At present, locating a convenient and proper, suitable area for installing a distribution transformer is one of the primary and main challenges encountered by the distribution companies. Particularly in urban areas, it is acute and critical, so power departments must plan for an apt and appropriate place for installation by analyzing the load, load center, possibility, and any additional development, etc. This type of transformer can be systematized on a single pole or H-pole depending on the transformer’s weight, size, and requirements. Subsequently, the opportunity for installation of this transformer can be done by the distribution company based on the capability, aptitude, and availability of space.
Meaning Of Distribution Transformer:
Distribution transformers are heavy and bulky devices, which are also known as a typical set of isolation transformers. It may have been mandatory to strengthen an appropriate specific section of the module floor or platform deck at the installation place for them. The installer should make sure that all transformers are positioned on a flat, level, and advanced prepared base in the location demonstrated on the relevant layout or design drawing. Once installed, it may be crucial to fill the transformer if it is a fluid-filled variant. Also, it must be acknowledged that some of these insulation fluid types are noxious, and hence, appropriate precautions will require to be taken.
The manufacturer’s agent must be called in after all the transformers have been placed and filled with supporting and witnessing the final checking, trial, and testing. Then, the Insulation tests will be finished, and after done with all the cabling, a second insulation test of all windings, attachments, and connections are followed to be carried out. Subsequently, after installing two or more transformers attached to a single switchboard, a phase polarity test must be carried out across the related bus segment.
The primary function of such a transformer is to adjust and modify the high voltage to the standard voltage like 240/120 V to utilize in electric power distribution. There are diverse types of transformers available in the distribution technique such as single-phase, 3-phase, pad-mounted, pole-mounted transformer, underground, etc.
Usually, these Distribution transformers manufacturers are obtainable in various sizes with efficiencies and abilities along with insulating oil. These transformers are available in varying sizes, efficiencies, and power. The choice of this transformer predominantly lies in the term, conditions, and budget of the user. There are four variants of distribution transformer connections available: star-star, delta-star, star-delta, delta-delta, and Zig Zag/delta zigzag.
Distribution Transformer Construction
The planning and designing of a Distribution Transformer can be done much specifically or like small-sized transformers. The principal parts of this transformer essentially involve Conservator, Temperature Detector, Buchholz Relay, Oil Tank, Breather Unit, Oil Indicator, Radiator, Pressure Relief Device, Thermal Relay, and Bushing.
- The oil tank is utilized to infuse the windings by positioning it in.
- A conservator is projected above the oil tank at the outside of the transformer structure. It is attached to the main tank with the support of a metallic tube. The oil inside the tank can be effortlessly contacted & expand throughout loading in order to increase and decrease the temperature of the oil.
- Buchholz Relay is utilized when a conservator tank is used as it denotes errors such as loss of oil once it goes low, the inapt flow of oil between the tank and transformer, etc.
- Breather Unit comprises silica gel that consumes moisture in the oil. It alters its color from blue color to pink color. It is not competent to incorporate moisture in the oil.
- The oil indicator designates the level of the oil inside the conservatory unit.
- The temperature indicator observes the temperature of the oil. If the temperature of the oil rises to a specified level, then the transformer will be disconnected from the service.
- A pressure relief device minimizes or limits the transformer’s pressure to ignore an explosion of the transformer.
- A thermal relay is adopted as an indicator for the temperature monitoring of the winding.
- The radiator is used to improve or strengthen the transformer’s cooling efficiency and competence.
- The bushing is utilized to connect the transformer’s internal windings with the aid of an external electrical network.
Uses and Applications of Distribution Transformer:
The usage and applications of the distribution transformer include the following:
- This transformer shifts from high voltage electricity to low voltage electricity, which is used in homes and even in organizations.
- The prime purpose of this is to move down the voltage to affiliate isolation between two windings, such as primary and secondary.
- This transformer distributes or dispenses the power to remote and isolated areas that are produced from the power plants.
- Usually, this transformer enables the electrical energy to industries with less voltage under 33KV and 440volts to 220volts for domestic usage and applications.
Types of Distribution Transformer:
These distribution transformers are classified into different types, including single-phase, three phases, underground, pad-mounted, pole-mounted transformers based on the usage, application, and requirement.
Single Phase: These transformers are utilized explicitly for networks wherever a three-phase supply is not needed. Usually, these are used for repairing and improving overhead distribution loads in residential. These are also appropriate in industrial lighting, power applications, and light commercial loads.
Three Phase: This type of transformer is utilized to maintain electrical energy from the principal distribution circuit to a trivial distribution circuit. This type of transformer transmits the current to a secondary distribution circuit and decreases the primary distribution circuit’s voltage. These transformers limit the voltage supply for the primary circuit depending on the consumer requirement.
This voltage always varies and can be dissimilar for residential, commercial, and light industry consumers. These transformers work on diverse voltage and frequency levels based on the standards existing in other various countries. These transformers are readily available in single-phase and three phases. Single-phase is practiced in residential applications and installations; on the other hand, 3-phase transformers with a pad are adopted in underground primary circuits.
Pad-Mounted: Pad-Mounted transformer constitutes a locked steel cupboard that is systematized on a concrete pad. This type of transformer is used and installed in places where they do not have a fenced enclosure domain. This transformer is practiced with electric power distribution lines at an overhead electrical route for diminishing the primary voltage to supply for the consumers. This type of single transformer of this type can benefit multiple homes or even a large building.
Pole Mounted: These transformers are set up on an electrical service pole at the height of the overhead cables. These are utilized for altering high distribution voltage to low, like 120/240-volt power. These types of transformers are used in various rural areas, ranges from 16 kVA to 100kVA. These are available in small size and cautiously to fit on single-pole structures. These transformers are guaranteed to harsh environments when they are adopted in remote or isolated areas.