Advantages of Dry Type Transformers:
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.
Reduced Line Losses:
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.
Increased Reserve Capacity
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.
Reduced Cost of Cabling
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.
Resistance to Humidity
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.
Friendly to the environment
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.
Improved Capability for Harmonic Loading
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.