CHAPTER 14 STEELWORK

Transcription

1 CHAPTER 14 STEELWORK 1. FOREWORD 2. SCOPE 3. GENERAL 4. CROSSARMS 4.1 New build 4.2 Refurbishment LV wood pole overhead lines Light duty HV overhead lines Heavy duty HV overhead lines kV Trident wood pole overhead lines 5. AUXILIARY EQUIPMENT STEELWORK 5.1 D-Unit steelwork Short kit Long kit 5.2 Transformer platforms Single pole kit H-pole kit 6. STEELWORK ERECTION 7. ASSOCIATED DRAWINGS 8. DOCUMENTS REFERENCED 9. KEYWORDS CP420 Pt1 Ch14.doc Issue 4 19/12/07 RG Ch14 Page 1 of 13

2 STEELWORK 1. FOREWORD 1.1 This chapter provides guidance for the use and installation of crossarms and steelwork equipment kits on overhead line wood pole structures. The type of erection procedure to be adopted will vary for different locations and terrain conditions and overall construction project. The supervisor shall decide which procedure is appropriate for each kit of steelwork to be erected. Guidance on the correct methods of erecting steelwork is given in CP Prior to any work being carried out, all working party personnel shall be fully acquainted with the procedures to be adopted in order to ensure the safety of the public and livestock, especially when erecting steelwork adjacent to public highways, footpaths or pastureland etc. Approved procedures and equipment shall be used. Reference shall always be made to the relevant sections of the Distribution Safety Rules prior to work being started. 2. SCOPE 2.1 This chapter contains information relating to the types, general arrangements of crossarms and support steelwork kits for ancillary equipment used for both new build and refurbishment, operating in the range LV up to and including 132kV, on wood poles. 2.2 This document shall be read with the understanding that it is not possible to show every possible arrangement but sets out the general arrangement that shall be transferred to other structure types where feasible. 3. GENERAL 3.1 Specifications governing the design of new overhead lines which include crossarm arrangements have changed over the years. The principal changes involve overhead lines with small section conductors, ie up to and including 38mm 2 Cu or 50mm 2 Al conductor, which are known as light duty. Historically, light duty specifications included crossarms with a smaller cross-section and reduced phase to phase clearances than their heavy duty counterparts. Light duty and heavy duty specifications have now been consolidated into one specification that uses the larger cross-section crossarm with increased phase to phase clearances. Light duty crossarms shall not be used for new construction work. 3.2 There are many kilometres of existing overhead lines in service that have been designed and constructed to historical specifications, many of which are light duty. The majority of these lines has performed and still is performing well and can be deemed fit for purpose. When carrying out maintenance or refurbishment work it is therefore inappropriate to replace light duty crossarms with a heavy duty crossarm if the line section and span has performed adequately with regard to conductor clashing. Crossarms that can be used for maintenance and refurbishment work on existing light duty lines can be found in Section 4 of this chapter. The British Standard EN for Overhead electrical lines exceeding AC 1kV up to and including AC 45kV, which came into force in 2005, states in Part 3 National Normative Annex (NNA), clause 1 as follows: This combined NNA is only applicable to all new overhead lines above A.C. 1kV. and CP420 Pt1 Ch14.doc Issue 4 19/12/07 RG Ch14 Page 2 of 13

3 This Euronorm is only applicable to new overhead lines and shall not be applied to maintenance, reconductoring, tee-offs, extensions or diversions to existing overhead lines unless specifically by the Project Specification. 3.3 Steelwork grades and finish shall be as specified in ES400S CROSSARMS 4.1 New build Details and arrangements of crossarms and their associated steelwork for new build overhead lines can be found in ES400O2, ES400O3, ES400O4 and ENA TS and as specified in ES400S Refurbishment Refurbishment can consist of a crossarm change on an existing pole, a complete pole replacement or a diversion to an existing overhead line based on the original line design specification LV wood pole overhead lines LV open wire overhead lines do not generally use crossarms but the steelwork that makes up their pole top arrangement shall be refurbished with the steelwork as detailed in ENA TS LV ABC overhead lines do not use crossarms but the steelwork that makes up their pole top arrangements shall be refurbished with the steelwork as detailed in ES400O Light duty HV overhead lines Crossarms as detailed in Figs LR1, LR2, LR3 and LR4 below and as specified in ES400S11 can be used to refurbish light duty HV lines only, ie BS 1320 and ENA TS and any historical light duty company specific derivatives. They shall not be used for the construction of new lines. These crossarms are modified type crossarms. There are 3 sets of holes on the vertical flange to allow installation on existing poles and new poles as shown. To left: Crossarm installed on existing pole utilising the existing crossarm tie-straps. To right: Crossarm installed on existing pole with new crossarm struts. CP420 Pt1 Ch14.doc Issue 4 19/12/07 RG Ch14 Page 3 of 13

4 To left: Crossarm installed on new pole with new crossarm struts. Crossarm Tie-Straps/Struts Fixing Arrangments Intermediate Crossarm - installed on an existing pole. Fig LR1 Intermediate (existing pole) Fig LR1 Intermediate (new pole) Intermediate Crossarm - installed on a new pole. Note the longer insulator pin (33kV) is on the centre phase to ensure that the conductor has sufficient clearance to the pole top. Materials List Intermediate Crossarm (LR1) Item ES Ref Item CC No Quantity 1ph 3ph Crossarm ES400S Crossarm Strut ES400S As As Bolt, M20, 300mm ES400F Bolt, M20, 60mm ES400F Washer, Square, Curved ES400F Insulator Pin Mounted ES400I Insulator Pin 11kV ES400S Insulator Pin 33kV ES400S As Helical Intermediate Tie ES400H2 To suit conductor 2 3 CP420 Pt1 Ch14.doc Issue 4 19/12/07 RG Ch14 Page 4 of 13

5 Note: Porcelain or Composite Disc insulators shown for reference but shall only be pigtail type. Fig LR2 Section Materials List Section Crossarm (LR2) Item ES Ref Item CC No Quantity 1ph 3ph Crossarm ES400S Crossarm Strut ES400S As As Bolt, M20, 300mm ES400F Bolt, M20, 60mm ES400F Washer, Square, Curved ES400F Section Strap ES400S Pilot Pin ES400S Helical Side Tie ES400H2 To suit 0 1 conductor Note: Porcelain or Composite Disc insulators shown for reference but shall only be pigtail type. Fig LR3 Section Angle Materials List Section Angle Crossarm (LR3) Item ES Ref Item CC No Quantity 1ph 3ph Crossarm ES400S Crossarm Strut ES400S As As Bolt, M20, 300mm ES400F Bolt, M20, 60mm ES400F Washer, Square, Curved ES400F Section Strap ES400S Pilot Pin ES400S Helical Side Tie ES400H2 To suit 1 2 conductor CP420 Pt1 Ch14.doc Issue 4 19/12/07 RG Ch14 Page 5 of 13

6 Note: Porcelain or Composite Disc insulators shown for reference only but shall be pigtail type. Fig LR4 Terminal Materials List Terminal Crossarm (LR4) Item ES Ref Item CC No Quantity 1ph 3ph Crossarm ES400S Crossarm Strut ES400S As As Bolt, M20, 300mm ES400F Bolt, eye, M20, 300mm ES400F Bolt, M20, 60mm ES400F Washer, Square, Curved ES400F Section Strap ES400S Heavy duty HV overhead lines Crossarms and associated steelwork shall be refurbished with crossarm arrangements as detailed in ES400O3 and specified in ES400S kV Trident wood pole overhead lines Crossarms and associated steelwork shall be refurbished with the steelwork as detailed in ENA TS and specified in ES400S11. CP420 Pt1 Ch14.doc Issue 4 19/12/07 RG Ch14 Page 6 of 13

7 5. AUXILIARY EQUIPMENT STEELWORK 5.1 D-Unit steelwork There are two D-Unit steelwork kits available, a short kit and a long kit. The correct choice of kit shall be made to ensure that when inserting and withdrawing Fuses or Links from the D-Units, the operating rods do not interfere with any other plant or conductors. Each kit can be mounted with the struts above or below the cantilever members Short kit Projection from pole centre to front face of D-Unit steelwork = 439mm Approximate overall weight (excluding D-units) = 30kg (66lbs) Single Pole Arrangements H-Pole Arrangements (shown for 1830mm/6ft centres) CP420 Pt1 Ch14.doc Issue 4 19/12/07 RG Ch14 Page 7 of 13

8 5.1.2 Long kit Projection from pole centre to front face of D-unit steelwork = 1079mm Approximate overall weight (excluding D-Units) = 43kg (95lbs) Single Pole Arrangements H Pole Arrangements (shown for 1830mm/6ft centres) CP420 Pt1 Ch14.doc Issue 4 19/12/07 RG Ch14 Page 8 of 13

9 5.2 Transformer platforms Transformer platforms are used for mounting transformers that are not of the single bolt fixing type. The following 2 kits are available Single pole kit Used for transformers up to and including 100kVA and a maximum weight of 750kg (1654lbs). Approximate weight of transformer platform kit is 31kg (68lbs) H-pole kit Used for transformers up to and including 200kVA and a maximum weight of 1400kg (3086lbs). Approximate weight of transformer platform kit is 59kg (130lbs). CP420 Pt1 Ch14.doc Issue 4 19/12/07 RG Ch14 Page 9 of 13

10 6. STEELWORK ERECTION 6.1 For new build overhead lines, crossarms are generally installed on the pole prior to pole erection. 6.2 The use of a manual lifting method will be of most use in locations where site access is poor and the use of winches or mechanically assisted equipment is prevented. There are crossarms lifters, transformer gins and cathead hoists (see attached copies of drawings from CP430 Part 1). The procedures can be found in CP430 Part The procedures can be used in reverse for dismantlement. 7. ASSOCIATED DRAWINGS I-430P1-M I-430P1-M I-430P1-M Installing Tee-off Crossarm Installing DOEF Steelwork Use of Crossarm Lifter 8. DOCUMENTS REFERENCED Electricity Safety, Quality and Continuity Regulations BS 1320: High Voltage Overhead Lines on Wood Poles for Line Voltages up to and including 11kV Conductors not exceeding 0.05sq.in. (NOW WITHDRAWN) BS EN :2005: Overhead Electrical Lines exceeding AC 1kV up to and including AC 45kV National Normative Aspects (NNA) for Great Britain and Northern Ireland ENA TS 43-10: 11kV Single Circuit Overhead Lines of Light Construction on Wood Poles. (NOW WITHDRAWN) ENA TS 43-30: Low Voltage Overhead Lines on Wood Poles ENA TS 43-50: 132kV Single Circuit Overhead Lines on Wood Poles. Distribution Safety Rules. CP423: Overhead Line Linemen s Manual Live Line Working. CP430 Part 1: Overhead Line Linesmen s Manuals Wood Pole. ES400O2: Overhead Lines of Compacted Covered Construction for 6.6, 11 & 33kV: Design and Construction. ES400O3: Bare Wire overhead lines on wood poles for 6.6, 11 & 33kV: Design and Construction. ES400O4: LV ABC Overhead Lines and Services: Design and Construction. ES400S11: Overhead Line Steelwork for Wood Pole Lines and Ancillary Steelwork for Lattice Steel Towers 9. KEYWORDS Crossarm; DOEF CP420 Pt1 Ch14.doc Issue 4 19/12/07 RG Ch14 Page 10 of 13

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