Film capacitors may have a segment of three sets of numbers written on them. 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.
Vishay’s General Technical Information on Film Capacitors (page 5) best describes what Climatic Category is all about:
CLIMATIC CATEGORY
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).
- 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.
(IEC 60068-1)
Capacitor Photo Examples:
PHE840MZ7100MF11R06L2 (Digi-Key # 399-5431-ND) made by Kemet
ECQ-U3A104MG (Digi-Key # P11116-ND) made by Panasonic