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The demand of electricity in Pakistan has been increasing rapidly in the last few years. There is a mushroom growth in the high rise buildings, shopping areas, petrol stations, etc. Installation of conventional oil type transformers in indoor sites is always a big safety risk. The developed as well as many developing countries are installing dry type transformers as a solution for ensuring safety in such scenarios.
Keeping in view the increasing demand of dry type transformers in Pakistan, PEL and IMEFY, Spain have joined hands together for fulfilling the need of the Cast Resin Dry Type transformers. PEL-IMEFY can supply transformers up to 36kV & 5MVA rating. PEL-IMEFY are offering CRT with both Aluminium and Copper windings, as per requirement of the customer. Dry type transformers are supplied with enclosures. Degree of protection of transformer is determined by the site conditions or as required by the client.
Enhanced Safety with the increasing costs of low voltage cables, it has become a trend to bring high voltage lines close to installed loads. For cost reasons, transformers are located near habitable areas such as buildings where fire risk has to be minimized. Additionally, industries such as chemical, mining, etc. are also a potential risk of fire. Dry type transformers have no fluids to spill, explode or burn, and the insulation used does not support combustion in air. Therefore, these transformers ensure enhanced safety of equipment against fire hazards.
Dry type transformers can be located close to their loads, such as; inside factories, schools, hospitals and apartments and as a result low-voltage lines can be shortened with a consequent reduction of the related losses.
If transformers are to be operated continuously at or near their rated loads, efficiency is of prime importance. In this case, one could select 80°C rise, allowing these units to operate continuously above (potentially up to 20 percent more than) the rated load (if needed, for example, due to unplanned expansions) at a much lower cost (in increased load loss) than that associated with adding an additional transformer.
Transformers are inherently reliable pieces of equipment. Surveys published by IEEE show failure rates of modern cast resin dry-type transformers equivalent to conventional fluid-filled units in the same power and voltage classes. However, in case of difficulty, dry types can be easily inspected and minor repairs conducted on site.
Dry type transformers require an annual inspection and only cleaning of dust which can block path of the cooling medium i.e. air. This is only where the maintenance is required to be carried out. This considerably reduces the running cost. Whereas periodic inspection for leaks and rust is required for liquid cooled transformers. Liquid coolants need continuous monitoring and have to be reconditioned when necessary.
Cast resin dry type transformers installation does not require particular fire safety arrangements; consequently the transformers can be installed near the load. This results in reducing the high costs of LT cabling.
Resin covering the coils and the other insulation components make it resistant to moisture and polluted atmospheres. This allows the placement of dry type units in many locations not considered in the past.
In these transformers, no liquid is used, thus no risks for any kind of leakage, moreover, no toxic or corrosive gasses, nor halogens are released from the transformer in case of any accident/fire. At the end of their useful life, dry type units can easily be dismantled, and the copper (or aluminum) conductors recovered, along with the steel core. A further impetus to wider use of dry-type transformers has been the PCB hazard which is present for many oil filled transformers.
Transformers supplying loads with heavy harmonic content frequently see high hot-spot temperatures. Standard transformers typically reduce the base temperature to compensate, which increases the size of the unit. Dry-type transformers still have a large reserve temperature capability to accommodate these hot spots, with no loss of life.