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DISTRIBUTION TRANSFORMERS IN AN ELECTRICAL DISTRIBUTION SYSTEM

DISTRIBUTION TRANSFORMERS IN AN ELECTRICAL DISTRIBUTION SYSTEMRole of Distribution Transformers in an electric utility and its functions?

Before voltages are converted into a level which can be utilized by a typical electric utility customer, voltage transformation occurs first in the distribution transformers. The function of a distribution transformer does not differ much of that a power transformer. The only obvious disparity is its voltage level.
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A distribution transformer basically reduces voltages from medium voltage level to low-voltage level of which that can be readily used by the end-users like in residential and commercials establishments. This voltage level is also termed as the final voltage transformation since this is the level used by the customers.

A distribution transformer in an electric distribution system can be either a pole-mounted transformer which is mounted and found attached to a utility pole or a pad-mounted transformer which can be located underground, on concrete pads or located in steel cases.

The load scope of a distribution transformer usually depends on the discretion of the utility as long as it satisfies the operation standards used in dealing with this kind of equipment. Usually, a distribution transformer can be used to cater multiple loads like in residential places or it can be design to serve one dedicated customer. The former are known as common distribution transformers while the latter is considered to be a solo type of distribution transformer.

Distribution transformers are coined by electric utilities as “load centers” since they are like mini-substation that serves its customers power demands. The volume of distribution transformers in an electric utility can be directly proportional to the number of customers it serves.

Like a power transformer, distribution transformers have a primary and secondary winding and are typically enclosed in a transformer tank. Some distribution transformers are oil-insulated and some are dry-type. A transformer is considered to be a distribution transformer if it has a KVA rating of not more than 500 kVA.

Also, like a power transformer, no load loss and Load loss also occurs in a distribution transformer since they have the same operating principle and function. A typical distribution transformer is design to be used for single phase application but nevertheless, a single unit three phase transformer is also available for use. However, the usual practice is to bank a single-phase distribution transformer to create a three-phase connection.

This three-phase connection can be wye-wye, wye-delta, delta-delta, delta-wye, or any combination possible. Unlike a power transformer, the application of a distribution transformer is somewhat less complicated since it does not require intensive protection and monitoring. A simple cut-out fuse is enough to protect the equipment from faults and overloads.

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