RadiMation Application Note 104
How to determine the current sensor transfer impedance
The transfer impedance of a current sensor is important and required to perform accurate current measurements. A typical current sensor transfer impedance can be retrieved form the manufacturer of the current sensor, or it can be determined in a calibration laboratory. It is however also possible to determine the transfer impedance of a current sensor yourself, if you have the correct equipment.
This Application Note explains how measurements can be done in RadiMation® to determine the transfer impedance of a current sensor. These measurements are done by using the Attenuation/Gain calibrations as they are provided by RadiMation®. After the Attenuation/Gain calibration is performed, some calculations are needed to determine the correct transfer impedance, however these can easily be done in Microsoft Excel. A verification of the calibration and recalculation of the data can be done to ensure that the expected current is indeed correctly measured by RadiMation®.
Performing the Attenuation/Gain system calibration
First we need to determine the absolute difference between the signal generator and the power meter, before we can measure the transfer loss of the current sensor. Therefor we first have to perform the Attenuation/Gain system calibration as described in Chapter 12 of the manual.
The measurement setup that should be used for this is:
Performing the Attenuation/Gain EUT calibration
Converting the measured data to a transfer impedance
Specifying the transfer impedance for the current sensor device driver
Verification
After the transfer impedance of the current sensor is determined and attached, it is also possible to verify if RadiMation® is able to measure the expected current.
