Kikusui PLZ1004W, User Manual, Page: 200 / 216

A-12 Appendix PLZ-4W
A.2.6 Operation of the CR+CV Mode
The PLZ-4W allows you to add CV mode to CR mode.
■
CR+CV mode operation
When the PLZ-4W is used in CR+CV mode, the PLZ-4W operates as a constant
resistance load and a constant voltage load (shunt regulator) as shown in Fig. A-14.
When operating as a constant resistance load and the voltage (V
M
) of the constant-
voltage power supply is varied, the PLZ-4W sinks current to meet I=V/R according
to the specified resistance R. When operating as a constant voltage load and V
M
is
greater than V, the input voltage V is kept constant even when the input current I
varies. Current does not flow when V
M
is less than or equal to V.
The switching between the modes is automatic. In the Fig. A-14, R1 is the internal
resistance of the constant-voltage power supply. In constant-voltage (CV) mode, the
PLZ-4W may operate unstably if R1 is low.
Fig. A-14 Equivalent circuit of the CR+CV mode and operation
■
Transition of the operating point: Overpower protection (OPP)
We will consider the case when checking the discharge characteristics of a battery of
Fig. A-14.
Fig. A-15 Transition of the operating point in CR+CV mode (OPP trip
point)
0
CV
setting
value
I
V
PLZ-4W Series Electronic Load
Battery
CR operation
Resistance (V/I) is constant
even when the voltage and
current vary
Current I
V
oltage V
V
M
CV operation
Voltage is constant even
when the current varies
R
1
Input current [A]
Input voltage [V]
Log scale
V
M
V
Q
Q
S
Constant power line
(OPP setting)
Constant voltage line
(Constant voltage setting)
Operating area
OPP trip point
M
N
I
N
I
OCP
M
1
M
2
P
N
P
N1
R
M1
R
M2
R
N
Constant resistance line
(Constant resistance settings: R
M1
, R
M2
, and R
T
)