In this method of laying underground cables, the cable is laid in open pipes or troughs dug out in the earth along the cable route. So if you are detailed engineering we would suggest considering rated short circuit current for cable also. Lay the cable warning tape and again backfill the remaining portion of the trench upto the ground level. The troughing is of cast iron, stoneware, asphalt or treated wood. Cable pulling cable laying cable rollers cable socks. Method statement for installation of high voltage hv cables. Iec xlpe cable systems specified according to iec international electrotechnical commission are among many other standards accepted. The laying of underground cable lines in the city is a major step towards creating better infrastructure. Underground problems, however, are out of sight and out of mind, at least until cables start failing. Work on laying underground ht power lines gathers pace the. The layout arrangement of the draw in the system is shown in the figure. As these cables are not exposed to the air atmosphere, this makes the ug cabling system less. Underground cable tenders online latest info about. Under ground cables presention linkedin slideshare.
Home technical articles ehvhv underground cable sheath earthing part 12 2540. Nov 06, 20 singlecore power cables can be run in a number of formations, the most common include flat or trefoil formations. Underground cable installation manual western power. Omac manufactures machines for laying underground cables and related equipment. The reliability of underground cable network highly depends upon proper laying of cables, quality of cable joints and branch connections etc. Practical cable crossbonding of underground cables practical transposition can also be performed on underground, singlecore coaxial cables called crossbonding. What are the advantages and disadvantages of underground. Excavation in excess of that specified for the laying of the cables. Undergrounding high voltage electricity transmission lines. Machinery and equipment for underground cable laying. This method is the most popular as it is simple and cheap.
In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to. Electrical safety clearance qatar general electricity. All cables shall be installed with approved identification bands at each end and over their entire length at 30mtr intervals. In ht cable the bonding system is so designed that the cable sheaths are bonded and earthed or with svl in such way as to eliminate or reduce the circulating sheath currents. Backfill the excavated soil leaving 300 mm from the ground level. Electrical safety clearance qatar general electricity part. The layout of this cable laying systems can show in the figure. Standard for distribution line design underground check this is the latest version before use page 2 standard stnw3369 ver 2 ergon energy corporation limited abn 50 087 646 062 2 references 2. Unless you lay your cables to rest properly, they may come back to haunt you. Cable laying method for road crossing and utility service crossing using upvc duct drawing below shows installation of underground cable in two environments. Ei 020019 installation of underground cables lv to 2kv. After the cable is laid in position, the troughing is filled with a bituminous or asphaltic compound and covered over. The top countries of suppliers are china, india, from which the percentage of underground cable laying machine supply is 99%, 1% respectively.
There are three main methods of laying underground cables, which are i direct laying, ii drawin system and iii. Western power underground distribution schemes uds manual. The trench is covered with a layer of fine sand of about 10 cm thickness and the cable is laid over this sand bed. Underground cables are, of course, meant to be installed or laid under the ground.
Link boxes are used with cable joints and terminations to provide easy access to shield breaks for test purposes and to limit voltage buildup on the sheath. Description voltage 33kv66kv2kv 220kv400kv the right of way row widths on either side of the center line of overhead transmission lines 25 meter 50 meter other than the roadways and boundary fences of security establishments any temporary or permanent. Wrong handling of cabals, such as damages due to wrong handling laying of cable also weakens the insulation of the cables. Service provider of cable laying services cable laying with cable trench, underground cable laying, lt cable laying and ht cable laying services offered by hitesh electrical, navi mumbai, maharashtra. Cables laid in this manner are usually plain lead covered because troughing affords good mechanical protection. After taking trench keep clean the trench for the following steps. But over the time, the insulation of cable may get damaged or weakened due to ageing.
Underground cable laying services we are among the reputed organizations, highly engaged in providing the optimum quality underground electrical cable laying services. Normally the lifespan of a cable is about 40 to 50 years. There are three main methods of laying underground cables a. The installation company responsible for laying the cables must heed the following parameters. Cable rollers cable pulling laying rollers, cable trench. Singlecore cables laid in trefoil or flat formations. The direct system of cable laying involves the cables laid in a cable trench and after that, the cable is filled with soil. As per this service, we can cover laying of drum lengths of cables through hume pipes, trenches or with excavation. Method statement for installation of high voltage hv.
Further, the vertical runs where the cable descends into the ground at the house side and emerges up from the ground at the outbuilding side must be housed in rigid conduit. Cables installed in ground shall be laid in a single, horizontal layer spaced 450mm apart. However the practice that i have seen in our refinery is that for cable trenches that pass through process units, the whole trench is filled with sand just after the cable laying is completed. A wide variety of underground cable laying machine options are available to you, there are 680 suppliers who sells underground cable laying machine on, mainly located in asia. This is known as direct burial, and if you do this, the uf cable must be at least 24 inches below the surface of the ground, to minimize the chance of the cable being pierced by routine shoveling.
Each cable formation has its benefits and drawbacks, were going to look at the differences between each way for laying these cables. Cable laying shall be started by rotating the drum in a direction, recommended and marked side of the cable drum and cables are pulled, accordingly. This method of laying underground cables is simple and cheap and is much favoured in modern practice. How to calculate size of a cable for 11kv or 33kv line. Underground cable laying, underground cabling in india. Underground cables, because of the insulation and surrounding environment, tend to retain the heat produced in the copperaluminium conductor. Cable laying services cable laying with cable trench. Next comes the short circuit current of the system, for a 240 volts single phase system, design short circuit is 6ka, for 11kv it is up to 25 ka and 33 kv it is up to 70 ka. Power cable installation guide cables installed into conduits or trays have installation parameters such as maximum pulling tensions, sidewall pressure, clearance, and jamming, which must be considered. Underground power cables high voltage underground cables 2 2 circuits 3000m 3x1x2000mm2 e.
In this method, the cable is laid into troughing of. The insulation method depends upon the type of cable used see section on underground cable technologies. Draw in system underground cable laying draw in system cable layout. To know the size of cable we must consider a couple of things. Methods of cable laying there are various methods of cable lying, such as y laying directly into the ground y drawing in ducts y laying on racks in air y laying on rack inside a cable tunnel y laying along building and structure underground cables ht cables can also be installed in the buried trenches. Most construction projects requires underground cabling system for its power supply, some times high tension system too. All cables and ducts laid into cable trrench should be overprotected by a cable protection cover or tape depending upon the highest voltage cable to be protected within the cable duct typically in the uk the following cable protection tapes and covers are used for lv, mv and hv cables. It does not legally have to be done by an electrician despite what some people may believe. This method is similar to that performed on overhead lines, but in this case the respective conducting layers are switched, while the core conductor remains untouched. The vde 0816 gives the following values, during laying. Buried cables, conduits, and ducts shall be at a sufficient depth to avoid being damaged by any reasonably foreseeable disturbance of the ground a rule of thumb is in a garden below one and half spade length or below 500mm and under drives and such under between 500750 mm. Electrical engineers understand the performance of the cable quite well, but to most, the soil behavior is a mystery, usually handled by. Laying electrical cable underground is a project that a lot of people undertake at some point in their lives. Ltht power cables, installation, jointing, termination, testing.
Besides, we can also lay these cables on cable trays. Such high voltage cables have metallic sheaths or screens surrounding the conductors, andor armour and metallic wires surrounding the cables. Installation of underground cables lv to 2kv document number. Underground cables are usually employed to deliver 3 phase power. Cable laying services have been our forte since inception. Laying of underground cables the reliability of underground cable network depends to a considerable extent upon proper laying. Normally the cables are layout in ducts or pipelines on the ground with certain manholes. Further, the vertical runs where the cable descends into the ground at the house side and emerges up from the ground at the outbuilding side must be housed. The cable is fed from the bottom of the reel so that its curvature is continuous with no reversed bends. The 66kv e xlpe cable shall be installed underground and normally buried directly in the ground complying with all applicable standards and is. Typical cable laying details for direct buried, low.
Insulation resistance of hv cable should be checked by using 5 kv megger after installation and before termination of cables and readings shall be submitted to the consultant. This is quantified by the soil thermal resistivity or thermal rho, ccmw, which can vary from 30 to 500ccmw. If you do decide to do it by yourself, you will have. Make a sand bed or fine riddled soil bed as per the measurements given in the drawing. First one shows direct buried cable installation and the second one shows cable passing through duct mainly where road crossing comes. High voltage xlpe cable systems techincal user guide brugg cables page 2 content 1. One of the main reasons trefoil formations are used is that it places the phases the same. Laying of underground cables direct laying of underground cables. This is in contrast to an overhead line, which does not have insulation. Cable laying 1excavation of cable trench, 2sand bed laying, 3 cable laying on sand bed, 4putting brick vertically on both sides of cable, 5again sand filling on cable area, 6horizontal. One of the main dangers which may arise when digging is that of possible injury from underground power cables.
Although utilities design their underground circuits for a 30year life, improper installations often can lead to premature field failures. Table of cable components 12 metallic screens earthing shortcircuit operating conditions 14 grounding methods 14 earth cable protection 15 earthing diagrams 1617 laying methods 1819 cable reels 20 permissible bending radius 20 pulling tensions 20 fastening systems 21 cable system tests 21. The sand prevents the entry of moisture from the ground and. Types of cable voltage range cable size manufacturing capacity. In this method of laying underground cables, a trench of about 15 metres deep and 45 cm wide is dug. The 3 main underground cable laying system use in practice. Type of cable basedon construction coaxial cable mineralinsulated copperclad cable twinax cable flexible cables nonmetallic sheathed cable or nonmetallic building wire, nm, nm b1 metallic sheathed cable or armored cable, ac, or bx1 multicore cable. Ankita singh gaur department of electrical and electronics engineering national institute of technology goa, india403401. For higher voltages, 3 cored constructions become too bulky, and hence, even with some limitations we employ single cored cables. A highvoltage cable hv cable is a cable used for electric power transmission at high voltage. Underground system was not favourable in developing and under developed countries.
I prezumed was that it must be related to probable hazard that a spark due to any cable. Beyond that, insulation required for the cable is too much. In this method, cast iron or concrete pipes or ducts are laid underground with manholes. Jul 01, 20 laying of underground cables the reliability of underground cable network depends to a considerable extent upon proper laying. The system of cable laid with a serving and its enough to protect the power. There are a lot of things that you have to take into consideration when doing this project. Ug oh line cable laying service provider from nagpur.
Laying uf underground feeder cable directly into the ground. Obtain consultants approval before cables are covered and trenches backfilled. Reliance jio cable laying workers waking up the neighborhood like chirping birds. Ht cable laying, testing, termination service ht cable hipot test service, ultima communication hanuman nagar, jaipur plot no. Underground cable installation manual part ii network standard ns 14. In urban areas, high voltage underground cables are commonly used for the transmission and distribution of electricity.
A guideline for laying of cables and installation of sleeves. The illustrations below outline the most common circumstances leading to contact with live electricity cables. High voltage xlpe cable systems technical user guide. Underground cable distribution up to and including 33kv infrastructure technical standards page b05. Highvoltage cables of differing types have a variety of applications in instruments, ignition systems, and alternating current. As these cables are not exposed to the air atmosphere, they are less susceptible to outages. Figure f2 cable feed into conduit at floor level c from cable reel to cable tray, the cable is fed from the top of the reel to maintain required curvature. Given a new cable installation task, both the departments have their separate speci.
The provided services are carried out by our skilled professionals using the finest grade tools and modern techniques. All the heat generated by an underground power cable must be dissipated through the soil. Singlecore power cables can be run in a number of formations, the most common include flat or trefoil formations. Underground cable laying ht and lt services ask price sunrise construction equipment teka. There are three main methods of laying underground cables, which are i direct laying, ii drawin system and iii solid system. Installation, testing and jointing of lt and ht power cables up to. Further, the vertical runs where the cable descends into the ground at the house side.
The trench also cover with bricks or concrete slab then again fill with soil. Why is sand filling required inside a concrete cable. Underground cable laying proposal to lay power cable and. Other installations, such as buried and aerial, have different installation parameters. Wrong handling of cables, such as damages due to wrong handlingbending or laying of cable also weakens the insulation of the cables. Since the mechanical strain on the cable in its laid form is significantly less, the permissible temperature range is greater than the range valid for the installation period. A cable includes a conductor and insulation, and is suitable for being run underground or underwater.