Method Statement for Transmission Line Lanco

March 24, 2018 | Author: Nenad Medelić | Category: Tension (Physics), Rope, Mechanical Engineering, Manufactured Goods, Transport


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PROJECT:-765KV S/C RAIGARH-CHAMPA TL.SAFETY ASPECTS OF CONDUCTOR INSTALLATIONS IN TRANSMISSION LINE METHODS ADOPTED FOR CONDUCTOR INSTALLATIONS IN 765 KV T/L a) Mechanized Paying out of conductors and installation Manually b) Manual Paying out of conductor and its manual installation. TYPE OF RISK ASSOCIATED: a) Fall of workmen from height b) Fall of objects from height, on workers and co-passers –by c) Collapse of towers, conductors and hardware Fittings on workers and passers –by d) Electrocution due to contact of person / Conductors with live wires e) Hit by Vehicles (Workmen and co passers-by) CONSEQUENCES OF ACCIDENTS: a) Fatality / Injuries to workers b) Fatality / Injuries to co-passers by c) Loss to properties including public property d) Lost of man-hours resulting in time and cost overruns e) Public resentments, disgrace f) Punishment under the relevant laws VARIOUS STAGES OF WORK IN THE INSTALLATION OF CONDUCTORS IN TRANSMISSION LINE a)Insulator and aerial roller hoisting b) Paying out of pilot wire c) Paying out and sagging of Earth wire. d) Paying out of conductor e) Rough sagging f) Final sagging g) Clipping and fixing of line spacers h) Fixing of jumpers i) Stringing of river crossing reaches j) Power line crossing k) Stringing across Highways and other service roads l) Transportation and stacking of conductor drums and Hardware fittings when must be ensured before hoisting insulator * Good condition single workmen string. precautions has given to cross arm i. harness shall be ensured. string insulator b) * Availability of 12mm dia hoisting. with insulator string. . c) Hit by tractor in path of his maneuvering. sheave pulleys of bearing b) REGULAR uses to get type only. Before insulator hoisting and for every tower lot of insulator erection must be complete in all regards. And for each down * Additional safety rope insulator through used foe securing single string insulator sheave pulleys of open hook hoisting. then additional safety rope shall be used for avoiding its accidental release. more importance shall be tower members provided . And for each hazardous * Good condition double insulator aspects of lanyard Safety belt. or while ascending and * Proper use of double lanyard type full body CHECK FOR--- A) REGULAR The most A) *Fall arrester.HAZARDS ASSOCIATED AT VARIOUS STAGES OF WORK: SL NO HAZARD INVOLVED REMEDIAL MEASURES CHECK POINTS .e all the been taken against sharp edges of tower connecting bolts and tower members. 2. ENGINEER releasing both the single sheave pulleys shall be * Good condition 16mm dia c) REGULAR guide rope ensured and also only bearing type pulleys wire rope sling. d) Hit Injury or crush injury while handling insulator boxes and heavy aerial rollers. b) Fall of insulator string b) * Proper fixing of cotter pins/split pins wire rope as a lifter. being used . * Check the wire rope (12mm) being used for insulator string hoisting for any type of visual damage. aerial roller. a) Fall of workmen from a) *Use of fall arrester must be ensured for cross arm sitting location making vertical movement over tower. string for or other tools and tackles. * only 16mm dia wire rope sling should be used for securing single sheave pulleys with plate or with IMPORTANT CHECK: D) Regular 1. hoisting is descending over tower. * Before hoisting proper working condition SITE type. * License and driving skill of LEADER crossing bottom yoke * if open hook type single sheave pulleys are operator/ driver. ACTION PERIODICI BY TY REMARK INSULATOR AND ARIEAL ROLLER HOISTING 1. boxes. / GANG For every road tied with shall be used. members must be in properly * Check for proper connection of aerial roller intact condition. P rope or wire rope shall a be tied with 3rd or 4th insulator disc from top. always suspected to failure. c COMMAN PRACTICE: it is very common practice t of using step bolts.  PAYING OUT OF PILOT WIRE 2.3. c) v * Only licensed and well trained driver e shall be engaged for operating tractor. generally noticed that local b) Fall from of workmen cross arm position/ aerial roller M lineman uses to give shutdown of 11kv and 33kv . B) Use of leather type hand gloves shall Jhulla arrangement Leader be ensured to minimize the severity in IMPORTANT CHECK: it is case of such incident. presence of ‘ p SIGNALMAN’ must be ensured . h o * Wooden planks having nails shall be kept f well away from site to avoid nail prick. a) Minor cut injury to A) Periodical visual inspection of pilot Condition of pilot wire fingers due to wires for wear and tear and other visual Condition of P. in D-shackles and in aerial o roller assembly . which are not meant for heavy r loading and .e. a d) *Over height stacking of insulator boxes t shall be avoided at location. i n * If at all any road crossing exist in g maneuvering path of tractor. used Engineer Effective Use of PPE’s / Gang pilot wire. P. n e Bending of insulator string may lead to failure u of R-clips.P rope being Site protruding wires of damages shall be done. t *WEARING OF SAFETY HELMET AND SAFETY r SHOE IS MUST BY ALL PERSONNELS a IRRESPECTIVE OF NATURE OF JOB. Always avoid bending of insulator string  while hoisting i. used r for insulator string hoisting. P rope. D)) Lanyard of safety belt shall be must be ensured in such c) operations--- Hit handling injury while wrapped around the insulator string. 3. P. be perfectly sure about distribution feeder (of the reel.pilot wire for any type of visual damages in – connectors: Pin and its threaded portion jumpers ensure the line is Roller & U-portion discharged through bundling G) Visual checks shall be done for the conductors by passing a any looping with other line near by and then decide the and interconnection of line) 3.p rope over it. gloves meant for working on H) Obtain proper shutdown before HV/EHV lines. Power line / road or lowering the conductors of any line 5.P rope C) Use of double lanyard full body hare power lines and fitters of through ness shall be insured. . stringing gang uses to lower roller) Or otherwise during ascending and Double arrangement for ascending over the conductor after deenergizing the line.( reel. precautions descending over tower. J) Suitable warning signs with signalman (equipped with walky-talky) shall be 4. The conductors shall be highway crossing crossing. pilot drum E)) Jhulla arrangement made of 20mm 1. substation . made for every P&T and road crossing. transportation of pilot drum reel. Ensures the does not have transporting pilot awareness should be created among drum workmen regarding safe handling & point of opening jumpers. 2. Ensure the use of hand lowered and kept in bundled condition. views of local people must E) OTHERS: F) Pilot wire connectors shall be checked be taken regarding the rout 1. (chances of I) Proper scaffolding capable of bearing electrocution / injury load of pilot wire and conductors shall be to co passers. eye splicing in pilot condition of eye loops made in pilot wire wire before every use. installed in D) Over turning of used. Before opening the p. insulator string shall be done as follows— Following min.(for passing P. tractor while F) Regular pep talk shall be done and 2. controlled from ground shall be particular line) . E) TSE machines shall be properly anchored with dead-end anchors in the ground. Hit injury to A) Proper care shall be exercised while shifting workmen— machine to a long distance. F) The puller shall be placed at a distance (from Ist normal tower). PAYING OUT OF CONDUCTOR 3.deployed at every road crossing irrespective of its type and users. PRE PAYING OUT CHECKS 4. Toppling of machine B) Check air pressure and find out the suitable while approach road for shifting. not less than three times the tower height. shifting/placing C) While shifting no workmen shall be allowed ride over it. D) Well-experienced tractor driver shall be taken for the task. A) DRUM POINT Site Engineer / TSE operator / gang leader POSITIONING OF TSE MACHINES . The preferable angle with ground should be 45* or less. used for reinforcement work. obstruction. the conductor drums at least and single ends B) Watch out for protruding wires. . machine.S or tor steel and TSE machine must be point. E) Check the Physical condition and load bearing capacity (from test certificate of supplier) of swivel joints (articulated joints) provided behind Headboard. C) Failure at D) Never replace drum-mounting shaft with C) The area between drums headboard assembles any other inferior means such M.A) Cut injury in fingers A) Hand gloves shall be used while handling IMPORTANTCHECK: A) place while placing two ends wire meshed single/ double end shocks. Use only kept recommended connectors only in drum lifting unauthorized entry. F) Check the condition of wire rope and single end wire meshed shocks before applying the load. PULLER POINT B) Check weather the conductor release from drum and entry into machine is and barricaded free to from avoid SITE ENGINEER / GANG LEADER jack. and 30 M back to the tensioner shocks. removes the same by cutting plier and if the B) Hit injury or cut wire mesh is severely damaged replaces it injury while placing with new one. G) place suitable capacity D-Shackles at each joint. ground to avoid is toppling. drum lifting jack or C) Place the drum-lifting jack on firm and level smooth conductor drums. removing from puller machine after complete B) hit injury/hit injury binding). Ensure use of fall arrester for ascending and descending over tower. The tightening of guy rope according to the resulting damage of guy in tower (cross-arm) Fall of person height while turnbuckles shall be done carefully to avoid extra loading on cross arm. /GANGLEADER A) Proper personnel precautionary measures SITE ENGINEER A) Cut injury in fingers . angle of guy rope shall not be more than 45* with cross arm. Pit for dead ment. while handling ( --Same as above-- loading/unloading) of pilot wire reel. from standards of logwood shall be maintained as mentioned above.while handling pilot shall be ensured in pilot wire reel (while wire reel. Ensure use of double lanyard full body harness while working at height. Ensure use of lifeline for making horizontal movement over cross arm. GUYING OF DEAD-END TOWER Failure of The make-up end tower shall be properly IMPORTANT CHECK: angle of anchorage or guy rope guyed before with the help of 18mm dia wire turn shall be maintained for itself rope and deadment anchor. PAYING OUT OF CONDUCTOR TIGHTIENING OF PILOT WIRE FROM PULLER END turn of line . Ensure effective tying of wire rope with cross arm. When puller STRATING starts tightening.This is the most critical & hazardous IMPORTANT TO WORKMEN AND activity of machine paying out operation. GREEN CHECKS: WITH RED FLAGS & WITH WHISTILES MUST BE PALCED PILOT WIRE OPERATION. AT LEAST TWO SIGNAL MAN WITH FLAG AND WALKI- TALKI SHALL BE POSTED ON ALL ROAD CROSSINGS. PULLING OF CONDUCTORS SITE ENGINEER SEVERE HIT INJURY . pilot wire uses to uplift TIGHTIENING CROSSING) with high swing and speed. SIGNALMAN SIDE PASSERS. It is well known that pilot wire are laid on ANIMALS & ground through out entire section IN BETWEEN EACH BEFORE VEHICLES (ROAD proposed for paying out. mid-span joints . SITE ENGINEER / GANG LEADER keep unauthorized personnel’s away from for . puller and tensioner operators and other ANIMALS & intermediate personnel’s positioned at VEHICLES (ROAD road / power line crossings) must have to structures where headboard CROSSING) move with head board.a)SEVERE HIT A) While conductor paying out is under IMPORTANT CHECK: INJURY TO progress one supervisor (must be capable The entire section proposed WORKMEN AND of making effective communication with SIDE PASSERS. and it must CONNECTOR connectors by deploying signalman’s at be cleared without taking RESULTING IN HIT every tower . C) Check SWL of pilot wire connector and its physical condition and also instruct operator (puller) slow down pulling when connector uses to enter in bull wheal of puller machine. keeping vigil in between spans so as to particular phase corridor. can stuck. hey may tasked with INJURY. MAKE UP & ROUGH SAGGING OF CONDUCTORS paying out shall be checked for visual hindrances such trees. B) FAILURE OF B) check out for free running of aerial Branches of tress falling in PILOT WIRE OR rollers and also obstruction free passing the line of headboard are PILOT WIRE of head board . buildings & any other type of any chance.pilot more dangerous. 0 ton best suited 10.0feet) and also condition / FAILURE OF CAME of wood log(length not less than 6.0-12. SITE ENGINEER/ GANGLEADER condition shall be used for holding conductors.O’’ section shall be ensured. SLOPE CUTTING AT 45* SHALL C) Availability of both side check nut.0ton capacity) E) never replace the pin of D-shackle with any other means.0 ROPE EMEREGS (FROM GROUND) AT LEAST 10. FOR THAT washers. . FINAL SAGGING OF CONDUCTORS CHECK FOR SAGGING ARRANGMENT AND TOOLS & TACKLES UPLIFT LOAD ON DEADMENT ANCHORE.FAILURE OF Ensure the effective depth for deadment DEADMENT ANCHOR (depth not less than 6.0 –12. following--- ENSURE A) Liner condition of came along clamp. 10-14inches)or steel beam of suitable IMPORTANT CHECK: 10.0 FEET AWAY B) Availability of all bolts& nuts and packing FROM TOP OF PIT. dia. 5.0 FEET 6. Use of 18mm or 20mm steel wire rope in good ENSURE THE EFFECTIVE DEPTH Check the condition of came along clamps& D- OF shackles being used for holding conductors for FEET. BE ENSURED TO AVOID DIECT D) Suitable capacity of D-shackle (min.0 feet and ALONG CLAMP. DEADMENT THAT NEALRY WIRE 6. 0M wire rope of 12. Use articulated joint of We must note final sagging is the most capacity not less 3. A) Near tip of the cross B) Use min. thickness of sag type pulley positioned.0-60. avoid its turning. A min. connecting sag plate with four-sheave pulley & lifter arrangement.0mm dia.0mm wire rope lead coming out from four sheave pulley set should be routed through close condition of welding. must give attention over sag chart and P. Such as fall of IMPORTANT CHECK: with 12.FAILURE OF TOOLS CHECK AND ARRANGMENT. kinking or twist in wire Before finalizing the tools and tackles we rope. length of lifter arrangement should be sufficient enough so as to ensure tightening of conductor.0 mm wire rope used in between sheave fourpulley arrangement to avoid towers injuries to workmen. GENERAL CONSEDRATION ACSR (QUAD) D/C LINE A) Check the condition of sag plate and The 12. Both four sheave pulley shall be separated a min. Wire rope cross arm with tower leg.0 ton capacity sag winch shall be used for giving load. of 10.P rope shall be tied at select the section that requires heaviest both end of four sheave loading and accordingly select tools and pulley shall be used to tackles for all sections. for making lifter arrangement with two four sheave pulley sets. Site engineer /gang leader TACKLES POINTS .0mm dia. 15ton capacity D-Shackle for arm. in. plate shall be of 12mm. length 50. B) Near bottom rafter of B) Use good condition 12.0 ton RESULTING IN IN FINAL SAGGING critical activity of stringing which involves application of very have load and failure of any kind can disastrous. 0mm wire rope for twin conductors tower leg.C)one set of lifter arrangement uses to lift two conductors in quad arrangement and one conductor in twin conductor arrangement.0mm wire rope for quad conductors. 10. be used for providing extra safety lock to wire rope after giving final load from sag winch. sheave pulley block (SWL of min. Check point for sag winch: Equalizer pulley and four-sheave pulley shall be A) Check the condition and connected directly with 15. B) proper working of locking arrangement. Three bolt earth wire clamp Use twin came along clamps for holding single or automatic clamp shall only conductor. Always avoid sudden loading during final sagging operation.o ton for twin). for holding sag winch with V-sling used for holding conductors shall of— A) 18. B) 22.o ton capacity D- suitability of bolts being used shackle. MARKING AND CONNECTING OF CONDUCTORS WITH HARDWARE FITTINGS CLIPPING ACTIVITY Site engineer /gang leader Accordingly select the suitable capacity of four- .0Ton for quad and 5. JHUMPERING AND SPACERING . in insulator hoisting. .Incorrect and may lead to failure of cross –arm from leg member and cross-arm rafter join position Correct sequence of looping wire rope from single sheave pulleys . 2. By passing / ignoring safety rules for reasons of misconceived convenience for faster Execution of work. Lack of good communication and commuting facilities. Negligence in using appropriate personnel protective equipments at work places. Lack of proper training and continuing education to workers. Lack of knowledge and experience in proper use of personnel protective equipments. Inadequate guying of towers or failure of tension bearing tools. Exhaustion due to over working by workers. General lack of awareness and commitment to safe working methods by workers. supervisors. 11. difficult in having proper control over work locations. Use of an inappropriate / damaged tools and tackles. 7. 12. Scattered working locations. 5. 14.COMMAN CAUSES OF ACCIDENTS IN THE WORK OF INSTALLATION OF CONDUCTORS IN T/L 1. 6. Failure of tension bearing materials/ equipments. 3. 15. 13. 8. Difficult terrains and natural topography . 4. 10. In adequate supervision of work by qualified and experienced personnel. supervisors and Engineers in construction methods. & site Engineers. Improper or over tightening of conductors during sagging operations. 9. Lack of discipline in controlling non-compliance of safety regulations. Identification of nearby hospital /medical center as a emergency preparedness. source and listing power lines in section where the work is set out. . 14. 7.MEASURES AND PRECAUTIONS TO BE TAKEN IN WORK OF INSTALLTION OF CONDUCTORS IN T/L PREPARATORY WORKS 1. Any restrictions on patter n of loading of towers shall be ascertained from designer. Providing temporary earth electrode for stringing equipments. 8. Information and caution to general public through caution boards and sign boards. 6. 2. 10. Removal of tress and other visual obstructions in line corridor. Inspection and testing of tools and tackles ( follow checklist) 4. of First –Aid kit shall be made available at all work places. Guying arrangement of towers shall be done as per given work procedure 3. Inspection of personnel protective equipments for adequacy and workability. Identification of existence. 13. Arrangements for road or highways crossing coming in pathway of line corridor. Pre-task briefing to workmen and gang leaders before starting the job and fixing of accountability. 5. Ascertaining for restrictions on placement of pulleys and application of tension for hoisting and sagging operation. Preparation of towers – tower shall be complete in all regards before starting stringing operation. 9. 11. Adequate no. 12. 2. 8. 7. Effective and clear communication system shall be made available . checking of all the towers immediately before commencement of insulator hoisting. All workers working at height above 2. tension and puller equipments and for holding conductors under rough sag. Proper counter weight anchors or log anchors to be installed for guying the towers. 6. 4. Clear path for maneuvering tractors puling the hoisting slings for lifting material / Tensioning.COURSE OF WORK 1. Availability of gang leader to co-ordinate pulling and lifting operation. (Refer insulator hoisting Methodology) 2. for tightening punching.0M heights shall have to wear safety belt. 5. Turn buckles used for stay wires should be tightened periodically. tack welding and availability of all members. Positioning of pulleys for hoisting of insulators and other materials and equipment to be done correctly to avoid improper pull on the cross arms and towers. There are basically two methods of stringing. this Method is used to keep the conductor clear of the ground and obstacles. These are i) Slack or Manual methods ii) Tension method i) Manual method: Using this method. which might cause conductor Surface damage and clear of energized circuits. a braking device is provided to prevent overrunning and backlash.or the drum is carried along the line on a vehicle and the conductor is deposited on the ground.METHODOLOGY OF STRINGING Stringing Methods & General Aspects Methods of stringing. Normally. The conductor drums are positioned on drum stands or jacks either placed on the ground or mounted on a transporting vehicle. For lighter conductors. the conductor is kept under tension during the stringing process. It requires the pulling of a light pilot line into the travelers. When the conductor is dragged past a supporting structure. The pulling line is then used to pull in the conductors from the drum stands using specially designed tensioners and pullers. the conductor is pulled along the ground by means of a pulling vehicle (normally tractor). thus permitting it to turn as the conductor is pulled out. ii) Tension Method: Using this method. pulling is stopped and the conductor is placed in travelers attached to the structure before proceeding to the next structure. . a lightweight pulling line may be used in place of the pilot line to directly pull in the conductor. These stands are designed to support the drum on an arbor. Usually. which in turn is used to pull in a heavier pulling line. Before hoisting of earth wire rollers. First. i) Paying out & stringing of earth wire. After one length of earth wire reel is exhausted. The earth wire is pulled from tower to tower manually or by using a tractor. ii) Guying arrangement of tower iii) Insulator and aerial roller hoisting iv) Paying out of pilot wire iv) Paying out & stringing of conductor. At the starting end of a section. earth wire reel is mounted on roller jacks or horizontal turntable. earth wire rollers are provided on the earth peaks of all the suspension towers in the section. After reaching the next tower the earth wire is passed through the suspended earth wire rollers with the help of a polypropylene rope and paying out is continued further. A lineman/ fitter may be kept on each tower to ensure free running of the rollers with a red & Green flag and whistle. the second length of wire is paid out for the balance section.STRINGING PROCEDURE The stringing procedure is broadly divided into the following steps. Mid span joint for earth wire is compressed on the ground joining the two lengths. v) Final sagging of earth wire & conductor. it may be ensured that the rollers are free from friction. vi) Fixing of line spacers viii) Fixing of jumpers i) Paying out & stringing of earth wire: Normally stringing of earth wire is done manually since handling the earth wire is easy and it does not get damaged easily. . vi) Clipping and fixing of accessories. is lowered and the pit is back filled while compacting.5m can be dug. instead of buried ground anchors. it is tightened by the turnbuckle. . The guys are anchored in the ground at an angle of 45 Degrees or less from the horizon.5mx0. a dead weights of sag 5 to 10 tonnes can be placed on the ground and sag wire attached to them securely. the angle towers where the stringing is to be started have to be Provided with guy supports for all the three phases. For making dead end anchors in the Ground. It is advisable to tighten the guy progressively at the time of rough sagging of the conductor. Excessive tightening of the guy should be avoided. pits of 1. After pulling up the slackness in the guy.6m. A set of steel beam and channels tied in the center with 16mm wire rope. The guy wire is attached to the dead end anchor wire with the help of turnbuckles of 10 tonnes capacity. The guys used generally are 20mm steel wire rope. Alternately. to the strain plates with suitable D shackles.Guying arrangement of tower Before commencement of stringing. The guys are attached to the tower at the tip of the cross arms and center of the bridge. for a depth of 1. attached to dead end anchors. HOISTING: After opening of the crates. insulators shall be laid in series. The crates shall be opened at the tower location. The neoprene rubber cushion on the outer rollers shall be checked for any cracks/wearing out and shall be changed if required. A single sheave pulley is fixed to the cross arm very near to the suspension hanger. of insulators required for string shall be joined and `R' clips in the clevis shall be expanded to avoid slippage of the pin. . The complete string with aerial roller is lifted up by pulling the rope through a pulley attached to one of the tower legs by using tractor/manually After reaching the top the string is attached to the suspension hanger and string is released slowly to hang free. of insulators shall be transported to the tower locations with the wooden packing. on wooden planks below the suspension points. Insulators shall be checked for any chipping or crack and shall be replaced with new one if found defective. The five wheels of the aerial rollers should be checked for free running. The insulators shall be cleaned with water and wiped dry with clean cloth free from grease and oil.Insulator and aerial roller hoisting Transportation of Insulators The required no. The joints of all insulators should be checked and `R' clips should be expanded. The bottom insulator is joined to the moose aerial roller. The no. The Insulator hoisting is done well in advance of Commencement of paying out operation. One end of the rope is firmly tied below the 3rd or 4th insulator. A 20 mm polypropylene rope or 12mm wire rope is passed through the pulley and both the ends are brought to the ground. INSULATOR HOISTING . The pilot wire is initially laid through the center wheel of the aerial roller. The distance of the drums from the tensioner shall be at least 25 to 30 mtrs so as to distribute the effect of sliding of outer strands due to low back tension. The puller machine can be Positioned behind the tension tower on one side and the tensioner in front of the tension tower on the other side. the pilot wire is laid from both sides and free ends are joined after obtaining the shutdown of the power line. A stand signalman shall be ensured with Red and green flag and also with walky-talky to ensure effective communication pilot wire pulling equipment (Tractor or Puller). The reel should be positioned so that it will rotate in the same direction as the bull wheels. .Paying out of pilot wire In tension stringing. A 22 mm dia pilot wire is generally used for pulling of quad moose ACSR conductor. Sound Scaffoldings shall be provided for P&T and road crossings before paying out of the pilot wire. A) Position of tensioner and puller: The paying out of conductor is done generally between two tension towers. Both the machines should be securely anchored with two dead end anchors in the ground and slackness is removed in the stay. The pilot wire can be laid length by length and joined with pilot wire connectors. a pilot wire is used to pull the conductor. Paying out & stringing of conductor. The entry of the pilot wire into the bull wheels of the puller machine and running out from tensioner machine should be as nearly horizontal as possible. At power line crossings. The placement of drum jacks should be such that the lateral angle of conductor approach into the bull wheel through guide rollers is low enough to avoid rubbing on the sides and creating loosening of the outer strands and bird caging. In long spans where conductor is likely to touch the ground. . The pulling of the conductor may be done at a moderate speed while the running board is passing through the aerial rollers.5 tones. rivulets. Aerial rollers etc. channels. The pilot wire is attached to the other end of the running board with swivel joint. The rope is pulled by starting the tensioner at low pay out tension to pass the conductor through bull wheels and are brought out through the guide rollers. The ropes are connected to the conductors. It shall be seen that normal services are not interrupted or damage caused to property. have to be crossed during stringing Operations. The sub conductors are attached to the equalizer pulley/running board by means of wire mesh/end socks and swivel joints. a 25 mm polypropylene rope is initially wound over each bull wheel pair in the same way as the conductor will pass during Running. telecommunication or overhead power lines.ow paying out of Bundle conductors with tensioner and Puller. Caution should be made over the wireless hand set to all the Staff who are at middle points and to the tensioner operator that pulling is about to be started so that they can stay clear of pilot wire. Platforms shall be erected with sturdy bellies. etc. while going up during tensioning. The tensioner can be initially set for a tension of 2 to 2. The conductor run shall be from the topside of the drum. A running ground shall be connected to the conductor and pilot wire before paying out near the tensioner and puller which shall be earthed at the nearest tower. The wire is passed through bull wheels of the puller and connected to the reel winder machine. This can be monitored by the staff who are posted in between the section and guiding the puller operator over the wireless sets. Care should be taken that the pilot wire does not get entangled in trees. ground rollers may be placed so that the conductor can pass without any scratches. At the puller site. the pilot wire is pulled to remove all slackness using the reel winder. scaffoldings. railway lines. where roads.The tension in the tensioner must be adjusted so that the conductors travel well over the ground.Paying out of conductor: For passing the conductor through the bull wheels of the tensioner. The puller is started to draw up the pilot wire until the bull wheels of the tensioner start moving. . The paying out is continued until the conductor reaches the puller end in sufficient length to be connected to the Tension hardware. The back tension is adjusted by means of brakes provided on the drum jack. The come. The mid span socks is removed and mid span compression joint is made. After anchoring. differences in elevation of supporting structures etc. The paid out conductor of first drum is held with bolted come-along clamps at a distance of 40 to 50 mtrs from the tensioner. After making mid span joint. The free end of the second drum is also prepared. The tension applied during stringing generally is about half the sagging tension. A running ground shall be connected to the conductor and pilot wire before paying out near the tensioner and puller which shall be earthed at the nearest tower. the joint is covered with joint protector sleeves which is designed to pass over the aerial roller grooves without damaging the mid span compression joint. The two ends are joined with a wire mesh mid span socks. Slower speeds may cause significant swinging of the running blocks and insulator hardware assemblies. Jointing of conductor: Just before one length of the conductor paying out is completed another drum has to be deployed in advance beside the first drum. The paying out has to be stopped by braking the tensioner and stopping the puller simultaneously. The speed of pulling of the conductor should be such that to achieve smooth operation. number and performance of travellers. the conductor is slowly drawn out from the two end socks. The conductor of the first drum is held and the free end is cut. . The paying out is again started by releasing the come along clamps until the mid span socks emerges outside the tensioner and pulling is stopped.along clamps are attached to the ground anchor stays. the tension at the puller may be higher than that at tensioner due to the length of conductor strung. Higher speeds can create greater damage in case of malfunction.The back tension of the conductor behind the tensioner has to be maintained as per the requirement of the tensioner deployed. When long lengths of conductors are strung. usual practice is to place the sag boards in the longest span of the section. For doing the sagging operation. it is rough sagged to a tension slightly less than the final Tension. The conductors are held by come-along clamps and attached to Separate four sheave pulleys at sufficient distance of say 40 to 50 mtrs depending upon rough sag condition and height of the tower. The tensioning and sagging shall be done in accordance with the approved stringing charts before the conductors are finally attached to the towers through the insulator strings. Only after the conductor is rough sagged on the adjacent section. are removed. The tension insulator strings are hoisted with all hardware on the tower.Rough sagging of conductor Before final sagging the conductor. a span has to be selected in the section to fix the sag board and check the sag. initially the double tension string assembly is assembled with insulators and hardware and hoisted to the cross arms/bridge as done in the case of suspension towers. For doing rough sagging. The dead end cones are compressed on both the sub conductor ends. Final sagging of conductor The sagging of the conductor shall be done using sagging winches. The conductor is held by come along clamps at a distance of 5 to 6 mtrs from the dead end cones and with the help of a pulley connected to a ground anchor. In the event of using sag tension charts showing sags in each of the actual spans and tension in each section. and in a span where the difference of elevation in the two suspension points is minimum.By holding the conductor with pulley. After being rough sagged the conductor shall not be allowed to hang in the stringing blocks for more than 96 hours before being Pulled to the specified sag. Since final sagging is done from one end of the section. The pulley is slowly released and the conductor will haul-up itself to the top. final sagging can be done in the preceding section to avoid overloading of towers. the conductor is pulled to slacken the free end of conductor (sufficient length to be attached to the hoisted insulator string assembly). The other ends of the four-sheave pulleys are connected to the line side yoke plate of the double tension string. The come along clamps and pulley etc. the dead end cones are attached to the tension string. The pulling wires of . the conductor is initially attached to the double tension string assembly on the other end. After reaching the final sag. The suspension clamp is connected to the string and the lifting device is . This entails removing the conductors from The rollers and placing them in suspension clamps attached to the insulator string.the four-sheave pulley are passed through a set of single sheave pulleys along the body of the tower to the ground level. The initial pulling is done with the help of tractor/truck. Then the Pulling ropes are attached to hand winches mounted on the legs of the tower or power winches duly Anchored. brought down and all clamps and pulleys are removed. The conductor is marked at the point where cutting is to be done and dead-end cone is to be pressed. The suspension clamp and armoured rods are fixed with neoprene rubber cushions centered over the marking. The free ends of the conductors are brought down and cut near the marking and dead end cones are pressed. the free end of the conductor is picked up and pulled by rope and pulley attachment along the line of the string. A wire rope is connected to Both the hooks passed through a pulley positioned on the cross arm tip in series with a pull-lift/ratchet lever hoist/four or two-sheave pulley. The center of the aerial roller is marked on the conductor. the conductor is earthed properly on suspension towers. The conductor is brought into final sag position with the help of winches and the sag is checked by sighting far end sag board from behind the near end sag thread by matching elevation tangent of the conductor curve. the four-sheave pulley is slowly released. Sighting should be done keeping sufficient distance from the sag line to avoid parallax error. The conductor is raised by about 75 to 100 mm and the aerial roller is removed and lowered by rope and pulley. Before taking Up clipping operation. The suspension clamp is placed over the armored rods and clamped with U bolts. The four-sheave pulley is slightly tightened to facilitate attaching the dead end cone to the tension assembly. The conductors are Held with hooks at 2 mtrs away from the aerial roller on both sides. After fixing. Clipping of conductors: The clipping of the conductor follows sagging operation. Wooden cross bars are tied to the body of the four sheave pulley and held by ropes in a Horizontal position to avoid over turning of the four-sheave pulley and twisting of the pulling wires. the spacer cycle is normally provided with travel meter. Installation of dampers: . The Verticality of the string may be checked with plumb bob.Released. the type and manufacture of the spacer and is normally done in accordance with the manufacturer's recommendations duly approved.) over which the cycle will pass. keeping sufficient clearance from the line. Fixing of line spacers : Following the clipping operations for bundled conductor lines. The person on the cycle can travel himself to cross over the section above the power line. Gunny bags or rubber pads may be used around the conductor to prevent damage to the outer strands. repair sleeves. the rope shall be drawn up to the cycle. The installation of the spacers on the conductor varies with span length. mid span joints etc. The spacer cycle is hoisted on the bundle at one tension end. car and equipment does not increase the sag sufficiently to cause hazards by obstructions (spacers. In case of engine-powered cycles. cycles may be hand powered or diesel powered. Care must be exercised to ensure that the concentrated load of the man. with the help of which the spacers are fixed at required distances as per the placement chart. For crossing the lines. spacers are usually installed. A number of models of spacers are being manufactured and the method of installation varies with the design of the spacers. the cycle is transferred to the next span by crossing the suspension clamp with the help of crossing ropes provided in the cycle. care should be taken while drawing the spacer cycle with rope. Care should be taken to prevent any damage to the conductor while being lifted by hooks. The insulator string will hang freely with the conductors suspended in the clamps. Safe electrical clearance should be maintained to the spacer cycle and rope. After reaching the next suspension tower. and brought down after crossing the line. the personnel pulling the cycle with rope measure the distances on ground and placement is done on the top. Depending on the length of line to be spaced and the equipment available. In case of spans crossing HT/LT lines. In case of hand-powered cycles. This is done by placing personnel on the conductors with the use of a conductor cycle normally known as spacercycle to ride from structure to structure. . so as to prevent transmission of electric shock. Pilot suspension insulator string shall be used if found necessary (Generally where angle of deviation is more than 45 degrees). These left out jumpering can be taken up during final inspections. Clearance to the tower body shall be checked as per the drawing. The inner and outer conductor of the bundled jumper are of different lengths. the distance between the jumper pads of dead end cones is measured by passing a rope in the shape of a jumper and by checking vertical clearance from the cross arm end. The jumpers in general are 10 to 15 mtrs in length. a local earthing should be made to avoid any static discharge that might occur due to the voltage induced on the line by existing power lines in the vicinity. The individual sections jumpered shall be kept earthed and earth shall be removed only before commissioning. The conductors are laid out on the ground parallelly and spacers are fixed as per the fixing instructions. jumper cone is pressed using hydraulic compressor. which at critical tensions and wind conditions can occur in a matter of hours. which shall be measured separately. For installation of jumpers. jumpers and the tower steel work shall be checked during erection and before commissioning the line. to restrict the jumper swings to the design values at both middle and outer phases. The jumper is hauled up from both ends of the tension clamps and jumper cone is attached to the connector of the dead end cone. Care should be taken to leave jumpers for one angle tower in a continuous stretch of 25 to 30 kms. While jumpering is made. Hence left over bits of conductor shall be used for jumpering.Vibration dampers/spacer dampers are normally placed on the conductors immediately following clipping to prevent any possible damage because of vibrations to the conductors. This will ensure a horizontal plane of the jumper bundle when installed. Jumpering The jumpers at the section/angle towers shall be formed to parabolic shape to ensure minimum clearance requirements. Clearance between the conductors and ground. Conductor is cut after making adjustment in length for the jumper cone dimension. After cutting the conductor. STRINGING SAFETY CHECK LIST . 132 KV. Built-up method or piecemeal method. as below i. Section method iii. 220 KV and 400 KV Transmission Line Towers due to the following advantages. which are described. . Built up method This method is most commonly used in this country for the erection of 66 KV. ii. Ground assembly method.SAFETY ASPECTS OF TOWER ERECTION IN TRANSMISSION LINE METHODS OF ERECTION There are THREE main methods of erection of steel transmission towers. The erection progresses from the bottom upwards. a small boom is rigged on one of the tower legs for hoisting purposes. ii.The cross braces of the first section which are already assembled on the ground are raised one by one as a unit and bolted to the already erected corner leg angles.This method consists of erecting the towers. Sketches indicating different steps of erection by built up method are shown at Figure 4. For smaller base towers/vertical configuration towers. the four main corner leg members of the first section of the tower are first erected and guyed off.two gin poles are placed one each on the top of the diagonally opposite corner legs. one gin pole is used instead of two gin poles. a small assembly party goes ahead of the main erection gang and its purpose is to sort out the tower members. This process is continued till the complete tower is erected. These two poles are used for raising parts of second section. keeping the members in correct position on the ground and assembling the panels on the ground which can be erected as a complete unit. The leg members and braces of this section are then hoisted and assembled. For heavier towers. are bolted in position. Sometimes more than continuous leg sections of each corner leg are bolted together at the ground and erected. Tower materials can be supplied to site in knocked down condition which facilitate easier and cheaper transportation. Tower erection activity can be done in any kind of terrain and mostly through out the year. member by member. The gin pole is thus moved up as the tower grows. In order to maintain speed and efficiency. iii. .7. For assembling the second section of the towers. The gin poles are then shifted to the corner leg members on the top of second section to raise the parts of third section of the tower in position for assembly. It does not require any heavy machinery such as cranes etc. The members/sections Are hoisted either manually or by winch machines operated from the ground. First section of the tower thus built and horizontal struts (bet members) if any.i. The tower members are kept on ground serially according to erection sequence to avoid search or time loss.Cross-arm members are assembled on the ground and raised up and fixed to the main body of the tower. Availability of workmen at cheap rates. iv.1 to Figure 4. Guying should be steel wire or polypropylene rope depending Upon requirements.8 for reference. The deadments for guying arrangements are to be properly made. . Nominal tension is to be given in guying wire/rope for holding the tower in position. A sample of deadments drawing is enclosed at Figure 4.Guying arrangement Guying arrangements are to be done at waist level/bottom cross-arm level as well as in the girder level/top cross-arm level depending on SC/DC towers and it is to be installed at 450 from vertical.
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