Abstract In order to meet the electromagnetic radiation emission limit requirements in the relay protection test signal source technical specification, the method of suppressing the common mode current on the unshielded cable is proposed for the current relay protection test signal source connection switch quantity and the analog cable radiation emission exceeding the standard problem. To reduce the radiated emission noise. Based on electromagnetic wave and antenna theory, a circuit model of relay protection tester and radiation transmission of unshielded cable is established. The main circuit parameters affecting the radiation emission intensity are analyzed. The results show that common mode radiation emission is in the range of 30~100MHz. The noise source is stronger than the differential mode radiation emission source and according to the characteristics of the common mode radiation emission circuit model, three processing methods for suppressing the common mode current of the cable are given, that is, the size of the common mode current is reduced and reduced. The frequency of the small current harmonic component reduces the length of the cable. The test results show that the method of suppressing the cable common mode current can reduce the radiation emission by 22dB, and has the characteristics of simple circuit processing and strong generality.
Feng Xiaowei,Wang Bentao,Liu Huanqiang等. Suppressing radiated noise of unshielded cable on the relay protection test signal source research[J]. Electrical Engineering, 2020, 21(3): 44-51.
2020, Vol. 21 
