Kikusui PLZ-30F, Operation Manuals

Page: 26 / 192

2-12 Installation and Preparation PLZ-U
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Load wire inductance
The load wiring has an inductance (L). When the current (I) varies in short time
period, it generates a large voltage at both ends of the wiring cable. This voltage
applies to all of the load input terminals of the PLZ-U when the impedance of the
EUT is relatively small. The voltage generated by the load wire inductance (L) and
the current variation (I) is expressed using the following equation.
E = L x ( Δ I / Δ T)
E : Voltage generated by the wire inductance
L : Load wire inductance
Δ
I : Amount of urrent variation
Δ
T : Variation period of current
Fig. 2-7 Load wire and inductance
In general, the wire inductance can be measured approximately 1 μ H per 1 meter. If
the 10 meters of load wires is connected between the EUT and the electronic load
(PLZ-U) with the current variation of 2 A/
μ s, the voltage generated by the wire
inductance will be 20 V.
The negative polarity of the load input terminal is the reference potential of the
external control signal, therefore, the device connected to the external control termi-
nal may get malfunctioned.
When operating under the constant voltage (CV) mode or constant resistance (CR)
mode, the load current is varied by the voltage at the load input terminal, so the
operation can be affected easily by the generated voltage.
The wiring to the EUT should be twisted and the shortest as possible.
If the load wire is long or has a large loop, the wire inductance is increased. Conse-
quently, the current variation that results when switching occurs will cause a large
voltage drop.
EUT
PLZ-U
L
I
Δ I/ Δ T
E
Load input terminal
+
-