Dec 11, 2013

Selection of Insulators

One of the foremost vital and however one amongst the foremost at risk relations in transmission and distribution network is insulators. Ceramic ware and hard-bitten glass materials are mainly used for supportive conductors on overhead transmission lines, and though these materials are comparatively brittle and inflexible, they need proved service expertise and are still wide used. The planning of artificial sort insulators has improved each electrically and automatically in recent times and that they are getting used in municipal areas to reduce radio interference and in zones wherever shooting or stone throwing may be a downside. Material damage might occur thanks to such wide variable causes as power arcs, lighting, corrosion, gunshot, stone throwing and pollution.

The succeeding points should be thought-about within the choice of the suitable insulation of transmission overhead line: 
  • 50Hz performance
  • Impulse abilities
  • Switching abilities 

Post Insulators

These type of insulators are single piece ceramic ware construction and have a concreted on a galvanized ductile forged iron base providing with a taped hole for fitting stud. It’ll be apparent that this kind of construction renders it virtually non-puncturable and an extra benefit is that if any enlargement of the cemented base joint ensures occur the ceramic ware is place into solidity. If this happens with the cemented joint of the fixed lead cap of the pin sort material as mentioned higher than, the ceramic ware is employed in tension, a sort of load, which it has slight capability to withstand, and therefore the porcelain can fail.

Where sufficient added insulation isn't providing by the provision (eg. fiber material, Timber, etc). Then the materials ought to be of 2 piece or non-puncturable construction to attenuate the chance of an electrical hazard thanks to insulator failure.

Pin Insulators

This category was in the middle of the initial design and though it's improved each electrically and automatically, it's altered very little in look. It provides the foremost cost-effective, humble and effective technique of conductor provision for voltage upto and as well as 33kV. Pin sort insulators for the lesser voltages are intended in order that the puncture voltage is on top of the electric arc voltage, but if the material glazing below the conductor is broken (commonly affected by vibration) the material might puncture.

Stay Insulators

The stay insulators inserted within the stay wire is typically of ceramic ware and is so designed that within the incident of the failure of stay insulator the stay wire won't fall to ground. Completely the stays wire attached to woody poles supporting lively conductors must be fixed with stay insulators. An insulators must be riding not but 2.7 meters perpendicularly beyond ground and require a misty power frequency flashover voltage not but one and a half times the best voltage conductor supported by the pole.

Cap and Pin type Disc Insulators

These types of insulators are used at strain situations (i.e. Suspension and termination) in high voltage transmission liness and are obtainable in 70kN and 160kV strength to suit the assorted conductor loading. The cap and pin style ensures that the ceramic ware or glass of the high material is usually in firmness. In the place of high pollution, notably coastal areas the pin of the material ought to be fitted with Zinc collar.

Insulation Testing

All porcelain padding's reserved out of service should be tested before reerection. Hardened glass insulators but, needn't be tested, since the tiniest fault can source disintegration of the material. Facts on choice of insulators are contained within the style manual section on “Insulators”.


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