7-2 ApplicationsFig. 7-1 AMN Principle: a) Δ-type or T-type LISN ; b) V-type LISN7.1.2.1 AMN AMNs are usually classified depending their configuration: V-typeNetworks, Δ-type Networks, T-type Networks.• The V-type Network is used for measuring the unsymmetrical RFIvoltage on AC and DC supply line. Standard impedances specified byCISPR and other international standards are 50Ω // 50 μH+5Ω and 50Ω// 5 μH+1Ω.• The Δ-type Network is used for measuring the symmetrical RFI voltageon balanced telecommunication lines. It is generally designed to permitswitchover between symmetrical and asymmetrical RFI measurements.Its use is limited; Standards usually specify the T-type Network instead.The most common impedance for Δ-type Network is 150Ω.• The T-type Network is used for measuring the asymmetrical RFIvoltage on balanced (electrically symmetrical) audio frequency, controland data lines. Standard impedance is 150Ω as well.An Artificial Mains Network shall be designed in order to:1. terminate each line (power, signal, etc.) of the EUT (Equipment UnderTest) with a standardized impedance;2. permit the feeding of the EUT with the proper supply voltage andcurrent or with the signal and data required for operations;3. isolate the side of the test circuit where EMI voltages are measuredagainst interference coming from mains network or from the auxiliaryequipment supplying the EUT with the required data;4. provide a suitable test point – to be connected to the test receiver - topick up the RFI voltages from the conductor under test;5. ensure that the impedance of the source (power, signal) is not varied ina significant way, otherwise EUT response to the interference maychange.lowpassfilter highpassfiltermains DUTtestreceiverRF load tointerferenceDUT50Ω8μF5Ω50μH 0.25μF testreceivermainsV-LISNV symV asymZ asymZ symV unsym Vunsym2μF250μHV unsym V unsymVsymL1 L 2 L 1 L 2L1a) b)V-LISN (only oneline is shown)
