable,
low
noise,
and
low
temper-
ature
(less
than
30ppm
per
degree
centigrade)
char-
acteristics.
A
switch
can
be
used
in
conjunction
with
various
resistance
values
in
order
to
obtain
discrete
output
voltages.
The
switch
should
have
make-before-break
contacts
to
avoid
momentarily
opening
the
programming
terminals
during
the
switching
interval.
3-22
Voltage Programming
(Figure
3-4).
Employ
the
strapping
pattern
shown
on
Figure
3-4
for
voltage
programming.
In
this
mode,
the
output
voltage
will
vary
in
a 1
to
1
ratio
with
the
programming
voltage
(reference
voltage)
and
the
load
on
the
programming
voltage
source
will
not
exceed
25
microamperes.
The
programming
accuracy
is
1%
of
the
programmed
voltage.
•
•
•

HP Lab Series Specifications

General

Brand	HP
Model	Lab Series
Category	Power Supply
Language	English