{"id":40842,"date":"2020-10-20T11:11:09","date_gmt":"2020-10-20T09:11:09","guid":{"rendered":"https:\/\/fhi.nl\/nieuws\/technical-blog-class-x-and-class-y-capacitors\/"},"modified":"2025-03-06T16:11:33","modified_gmt":"2025-03-06T15:11:33","slug":"technical-blog-class-x-and-class-y-capacitors","status":"publish","type":"news","link":"https:\/\/fhi.nl\/en\/news\/technical-blog-class-x-and-class-y-capacitors\/","title":{"rendered":"Technical Blog: Class X and Class Y capacitors"},"content":{"rendered":"
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\n\t\t\t\t\tTechnical Blog: Class X and Class Y capacitors\t\t\t\t<\/h1>\n\n\t\t\t\t
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Many safety regulations mandate that Class<\/p>\r\n

Lightning strikes and other sources cause high voltage surges in mains power. Safety capacitors protect humans and devices from high voltage surges by shunting the surge energy to ground.<\/p>\r\n

In particular, safety regulations mandate a particular arrangement of Class X and Class Y mains filtering capacitors.<\/p>\r\n

In principle, any dielectric could be used to build Class X and Class Y capacitors; perhaps by including an internal fuse to improve safety. In practice, capacitors that meet Class X and Class Y specifications are typically ceramic RFI\/EMI suppression capacitors or plastic film RFI\/EMI suppression capacitors.<\/p>\r\n

Electromagnetic Interference (EMI) or Radio Frequency Interference (RFI) suppression film capacitors, also known as \u201cAC line filter safety capacitors\u201d or \u201cSafety capacitors\u201d, are used as crucial components to reduce or suppress electrical noise caused by the operation of electrical or electronic equipment, while also providing limited protection against electrical shocks.<\/p>\r\n

A suppression capacitor is an effective interference reduction component because its electrical impedance decreases with increasing frequency, so that at higher frequencies they short circuit electrical noise and transients between the lines, or to ground. They therefore prevent equipment and machinery (including motors, inverters, and electronic ballasts, as well as solid-state relay snubbers and spark quenchers) from sending and receiving electromagnetic and radio frequency interference as well as transients in across-the-line (X capacitors ) and line-to-ground (Y capacitors) connections. X capacitors effectively absorb symmetrical, balanced, or differential interference. On the other hand, Y capacitors are connected in a line bypass between a line phase and a point of zero potential, to absorb asymmetrical, unbalanced, or common-mode interference.<\/p>\r\n

RFI\/EMI suppression with X- and Y-capacitors for equipment without and with additional safety insulation<\/em><\/p>\r\n

Appliance Class I capacitor connection<\/p>\r\n

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Appliance Class II capacitor connection<\/p>\r\n

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EMI\/RFI suppression capacitors are designed and installed so that remaining interference or electrical noise does not exceed the limits of EMC directive EN 50081 Suppression components are connected directly to mains voltage semi-permanently for 10 to 20 years or more, and are therefore exposed to overvoltages and transients which could damage the capacitors. For this reason, suppression capacitors must comply with the safety and flammability requirements of international safety standards such as the following:<\/p>\r\n