Class-X and Class-Y capacitors are safety-certified and generally designed and used in AC line filtering in many electronic device applications. These safety capacitors are also known by other names, including EMI/RFI suppression capacitors and AC line filter safety capacitors. (EMI stands for electromagnetic interference. Class-X and Class-Y capacitors are classified according to: 1. their peak voltage/rated voltage and 2. the peak impulse voltage that they can safely withstand. Tables 1 and 2. Subclass X2 and Y2 are the most commonly used safety-certified capacitors. Depending upon your own application and requirements, they are probably the ones you'll want to use. This is assumed because X2 and Y2 safety. Because Class-X and Class-Y capacitors must be connected directly to AC lines (line-to-neutral or line-to-ground) in order for them to perform their EMI and RFI filtering functions, they. All safety-certified capacitors should have the proper logo markings/symbols on their casing. See Figure 4 below for an example and see Figure 5.
