Interference suppression capacitors are used to reduce interference to radio reception. They dissipate high- frequency interference signals to ground. They are used in devices generated by electric motors with collectors. For example, in household appliances or tools.
Spark interference suppression capacitors prevent the interference radiation caused by sparking from entering the supply network via the power cable or prevent interference from the power network from entering the device. For this purpose, interference suppression capacitors are located immediately after the mains switch or in mains filters and can thus short-circuit incoming or outgoing interference radiation to ground or protective earth.
Metal paper capacitors or ceramic capac itors are used as interference suppression capacitors, but also film capacitors. Metal-paper capacitors have the advantage over other capacitors of self-healing, since the thin metal layer around the breakdown point evaporates in the event of voltage flashovers.
Suppression capacitors used in tools and household appliances are preferably symmetrically constructed capacitors with a center conductor, also known as a Y capacitor. Since these devices are mainly operated on single- phase AC mains, both conductors - the phase-carrying outer conductor and the neutral conductor - must be discharged, since it cannot be ensured on which plug pin of the mains plug mains phase or the neutral conductor is located. Simply turning the mains plug changes the assignment. Interference suppression capacitors must attenuate interference signals in accordance with the EMC guidelines for electromagnetic compatibility.