Schwarzbeck NTFM 8131 2-Wire Impedance Stabilisation Network, 9 kHz - 30 MHz

Application:

The "Impedance Stabilisation Network", also known as T-LISN, are used to measure the asymmetrical interference voltage on symmetrical data or telecommunication lines. Since 2002 the T-LISN is used for measurements of the asymmetrical disturbance voltage according EN 55015 (electrical lighting equipment). In contrast to the widely used T-LISN the NTFM 8131 was designed to withstand 400 V AC at maximum currents of 3 A.

Safety Precautions

A maximum voltage of 400 V RMS AC can be applied to the NTFM 8131, therefore the common safety rules for work with mains voltage must be applied. In contrast to the originally by CISPR 22 provided capacitors of 4.7 µF the capacitors of the NTFM 8131 have 0.47 µF, which has several advantages. In the nominal frequency range there is no difference, for low frequencies the resistors of the 8131 do produce less heat and the measurement equipment and personnel is less endangered. It is strongly recommended to establish all connections without mains voltage and to re-check their correctness carefully. The BNC-connector may guide high voltages, especially in cases with very unsymmetrical mains conditions, which can endanger both test equipment and personnel! Especially RF-test equipment without blocking capacitor at the input can be damaged if the mains symmetry is not sufficient. Therefore we recommend to check the voltage at the BNCconnector with a multimeter. Please note: most multimeters (battery driven models) are measuring on floating potential, most coaxial test equipment is grounded via the protection earth wire and the coaxial outer conductor.