• Rated Capacitance CR: The designed capacitance value, usually marked on the capacitor.

 

  • Capacitance Tolerance : Admitted capacitance deviation from the rated capacitance at 20°C

 

  • Rated Voltage UR:  The maximum direct voltage or the maximum rms alternating voltage or the peak value of a pulse voltage which may be continuously applied to a capacitor at any temperature between the lower category temperature and the rated temperature.

 

  • Category Voltage UC:  The maximum voltage which may be continuously applied to a capacitor at its upper category temperature.

 

  • Climatic category:  The climatic category which the capacitor belongs to is expressed in numbers (standard IEC60068-1: example 55/85/21). The first number represents the lower category temperature; the second number represents the upper category temperature; the third number represents the number of days relevant to the damp heat test.

 

  • Rated Temperature :  The maximum ambient temperature at which the rated voltage may be continuously applied

 

  • Upper Category Temperature:  The designed maximum ambient temperature at which the capacitor can continuously operate.

 

  • Temperature coefficient of capacitance: The change rate of capacitance with temperature measured over a specified range of temperature. It is normally expressed in parts per million per Celsius degree (10-6/ °C)

 

  • Dissipation Factor: The ratio between the resistive and the reactive part of the impedance of the capacitor submitted to a sinusoidal voltage of specified frequency.

 

  • Insulation Resistance/Time Constant: It is expressed in MO¸ measured after a minute of charge under a specified voltage.

 

  • The time constant is expressed with the following formula: T= RC ( s )
    The time constant of a capacitor equals to the product of the insulation resistance and the capacitance in value.