Constant Voltage Or Constant Current Source - Fluke PM2811 User Manual

Using your Programmable Power Supply
5.5.3

Constant voltage or constant current source

Your power supply has been designed according to the automatic crossover
principle. This means that each output channel will operate in the Constant
Voltage (CV) mode or in the Constant Current CC mode, depending on:
• the programmed output voltage V
• the resistance (impedance) of the load R
For a given V and I
set
in the CV mode if
In the CV mode the output is a constant voltage, so the current through the load
depends on the load resistance (R
In the CC mode the output is a constant current, so the voltage across the load
depends on the load resistance (R
The following picture shows when the output channel goes into the CV or into the
CC mode of operation, when connected to a variable resistor R
R= (open circuit)
V(set)
Figure 5.5.7 Power Output Crossover Point
If R increases (R
load
reducing the current through the load.
If R decreases (R
load
reducing the voltage across the load.
, an output channel is either:
set
V
set
R or in the CC mode if
>
load
I
set
load
load
Rload >Rc
CV
CC
I(set)
> R ), the output channel goes into the CV mode,
load c
< R ), the output channel goes into the CC mode,
load c
and current I
set set
, connected to the output channel
load
).
).
Rc= Vset
(crossover point)
Iset
Rload <Rc
R= 0 (short circuit)
Current
V
set
R .
<
load
I
set
.
load
ST5848
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