- The recommended voltage sensor is the LV25 from LEM. It is a closed loop sensor. capable of measuring DC and AC with the maximum voltage of 500 V. Do not use this sensor if the voltage is more than 500 V.
- Rpri depend on the maximum Vmeasure:
Rpri = 100 Vmeasure - The rating Rpri is very important to avoid the resistance from damage and get accurate reading:
Ppri > Vmeasure / 100 - The Rsec needs to be 100 Ω to 340 Ω based on the datasheet. If the Rsec becomes higher, the reading becomes non-linear. It is recommended to choose not more than 300 Ω to obtain linear reading.
- The Rsec depend on the maximum voltage rating for analogue to digital converter (ADC) for the hardware platform.
5 V < Vsensor(max) < 8.5 V - Since the dSPACE ds1104 has 10V ADC, the LV25 are out of range of VsensorV(max). The LEM LV25 still can be used for the dSPACE ds1104. However, the sensitivity of the measurement is reduced. As a result, the accuracy of the measurement becomes lower. It is recommended to use 300 Ω for Rsec in dSPACE ds1104 application with 25% sensitivity reduction (7.5 V Vsensor(max) out of 10 V from the ADC). However, this is good safety factor if measurement overshoot occurs. To improve the sensitivity of the measurement, the amplifier circuit is needed..
- Rsec is recommended to have low tolerance (check the forth colour band at the resistance) and 0.5 W or 1.0 W rating to increase measurement accuracy and reduce the effect from temperature change.