What is a transformer
A transformer is an electromagnetic passive electrical device, which operates on the principle of faraday’s law of induction and the value of electrical energy will be converted from one value to others. A transformer converts the value of electrical energy, in order to do this transformer links two or more electrical circuits using a common oscillating magnetic circuit. The transformer does its operation by the principle of electromagnetic induction in the form of mutual induction.
What is a distribution transformer and where is it used
Distribution transformers are normally located at a service drop, where the distribution of the power will end at customer premises. It is also used for the power supply of the facilities outside settlements such as isolated houses, farmyards. Another application of this transformer is that in case of power supply for the overhead wire of railways electrified with AC, so a single-phase distribution transformer is used for this purpose. Distribution transformers can supply power to the customers according to the number of customers in an area. In urban areas, several homes may be fed off by using a single distribution transformer, while in case of rural distribution one transformer may be needed per customer. Multiple distribution transformers would be used for a large industrial complex. Distribution transformers are also used in wind farms, they would be located in the power collector network in which they step up power from each wind turbine to connect to a substation which would be miles away.
What is the purpose of a distribution transformer
The distribution transformer transmits electric power to the customer by reducing the primary voltage so that it can be utilized by the customers. Distribution transformers are used to transfer electric power by electromagnetic induction from one circuit to others with different values of voltage and current but with the same frequency. If distribution transformers are mounted on a pole they can be called pole-mount transformers. If the distribution lines are located at ground level or underground, or they could be mounted on a concrete pad and locked in steel cases, and it would be known as pad mount transformers.
Distribution transformers are used to convert electrical energy of higher voltage, usually, up to 36KV, to a lower voltage which would be 250 to 435V, with an identical. The application of the product is mainly within the suburban areas of public supply authorities and industrial customers. Distribution transformers are the last item in the chain of electrical energy supply to households and industrial enterprises. Small distribution transformer does not generate much heat and most of them are dry type. Dry types are less flammable and can be used in confined spaces.
How does the distribution transformer operate and how is it Constructed
Single-phase distribution transformer has a primary and secondary winding wound on a laminated steel core. If the load is disconnected from the secondary winding of the transformer and a high voltage is applied to the primary winding of the transformer then a magnetizing current will flow in the primary winding. The resistance of the primary winding is small, and the current is limited by the counter voltage of self-induction induced in the highly inductive primary winding. The exciting current magnetizes or produces a magnetic flux in the steel transformer core. Magnetic flux will reverse each half-cycle as a result of the alternating voltage applied in the primary winding. The produced magnetic field cuts the turns of primary and secondary windings. This process will induce a voltage in the primary winding and produces a voltage in the secondary winding. The voltage induced in the primary and secondary is approximately equal.
Distribution transformers are constructed mainly of two types they are core and shell-type. In the core type, the core is in the form of a rectangular form with the coils placed on two vertical sides. The coils are cylindrical and long, they are divided, part of each primary and secondary being on each of the two vertical legs. In shell-type, the core surrounds the coil, instead of coils surrounding the core. The coil in this type is flat and the primary and secondary coils are altered. The core and coil assembly of the distribution transformer is completely immersed in oil to keep the operating temperature low and to provide additional insulation for the winding.
How power transformer is different from distribution transformer
Power transformers do the transmission of higher voltages in the transmission network and they are rated above 200MVA. While the distribution transformers are used for lower voltage transmission network as the means to end-user connectivity and are rated below 200MVA. Power transformers are used for transmission purposes at heavy load high voltage greater than 33KV and with great efficiency, these transformers are bigger than the distribution transformer and they are used in transmission and generating stations. The distribution transformer is used to transfer electrical energy at low voltages which would be less than 33KV, it is of small size and have low efficiency. Distribution transformers are designed to operate efficiently at 60-70 percent load and it doesn’t operate at full load all the time. Whereas power transformer is designed for maximum efficiency at 100 percent load.