What is a transformer and why it is so important?

What is a transformer:

An electrical transformer (T/F) is an essential device that is used to transfer energy from one circuit to another through inductive coupling. It is used to convert alternating current (AC) from one voltage level to another voltage level. This device is used in many applications ranging from small household appliances to large power plants.

T/F are made up of two or more coils of wire wrapped around a core of ferromagnetic material, such as iron. When an alternating current is applied to one of the coils, it induces a magnetic field in the core, which in turn induces an alternating current in the other coil. The ratio of the number of turns in the coils determines the ratio of the primary and secondary voltages.

The most common type of T/F is the step-down transformer, which is used to reduce the voltage from the primary to the secondary. This is the type of T/F used to reduce the voltage from the power line to the voltage used in the home. A step-up T/F is used to increase the voltage from the primary to the secondary. This type of transformer is used to power large industrial motors.

The other important feature of a transformer is its ability to isolate two circuits from each other. This is done by using a two-winding transformer.

Working principle of a transformer:

A transformer works on the principle of electromagnetic induction. It consists of two or more coils of wire wrapped around a metal core. When an alternating current (AC) is applied to the primary winding of the transformer, a magnetic field is created around the core.

What is a transformer — image credit: wikimedia commons

What is electrical circuit and why it is so important?

This magnetic field induces an alternating voltage in the secondary winding, which is then used as output. The ratio of the number of turns in the primary winding to the number of turns in the secondary winding determines the voltage transformation ratio.

Voltage and current ration in transformer:

The voltage and current ratio in a T/F is determined by the primary to secondary turns ratio. This ratio is the number of turns in the primary winding divided by the number of turns in the secondary winding. For example, if the primary winding has 500 turns and the secondary has 250 turns, the ratio is 2:1. This means the voltage of the secondary winding will be half of the voltage of the primary winding.

What is the EMF equation in Transformer?

The EMF equation of a T/F is given by: EMF = 4.44 × N × f × A × B, where N is the number of turns in the primary winding, f is the frequency of the alternating current, A is the area of the core, and B is the magnitude of the magnetic flux.

Types of transformers:

On the basis of phase
On the basis of voltage level
On the basis of cooling
On the basis of frequency
On the basis of core
On the basis of winding arrangements
On the basis of installation location

On the basis of phase:

Single phase transformer: A single-phase T/F is a type of electrical transformer that utilizes a single alternating current (AC) source to create a separate voltage. It is used to step up or step down the voltage between two or more circuits. It works by taking the input voltage, isolating it from the output voltage, and then stepping either up or down to the desired voltage.
Three phase Transformer: A three phase T/F is an electrical device used to convert three-phase electrical power from one form to another form. It consists of three single-phase windings, which are connected in either a Delta or Wye configuration. Three-phase T/F can be used to step up or step down voltage, to provide isolation between circuits, or to provide power to three-phase equipment.

On the basis of voltage level:

Step-up Transformer: A step-up T/F is a device that increases the voltage of an alternating current (AC) electrical circuit. It increases the voltage by using a magnetic field to convert the current from one voltage level to a higher voltage level. The step-up T/F typically has a primary winding that is connected to the AC power source and a secondary winding that is connected to the load. The ratio of the number of turns in the primary winding to the number of turns in the secondary winding determines the voltage output of the step-up T/F.
Step-down Transformer: A step-down T/F is a device that reduces the voltage of an alternating current (AC) electrical circuit. It works by transferring energy from a primary winding to a secondary winding through electromagnetic induction. The primary winding is connected to a higher voltage source, and the secondary winding is connected to a lower voltage load, resulting in a decrease in voltage between the two. Step-down T/Fs are used in a wide variety of applications, including power distribution, industrial processes, and consumer electronics.

On the basis of cooling:

Oil cooled Transformer: An oil cooled T/F is a type of transformer that uses oil to cool the winding and core of the T/F. The oil helps to transfer the heat away from the transformer, cooling it down and preventing it from overheating.
Air or dry type Transformer: A dry type transformer is a T/F that is cooled without the use of oil. Air is used to cool the transformer.

On the basis of Frequency:

Low frequency Transformer: A low frequency T/F is a type of electrical transformer designed to work with frequencies below 50 Hz, such as the frequencies used in audio and low voltage power circuits. These T/Fs are commonly used in power supplies and audio applications.
High frequency Transformer: High frequency T/Fs are electrical devices that transfer electrical energy from one circuit to another at high frequencies. These transformers are used in applications such as radio frequency (RF) transmission, oscillators, signal processing, audio amplifiers, and power supplies. High frequency transformers are typically constructed using materials such as ferrite cores, copper wire, and various insulation materials.

On the basis of core:

Air Core Transformer: An air core transformer is a type of transformer that does not use a ferromagnetic core, instead relying on the magnetic field created by the windings of the transformer. Its main advantages are the lack of hysteresis losses, the absence of eddy current losses, and the ability to operate at higher frequencies. However, the lack of a ferromagnetic core also means that air core transformers are more difficult to design and build, requiring more turns of wire and thus, more insulation.
Iron core Transformer: An iron core transformer is a type of transformer that uses an iron core to pass magnetic flux between its windings. This type of T/F is used in electrical devices such as power supplies, audio amplifiers, and even some electric motors. The core of an iron core T/F is made up of a stack of thin sheets of laminated iron, which are stacked together in a specific pattern. This helps to reduce electrical losses and increase the efficiency of the T/F.

On the basis of winding arrangement:

Auto- transformer: Auto-transformers are designed to change the voltage of an alternating current. They are used to step up or step down the voltage in an electrical circuit, allowing for the transfer of energy from one circuit to another without changing the frequency. They consist of a single winding which is connected in series to both the source and the load. As the input voltage changes, the ratio of the voltage between the source and load is also changed, resulting in a different output voltage.

On the basis of installation location:

Instrument transformer: An instrument T/F is a transformer used for measurement or protection of electrical systems. It is designed to provide a precise ratio between its primary and secondary windings to accurately measure or control electrical quantities such as voltage, current, or power. Instrument transformers provide insulation between the high-voltage circuit being measured and the control or measuring instruments.
Power Transformer: A power T/F is an electrical device used to transfer electrical energy from one circuit to another through electromagnetic induction. It is typically used to convert voltage levels between high and low voltage circuits, or to change the impedance of the circuits.
Distribution Transformer: A Distribution T/F is a type of electrical T/F that is used to convert high-voltage electricity to a lower voltage that is suitable for use in homes and businesses. It is a key part of the power grid and is used to reduce the voltage of electricity so that it can safely be used in homes and businesses.

Application

Electrical power distribution: T/Fare used to step up and step down the voltage of an electrical power source for transmission purposes.

Electrical isolation: Transformers are used to provide electrical isolation between two circuits.

Rectification: Transformers are used in rectification circuits to convert AC to DC.

Signal processing: Transformers are used in audio systems to provide impedance matching between stages.
Lighting: Transformers are used in lighting circuits to step down the high voltage from the mains to a lower voltage to power the lamps.
Welding: Transformers are used in welding machines to provide a high current for the welding process.

Parts

Primary Winding: This is the input winding of the T/F, which is connected to the alternating current source.
Secondary Winding: This is the output winding of the T/F, which is connected to the load.
Core: The core is the central component of the transformer. It is made of magnetic material and provides the path for the magnetic flux.
Insulating Layers: The insulating layers are used to separate the primary and secondary windings from each other as well as from the core.
Damping Windings: Damping windings are used to reduce the noise generated by the transformer.
Tank: The tank is the outermost component of the T/F. It is usually filled with oil or other coolant to dissipate the heat generated by the transformer.

What is ideal transformer?

An ideal transformer is a theoretical device with perfect efficiency and zero losses that perfectly transfers electrical energy from one circuit to another through the process of magnetic coupling. It has no core losses, no leakage flux, no winding resistance, and no magnetizing current. It is an idealized model of a real T/F, used for analysis and design.

What is efficiency of a transformer?

The efficiency of a T/F is a measure of how well the T/F converts electrical energy from the input to the output. It is typically expressed as a percentage and is calculated by dividing the output power by the input power. The higher the efficiency of a T/F, the less energy is lost as heat during the conversion process.

The percentage efficiency of a T/F depends on its specific design and application. Generally, the efficiency of a transformer ranges from 95-99%, but can be higher or lower depending on the design.