The lowest frequency at which the impedance of the capacitor is a minimum when applying a sinusoidal voltage. The ambient free air temperature is the temperature of the air surrounding the component. The climatic category code (e.g. 50 / 100 / 56) indicates to which climatic category a film capacitor type belongs.
Examples include 55/100/56, 40/85/21, 40/105/21, 40/100/56, -25/70/21, etc. This code is called the Climatic Category and consists of the climatic conditions that can be present when the capacitor is in use. It does not describe any other parameters of the capacitor such as capacitance, voltage rating or package.
It is common for manufacturers to specify in data sheets whether external cooling is required or not. Climatic category The performance characteristics of a capacitor are significantly dependent on the climatic conditions under which a component is used. One of the most important environmental conditions to consider is temperature.
The capacitors are exposed to a damp heat environment, which is maintained at a temperature of 40 °C and an RH of 90 % to 95 % for the number of days specified by the third set of digits of the climatic category code.
The first group indicates the lower category temperature (- 55 °C). The second group the upper category temperature (+ 100 °C). The third group indicates the number of days (56) which the capacitor can withstand within specified limits if exposed to a relative humidity of 95 % and a temperature of + 40 °C.
The climatic category indicates the climatic conditions which the capacitor may be operated. According to IEC 60068-1 the climatic category is expressed by a three group coding e.g. 55/100/56. The first group indicates the lower category temperature (- 55 °C). The second group the upper category temperature (+ 100 °C).