Anti-interference safety capacitors

Can radio interference suppression capacitors be used in a mains application?

Before radio interference suppression capacitors can be used in a mains application, they must fulfil safety standards defined by national authorities. The basic world standard for these components is the IEC 60384-14 (ed.3).

What are safety capacitors used for?

EMI filtering, for instance, in AC/DC power supplies or AC-mains powered motor drives, is the primary use of safety capacitors. More recently, capacitively-coupled DC/DC converter designs have appeared that use safety capacitors to provide input-to-output isolation. And safety MLCCs are finding use in antenna coupling applications.

What are the different types of Safety capacitors?

Safety capacitors are grouped into a number of different classes. For X Type capacitors there are class X1, X2 and X3. For Y Type capacitors there is class Y1, Y2, Y3 and Y4. The only types you will probably see for sale are X1 (impulse tested to 4000 Volts), X2 (tested to 2500 V), Y1 (tested to 8000 V) and Y2 (tested to 5000 V).

Which X-capacitor is used for radio interference suppression?

Figure a) shows the radio interference suppression of the motor of a piece of electrical equipment (vacuum cleaner, portable drill, etc.) of protection class I. Capacitor Cx, which is used for reducing the symmetrical interference voltage, is located between the conductors of the mains and is therefore an X-capacitor.

Are EMI/RFI capacitors safe?

EMI/RFI capacitors must comply with the safety and inflammability requirements of international safety standards, such as the following: A design consideration when using X capacitors is the need to automatically discharge the capacitor upon loss of power to the power converter to comply with safety standards.

What are safety capacitors made of?

Construction of Safety Capacitors: Safety capacitors are available in ceramic disc and metalized film or paper. The film type are made of self-healing metalized polyester, polypropylene or paper and usually come in a “box” style casing as the capacitor is encased is a flame retardant or flame-proof case.