The Electronic Load

The Electronic Load
Application Notes ZS PL H&H
ZSLC
Water-cooled
ZSLV
Low Voltage
PMLI
Multi-channel
ZSAC
AC
NL
Source-Sink
Accessories
H&H Application Note #3
Simulation of exponential inrush currents
Function
Via the analog control input of
the ZS electronic load with the
help of a few passive
components a control signal can
be generated which simulates
the current consumption of
devices with exponentially
decaying inrush current peaks.
Applications
Simulation of current
consumption of devices at the
point of switching on, e.g. light
bulbs, engines etc.
Measurement set-up
As stated in the circuit, the
connected input voltage is fed
via an RC network to the
analog control input of the
device.
As soon as the SW1 switch is
closed, at the AIN10+ control
input the RC network
generates a rapid voltage rise
with a subsequent exponential
fall.
The peak current is
determined by the value of the
connected voltage and the
resistors R2 and R3.
R1 is used to generate the
continuous current which is set
after the decay of the poweron
process.
The current can be calculated
from the voltages at the
voltage divider R1, R2 and R3
and the technical data of the
electronic load.
If using the 10 V control
input the full current of the
selected range flows at 10 V.
The decay time constant is
calculated from the resistors R2
and R3 with the capacitor C1.
The input resistance of the
analog control input - 20 kOhm
- must also be taken into
account.
The device must be set to
constant current operating
mode and external control.
For smaller input voltages the
5 V control input can also be
used in place of the 10 V control
input.
Note
Example:
R1: 10 kΩ
R2: 1 kΩ
R3: 1 kΩ
C1: 100 µF
Input voltage: 12 V
Electronic load: ZS3606
Note that the load current value
depends on the input voltage.
Input voltage interferences are
coupled by capacitor C1 directly
to the control signal.
The resistances must be
dimensioned such that 10 V is
not exceeded at the control
input.
Otherwise the electronic load
could be damaged.
Software
GTC
H&H offers no guarantee for the function of
the suggested applications.
H&H offers no guarantee for damage resulting
from such applications.
Switch-on process with
electromechanical relay
and contact bounce
The current also follows the
input voltage during the
contact bounce.
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