In most applications as well as transmission, alternating current, AC, voltages and currents are used. Alternating Current, AC can be generated at manageable levels and transformed to higher voltages for distribution along the grid that covers very long distances. The ability to generate AC power and transmit it conveniently is one of the main reasons why it is vastly used.
By increasing the voltage to get higher distribution voltages, the lines carry lower current for the same power, thus reducing losses P=I2R, in the electrical grid. Once the transmitted power reaches its destination, the AC voltages can be reduced to useable levels, which are much lower, safer and more convenient. Most electrical equipment and home and workplace appliances use single-phase (120V/240V) or three-phase (208V/415V). Thus, the a need for a transformer.
In this article we delve into the realm of electrical transformers, investigating their concepts, types, applications, and importance in our daily lives. In typical operation, transformers are used to change the voltage to the required levels through inductance.
What is a Transformer?
A transformer is a device used to convert electrical energy from one circuit to another without changing the frequency or power. These systems transfer electrical energy from one circuit to another through electromagnetic induction. The conversion that transformers are used for is raising and lowering voltages and current to meet needed specifications, thus improving efficiency and safety in operations.
Essentially, a transformer is an electrical component rather than an electronic component. An electrical transformer is a static device that uses electromagnetic induction to convert electrical energy from one circuit to another. It works on the principle of Faradays Law of Induction. A transformer's fundamental components are two wire coils known as the primary and secondary windings, as well as a magnetic core. To improve magnetic coupling, these coils are looped around the core, which is commonly made of laminated iron or steel.
Transformers Working Principle
As stated, transformers work on Faradays Law of Induction and the principle of electromagnetic induction. It states that a current-carrying conductor induces a magnetic field around it and vice versa. A transformer operates on the principle of electromagnetic induction, through a process of mutual induction. By linking two or more electrical circuits using a common oscillating magnetic circuit, commonly a magnetic iron core, a transformer is formed.
A transformer consists of two sets of wires, that is two windings; a primary winding, that collects power and a secondary winding that provides power. These two are wound together on a magnetic iron core, the two coils are never in contact with each other. When alternating current (AC) flows through the primary winding, it creates a magnetic field around the coil. The magnetic field links both windings by mutual induction. The changing magnetic field induces a voltage in the secondary winding, leading to the transfer of electrical energy. The key factor in this process is the turns ratio, which determines the voltage transformation from the primary to the secondary side.
The voltage produced on the load side is proportional to the number of turns in the secondary winding in comparison to the number of turns in the primary winding.
N1 / N2 = I2 / I1 = V1 / V2
V1: The voltage applied to the primary winding of the transformer.
V2: The voltage produced by the transformer's secondary (load) winding.
N1: The total number of turns in the principal winding.
N2: The number of secondary windings turns.
I1: Primary winding current
I2: Current flowing via the secondary winding
Types of Transformers
There are several ways in which transformers can be categorized; based on their construction, based on their purpose, their use and based on their power supply.
Based on their construction, that is how the primary and secondary windings are wound around the iron core, transformers can be core-type transformers or shell-type transformers. The primary and secondary coils in a core-type transformer are wound outside and surround the core ring. The primary and secondary windings in a shell-type transformer pass inside the magnetic steel core, forming a shell surrounding the windings.
On the other hand, transformers can be used with single-phase or three-phase power supply, thus transformers can also be classified as single-phase transformers or three-phase transformers.
Lastly, transformers can be classified based on their purpose. In this article, we will look at transformers based on their purpose.
- Step-up Transformers
These transformers boost the voltage from the primary winding to the secondary winding, providing higher voltages and lower current. High voltages are often utilised in power transmission from generation plants to substations, where they minimise energy losses during long-distance transmission.
They can also be commonly found in electrical equipment such as stabilizing systems and power inverters.
- Step-Down transformers
Step-down transformers, on the other hand, reduce the voltage from the primary to the secondary winding, increasing the current level. They are commonly used in distribution networks to reduce voltage levels to a safe and useful level for homes and industries. Thus, they are found on the other end of transmission at the consumer level.
Step-down transformers are used in electronic circuits to reduce the incoming electrical supply. If a device receives 240V, the voltage may need to be reduced to 5V, 9V, 12V, 24V, or 48V. This would be accomplished by employing a step-down transformer with the appropriate winding ratio.
Step-down transformers can be found in phone chargers, computer/game console power adaptors, and other consumer electronic devices.
- Isolation Transformers
Unlike step-up and step-down transformers, isolation transformers do not adjust the voltage or current levels in a circuit. The ratio between the primary and secondary windings is 1. Instead, they are used to separate the two circuits on either side of the transformer
These transformers provide electrical isolation between the primary and secondary windings, offering protection against electrical faults, reducing noise transfer from either circuit and improving safety in various applications.
- Auto Transformers
Autotransformers offer the option of variable transformer ratios. Autotransformers use a single winding with several taps to provide variable voltage output. They are frequently employed in situations requiring precise voltage control.
- Instrument Transformer
These are specialized transformers that are used for measurement and protection. Instrument transformers are used in relays and commercial metering systems to offer insulation and safety. These transformers also measure extremely high voltages that a standard voltmeter cannot detect. Instrument transformers are classified as either current or voltage transformers.
Common Applications of Transformers
- Transformers serve an important role in efficiently transporting electricity from power plants to substations and ultimately to homes and businesses. This is done by the use of step-up and step-down transformers. They aid in the reduction of energy losses during long-distance transmission.
- Step-down transformers are used to reduce the voltage in residential appliances, inverters, power distribution networks, and transmission lines.
- When high voltage levels are required, step-up transformers are utilised. Electric motors, X-ray equipment, and microwave ovens are all powered by transformers.
- Voltage regulation: Transformers assist power grids in maintaining consistent voltage levels, ensuring that consumers receive electricity at the correct voltage for their devices.
- Transformers are used in industries to power machinery and equipment that often require certain voltage levels.
- The isolation of electrical circuits offers both protection and a noise filter for the systems.
Final Thought
The importance of transformers cannot be overstated in the current world, from the generation of electrical power, distribution and consumption in homes and industries. They ensure the safe and efficient delivery of electricity. Thus, by understanding their working principle, types and applications, it becomes easier to implement electrical systems using these electrical components.
