Power Supply Transformer

The transformer consists of two or more coils of wire, known as the primary and secondary winding, that are separated by a core of ferromagnetic material. When an AC voltage is applied to the primary winding, it creates an alternating magnetic field in the core, which in turn induce an AC voltage in the secondary winding. 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 of the transformer.

Construction of transformer

The basic construction of a transformer consists of two or more coils of wire, known as the primary and secondary winding, that are separated by a core of ferromagnetic material. The primary winding is connected to the input AC voltage, and the secondary winding is connected to the load. The transformer operates based on the principle of electromagnetic induction, where an AC voltage applied to the primary winding creates an alternating magnetic field in the core, which in turn induce an AC voltage in the secondary winding.

The transformer core is typically made of a stack of thin sheets of silicon steel or other ferromagnetic material, which helps to concentrate the magnetic field and increase the transformer’s efficiency. The primary and secondary windings are usually made of copper or aluminum wire, and they are wound onto the core in a specific pattern to minimize the amount of space required and to optimize the transformer’s performance.

In some transformers, the primary and secondary windings are wound on separate legs of the core, while in others they are wound on the same leg. The type of winding used depends on the design and requirements of the transformer.

The transformer also has an enclosure or casing, which houses the core and windings and protects them from damage and the environment. The enclosure may be made of metal, plastic, or other materials, and it may also include cooling fins or other cooling features to dissipate the heat generated by the transformer.

Where are transformers used?

Transformers are widely used in electrical power systems to transfer electrical energy between circuits. They are used in a variety of applications, including:

1. Power transmission and distribution: Large transformers are used to step up the voltage of electricity generated at power plants to high levels for transmission over long distances, and then step it down to lower levels for distribution to consumers.
2. Power conditioning: Specialized transformers called “isolation transformers” are used to isolate electrical equipment from the power supply to protect it from electrical noise and surges.
3. Electronic circuits: Small transformers are used in electronic circuits to provide electrical isolation and to step up or step down the voltage of a power supply.
4. Audio systems: Audio transformers are used in audio systems to match the impedance of speakers and microphones to the amplifier.
5. Welding: Large transformers are used in welding machines to provide the high current needed for the welding process.
6. Other applications: Transformers are also used in a variety of other applications, including radar systems, medical equipment, and electric vehicles.

Types of transformer

There are several types of transformers, which are classified based on various criteria such as the purpose of use, the type of core, the type of winding, and the method of cooling. Some common types of transformers include:

1. Step-up transformer: A transformer that increases the voltage of the input AC power.
2. Step-down transformer: A transformer that decreases the voltage of the input AC power.
3. Isolation transformer: A transformer that provides electrical isolation between the primary and secondary windings. It is used to isolate electrical equipment from the power supply and to protect it from electrical noise and surges.
4. Three-phase transformer: A transformer that has three windings, each of which is connected to a different phase of a three-phase power supply.
5. Auto transformer: A transformer that has a single winding that is shared by both the primary and secondary circuits. It is used to step up or step down the voltage in a circuit with a small transformation ratio.
6. Variable transformer: A transformer that has a movable core, which allows the transformation ratio to be varied. It is used to continuously adjust the voltage or current in a circuit.
7. Rectifier transformer: A transformer that is used in conjunction with a rectifier to convert AC power to DC power.
8. Resonant transformer: A transformer that is designed to operate at a specific resonant frequency. It is used in electronic circuits to generate high voltage pulses.
9. Audio transformer: A transformer that is used in audio systems to match the impedance of speakers and microphones to the amplifier.
10. Furnace transformer: A transformer that is used to supply power to an electric furnace. It is designed to operate at high temperatures and to withstand the high current demands of the furnace.

If a load on secondary side of a transformer increases, the current on the primary side:

If the load on the secondary side of a transformer increases, the current on the primary side will also increase. This is because the transformer is a linear device that obeys Ohm’s law, which states that the current through a conductor is directly proportional to the voltage across it and the resistance of the conductor.

In the case of a transformer, the voltage across the primary winding is fixed by the input AC voltage, and the resistance of the primary winding is also fixed. Therefore, if the load on the secondary side increases, the current through the primary winding must also increase in order to maintain the same voltage across the primary winding. This increase in primary current is due to the increased demand for energy by the load on the secondary side.

However, it is important to note that the current on the primary side will not increase in direct proportion to the load on the secondary side, due to the voltage transformation ratio of the transformer. The voltage transformation ratio is the ratio of the voltage on the secondary side to the voltage on the primary side, and it is determined by the ratio of the number of turns in the primary winding to the number of turns in the secondary winding. If the voltage transformation ratio is not 1:1, then the current on the primary side will not increase in direct proportion to the load on the secondary side.

Transformers are typically rated in kVA (kilovolt-amperes) because the kVA rating is a measure of the transformer’s capacity to transfer electrical power. The kVA rating is determined by the product of the transformer’s voltage rating and the current rating, and it is used to ensure that the transformer can handle the electrical load that it is designed for.

For example, a transformer with a rating of 500 kVA has the capacity to transfer 500,000 VA (volt-amperes) of electrical power. The VA rating is a measure of the apparent power in an AC electrical circuit, and it is equal to the product of the voltage and current in the circuit. The kVA rating is used instead of the VA rating because it takes into account the power factor of the load, which is the ratio of the real power (measured in watts) to the apparent power (measured in VA).

The kVA rating of a transformer is important because it determines the size and cost of the transformer, as well as the amount of electrical power that it can transfer. A transformer that is too small for the load will not be able to transfer the required amount of power and may overheat or fail, while a transformer that is too large will be unnecessarily expensive and may not operate efficiently.

Instrument transformer

An instrument transformer is a type of transformer that is used to isolate, step up, or step down the voltage or current in an electrical measurement or protection system. Instrument transformers are used to measure and control the electrical quantities in a power system, such as voltage, current, frequency, and power factor.

There are two main types of instrument transformers:

1. Current transformers (CTs): Current transformers are used to measure and control the electric current in a circuit. They are used to isolate the measuring or protection equipment from the high currents in the circuit and to provide a convenient low-current secondary winding that can be connected to the measuring or protection equipment.
2. Voltage transformers (VTs): Voltage transformers are used to measure and control the electric voltage in a circuit. They are used to isolate the measuring or protection equipment from the high voltages in the circuit and to provide a convenient low-voltage secondary winding that can be connected to the measuring or protection equipment.

Instrument transformers are commonly used in electrical power systems to measure and control the electrical quantities in transmission and distribution systems, and they are also used in a variety of other applications, including industrial, commercial, and residential settings.