Various types of insulators ~ MONU TUTORIALS ACADEMY

Various types of insulator

Pin type
Suspension type
Strain type
Spool type or shackle type

Pin type insulator

this insulator are mounted with the central threaded hole so that the insulator is supported from thread insulator in mounted on the cross arm. For low voltage, pin insulator are generally grouped on the side or top to support the wires. Medium voltage insulator have groups on both top and sides.High voltage pin insulator are stronger in construction and they consist of two or three pieces of porcelain cemented together. These pieces phone what we call Petticoats.

the conductor is placed in the group at the top of the insulator and is then attached to the insulator by tyingit down with the help of binding wire which is value of the same material as the conductor.

Advantage and disadvantage of pin type insulator over suspension

Advantage

It is cheaper than suspension insulator.
Pin type insulator is placed on the top of the ball to achieve more conductor clearance above the ground.pin insulator rises the conductor above the cross arm while the suspension insulator suspended it below the cross arm.

Disadvantage

Beyond 33 kv, line voltage transmission, pin type insulator become too bulky and hence it is not economical.
Replacement cost is more.
It is often less flexibility to the line conductors.

Suspension type insulator

As discussed above, the pin type insulator is not suitable beyond 33kv transmission voltage for higher voltage of transmission the conductor are insulated by means of suspension insulators.the suspension insulator hangs from the cross arms And the line conductor is attached to its lower end.as there is no pin problem we can put any distance between the suspension insulator and conductor just by adding more insulator to the string. The entire unit of suspension insulator is called as string. How how many insulator the string should contain depend on the voltage the weather condition the type of transmission construction and the size of insulator used.

Several advantage of suspension insulator are,

is insulator is designed for a comparatively low working voltage usually about 11KV and the insulation for any required line voltage can be obtained by using a suitable number of such insulator in a string.
In the event of failure of an insulator,one unit, instead of the whole string has to be replaced.
Suspension type insulator placed on steel tower, also protect the line conductor partly from lightning, as the conductor ran below the earthed cross arm.

The disadvantage of suspension insulator are:

it requires large spacing between conductor then with pin type insulator due to large amplitude of the swing of the conductors.
it is costlier than pin type insulator so is generally not used below 33 KV transmission voltage.

Strain insulator

Sometimes a line must withstand great strength for instant at a corner, atisha curve or at dead end. Such situation, the pool is sustained and insulation is provided by a strain insulator on a transmission line.the strain insulator of 10 consists of an assembly of suspense insulator with some protective arcing horn added.the strain insulator must have considerable strength as well as the necessary electrical properties. Strain insulator are also used for insulating stay wire, guard wires etc. When the tension is exceedingly higher sat along river spans, two, three or four string in parallel are used. Actually when used as strain insulator,the suspension insulator disc are in vertical instant of being in horizontal plane.

Spool for shackle insulator

these types of insulator along with single wire oreck assemblies for supporting lotensin lines on the sides of poles and buildings both the low-voltage distributor and house service wire are attached to the spool insulator.the insulator has a tapered hole and does distribute the load more evenly and minimises the possibility of breakage when heavily load. Nowadays shackle insulator are used all along the LT lines.

Egg or stay insulator

such insulator are of X shape and are used in stay wire section to avoid flow of any leakage current to earth. Moreover, 2000 mountant at height of 3 metre from the ground level. These insulator are usually of porcelain.2000 design that in case of breakage of the insulator the guidewire will not fall ground.

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