IEC 60063 pdf download.Preferred number series for resistors and capacitors
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply. 3.1 E series infinite series of numeric values with a given number of elements per decade, rounded or derived from the elements of a geometric series Note 1 to entry: The number of elements within a decade, r , is given in the designation of the E series, E r , e.g. E24 for a number series with 24 values per decade.
4 Number series
4.1 Number series with two significant digits The series E24, E1 2, E6 and E3 with two significant digits are the decimal multiples and sub- multiples of the respective values given in Table 1 .NOTE The values of the E24 series in the range of 27 through 47, and the value 82, divert from the exact mathematical rule. However, a correction of this deviation has never seemed appropriate in light of the historical relevance of this series, having been established prior to the 1 952 release of the first edition of this standard. The E1 2 series is derived from the E24 series by omitting every second term, and likewise is the E6 series derived from the E1 2 series and the E3 series derived from the E6 series by omitting every second term thereof. 4.2 Number series with three significant digits The series E1 92, E96 and E48 with three significant digits are the decimal multiples and sub- multiples of the respective values given in Table 2.
5 Application of an E series
5.1 Relationship between E series and tolerances A sequential range of components is usually established in a way that a tolerance range of any given value, i.e. the range defined by that given value minus and plus the given tolerance, does not significantly overlap with the tolerance range of the next succeeding value. This consideration suggests a fixed relationship between the tolerance and the progression ratio of any range of components. Table 3 gives the recommended assignment of the E series and the tolerance for components with symmetrical tolerances.5.2 Deduction from the marking and coding of values There are marking and coding systems established in IEC 60062 for values with two and with three significant digits. These marking and coding systems also permit the indication of the tolerance. In many cases however, the space available on a component for application of a marking is not sufficient to permit the additional tolerance information. In such cases it has become common practice to apply the reverse of the relationship shown in Table 3, by concluding from the numerical resolution of a coding to the feasible E series and then to the feasible tolerance, like – a three-character coding only represents values with two significant digits, hence from an E series up to E24, which in turn is related to a tolerance of not tighter than ±5 %; or – a four-character coding only represents values with three significant digits, hence from an E series of E48 or higher, which in turn is related to a tolerance of ±2 % or tighter. It is obvious from this illustration that the conclusion may be ambiguous by itself, and therefore shall not be assumed as a general relationship. It only supports the distinction between pre-defined options, like e.g. E24 and ±5 % versus E96 and ±1 %, and hence depends on a precise and suitable documentation and specification of the respective components.
IEC 60063 pdf download
