Capacitance tolerance of various types of capacitors and its marking

Capacitors are one of the most common types of electrical and electronic circuit components. As a rule, when choosing them, attention is paid to the type of capacitor, its capacitance, maximum voltage, but sometimes such an important parameter as capacitance tolerance is overlooked. Meanwhile, this parameter directly depends on the type of capacitor and its manufacturing technology, and, in some cases, the deviation from the nominal capacitance within the tolerance can be significant during the operation of the circuit, or not have any effect at all. Therefore, when designing, the place of application and function of each capacitor should be taken into account in order to correctly select not only its type, but also its tolerance.

Capacitance tolerance is the range within which the actual capacitance value of a particular capacitor can deviate from its nominal value, expressed in%. To indicate the tolerance on the capacitor, both special codes and a direct indication of the capacitance range can be used. In the example of TDK (EPCOS) electrolytic capacitors, the approval code is given next to the capacitance rating:

An example of marking capacitors TDK (EPCOS)

Permissible tolerance limits, and the codes corresponding to them, are regulated by the international standard IEK 60052 (adopted in the Russian Federation as GOST IEC 60062-2014). The tolerance can be either symmetrical about the nominal value (for example, codes K, M, N), or not symmetrical (asymmetric). Therefore, when choosing a capacitor, it is important to pay attention to the capacitance tolerance coding, since for some types and ratings of capacitors, the deviation from the nominal value can be significant. The most common capacity tolerance codes are:

Capacity Tolerance Marking Codes and Meanings

The capacitance tolerance directly depends on the type of capacitor, the materials used in its manufacture, the quality of production, technical characteristics and other factors. Among the most popular types of capacitors, the following large groups can be distinguished:

• Aluminum electrolytic capacitors. The capacitance tolerance of electrolytic capacitors is usually large, on the order of ±20% (type M) . But for some applications there is also an asymmetric tolerance of -10/+30% (type Q) .
• film capacitors. As a rule, they have a better tolerance, with a smaller deviation from the nominal value. Of the most common: tolerance ±5 (type J) or ±10% (type K) .
• ceramic capacitors. They have a greater or equal tolerance as that of film capacitors - about ± 10% .

Separately, it is worth noting that during operation, the so-called "leaving" or a change in capacity can occur. Capacitance changes can be either reversible or irreversible. Capacitance drift is equal to the sum of all time-dependent capacitance changes over the life of the capacitor, expressed as a percentage of the original capacitance value for the series. Therefore, for critical applications, both capacitors with optimal tolerances should be used, and appropriate operating conditions should be ensured so that the life of the capacitor is as long as possible for its type.

More detailed technical characteristics, including capacitance tolerance, of capacitors can be found in the Specifications on the product page.