HP 6296A - Page 20

that
these
leads
be
as
heavy
as
the
load
leads.
However,
they
must
be
twisted
or
shielded
to
minimize
noise
pick-up.
Fiqure
3-7.
Remote
Sensing
CAUTION
Observe
polarity
when
connecting
the
sensing
leads
to
the
load.
3-32
Note
that
it
is
desirable
to
minimize
the
drop in
the
load leads
and
it
is
recommended
that
th~
drop
not
exceed
1
volt
per
lead
if
the power
supply
is
to
meet
its
DC
specifications.
If a
larger
drop must
be
tolerated,
please
consult
a
Hewlett-Packard
field
representative.
NOTE
Due
to
the
voltage
drop
in
the
load
leads,
it
may
be
necessary
to
re-
adjust
the
current
limit in
the
remote
sensing
mode.
3-33
The procedure
Just
described
will
result
in a
low
DC
output
impedance
at
the
load.
If
a low
AC
impedance
is
required,
it
is
recommended
that
the
following
precautions
be
taken:
a.
Disconnect
output
capacitor
C803
by
disconnecting
the
strap
between
A2
and
+s.
b.
Connect
a
capacitor
having
similar
char-
acteristics
(approximately same
capacitance,
same
voltage
rating
or
greater, and having
good
high
frequency
characteristics)
across
the
load·using
short
leads,
3-34
Although
the
strapping
patterns
shown
in
Figures
3-3
through
3-6
employ
local
sensing,
note
that
it
is
possible
to
operate
a power
supply
simultaneously
in the remote
sensing
and
Constant
Voltage/Constant
Current
remote proqramming
modes.
3-35
SERIES
OPERATION
3-36
Normal
Series Connections (Figure
3-8).
Two or more power
supplies
can
be
operated
in
series
to
obtain
a higher voltage
than
that
avail-
able
from a
single
supply. When
this
connection
3-4
r"Al"""'l"'--r~r--.,..-..,.;;;...----....-..--.....-..,.;.;;~A6.;;.,.;117
U
~~~~c@
0
Figure
3-8.
Normal
Series
Connectii:>ns
•
is
used,
the
output
voltage
is
the
sum
of
the
voltaqes
of
the
individual
supplies.
Each:
of
the
individual
supplies
must
be
adjusted
in
oz'der
to
obtain
the
total
output
voltage.
The
powe·r
supply
contains
a
protective
diode
connected
int~!mally
across
the
output
which
protects
the
supply
if
one
power
supply
is
turned off while
its
serie:;
part-
ner(s)
is
on.
3-37
Auto-Series
Connections
(Figure
3-~ll..
The
Auto-Series
configuration
is
used
when
it
is
de-
sirable
to
have
the
output
wltage
of
each
of
the
series
connected
supplies
vary
in
accordc1nce
with
the
setting
of
a
control
unit. The
control
unit
is
called
the
master;
the
controlled
units
arE!
called
slaves.
At maximum output
voltage,
the
voltage
of
the
slaves
is
determined
by
the
setting
of
the
front
panel
VOLTAGE
control
on
the
mastei~.
Th.
master
supply
must
be
the
most
positive
supply
the
series.
The
output
CURRENT
controls
of
all
series
units
are
operative
and
the
current
limit
is
equal
to
the
lowest
control
setting.
U
any
output
CURRENT
controls
are
set
too
low,
automatic
crossover
to
constant
current
operation
wl.11
occur
and
the
output
voltage
will
drop, Remote
sensing
and
programming
can
used:
however,
the
strapping
arrangements
shown in
the
applicable
fig1J.res show
local
sensing
and
programming.
Al
0
MASTER
0
St.\VE
Al
Figure
3-9.
Auto-Series,
Two
Units
•