Kikusui PLZ-4W Series, User Manual

Page: 32 / 218

2-12 Installation and Preparation PLZ-4W
If the load wire is long or has a large loop, the wire inductance is increased. Conse-
quently, the current variation at the time of switching operation will cause a large
voltage drop.
When the value of instantaneous voltage drops under the minimum operating volt-
age depends on the generated voltage at the load input terminal, the response of
recovery will be extensively delayed. In such event, the PLZ-4W may generate
unstable oscillation or becomes into the hunting operation. In such condition, the
input voltage may exceed the maximum input voltage and cause damage to the
PLZ-4W.
Fig. 2-8 Waveform example: Generate unstable oscillation or hunting operation
You must be careful especially when the slew rate setting is high or switching is per-
formed using large currents through parallel operation.
To prevent problems, connect the PLZ-4W and the equipment under test using the
shortest twisted wire possible to keep the voltage caused by inductance within the
minimum operating voltage and maximum input voltage range or set a low slew rate.
If the high-speed response operation is not required, set the lower response speed
and decrease the slew rate setting.
In the case of DC operation also, the phase lag of the current may cause instability
in the PLZ-4W control inducing oscillation. In this case also, connect the PLZ-4W
and the equipment under test using the shortest twisted wire possible. If only DC
operation is required, a capacitor and a resistor may be connected to the load input
terminal as shown in Fig. 2-9 to alleviate oscillation. In this case, use the capacitor
within its allowable ripple current.
Fig. 2-9 Length of wiring
Current
Voltage at Load
Input Terminal
Minimum operating
voltage
ΔT
ΔI
When the voltage drops under minimum
operating voltage, the electronic load may
generate unstable oscillation or becomes
into hunting operation.
Example of waveform
Voltage at the load input terminal
Current
Equipment
under test PLZ-4W Series
Electronic Load
Keep the wire short
100 cm or less
Twist
– –
+ +
R
C
Example: R=10
Ω
, C=100
μ
F