What is overhead line construction?
An overhead power line is a structure used in electric power transmission and distribution to transmit electrical energy across large distances. It consists of one or more uninsulated electrical cables (commonly multiples of three for three-phase power) suspended by towers or poles.
What are the major components of overhead construction?
An overhead line consists of conductors and ground wires, towers, insulation, hardware, and foundations. The transmission line conductors are specialized, with large cross section and relatively few strands.
What are power line supports called?
A transmission tower, also known as an electricity pylon or simply a pylon in British English and as a hydro tower in Canadian English, is a tall structure, usually a steel lattice tower, used to support an overhead power line.
What are the various components of an overhead line?
Components of Overhead Lines :
- Conductors :
- Insulators :
- Supports :
- Cross-arms and Clamps :
- Guys and Stays :
- Lightning Arrestors :
- Fuses and Isolating Switches :
- Earth Wire :
Why overhead lines are not insulated?
Because they carry large quantities of electricity at a very high voltage, transmission lines are not covered by an insulating sheath. The air around them provides insulation. Therefore, it’s important that nothing come close enough to the lines to cause an electric arc.
What is the long time clearance of overhead line?
23.1 All overhead power line crossings upto and including 33 kV – provided with guarding under the power line….17. Clearance between the overhead line & railway track:
| Normal System Voltage (kV) | Min. Safe clearance (In metre) |
|---|---|
| 220 | 3.50 |
| 400 | 6.00 |
| 500 | 7.25 |
| 800 | 11.50 |
What are the two main types of support for overhead lines?
The concrete poles used for supporting overhead electric lines are of two types. They are RCC type and PCC type. Presently, PCC type electric poles are widely used for supporting 11KV and 400/230V electric lines. Sometimes, PCC type electric poles are also used for 33kv lines.
What are different types of line supports?
The line support used for transmission and distribution of electric power are of various types including wooden poles, steel poles, R.C.C. poles and lattice steel towers. The choice of supporting structure for a particular case depends upon the line span, X-sectional area, line voltage, cost and local conditibns.
How many volts are transmission lines?
Transmission voltages usually run between 23,000 volts and 765,000 volts. Compare that to the voltage of your home’s electrical sockets: 120 volts for most outlets, 240 volts for a clothes dryer or stove range. Voltages in your home are enough to kill you, so power lines carry a much greater wallop.