If the insulator industry overcomes the current challenges, it has a bright future ahead, says Daya Kingston.The global market for insulators is estimated at Rs 15,000 crore and the Indian industry clocks Rs 2,000 crore. Pin insulators, cap and pin insulators, post insulators, solid core line post insulators, disc insulators, shackle insulators, guy insulators and long rod insulators are the major types. Based on material, they are broadly classified into ceramic or porcelain insulators, composite or polymer and glass insulators. Ceramic insulators have the highest demand followed by composite insulators.The initial insulators that were built were made of porcelain and later glass insulators became popular. With the growth in technology, composite insulators made from polymers are gaining popularity.The major advantages of porcelain insulators are that they offer superior electrical properties, have good mechanical properties (especially tensile strength), good creep resistance at room temperature, high corrosion resistance, minimal leakage problems and are less adversely affected by any temperature changes. Though a porcelain insulator can be damaged by rough handling, vandalism or flashover, the glaze normally sustains only superficial damage. Since the electrical or mechanical strengths are generally not affected, it does not need to be changed. The disadvantage of porcelain insulators is that there are impurities or voids in the porcelain dielectric and expansion of the cement in the pin region can lead to radial cracks in the shell. Glass insulators offer high mechanical durability and when it comes to their size and weight, they are almost the same as porcelain. The disadvantage is that they have less electric resistance and moisture condenses easily on its surface, limiting its use to lower voltages.Composite or polymer insulators offer advantages like hydrophobic - water-repellent properties, reliable performance in desert and sea-side environments, lower costs, lighter weight, easier installation, vandalism-proof, etc.DPK Udas, Vice President, Goldstone Infratech and Vice Chairman of Insulator division of IEEMA, said, “We at Goldstone manufacture silicone rubber insulators (composite insulators). Porcelain is the oldest and proven insulating material and has been in use in the industry for a long time. The only issue with this material is that it is fragile, punctures due to electrical stresses and additionally the crack is difficult to locate. Though glass has similar properties like porcelain, if it develops a crack, it can be easily seen. Since glass and porcelain can get damaged during transit and erection, the industry was forced to look for an alternative material. Silicone rubber has good insulating property but due to lack of strength it is used along with a fibre glass rod which gives adequate mechanical support. Since two materials are used in one insulator, it is called a 'composite'. There are no issues while installing such composite insulators and they are light in weight and easy to handle. Also they do not break while installing.”Insulators by voltageBased on the voltage, insulators are classified into: Low voltage – less than 1,000 volts, medium voltage (distribution) – between 1,000 volts (1 kV) to about 33 kV, high voltage (sub transmission less than 100 kV; sub-transmission or transmission at voltage such as 115 kV and 138 kV), used for sub-transmission and transmission of bulk quantities of power and connection to very large consumers, extra high voltage (transmission) – over 230 kV and up to about 800 kV for long distance, very high power transmission and ultra high voltage – higher than 800 kV.Quality control & R&DDPK Udas said, “Quality control is an integral part of insulator manufacturing. It is required at the raw material stage and also during manufacturing. The firing is applicable for porcelain insulators. There are some customer-hold points wherein non-destructive testing (NDT) is done before the insulator is assembled. India today has become a source for power products across the world. The days when we imported the latest technology from overseas have gone as many technologies are being developed here. Many multi-national companies have made India their manufacturing base as the availability of technical manpower is maximum in India and it is the only country wherein entire transmission line equipment is available indigenously. We are not dependent on any imports. Nevertheless in the composite insulator field there are some developments with regard to liquid silicone being used to make insulators and field trials for the same are being conducted."Industry scenarioThe Indian insulator industry is quite mature and there is a healthy mix of large, medium and small sector players.Growing opportunitiesThe Indian insulator industry has quite a positive outlook thanks to the ambitious plans of the Ministry of Power for the 11th as well as the 12th Five Year Plans.The Chinese threatThe biggest threat that Indian insulator companies face is from Chinese companies. Their low cost products have not only eaten into the margins of Indian manufacturers but also their market share. What adds fuel to the fire is the fact that even some public sector transmission companies and state electricity boards have started giving bulk contracts to Chinese companies. Chinese companies have a distinct advantage in terms of a pricing benefit of 22.9 per cent arising from export subsidy, low interest rates and beneficial tax policies.Other threatsThe prices of raw materials used in the manufacture of insulators like steel and silicon rubber are highly volatile in global markets, which can affect the bottomline of companies.Tips to maintain insulatorsThe pollutants that can settle on insulators include salt, lime, dust, chemicals, bird droppings, smog, cooling tower effluents and so on. One of the key problems that insulators exposed to the elements face is pollution deposition.Coastal pollution is the result of salt spray from the sea or solid material like sand that contains salt and makes its way through the wind and deposits on insulators. Industrial pollution results when insulators are located close to industrial complexes and are exposed to stack emissions which deposit salts and acids.All kinds of insulators need to be regularly cleaned with water and compressed air with dry abrasives. Silicone grease should be applied to insulators, bushings and lightning arresters. In high contamination areas, a silicon rubber protective coating can help. DPK Udas said, “The periodicity of line maintenance varies from utility to utility. This is required mainly to detect punctures and breakages of porcelain and glass insulators. The puncture can happen immediately after installation or after a few years. Long rod type insulators are Type A as per IEC and they do not puncture. Some utilities remove composite insulators on a selective basis and check for electrical and mechanical properties.”If the Indian insulator industry overcomes the current challenges, it has a bright future ahead.
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