IEC 60287-1-2:2023
Electric cables - Calculation of the current rating - Part 1-2: Current rating equations (100 % load factor) and calculations of losses - Sheath eddy current loss factors for two circuits in flat formation
Abstract
IEC 60287-1-2:2023 provides a method for calculating the eddy current losses 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 no significant sheath circulating currents. Where metallic sheaths are bonded at both ends there are significant circulating currents which result in a lower current-carrying capacity. A method of calculating circulating current losses for double circuits is provided in IEC 60287-1-3.
The method descibed in this document provides coefficients which are applied as corrections to the loss factors for the sheaths of one isolated three-phase circuit. These corrections are negligible for cables where the parameter m is less than approximately 0,1 (m = ω/(Rs · 107)), which corresponds to a sheath longitudinal resistance higher than 314 µΩ/m at 50 Hz.
Consequently, the method is used for most sizes of aluminium-sheathed cables, but is not required for lead-sheathed cables unless they are unusually large.
The coefficients are provided in tabular form and have been computed from fundamental formulae for sheath losses, the evaluation of which calls for expertise in computer programming which will possibly not be readily available in general commercial situations. The development of simplified formulae for some of the tabulated coefficients is under consideration.
Losses for cables in a single circuit is covered in IEC 60287-1-1.
The method descibed in this document provides coefficients which are applied as corrections to the loss factors for the sheaths of one isolated three-phase circuit. These corrections are negligible for cables where the parameter m is less than approximately 0,1 (m = ω/(Rs · 107)), which corresponds to a sheath longitudinal resistance higher than 314 µΩ/m at 50 Hz.
Consequently, the method is used for most sizes of aluminium-sheathed cables, but is not required for lead-sheathed cables unless they are unusually large.
The coefficients are provided in tabular form and have been computed from fundamental formulae for sheath losses, the evaluation of which calls for expertise in computer programming which will possibly not be readily available in general commercial situations. The development of simplified formulae for some of the tabulated coefficients is under consideration.
Losses for cables in a single circuit is covered in IEC 60287-1-1.
Additional information
Publication type | International Standard |
---|---|
Publication date | 2023-05-12 |
Edition | 2.0 |
Available language(s) | English |
TC/SC | TC 20 - Electric cablesrss |
ICS | 29.060.20 - Cables |
Stability date | 2030 |
Pages | 30 |
File size | 1227 KB |
The following test report forms are related:
Share your publications
Learn how to share your publications with your colleagues, using networking options.
Payment information
Our prices are in Swiss francs (CHF). We accept all major credit cards (American Express, Mastercard and Visa, JCB and CUP), PayPal and bank transfers as form of payment.
Keep in touch
Keep up to date with new publication releases and announcements with our free IEC Just Published email newsletter.
Contact customer services
Please send your enquiry by email or call us on +41 22 919 02 11 between 09:00 – 16:00 CET Monday to Friday.