I
1. "Sens e" switch in "EXT" position.
2 . Set the voltage control to zero and the " Current limit'' control to a value,
well above the current desired, but below the value that could damage the
load. The output current cannot exceed the CL value in this application.
3, Increas e the voltage control, until the current reaches its desired value.
This will happen when the voltage control shows 4, 0 V, provided that the
shunt is designed for that value.
The CV lamp should be lit in this application (note not the CC one).
0.
C O N ST A NT C U R R E NT P R O G R A M M I N G
When constant current with external shunt is used, the resolution of the
voltage control (controlling the current) might not be satisfactory . In such a
case constant current programming is recommended.
D
0
0
EXT
E)
Figure 16
0
Rp
Also refer to section 3 N .
1 .
Set "sense" switch at "EXT" .
0
Load.
2. Set voltage control at zero and control output current
With 4 V maximum across the shunt:
R
=
1070
ohms
for
models
with
K
=
3 , 75
p
p
R
12 10
ohms
for
models
with
K
=
3 , 35
p
p
0
with
R .
p
For more information about K
,
see s ection 3E . For other voltages across
the shunt: R
=
Us
P
p
where : Us
K
p
voltage across the shunt and K
=
see section 3E .
p
P " A C C E S S O R I E S
a. COOLR AC
When good vertical ventilation can be assured, RAC PAC does not need a fan .
Typical such applications are, when standing free on a work bench with the
plastic feet mounted or when rackmounted with generous distance between
RACPAC and other instruments (see also section 3B) .
19
