There are various types of distribution transformers on the basis of various factors such as mounting location, types of insulation used, number of phases e.t.c.
Types of Distribution Transformer on the basis of Number of Phase
On the basis of number of phase, there are two types of distribution transformer which are explained below.
1) Single Phase Distribution Transformer
Single phase distribution transformer is a single phase step-down transformer that step downs the single phase voltage and step up the current as power and frequency remains constant. They are used where there is no need of three phase supply. This type of transformer can be connected with either one phase and neutral or earthing.
This types of transformer is used to supply single phase load such as for lighting purpose in industries or cities, for repairing overhead distribution load in residential areas, for power applications e.t.c.
2) Three Phase Distribution Transformer
Three phase distribution transformer is a three phase step-down transformer that step downs the all three phase voltage and step up their current as power and frequency remains constant. This type of distribution transformer is used to transfer electrical energy from primary distribution system to secondary distribution by step-down the primary distribution level voltage to secondary distribution level as per requirement.
In three phase distribution transformer, primary side of transformer are to all phases ( R,Y,B) of primary distribution system and secondary side is to secondary distribution system having all R,Y,B phase along with neutral in which loads are connected. Neutral must me earthed.
This type of transformer works at different rating of voltage and frequency level based on the standards of existing countries. These types of transformers are used to supply all types of consumer in an distribution network for all types of loads i.e for both single phase and three phase load.
Types of Distribution Transformer on the basis of Mounting Location
On the basis of mounting location, there are three types of distribution transformer which are explained below.
1)Pole Mounted Distribution Transformer
This type of distribution transformer are mounted on the power pole at the height of overhead cables. They are installed either on wooden or steel pole. They are generally used in rural areas to convert high primary distribution voltage i.e 11kv to low secondary distribution 230/400v voltage. This types of transformer ranges from 16kva to 100kva.
They are designed to be compact, lightweight, small in size and easily can be mount on a pole. They are reliable against harsh climate (i.e. extreme changing climate) and its tank are protected against corrosive materials and water accumulation. In highly corrosive region, stainless tans are used.
2)Pad Mounted Distribution Transformer
The pad mounted distribution transformers are consists of a locked steel cupboard located on a concrete base. This types of transformer are installed where enough space for fenced enclosure is not available. This type of distribution transformer are also used to to convert high primary distribution voltage i.e 11kv to low secondary distribution 230/400v voltage as pole mounted distribution transformer.
In this types of distribution transformer fuse and mccb are also enclosed or locked within steel cupboard. This types of distribution transformer are ranges from 75kva to 5000kva. They can be used in both overhead and underground distribution system but usually used for underground distribution system.
3)Underground vault Mounted Distribution Transformer
This types of distribution transformer is also known as Submersible Distribution Transformers. They are designed to install underground vaults, wells and water filled pits. Their vault are designed and provided with watertight seal to resist water and keep system dry and safe. They can also be installed in the areas where flood may occurs.
They are used to distribute in rural areas usually in underground distribution system. They are also used to convert high primary distribution level voltage to secondary distribution level voltage in rural areas.