ELECTRIC CABLES - CALCULATION OF THE CURRENT RATING - PART 1: CURRENT RATING EQUATIONS (100 % LOAD FACTOR) AND CALCULATIONS OF LOSSES - SECTION 2: SHEATH EDDY CURRENT LOSS FACTORS FOR TWO CIRCUITS IN FLAT FORMATION
International Electrotechnical Committee
FOREWORD
1 Scope
2 Normative references
3 Symbols
4 Description of method
4.1 General
4.2 Outline of method
4.3 Criteria for use of formulae and co-efficients
5 Formulae for sheath loss factors for high-
resistance sheaths in a single circuit
6 Calculation of the coefficients H, N and J
6.1 Allocation of coefficients to each cable,
time sequence and phase identification
6.2 Calculation of coefficients H(1,2 and 3)
table 1
6.3 Calculation of coefficients N(1,2,3,4,5 and 6)
table 2
6.4 Calculation of coefficients J(1,2,3,4,5 and 6)
tables 3 to 11
6.5 Calculation of coefficients Gs and gs
7 Notes on transposition of cables
8 Worked examples of calculation of eddy current losses
8.1 Introduction
8.2 Example 1
8.3 Example 2
Tables
Gives procedure for calculating the eddy current in the metallic sheaths of single core cables arranged as a three phase, double circuit in flat formation. The sheaths are bonded at one point or are cross bonded so that there are not significant circulating currents which result in a lower current carrying capacity. The method provides coefficients which are applied as corrections to the loss factors for the sheaths of one isolated three phase circuit. The method should be used for most sizes of aluminium sheathed cable, but is not required for lead sheathed cables unless they are unusually large.
| Document Type | Standard |
| Status | Current |
| Publisher | International Electrotechnical Committee |
| Committee | TC 20 |
| Supersedes |
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