Using a current sensor correction file

Discussion and questions regarding the Radiated Immunity and Conducted Immunity modules of RadiMation.
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james
Posts: 4
Joined: 26 May 2020, 10:55

Using a current sensor correction file

Post by james »

We received a calibration file for our current sensor, it contains for each frequency point a transfer impedance (in dB).
However the RadiMation manual states a correction of impedance (resistance) in ohm units.
How can we apply this correction correctly?
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joro
Posts: 440
Joined: 24 Aug 2011, 09:55
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Re: Using a current sensor correction file

Post by joro »

To be able to represent the actual current flowing through a current sensor, it is indeed important that a device specific calibration factor is linked to the current sensor device driver in RadiMation.
The impedance (or resistance) of the current sensor is required in the correct calculation of the current, and this value is also frequency dependant

By using a RadiMation correction file, the correct impedance of the current sensor can be specified and linked to the current sensor.
Once a correction file (.COR) is created it can be selected as the 'Impedance (Ohm)' correction file to a current sensor device driver.
The device driver configuration dialog of a current sensor
The device driver configuration dialog of a current sensor
CurrentSensorConfiguration.png (19.77 KiB) Viewed 2185 times
The '(Ohm)' prefix indicates that the values in the correction file are interpreted as being specified in Ohm. This is if the values are specified in the 'Correction' column of the correction file. However several manufacturers and calibration laboratories specify the impedance in another unit. If a value is for example specified in dBOhm, the value should first be recalculated to Ohm before it is inserted in the 'Correction' column.

This recalculation can also be done by RadiMation, if a 'Resistance' column is selected instead of a 'Correction' column in the correction file.
  1. Select from the main menu: File > New > Correction file. A new correction file with a 'Frequency' and a 'Correction' column is shown.
  2. Click on the 'Columns/Units' button.
  3. Select the 'Correction' column on the left-hand side, and click on the 'Remove >>' button.
  4. Select the 'Resistance' column on the right-hand side, and click on the '<< Add' button.
  5. A 'Frequency (MHz)' and a 'Resistance (Ohm)' column is now available, where the 'Resistance' is expressed in 'Ohm'.
  6. Select the 'Resistance' column on the left-hand side, and click on the 'Unit' button.
  7. Change the selected 'Ohm' unit into another desired unit in which the impedance is going to be specified. For example select the 'dBOhm' unit.
  8. Click on 'Ok' and 'Close' to close the dialogs
  9. The correction file now contains a 'Frequency (MHz)' and a 'Resistance (dBOhm)' column.
  10. Specify the correct correction data for all the frequences. This can also be done by pasting the data from the clipboard.
  11. Save the correction file, by selecting from the main menu: File > Save Correction As.
  12. Select the saved correction file in the current sensor device driver configuration.
In this configuration the data that is stored in the correction file is expressed in dBOhm values. Because the unit of the 'Resistance' column is configured to maintain the data in dBOhm, RadiMation will perform the correct recalculation to Ohms, to perform the correct calculation of the current flowing through the current sensor.
Correction file with Frequency and Resistance (in dBOhm) column
Correction file with Frequency and Resistance (in dBOhm) column
CorrectionFileResistancedBOhmColumn.png (43.17 KiB) Viewed 2185 times
Also see the RadiMation manual at: https://wiki.radimation.com/wiki/index. ... tion_files
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