Contactless position measurement for EMC apparatus

The measurement of radio disturbance power in the frequency range between 30 MHz and 1 GHz is usually conducted using an absorbing clamp. The absorbing clamp assembly that incorporates also a current transformer is moved along the track of the power supply cable and is used to measure electromagnetic interference radiated from the equipment under test (EUT) through its connecting mains cable, to pick up the location of the maximum disturbance and to check the compliance with relevant EMC standards. Manual operation of the clamp is time consuming and tedious, it requires a hand-driven advance of the clamp, sealing the screened room, conduction a next test and doing this many times. This paper reports on the development of the remote sensing of an absorber clamp system that has the potential of reducing the EMC test time and increasing its accuracy. An overview of the implementation method and background reasoning is given on the developed system. The EMC emission tests confirm that the position measurement system complies with the EMC norms.