Standard IEC Ratings

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Contents

Introduction

Most IEC rated equipment have standard sizes that correspond to full sets or subsets of Renard numbers, especially from the four preferred series of Renard numbers outlined in ISO-3: R5, R10, R20 and R40.

Transformers

For transformer ratings under 10MVA, IEC 60076-1 suggest preferred values based on the R10 series: 10, 12.5, 16, 20, 25, 31.5, 40, 50, 63, 80, 100, and multiples of 10n. For example, the preferred transformer sizes from 500kVA to 4000kVA are: 500, 630, 800, 1000, 1250, 1600, 2000, 2500, 3150, 4000.

Motors and Generators

IEC 60072-1 Table 7 suggests the following preferred ratings (based on a subset of the R40 series) for motors (in KW) and generators (in kVA):

0.06 0.09 0.12 0.18 0.25 0.37 0.55 0.75 1.1 1.5 1.8* 2.2 3* 3.7 4* 5.5 6.3* 7.5 10* 11 13* 15 17* 18.5
20* 22 25* 30 32* 37 40* 45 50* 55 63* 75 80* 90 100* 110 125* 132 150 160 185 200 220 250
280 300 315 335 355 375 400 425 450 475 500 530 560 600 630 670 710 750 800 850 900 950 1000

(*) Note that these are "secondary series" ratings and are only to be used in cases of special need.

Cables

Standard cable sizes (in mm2) are as follows:

0.5 0.75 1 1.5 2.5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 400 500 630 800 1000
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