# Technical Terms Related To Capacitors

**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.