An overview of the production and classification of Overhead transmission lines

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Construction Towers for the aid of the lines are manufactured from timber both grown or laminated, metal or aluminum, concrete, and once in a while bolstered plastics. The naked cord conductors at the line are normally manufactured from aluminum, even though a few copper wires are utilized in medium-voltage distribution and low-voltage connections to purchaser premises. A predominant intention of overhead electricity line layout is to keep ok clearance among energized conductors and to offer dependable aid for the conductors, resilience to storms, ice hundreds, earthquakes, and different capability harm causes- Power to Choose .

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Classification of transmission lines

By running voltage Overhead electricity transmission lines are categorized withinside the electric electricity enterprise via way of means of a variety of voltages:

  • Low voltage (LV), less than one thousand volts, is used for connection among a residential or small business purchaser.
  • Medium voltage (MV; distribution), among one thousand volts (1 kV) and sixty-nine kV, is used for distribution in city and rural areas.
  • High voltage (HV; sub-transmission much less than one hundred kV;
  • sub-transmission or transmission at voltages inclusive of a hundred and fifteen kV and 138 kV), is used for sub-transmission and transmission of bulk portions of electrical electricity and connection to very massive consumers.
  • Extra excessive voltage (EHV; transmission) – from 345 kV, as much as approximately 800 kV, used for lengthy distances, very excessive electricity transmission.
  • Ultra excessive voltage (UHV), is frequently related to≥ ±800 kVDC and ≥ one thousand HVAC


Structures for overhead lines take a whole lot of shapes relying on the kind of line. Structures can be as easy as timber poles without delay set withinside the earth, sporting one or greater cross-arm beams to aid conductors or armless production with conductors supported on insulators connected to the facet of the pole.

Tubular metal poles are usually utilized in city areas. High-voltage lines are frequently carried on lattice-kind metal towers or pylons. For faraway areas, aluminum towers can be located via way of means of helicopters.

Concrete poles have additionally been used. Poles manufactured from bolstered plastics also are available, however, their excessive price restricts application. Each shape should be designed for the hundreds imposed on it via way of means of the conductors. The weight of the conductor should be supported, in addition to dynamic hundreds because of wind and ice accumulation, and outcomes of vibration. Where conductors are in a straight line, towers want the handiest to face up to the burden because of the anxiety withinside the conductors about balances and not using a resultant pressure at the shape.

Flexible conductors supported at their ends approximate the shape of a catenary, and plenty of the evaluation for the production of transmission lines is based on the residences of this shape. Depending on the layout standards for a particular line, semi-bendy kind systems may also depend upon the burden of the conductors to be balanced on each aspect of every tower. More inflexible systems can be meant to stay status although one or greater conductors are broken. Such systems can be established at durations in electricity lines to restrict the dimensions of cascading tower failures. Foundations for tower systems can be massive and costly, in particular, if the floor situations are poor, inclusive of wetlands. Each shape can be stabilized drastically via way of means of the usage of man wires to counteract a number of the forces implemented via way of means of the conductors.