TABLE OF CONTENTS FOREWORD...3 INTRODUCTION SCOPE NORMATIVE REFERENCES DEFINITIONS AND ABBREVIATIONS REQUIREMENTS...

Transcription

1 TITLE SPECIFICATION FOR PORTABLE DATE: JULY 2006 PAGE: 1 OF 25 TABLE OF CONTENTS Page FOREWORD...3 INTRODUCTION SCOPE NORMATIVE S DEFINITIONS AND ABBIATIONS REQUIREMENTS General Panel portable earthing gear Overhead line portable earthing gear High voltage portable earthing gear Clamps and terminations Magnefix earthing kits Interswitch earthing kits Equipotential earthing foot plates Fixed earthing ball joint/connector TESTS MARKING AND PACKAGING DOCUMENTATION TRAINING QUALITY ASSURANCE...9 Annex A - Bibliography...10

2 PAGE 2 OF 25 Annex B - Revision information...11 Annex C

3 PAGE 3 OF 25 FOREWORD Recommendations for corrections, additions or deletions should be addressed to the: Technology Services Manager City Power Johannesburg (Pty) Ltd P O Box Booysens 2016

4 PAGE 4 OF 25 INTRODUCTION Earthing of power systems is an essential and integral part of the safety of personnel working on City Power s electrical infrastructure. Under operational conditions, this earthing is carried out by means of portable earthing equipment. Failure of any part of the earthing equipment could result in serious and potentially catastrophic consequences. It is therefore important to ensure that all earthing equipment complies with the required specifications and is of acceptable quality. As this is difficult to manage within the present City Power business structures it has been decided that SABS support structures will be relied upon to manage compliance to specification as well as quality. The implication to suppliers is that City Power will only purchase portable earthing equipment that bears the SABS mark, or alternatively has been type-tested in terms of the relevant specifications. 1 SCOPE This specification covers City Power s requirements for portable earthing equipment in accordance with SANS 1934, SANS and IEC NORMATIVE S The following documents contain provisions that, through reference in the text, constitute requirements of this specification. At the time of publication, the editions indicated were valid. All standards and specifications are subject to revision, and parties to agreements based on this specification are encouraged to investigate the possibility of applying the most recent editions of the documents listed below. SANS 1934, Live working Portable equipment for earthing or earthing and short-circuiting National modifications to international requirements SANS 61230, Live working Portable equipment for earthing or earthing and short-circuiting IEC 1138, Cables for portable earthing and short-circuiting equipment, Specification for earth rods, couplers and copper clad steel conductors CP_TSSPEC_111, Specification for insulating rods for use with portable earthing equipment 3 DEFINITIONS AND ABBIATIONS The definitions and abbreviations in the above documents shall apply to this specification.

5 PAGE 5 OF 25 4 REQUIREMENTS 4.1 General Several different types of portable earths are required, namely panel earths, overhead line earths and high voltage earths. In addition, portable earthing kits for Magnefix and Interswitch resin-insulated compact switchgear as well as equipotential earth foot plates are required The portable earthing gear shall be designed for use in a system that may be either solidly or resistively earthed The portable earthing gear will be installed in areas subject to frequent high intensity lightning storms All portable earthing gear shall comply with the requirements of SANS 1934 and SANS The material of all conductors shall be multi-stranded copper complying with IEC No other material shall be considered All earthing conductors shall be flexible and lightweight. To this end no component, or set of components if inseparable under normal operating conditions, shall have a mass of more than 8 kg The earthing conductor shall be covered with an ultra-violet resistant flexible sheath to protect the copper conductor from mechanical and environmental damage. The sheath shall be transparent to permit inspection of the conductor for signs of corrosion or surface strand damage The portable earths shall be designed for a one second fault rating of 20 ka in the case of 95 mm 2 conductors, and 13,1 ka in the case of 70 mm 2 conductors Unless otherwise specified, all earthing equipment shall be suitable for use on systems with nominal voltages from 400 V to 33 kv. 4.2 Panel portable earthing gear The panel earths shall be supplied as a single device from the manufacturer The panel earths shall be suitable for use on MV and LV systems The panel earths shall consist of three phase conductors having a length of 0,5 m each, connected to a single earthing conductor having a length of 1,0 m. The central connecting point for the phase and earth conductors shall be fully insulated The line clamp shall be capable of clamping onto cable terminations and rigid bus bars. The earth clamp shall be capable of being securely connected to an earth point i.e. structure, earth rod, etc The cross-sectional area of all conductors used for the panel earth shall be 95 mm Overhead line portable earthing gear The overhead line earths shall be supplied as a complete set from the manufacturer The overhead line earths shall be suitable for use on MV and LV systems.

6 PAGE 6 OF Each set of overhead line earths shall consist of four inter-phase conductors having a length of 1,5 m each, and a single earthing conductor having a length of 13,0 m The inter-phase conductor line clamps shall be capable of clamping onto overhead line conductors from 5 mm to 40 mm in diameter. The inter-phase conductors shall have such clamps at each end. The single conductor of 13 m length shall have a line clamp and an earth clamp connected to it. The earth clamp shall be capable of being securely connected to an earth point i.e. structure, earth rod, etc The cross-sectional area of all conductors used for the overhead line earth shall be 70 mm The overhead line earth clamp shall be suitable for connection to a separate 1,2 m portable earth rod, complying fully with the requirements of CP_TSSPEC_056, to enable an operator on site to obtain a temporary connection to the general mass of earth where no permanent earth connection is available, by driving the portable earth rod a minimum of 750 mm into the ground The overhead line earth set shall be designed to facilitate the future conversion to an equipotential earth system, by the supply of a cluster bar and relevant additional clamps. 4.4 High voltage portable earthing gear The high voltage earths shall be supplied as a complete set from the manufacturer The high voltage earths shall be suitable for use on MV and HV systems (from 11 to 88 kv) Each set of high voltage earths shall consist of three conductors having a length of 6,0 m The line clamps shall be capable of clamping onto stranded or tubular conductors from 10 mm to 100 mm in diameter. The conductors shall each have a phase clamp and an earth clamp. The earth clamps shall be capable of being securely connected to an earth point i.e. structure, earth rod, etc The cross-sectional area of all conductors used for the high voltage earth shall be 95 mm Clamps and terminations Snap-on type line clamps shall not be acceptable. Only those clamps which are tightened by means of a bayonet-type (or similar) device attached to an insulating earthing stick shall be considered. The design of the clamps shall be such that an operator standing in the bucket of an aerial platform or on a ladder can attach the clamp to the appropriate conductor and tighten it to the correct torque using an insulated earthing stick complying with CP_TSSPEC_ The clamps shall provide reliable and secure clamping action on strung conductor and be able to withstand the thermal and mechanical stresses produced by the rated fault current. To this end the contact surface of the clamps shall be serrated or similar The attachment of the clamp shall be a T-pin type compatible with the bayonet head of the insulating stick, which shall fit over the T-pin attachment The line clamps of the panel earths shall be suitable for connection to rigid bus bars or cable terminations of up to 30 mm thickness. The line clamps of the overhead line earths shall be suitable for use with stranded conductors from 5 mm to 40 mm in diameter. The line clamps of the high voltage earths shall be suitable for use with stranded or tubular conductors ranging from 10 mm to 85 mm diameter. Line clamps for the panel earths shall be made of leaded brass. Line clamps for the overhead and high voltage earths shall be made of aluminium alloy,

7 PAGE 7 OF 25 and all T-pin screw threads shall be made of grade 304 (or better) stainless steel. Full details of the alloy used shall be supplied with the tender Earth clamps may be hand tightened, and shall be of a screw-on type with contact surfaces suitable for fastening onto flat surfaces of thickness between 2 and 30 mm. Earth clamps shall be made of leaded brass and suitably protected against corrosion All clamps shall be able to withstand the tightening forces without sustaining damage. Preference will be given to designs which overcome friction and wear due to contact between dissimilar surfaces. Preference will also be given to devices not requiring maintenance in the form of lubrication, etc All lugs used shall be made of tinned copper. The thickness of the tin shall be between 19 µm and 25 µm. The lug barrel shall be profiled to facilitate easy entry of the copper conductor and to prevent mechanical damage of the conductor during movement under Aeolian forces, etc The lug shall lock positively to the line and earth clamps to prevent unintentional loosening of the terminations All lugs shall be crimped onto the copper conductor so as to ensure compliance with the ka rating criteria. At least one crimp shall be onto the insulation (sheathing) of the copper conductor. A protective sleeve shall be applied over the crimped section of the lug and shall extend at least 50 mm over the conductor insulation The terminations shall be sealed to prevent the penetration of moisture All bolted connections shall be made with hardware made from stainless steel of at least grade 304 or better. Where a bimetallic connection is made, suitable means shall be provided to prevent any possibility of galvanic action. In all cases, all bolts and nuts shall be tightened to the manufacturer s torque specification for the selected bolt and size. 4.6 Magnefix earthing kits The kits shall be suitable for the earthing of the Holec Magnefix type MD4 ring main unit The insulating guides shall be suitable for use with the MD4 unit The earthing kit shall be similar to the panel earthing gear described in clause 4.2 except that the cross-sectional area of conductor required is 70 mm The earthing kit shall be able to be attached and removed using an insulated earthing stick complying with CP_TSSPEC_ Interswitch earthing kits The kits shall be suitable for the earthing of the Interswitch B20 ring main unit The insulating guides shall be suitable for use with the B20 unit The earthing kit shall be similar to the panel earthing gear described in clause 4.2 Note: the cross-sectional area of conductor required is 95 mm The earthing kit shall be able to be attached and removed using an insulated earthing stick complying with CP_TSSPEC_111.

8 PAGE 8 OF Equipotential earthing foot plates Equipotential earthing foot plates shall be manufactured from 6 mm thick chequered aluminium plate and shall be a minimum of 500 mm 700 mm in size A 2,0 m earthing lead complying with clause 4.1 of this specification and with a crosssectional area of 35 mm 2 shall be attached to the foot plate. The other end of the conductor shall be fitted with an earth clamp as contemplated in clause 4.5 of this specification The foot plate shall be fitted with a suitable handle so that it may be carried without undue effort within substation yards and similar environments where the use of such a device may be required If so required by the purchaser, the supplier shall provide details of provision for the fitting of foot plates to vehicle-mounted cranes. 4.9 Fixed earthing ball joint/connector The fixed earthing ball joint shall be tinned copper with a tin thickness of between 19 µm and 25 µm. Alternatively, it shall be made of grade 304 (or better) stainless steel The fixed earthing ball joint shall be supplied with a flat washer, spring washer and nut, which shall all be manufactured from grade 304 (or better) stainless steel The fixed earthing ball joint shall have the following dimensions: a) Ball: 25 mm diameter; b) Shank: 11 mm diameter with a minimum length of 15 mm; c) Flange: 24 mm hexagon with a length of 24 mm; and d) Stud: M16 thread with a minimum length of 45 mm. 5 TESTS 5.1 The portable earthing equipment shall have been type tested in accordance with the requirements of SANS MARKING AND PACKAGING 6.1 The sheath of each conductor shall be clearly and indelibly marked with the following information: a) the name or trade mark of the manufacturer; b) the model or type reference; c) cross-sectional area of the conductor in mm 2 ; material and SABS mark or double triangle symbols at 1 metre intervals on each cable; d) the year of manufacture; and e) the ka rating of the device as tested. The markings shall be legible, durable and the letters shall be at least 3 mm high.

9 PAGE 9 OF Each portable earthing set shall be supplied with a suitable heavy-duty storage/carry bag. The bag shall be durable and shall be provided with one or more handles for the easy carrying of the kit. 6.3 Each carry bag shall be marked with the City Power logo and a description of the contents (type of earth, size and number of items in the complete set). 6.4 The fixed earthing ball joints shall be supplied individually in cardboard boxes. 7 DOCUMENTATION 7.1 Each portable earthing equipment set shall be supplied with comprehensive instructions for use and a certificate. 7.2 Full details of the clamp construction (including drawings) and materials used in the manufacture of the clamps shall be supplied. 7.3 In all cases, detailed type test reports shall be supplied for the portable earthing equipment to be considered. The type test reports required are as follows: a) Electrical type test reports as detailed in SANS for both rigid bus bar applications as well as overhead line applications; and b) Mechanical type test reports as detailed in SANS (i.e. pull, fatigue and humidity tests). 7.4 In addition to the documentation required above, a certificate from the manufacturer of the cable used in the earthing devices shall be supplied to confirm that the cable used complies fully with the requirements of IEC Any offer that lacks the above documentation will not be considered further. The onus is on the supplier to ensure that he or she is in possession of the relevant documentation and that he or she supplies such documentation with the tender/quotation. 8 TRAINING 8.1 The following certified training courses shall be offered for City Power s staff: a) Correct handling and care of the portable earthing equipment; and b) Correct and safe use of the portable earthing equipment. 8.2 The associated costs for the certified training courses in 8.1 shall be given per person and shall be fixed for the period of the contract. 9 QUALITY ASSURANCE A quality management system shall be set up in order to assure the quality of the portable earthing equipment during design, development, production, installation and service. Guidance on the requirements for a quality management system may be found in the following standards: SANS 9000, SANS 9001, and SANS The details shall be subject to agreement between the purchaser and supplier.

10 PAGE 10 OF 25 Annex A - Bibliography Previous informal City Power specification for portable earths ethekwini Electricity specification for portable earthing gear ethekwini Electricity specification for Magnefix earthing kits Eskom document SCSSCAAN3, Specification for portable earthing gear

11 PAGE 11 OF 25 Annex B - Revision information DATE. NO. NOTES Feb First issue July Included reference to SANS 1934 Clause 4.3: Inclusion of ability to connect to portable earth spike for overhead line earths Clause 4.3: Inclusion of ability to facilitate conversion to equipotential earthing system Clause 4.4.4: Changed HV line clamp range upper limit to 100 mm to cater for tubular aluminium busbars Inclusion of clause 4.6: Magnefix earthing kits Inclusion of clause 4.7: Interswitch earthing kits Inclusion of clause 4.8: Fixed earthing ball joints Inclusion of clause 4.9: Equipotential foot plates Clause Changed fault rating to 20 ka and 13,1 ka for 95 mm 2 and 70 mm 2 conductors respectively Updated Bibliography (Annex A) Updated technical schedules (Annex C)

12 PAGE 12 OF 25 Annex C - for Panel Earths Schedule A: Purchaser's specific requirements Schedule B: Guarantees and technical particulars of equipment offered Item Sub-clause of Description Schedule A Schedule B 1 Name of manufacturer XXXX 2 Place of manufacture XXXX 3 Manufacturer s identification reference XXXX Specification to which portable earthing gear complies SANS 1934 & SANS System voltage suitability kv 0,4 to Fault level withstand (1 second rating) for complete earthing set (incl. clamp) ka Conductor material Stranded copper Conductor C.S.A. mm Conductor quantity and length m 3 0,5 and Line clamp material Leaded brass Earth clamp material Leaded brass Line clamp application Rigid bus bar and cable terminations Line clamp range mm up to Earth clamp range mm 2 to Marking as per clause 6 Yes/No Yes 16 6 Packaging as per clause 6 Yes/No Yes 17 7 Is all the information requested in clause 7 supplied? Yes/No Yes Tenderer s Authorised Signatory:

13 PAGE 13 OF 25 Deviation schedule Any deviations offered to this specification shall be listed below with reasons for deviation. In addition, evidence shall be provided that the proposed deviation will at least be more costeffective than that specified by City Power. Item Sub-clause of Proposed deviation

14 PAGE 14 OF 25 for Overhead Line earths Schedule A: Purchaser's specific requirements Schedule B: Guarantees and technical particulars of equipment offered Item Sub-clause of Description Schedule A Schedule B 1 Name of manufacturer XXXX 2 Place of manufacture XXXX 3 Manufacturer s identification reference XXXX Specification to which portable earthing gear complies SANS 1934 & SANS System voltage suitability kv 0,4 to Fault level withstand (1 second rating) for complete earthing set (incl. clamp) ka 13, Conductor material Stranded copper Conductor C.S.A. mm Conductor quantity and length m 4 1,5 and Line clamp material Aluminium alloy Earth clamp material Leaded brass Line clamp application Overhead line Line clamp range mm 5 to Earth clamp range mm 2 to Marking as per clause 6 Yes/No Yes 16 6 Packaging as per clause 6 Yes/No Yes 17 7 Is all the information requested in clause 7 supplied? Yes/No Yes

15 PAGE 15 OF 25 Deviation schedule Any deviations offered to this specification shall be listed below with reasons for deviation. In addition, evidence shall be provided that the proposed deviation will at least be more costeffective than that specified by City Power. Item Sub-clause of Proposed deviation

16 PAGE 16 OF 25 for High voltage portable earths Schedule A: Purchaser's specific requirements Schedule B: Guarantees and technical particulars of equipment offered Item Sub-clause of Description Schedule A Schedule B 1 Name of manufacturer XXXX 2 Place of manufacture XXXX 3 Manufacturer s identification reference XXXX Specification to which portable earthing gear complies SANS 1934 & SANS System voltage suitability kv 11 to Fault level withstand (1 second rating) for complete earthing set (incl. clamp) ka Conductor material Stranded copper Conductor C.S.A. mm Conductor quantity and length m Line clamp material Aluminium alloy Earth clamp material Leaded brass Line clamp application Stranded and tubular conductors Line clamp range mm 10 to Earth clamp range mm 2 to Marking as per clause 6 Yes/No Yes 16 6 Packaging as per clause 6 Yes/No Yes 17 7 Is all the information requested in clause 7 supplied? Yes/No Yes

17 PAGE 17 OF 25 Deviation schedule Any deviations offered to this specification shall be listed below with reasons for deviation. In addition, evidence shall be provided that the proposed deviation will at least be more costeffective than that specified by City Power. Item Sub-clause of Proposed deviation

18 PAGE 18 OF 25 for Magnefix earthing kits Schedule A: Purchaser's specific requirements Schedule B: Guarantees and technical particulars of equipment offered Item Sub-clause of Description Schedule A Schedule B 1 Name of manufacturer XXXX 2 Place of manufacture XXXX 3 Manufacturer s identification reference XXXX Specification to which portable earthing gear complies SANS 1934 & SANS System voltage suitability kv 6,6 to Fault level withstand (1 second rating) for complete earthing set (incl. clamp) ka 13, Conductor material Stranded copper Conductor C.S.A. mm Conductor quantity and length m 4 0,5 and Line clamp material XXXX Earth clamp material Leaded brass Line clamp application Magnefix MD4 13 Line clamp range mm XXXX Earth clamp range mm 2 to Marking as per clause 6 Yes/No Yes 16 6 Packaging as per clause 6 Yes/No Yes 17 7 Is all the information requested in clause 7 supplied? Yes/No Yes

19 PAGE 19 OF 25 Deviation schedule Any deviations offered to this specification shall be listed below with reasons for deviation. In addition, evidence shall be provided that the proposed deviation will at least be more costeffective than that specified by City Power. Item Sub-clause of Proposed deviation

20 PAGE 20 OF 25 for Interswitch earthing kits Schedule A: Purchaser's specific requirements Schedule B: Guarantees and technical particulars of equipment offered Item Sub-clause of Description Schedule A Schedule B 1 Name of manufacturer XXXX 2 Place of manufacture XXXX 3 Manufacturer s identification reference XXXX Specification to which portable earthing gear complies SANS 1934 & SANS System voltage suitability kv 6,6 to Fault level withstand (1 second rating) for complete earthing set (incl. clamp) ka Conductor material Stranded copper Conductor C.S.A. mm Conductor quantity and length m 3 0,5 and Line clamp material XXXX Earth clamp material Leaded brass Line clamp application Interswitch B20 13 Line clamp range mm XXXX Earth clamp range mm 2 to Marking as per clause 6 Yes/No Yes 16 6 Packaging as per clause 6 Yes/No Yes 17 7 Is all the information requested in clause 7 supplied? Yes/No Yes

21 PAGE 21 OF 25 Deviation schedule Any deviations offered to this specification shall be listed below with reasons for deviation. In addition, evidence shall be provided that the proposed deviation will at least be more costeffective than that specified by City Power. Item Sub-clause of Proposed deviation

22 PAGE 22 OF 25 for Fixed earth ball joints Schedule A: Purchaser's specific requirements Schedule B: Guarantees and technical particulars of equipment offered Item Sub-clause of Description Schedule A Schedule B 1 Name of manufacturer XXXX 2 Place of manufacture XXXX 3 Manufacturer s identification reference XXXX 4 Specification to which portable earthing gear complies XXXX System voltage suitability kv 0,4 to Fault level withstand (1 second rating) for complete earthing ball joint ka Material of fixed earthing ball joint Tinned copper/ stainless steel Material of washers and nut Stainless steel a) Ball diameter mm b) Shank diameter mm b) Minimum shank length mm c) Does flange have a 24 mm hexagon? Yes/No Yes c) Flange length mm d) Stud diameter M d) Minimum stud length mm Packaging as per clause 6 Yes/No Yes 17 7 Is all the information requested in clause 7 supplied? Yes/No Yes

23 PAGE 23 OF 25 Deviation schedule Any deviations offered to this specification shall be listed below with reasons for deviation. In addition, evidence shall be provided that the proposed deviation will at least be more costeffective than that specified by City Power. Item Sub-clause of Proposed deviation

24 PAGE 24 OF 25 for Equipotential earthing foot plates Schedule A: Purchaser's specific requirements Schedule B: Guarantees and technical particulars of equipment offered Item Sub-clause of Description Schedule A Schedule B 1 Name of manufacturer XXXX 2 Place of manufacture XXXX 3 Manufacturer s identification reference XXXX 4 Specification to which portable earthing gear complies XXXX System voltage suitability kv 0,4 to Minimum thickness and material of foot plate mm chequered aluminium Dimensions of foot plate (minimum) mm Conductor material Stranded copper Conductor C.S.A. mm Conductor quantity and length m 1 2,0 11 Earthing lead fixing arrangement XXXX Earth clamp material Leaded brass 13 Foot plate application Equipotential earthing Does foot plate have a handle? Yes/No Yes Earth clamp range mm 2 to Marking as per clause 6 Yes/No Yes 17 6 Packaging as per clause 6 Yes/No Yes 18 7 Is all the information requested in clause 7 supplied? Yes/No Yes

25 PAGE 25 OF 25 Deviation schedule Any deviations offered to this specification shall be listed below with reasons for deviation. In addition, evidence shall be provided that the proposed deviation will at least be more costeffective than that specified by City Power. Item Sub-clause of Proposed deviation