Design of a 3-Phase Line Impedance Stabilization Network For Conducted Emission Test Mohammad H. Hedayati and Vinod John Department of Electrical Engineering Indian Institute of Science Bangalore 560 012, INDIA mhhedayati@ee.iisc.ernet.in vjohn@ee.iisc.ernet.in Abstract—Conducted Emission (CE) tests are carried out to find out the amount of high frequency noise injected to the grid by the equipments. Line Impedance Stabilization Networks (LISN) are utilized in order to obtain noise measurements, under different grid conditions, which meet the CE standards. This paper presents how to make a 3-phase 10kV A LISN which costs about 5% of a commercialized ones. The procedure is explained for making the air core inductors. The simulation and experimental results are presented which shows the effectiveness of the design. The guidelines for selection of components are explained. The LISN is used to evaluate a SMPC and a 3- phase drive. The readings from the LISN is compared with common mode current measurement on the SMPS to validate the effectiveness of the LISN. Index Terms—Conducted Emissions (CEs), Electromagnetic Compatibility (EMC) Measurements, EMC Test Setup, Line Impedance Stabilization Networks (LISN). I. I NTRODUCTION One of the major challenges for designing power converter equipments is the Electromagnetic Compatibility concerns. If an equipment is meant to be commercialized, it has to pass all the standard electro magnetic emission tests. Conducted emission test is a standard test which identifies the amount of high frequency noise injected to the grid by the equipments. Standards like CISPER 16 [1] indicates the guidelines for the conducted noise measurement test. In CISPER 16 it is proposed to use a Line Impedance Stabilization Network (LISN) between the grid and the Equipment Under Test (EUT). According to this standard, the LISN should fulfil the following requirements [1], [2]: 1- To stabilize the mains impedance in order to standardize the measurement. 2- To filter out the high frequency noise coming from the grid and prevention of affecting the measurements. 3- To provide a path for high frequency noise coming from the EUT to the EMI receiver. Also, providing 50Ω match connectors for the receiver. It is possible to measure the conducted electromagnetic emis- sion without using LISN [3], but numerical treatment would be needed to be performed on the the data. In [4] a LISN is proposed where the number of components are doubled. However, any advantage of the circuit over the circuit proposed A B C a b c EUT E To receiver Fig. 1. Typical 3-phase CE compliant measurement set-up schematic to measure conducted EMI from a test equipment. by the CISPER is not observed. In [5] two novel 3-phase com- mon mode/differential mode noise separation networks, which are passive and active networks presented for measurement of conducted emission test. However, it is possible to observe conducted EMI performance even without such separation network. Commercially LISN’s are available from a number of manufacturers [7]. In this paper steps involving the design procedure and building a low cost 10kV A 3-phase LISN is presented. The circuit topology used in this paper is shown in Fig. 1. The circuit is analysed and the output to input transfer functions are derived analytically. The frequency responses of the system are measured using network analyser. The LISN components are then analysed to identify the cause of derivation of the practical LISN from the analytical circuit model. The experimental and analytical results comparison shows the effectiveness of the design. II. LISN CIRCUIT TOPOLOGY AND TRANSFER FUNCTION ANALYSIS Fig. 1 shows a typical 3-phase LISN. The resistance, capacitance and inductance values are tabulated in Table I. There are three terminals available in the circuit, input to the LISN (V in ), output of the LISN (V out ) and the port for the measurement (V rec ). Three input-output transfer functions are considered and their relationships are derived. Bode magnitude