In this tutorial, I am describing one of the most important topics- what is Electrical Transformer? with transformer construction and it’s main parts.
Also, I will add the functions of each part of the Transformer. So, it will make you understand easily.
Let’s study of the transformer in detail.
What is Electrical Transformer?
The basic definition of a transformer-
An electromagnetic device which is used for step up or step down the voltage level with respect to increasing or decreasing current level at constant frequency. This device called as Electrical Transformer.
Sometimes, an electrical transformer is called an Electrostatic device. Because, it doesn’t consist of removing apart.
Here are listing some important points about the transformer.
- The electrical connection does not occur in the transformer, only the magnetic connection occurred.
- It works on a principle of Faraday’s Laws of Electromagnetic induction.
- It requires and works only the AC voltage source. And AC source helps to generate the magnetic flux in the electromagnetic field.
- It is a protective device by regulating (raising or lowering) voltage in an electrical power system.
- The main function transformer is to transform the power from one circuit to another circuit at a constant frequency.
- The transformer is more power-efficient and has very low transformer losses as compared to other electrical machines.
- The generating power in the transformer is always measured in KVA rating, not kW.
What is the Construction of the Transformer?
The transformer is made of laminated iron core and steel strips. Core laminations consist of thin metal strips of insulated metal. These laminations are insulated by a coat of varnishes or papers and wrap around the limb.
You can easily understand the following figure.
It consists of two types of windings such as primary winding and secondary winding. These windings are separate and made by an electrical copper coil (number of turns). AC voltage source is provided to the primary winding and load is connected to the secondary winding.
We were already discussing, the transformer winding is not electrically connected to each other, but it is magnetically connected.
The main function of Core to support the winding and to provide a low reluctance path for flowing magnetic flux whose maybe a flowing useful flux.
What are the Main Parts of a Transformer?
Several parts of the transformer are given different function with the works as follow.
- Laminated Iron Core
- Transformer Winding
- Insulating Material
- Tap Changer
- Transformer Tank
- Oil Conservator Tank
- Buchholz Relay
- Cooling Tube and Radiator
- Explosion Vent
Part of Transformer (Image source)
Let’s study of each part one by one.
1. Laminated Iron Core
The transformer’s core is made up of iron or silicon steel or ferromagnetic materials. The iron core made by thin metal strips and lamination insulated by a coat of varnishes or papers. Each metal strip has thickness near about the o.5mm.
In the below figure, you can see the number of metal strips connected to each other with the lamination layer and form a single core.
Laminated Iron Core
Basically, ‘L’ and ‘E’ shaped laminations are used in different types of transformer. In the core type transformer, ‘L’ or ‘U’ shaped lamination is used.
And shell types transformer ‘E’ or ‘I’ shaped lamination is used.
These core lamination helps to reduce the eddy current loss and hysteresis loss. And It provides a low reluctance path and high permeability for the flux in the magnetic circuit.
2. The winding of the Transformer
The transformer winding is consists of several turns of the copper coil. It is wrapped around the limb or core with the lamination. These windings laminated by the insulation coating because it prevents the short circuit condition.
The winding of the transformer is separated by the primary side and secondary side.
On the bases of supply two types as
- High voltage winding
- Low voltage winding
Simply two types of winding are used as
- Concentric types winding
- Sandwich types winding
I. Concentric types of Winding:
Concentric types of windings are generally used in core types of transformer. It contains the only single path for mutual flux (Φ). And theses flowing flux are equally distributed on the side limbs of the core.
The single flux path is shown in the following figure.
Concentric types of winding consist of various kinds of winding like,
- Helical types winding
- Disc types winding
- Core types winding
In these core types of the transformer, windings are surrounded by the core. So, it requires a huge amount of copper coil and laminated materials.
II. Sandwich types of the Winding:
Sandwich types of winding are used in shell type transformer. In a shell-type transformer, the primary and secondary winding is placed on the central limb.
This central limb carries two flux paths (mutual flux and leakage flux) in the magnetic circuit.
You can see the above diagram, in shell types of the transformer, the core surround by the winding.
3. Insulating Material
In the transformer, insulating materials rely on their voltage rating. Different types of insulating materials are used in the transformer.
These insulating materials maybe a transformer oil, insulating paper, wood, the insulating glass material, tap changer insulating coil from grounding, etc.
4. Tap Changer
Tap changer to regulate supply voltage or load and maintain both conditions by changing the variable turn.
The tap changer is easily removed the first turn and connect the next turn ratio. Tap changers can occur on the primary side or secondary side.
Generally, tap changer use in the high voltage winding side because it reduces load current.
Classification of Tap Changer –
It is classified into two following category,
- No-load tap changer
- On-load tap changer
5. Transformer Tank
The transformer tank is a cylindrically shaped tank. It is made of steel metal with a high thickness. Core and transformer winding is placed in the transformer tank.
The transformer tank is needed to store the oil especially mineral oil. This oil provides insulation and cooling to the transformer winding.
6. Oil Conservator Tank
The oil conservator tank looks like a rectangular tank. It stores the extra oil and directly connected with the transformer tank.
The oil conservator tank is played an important role in the transformer.
The purpose of the conservator tank is to protect the expansion of oil in the main tank of the transformer. The oil is used in the transformer two purposes-
When the oil level reduces due to losses or leakage, the conservator will be delivering oil to the transformer. Thus, It acts as reservoir oil.
Breather is connected with the conservator tank. It is a cylindrical vessel which filled blue color silica gel.
They have two purposes -remove the moisture from the air and to have the capacity to absorb the moisture in a transformer.
It plays a role to act as the air filter and provide the free moisturizing air to the conservator tank.
8. Buchholz Relay
Buchholz relay is a protective device that is oil and gas-operated the relay. It is connected to the main transformer tank and conservator tank.
When the internal fault occurs in the transformer due to leakage flux, insulation core, core connection, breakdown core, etc. by producing excess heat.
This excess heat decomposes oil in the transformer and gas bubbles formed. Gas bubbles flow in the upward direction to the conservator and collected in the relay.
Buchholz relay is a fault detected by the amount of nature of gas and oil level in a transformer.
During several fault conditions, an alarm is alert then this command send to the circuit breaker and isolates the transformer.
The bushing is an insulating device that is made up of porcelain materials. The terminal of the bushing is provided a path of the conductor to the transformer tank.
With the help of the terminal, the transformer gives and provides the supply to another system.
In the transformer, two types of the bushing are mostly used- high voltage (HV) bushing and low voltage (LV) bushing. Its rely on voltage ratings may be a high voltage or low voltage.
10. Cooling Tube and Radiator
The cooling tube is necessary for maintaining the temperature and circulating cooling oil in the transformer.
And the radiator is connected with the transformer tank. It is also made of a number of metal strips or pipes.
Both the cooling tube and the radiator provide the same function in a different way. When losses occur in the transformer, heat is produced. This heat absorbs by the cooling tube and radiator in the form of cooling systems.
It is divided into two types of cooling systems.
- Natural cooling system
- Forced cooling system
In the natural cooling system, a cooling tube and radiator are used. And In the forced cooling system, we can connect the extra air fan to the transformer.
11. Explosion Vent
The explosion vent is located at the topmost position on the transformer. The conservator tank is directly connected to the explosion tank with the help of a pipe.
The main purpose to prevent damage transformer oil tank by expelling boiling oil during an internal fault. And it is necessary to remove heated oil (in the form of gas) in the transformer.
This explosion tank use only for emergency purposes. It mostly works when a breather and Buchholz relay will not doing work properly.
These eleven main important parts of transformers are covered with the help of the tutorial.
If you are interested more about to learn practically and building projects, here is the listing of the topmost challenging ideas for the Electrical Engineering Project based on Transformer.
- Classification of Transformer
- Alternating Current (AC) Vs Direct Current (DC)
- What is Relay?
- Electrical Circuit Vs Magnetic Circuit
- Single Phase Vs Three Phase
Let me know if you have any queries, you can share in the comment section.
Thanks for Reading!
I am a master in Electrical Power System. I work and write technical tutorials on the PLC, MATLAB programming, and Electrical on DipsLab.com portal.
Sharing my knowledge on this blog makes me happy. And Sometimes I dwell on Python programming.