ISBN 978-0-626-31488-0 SOUTH AFRICAN NATIONAL STANDARD Switchgear Metal-enclosed ring main units for rated a.c. voltages above 1 kv and up to and including 36 kv WARNING This document references other documents normatively. Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001 Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS
Table of changes Change No. Date Scope Foreword This South African standard was approved by National Committee SABS/TC 067/SC 01, Electricity distribution systems and components High-voltage switchgear, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was approved for publication in March 2015. This document supersedes SANS 1874:2011 (edition 2.1). Annex C forms an integral part of this standard. Annexes A, B, D and E are for information only.
Contents Page 1 Scope... 3 2 Normative references... 3 3 Terms, definitions and abbreviations... 4 4 Requirements... 6 4.1 Service conditions... 6 4.2 Ratings... 7 4.3 General... 9 4.4 Switch-disconnectors for rings and tee-offs... 12 4.5 Switch-fuse combinations for tee-offs... 13 4.6 Circuit-breakers for tee-offs... 15 4.7 Busbars... 16 4.8 Cable termination enclosures and terminations... 17 4.9 Automation requirements (if applicable)... 17 4.10 Additional requirements for sulfur hexafluoride (SF 6 )-filled switchgear... 20 4.11 Earthing... 21 4.12 Live circuit indication... 21 4.13 Earth fault indication... 22 4.14 Kiosks (for free-standing outdoor ring main units)... 22 4.15 Raising base (for indoor ring main units)... 24 4.16 Accessories... 24 4.17 Rating plates... 25 4.18 Protection against corrosion (ring main units, kiosks and raising bases)... 26 5 Tests... 26 5.1 General... 26 5.2 Type tests... 27 5.3 Routine tests... 27 5.4 Tests on painted surfaces... 28 6 Marking and labelling... 28 7 Recommended spares... 30 8 Documentation... 30 8.1 Required documentation... 30 8.2 Documentation to be supplied with each tender... 30 8.3 Documentation to be supplied with each ring main unit... 32 Annex A (informative) Guide to purchasers on preparing an enquiry... 33 Annex B (informative) Model form for schedules A and B... 35 Annex C (normative) Notes to users of SF 6 -filled switchgear... 39 Annex D (informative) Drawings... 40 Annex E (informative) Choice of equipment... 44 Bibliography... 45 1
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Switchgear Metal-enclosed ring main units for rated a.c. voltages above 1 kv and up to and including 36 kv 1 Scope This standard specifies the characteristics of new factory-assembled metal-enclosed ring main units that are rated for use on a three-phase cable system for rated a.c. voltages above 1 kv and up to and including 36 kv, and are designed for indoor or outdoor operation at a rated frequency of 50 Hz. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. Information on currently valid national and international standards can be obtained from the SABS Standards Division. EN 50181, Plug-in type bushings above 1 kv up to 36 kv and from 250 A to 1,25 ka for equipment other than liquid filled transformers. IEC 60376, Specification of technical grade sulfur hexafluoride (SF 6 ) for use in electrical equipment. NRS 013, Medium-voltage cables. SANS 97, Electric cables Impregnated paper-insulated metal-sheathed cables for rated voltages 3,3/3,3 kv to 19/33 kv (excluding pressure assisted cables). SANS 279/ISO 1518, Paints and varnishes Scratch test. SANS 876/NRS 012, Cable terminations and live conductors within air-filled enclosures (insulation co-ordination) for rated a.c. voltages from 7,2 kv up to and including 36 kv. SANS 1091, National colour standard. SANS 1186-1, Symbolic safety signs Part 1: Standard signs and general requirements. SANS 2409/ISO 2409, Paints and varnishes Cross-cut test. SANS 9227, Corrosion tests in artificial atmospheres Salt spray tests. SANS 10198-13, The selection, handling and installation of electric power cables of rating not exceeding 33 kv Part 13: Testing, commissioning and fault location. 3