1-8
that the current limit value can be set from zero to maximum
rated value.
OPERATING MODES
The settin
of the rear panel switch determines the operatin
modes of the power suppl
. The local operatin
mode is set so
the power suppl
senses the output volta
e directl
at the output
terminals (local sensin
) for operation usin
the front panel con-
trols (local pro
rammin
). Other operatin
modes are: remote
volta
e sensin
and remote pro
rammin
of output volta
e and
current usin
external volta
es.
LOCAL OPERATING MODE
The power suppl
is shipped from the factor
confi
ured in the
local operatin
mode. Local operatin
mode requires the switch
settin
s of the rear panel, as shown in Fi
ure 4. The power sup-
pl
provides constant volta
e(CV) or constant current(CC) output.
Constant Volta
e Operaton
To set up a power suppl
for constant volta
e operation, proceed
as follows:
a. Turn on the power suppl
and adjust 10-turn VOLTAGE con-
trol for desired output volta
e (output terminals open).
b. While depressin
DISPLAY OVP/CC SET switch, adjust 10-
turn CURRENT control for the desired current limit.
c. With power off connect the load to the output terminals.
d. Turn on the power suppl
. Verif
that CV LED is li
hted.
Durin
actual operation, if a load chan
e causes the current
limit to be exceeded, the power suppl
will automaticall
cross over to constant current mode and the output volta
e
will drop proportionatel
.
Constant Current Operation
To set up a power suppl
for constant current operation, proceed
as follows:
a. Turn on power suppl
.
b. While depressin
DISPLAY OVP/CC SET switch, adjust
CURRENT control for the desired output current.
c. Turn up the VOLTAGE control to the desired volta
e limit.
d. With power off connect the load to the output terminal.
e. Turn on power suppl
and then verif
that CC LED is li
hted.
(If CV LED is li
hted, choose a hi
her volta
e limit. A volta
e
settin
that is
reater than the current settin
multiplied b
the
load resistance in ohms is required for CC operation.) Durin
actual operation, if a load chan
e causes the volta
e limit to
be exceeded, the power suppl
will automaticall
cross over
to constant volta
e operation at the preset volta
e limit and
output current will drop proportionatel
.
Overvolta
e Protection (OVP)
Adjustable overvolta
e protection
uards
our load a
ainst over-
volta
e. When the volta
e at the output terminals increases (or is
increased b
an external source) to the OVP shutdown volta
e as
set b
the OVP ADJUST control, the suppl
's OVP circuit dis-
ables the output causin
the output volta
e and current to drop to
zero. Durin
OVP shutdown the OVP LED li
hts.
False OVP shutdowns ma
occur if
ou set the OVP shutdown
too close to the suppl
's operatin
volta
e. Set the OVP shut-
down volta
e 4% of output +2.0 V or more above the output volt-
a
e to avoid false shutdowns from load-induced transients.
Ad
ustin
OVP.
Follow this procedure to adjust the OVP shut-
down volta
e.
a. With the VOLTAGE control full
counter clockwise, turn on
the power suppl
.
b. While depressin
DISPLAY OVP/CC SET switch, adjust
the OVP Adjust control to the desired OVP shutdown usin
a small, flat-blade screwdriver.
c. Follow the procedure for CC or CV operaton to set the out-
put volta
e and current
Resettin
OVP. If OVP shutdown occurs, reset the suppl
b
turnin
power off. Wait one or more seconds, and turn power on
a
ain. If OVP shutdown continue to occur, check the connections
to the load and sense terminals, and check the OVP limit settin
..
Stron
electrostatic dischar
e to power suppl
can make
OVP trip and eventuall
crowbar the output, which can
effectivel
protect output loads from the hazardous ESD
current.
CONNECTING LOADS
The output of the suppl
is isolated from earth
round. Either out-
put terminal ma
be
rounded or the output can be floated up to
240 volts off
round. Total output volta
e to
round must not
exceed 240 Vdc.
Each load should be connected to the power suppl
output terminals
usin
separate pairs of connectin
wires. This will minimize mutual
couplin
effects between loads and will retain full advanta
e of the
low output impedance of the power suppl
. Each pair of connectin
wires should be as short as possible and twisted or shielded to
reduce noise pick-up. (If a shield is used, connect one end to the
power suppl
round terminal and leave the other end unconnec-
ted.)
If load considerations require that the output power distribution
terminals be remotel
located from the power suppl
, then the
power suppl
output terminals should be connected to the remote
distribution terminals via a pair of twisted or shielded wires and
each load separatel
connected to the remote distribution termi-
nals. For this case, remote sensin
should be used (See para-
raph "Remote Volta
e Sensin
").
OPERATION BEYOND RATED OUTPUT
The output controls can adjust the volta
e or current to values up
to 5% over the rated output. Althou
h the suppl
can be operated
in the 5% overran
e re
ion without bein
dama
ed, it can not be
uaranteed to meet all of its performance specifications in this
re
ion.
