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Overhead line insulators are used to separate line conductors from each other and the supporting structures electrically. Insulators protect the transmission line from overvoltages which occur due to lightning, switching, or other causes under the severe condition.
Which insulator is used in overhead lines answer?
The most commonly used material for overhead line insulators is porcelain. The typical strain insulator is made of glass, porcelain, or composite.
Which material is used in overhead lines?
Commonly used conductor materials: The most commonly used conductor materials for overhead lines are copper, aluminium, steel-cored aluminium, galvanised steel and cadmium copper. The choice of a particular material will depend upon the cost, the required electrical and mechanical properties and the local conditions.
What is the most common cause of failure of overhead line insulators?
Explanation: Failure of overhead line insulators due to mechanical stress is rare because defective pieces are separated during routine factory test. Failure due to porosity and improper vitrification is also very low. The most common cause of failure of overhead line insulator is flashover.
What are types of insulators?
Insulator Types Pin-type insulators. These insulators are used for the transmission and distribution of electric power at voltages up to 33 kV. Line post insulators. Suspension insulators. Strain insulators. Shackle insulators. Post insulators. Cap and pin insulators. Stay insulators.
What is the use of overhead lines?
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 is the long time clearance of overhead line?
1,2 & 3 attached to the Regulations. 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) 66 2.00 110 2.25 132 2.50 220 3.50.
What are the main components of overhead transmission lines?
Transmission Lines are made up of various components, namely poles, lattice structures, conductors, cables, insulators, foundations and earthing systems. These components are described in more detail in this document. The primary functions of transmission line structures are to provide mechanical support to conductors.
What are the cause of failure of line insulators?
Causes & Modes of Insulator Failure The failure of an insulator could also be caused by service conditions, such as insulator separating when abnormally high ice accretion or heavy winds cause mechanical load to exceed the unit’s rated value.
How many classifications of overhead line insulators are there?
There are 5 types of insulators used in transmission lines as overhead insulation: Pin Insulator. Suspension Insulator. Strain Insulator.
Where is the suspension type of insulators mainly used?
The main advantage of suspension insulator is that it uses low voltage and is highly flexible. These kinds of insulators can be mainly seen in railway lines, over headed poles, etc.
What are 4 examples of insulators?
Examples of insulators include plastics, Styrofoam, paper, rubber, glass and dry air.
What are 3 types of insulators?
List the Different Types of Insulators Suspension insulators. Pin insulators. Strain Insulators. Stay Insulators. Shackle Insulators.
What are 5 insulators?
Insulators: glass. rubber. oil. asphalt. fiberglass. porcelain. ceramic. quartz.
How do overhead lines work?
An overhead line consists of one or more wires (or rails, particularly in tunnels) situated over rail tracks, raised to a high electrical potential by connection to feeder stations at regular intervals. The feeder stations are usually fed from a high-voltage electrical grid.
Why are there 3 power lines?
High-voltage transmission lines are quite obvious when you see them. They are normally made of huge steel towers like this: All power towers like this have three wires for the three phases. These are ground wires and are there primarily in an attempt to attract lightning.
What are the advantages of overhead transmission lines?
Advantages High Power transmission. Low installation and material cost. Long-distance transmissions. The fault or damage in overhead lines can easily locate. Maintenance of the line is easier. Extension or joining on overhead lines can be performed easily and also it facilitates easy replacing.
Which support for overhead line is no longer used?
Wooden poles: It is one of the cheapest types of line supports and used for lines where spans are short, and tension is low. It has very less life. Concrete poles: Concrete pole gave greater strength and used in place of a wood pole.
Which is a part of overhead line?
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 is the minimum ground clear distance for 11KV overhead line?
Clearance above ground of the lowest conductor As per IE Rule 77 Over head Line Across Street Low and Medium Voltage 5.8 Meter Low/Medium /HT line up to 11KV If Bare Conductor 4.6 Meter Low/Medium /HT line up to 11KV If Insulated Conductor 4.0 Meter Above 11 KV Line 5.2 Meter.
What are components of overhead?
Overhead expenses include accounting fees, advertising, insurance, interest, legal fees, labor burden, rent, repairs, supplies, taxes, telephone bills, travel expenditures, and utilities. There are essentially two types of business overheads: administrative overheads and manufacturing overheads.
What are the different components of overhead?
Components of Overhead Lines : Conductors : Insulators : Supports : Cross-arms and Clamps : Guys and Stays : Lightning Arrestors : Fuses and Isolating Switches : Earth Wire :.
What are different types of transmission lines?
Types of transmission line include parallel line (ladder line, twisted pair), coaxial cable, and planar transmission lines such as stripline and microstrip. The higher the frequency of electromagnetic waves moving through a given cable or medium, the shorter the wavelength of the waves.
Which insulator is used above 132 kv lines?
Disc type insulators: The pin insulator is used in power distribution for the voltage up to 33kV.
How do the insulators fail?
If the surface of porcelain insulator is not properly glazed, moisture can stick over it. This moisture along with deposited dust on the insulator surface, produces a conducting path. As the flash over distance is reduced, the chance of failure of insulator due to flash over becomes more.
What causes insulation failure?
What causes insulation failure? Some of the more common causes of insulation failure include: excessive heat or cold, moisture, dirt, corrosive vapors, oil, vibration, aging and nicked wiring. There are numerous maintenance tests for assessing insulation quality.
How many classifications of overhead line insulators are there Mcq?
How many classifications of overhead line insulators are there? Explanation: There are basically 3 types of overhead line insulators. They are Pin type, Suspension type and Stray Insulator type.
How many types of pin insulators are there?
Single or multiple pin insulators can be used on one physical support, however, the number of insulators used depends upon the application’s voltage. Pin insulators are one of three types of overhead insulators, the others being strain insulators and suspension insulators.
Why is the wavy structure of pin insulators used?
mechanical strength. puncture strength. flash-over voltage.
