Preferred number

The standard numbers or Renard series are in the standards ISO 3, DIN 323 specified, preferred numbers on the basis of geometric sequences. Mathematically, this series described by the multiplier. In this case, a whole number greater than 1 of the standard values ​​for use in the practice rounded. Thus, in the standardization of screws easily achieved, for example, that for larger screw diameters, a larger maßlicher distance between a screw and the next largest is, while smaller screws are fine tuned.

Number sequences that are used for the gradation values ​​of the electrical components such as electrical resistors, the E series.

General

The Renard series go back to the French military engineer Charles Renard, of 1877, the strength of the cables used for the tethered balloon on the geometric progression

Normalized and so the variant number decreased from 425 to 17. The choice of the base 10 fits well with the decimal prefixes for units because they have different result at a distance of m elements only in the decimal place.

In many cases standards that are based on such a series, mistaken for duty- based, as the crooked numbers on someone who is used to the metric system, act strange and usually occurring 25 to the rounded value of a millimeter inch (25.4 mm) corresponds.

For appropriate values ​​can optionally be multiplied by 10n and used only a part of a series on demand, to the series in parentheses are the start and end values ​​specified by name. If the step size to be changed, it is connected with a slash in the name. For example, " R10 / 3 ( 10, .315 ) ": 10, 20, 40, 80, 160, 315, because of the R10 series only every third value will be used.

Values

Relevant ISO standards:

  • ISO 3:1973, Preferred numbers - Series of Preferred Numbers.
  • ISO 17:1973, Guide to the Use of Preferred Numbers and Series of Preferred Numbers of.
  • ISO 497:1973, Guide to the Choice of Series of Preferred Numbers and of Series Containing More Rounded Values ​​of Preferred Numbers.

For one of the form (with, so m = 3, 6, 12, 24, ...) we obtain the values ​​which are the E series of electronic components based.

Created also as geometric sequence are the DIN paper sizes, but on the basis of the doubling and not the tenfold.

Integer Preferred number#E series: Capacitors and resistors Moored balloon
240950
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