This document applies to decoupling filters installed on the low voltage mains network and operating in the frequency range 3 kHz to 148,5 kHz. It does not apply to EMI suppression filters incorporated in household equipment or other general electric equipment. It specifies the definitions, requirements and test methods of the functional, technical and environmental characteristics of the decoupling filter, e.g. impedance, transfer function, voltage drop, leakage current and power dissipation. The impedance and the transfer function are referred to the decoupling filter mains power ports (see Figure 1).