A capacitor for Electromagnetic Interference Suppression must be approved by a relevant authority either as an electromagnetic interference capacitor or as part of a complete unit of equipment. The standards for EMI capacitors are EN/IEC 60384-14:2005. The capacitors are subdivided into two groups, X and Y.
X capacitors are for use in positions where a failure of the capacitor would not expose anybody to the danger of electric shock.
- IEC 60664 installation category II
- General application purpose
Y capacitors are for use in positions where a failure of the capacitor could expose somebody to a dangerous electric shock.
- Y1 - Double insulation or reinforced insulation, rated voltage ≤500 V, peak impulse voltage before endurance test 8.0kV
- Y2 - Basic insulation or supplementary insulation, rated voltage ≥150 V, ≤300V, peak impulse voltage before endurance test 5.0kV
Note: A short circuit of a Y capacitor, or a too high capacitance, is hazardous if the earth line should be an open circuit or connected to earth through a too high resistance. The National Approval Boards stipulate the maximum permitted current towards earth for different applications. A frequent current value for household equipment and portable tools is ≤0.5mA.
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