PLZ-4WL
119
Operating Area
App.
How constant current (CC) mode works
In constant current (CC) mode, the PLZ-4WL maintains the same current even if the voltage
changes.
Constant current mode operation
When the PLZ-4WL is used in constant current (CC) mode, it operates as a constant-current
load as shown in the figure below. The PLZ-4WL sinks the specified current (I) regardless of
the output voltage (V1) of the constant-voltage power supply.
Transition of the operating point: overpower protection (OPP)
In this example, we will assume that the PLZ-4WL is being used in constant current (CC)
mode to test the load characteristic of a constant-voltage power supply.
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Operation on segment AB
If the voltage of the constant-voltage power supply is set to V1 and the input current (load
current) of the PLZ-4WL is increased, the operating point moves along segment AB.
When point B is reached, overpower protection (OPP) is activated. At this point, one of two
types of operations occurs, depending on the protection action setting for OPP.
If the protection action is set to LOAD OFF, the load turns off.
If the protection action is set to LIMIT, the PLZ- 4W sinks current as a constant-power load at
point B. Even if you attempt to increase the input current, the current will not increase beyond
point B. If you decrease the input current, overpower protection (OPP) is cleared. The PLZ-
4WL returns to constant current (CC) mode, and the operating point moves along segment
AB.
PLZ-4WL Series
I
V
Constant-voltage
power supply
The current is constant
even when the voltage
varies.
Current I
Voltage
V
0
V
1
CC setting
Input current [A]
Input voltage [V]
Logarithmic scale
A
B
C
(OPP setting)
Constant power line
Operating area
OPP activation point
D
V1
V2
Point B
LOAD OFF
The load is turned off (no current flows).
The PLZ-4WL stops operating as a load.
LIMIT
The PLZ-4WL switches out of constant current (CC) mode.
Overpower protection (OPP) continues, and the PLZ-4WL operates
as a constant-power load.