Programmable AC/DC Electronic Load 63800 Series Operation & Programming Manual
3.7 AC Load Simulation -- Constant Resistance
Mode
Figure 3-8 Constant Resistance Mode
In CR mode, the Load will sink a current linearly proportional to the input voltage in
accordance with the programmed resistance. The waveform of the current is the same as the
waveform of the input voltage, so the power factor allowed is 1.
The Electronic Load modules implement constant resistance mode by using CC circuits to
regulate the input. The input voltage of the load is regarded as reference for current control.
The formula I/V = 1/R.
V : input voltage.
I : controlled parameter to determine the resistance.
1/R : conductance, reciprocal of resistance.
The specifications of CR mode accuracy are specified as conductance. The effect on the
programmed resistance value is not linear over the resistance range, because resistance is
the reciprocal of conductance. The electronic load is designed for high current applications of
CR mode. Therefore, when large resistance is required, accuracy can be improved by reading
the voltage and current from the load, calculating the actual resistance, and adjusting the set
value.
To calculate the accuracy of programmed value error, the programmed value must be
reciprocated first. The error is then applied to the programmed value (conductance), and the
result is once again reciprocated. The following example illustrates the worst-case error of CR
mode.
Example: 1 to 1000 ohm range of model 63804
The accuracy for this range is specified as 0.5% + 0.5%FS.
If 5 ohm is programmed, the actual resistance will be
conductance : 0.2+(0.2×0.5%+1×0.5%) to 0.2 − (0.2×0.5%+1×0.5%)
resistance : 4.854Ω to 5.154 Ω
If 100 ohm is programmed, the actual resistance will be
V
Input
Voltage Slope
(R setting)
I
Load Current
To Next Page
Loading...
Need help?
General
