Transformer construction

A power transformer is an electrical device that transfers electrical energy from one circuit to another through electromagnetic induction. It is used in power transmission and distribution to step up (increase) or step down (decrease) voltage levels while maintaining the same frequency.

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Basic Working Principle

The power transformer operates on Faraday’s Law of Electromagnetic Induction, which states that a changing magnetic field in a coil induces a voltage in a nearby coil.

Basic Principle of a Power Transformer

1. Primary Coil (Input Side):
   • When an alternating current (AC) flows through the primary winding, it creates a changing magnetic field in the transformer’s core.
2. Magnetic Core:
   • The magnetic field is transferred through a laminated iron core to the secondary coil.
3. Secondary Coil (Output Side):
   • The changing magnetic field induces a voltage in the secondary winding, transferring electrical energy from the primary to the secondary side.
4. Voltage Transformation:
   • The voltage transformation depends on the turns ratio of the windings: V2V1=N2N1\frac{V_2}{V_1} = \frac{N_2}{N_1}V1​V2​​=N1​N2​​ Where:
     • V1V_1V1​, V2V_2V2​ = Primary and secondary voltages
     • N1N_1N1​, N2N_2N2​ = Number of turns in primary and secondary windings
5. Types of Power Transformers:
   • Step-Up Transformer: Increases voltage (more turns in secondary winding than primary).
   • Step-Down Transformer: Decreases voltage (fewer turns in secondary than primary).

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Key Features of a Power Transformer

✅ Operates on AC – Works only with alternating current since a changing magnetic field is needed.
✅ Highly Efficient – Can have efficiency up to 99% due to minimal energy losses.
✅ Isolation – Provides electrical isolation between circuits.

Transformers can refer to different concepts depending on the context. Here are the main types:

1. Electrical Transformers (Used in Power Systems)

Electrical transformers are devices that transfer electrical energy between circuits through electromagnetic induction. They come in various types:

By Construction

• Core Type Transformer – Windings are around a laminated core.
• Shell Type Transformer – The core surrounds most of the windings.

By Function

• Step-Up Transformer – Increases voltage (e.g., in power stations).
• Step-Down Transformer – Decreases voltage (e.g., for home use).
• Isolation Transformer – Provides electrical isolation between circuits.
• Auto Transformer – Has a single winding serving as both primary and secondary.
• Instrument Transformers
  • Current Transformer (CT) – Measures high currents safely.
  • Potential Transformer (PT) – Measures high voltages safely.

By Phases

• Single-Phase Transformer – Used in residential applications.
• Three-Phase Transformer – Used in industrial power distribution.

It looks like you are referring to a Core Type Transformer, which has windings arranged around a laminated magnetic core. Here is a brief breakdown:

By Construction

Core Type Transformer

• The core is rectangular and made of laminated silicon steel to reduce eddy current losses.
• Windings (Primary & Secondary) are placed around the two limbs of the core.
• Typically, cylindrical coils are used for the windings.
• The magnetic flux mainly follows the core’s path, reducing leakage flux.
• Better cooling since windings are exposed to the surrounding air.

Applications

• Power transformers
• Distribution transformers
• High-voltage applications

Yes, in a Shell Type Transformer, the core surrounds the majority of the windings. This design contrasts with the Core Type Transformer, where the windings surround the core.

Shell Type Transformer Characteristics:

• Core Structure: The core is laminated and encloses the windings on both sides, forming a closed magnetic circuit.
• Windings Placement: The primary and secondary windings are placed on the central limb of the core.
• Flux Path: The magnetic flux is divided into two symmetrical paths through the side limbs.
• Efficiency & Performance:
  • Offers better short-circuit strength due to its compact winding arrangement.
  • Higher leakage reactance, useful in applications requiring controlled voltage regulation.
  • Lower core losses and better cooling compared to core-type transformers.

Applications:

• Power Transformers
• Rectifier Transformers
• High-Frequency Transformers
• Distribution Transformers (where compact design is required)

By Function

Step-Up Transformer – Increases voltage (e.g., in power stations).

A Step-Up Transformer is an electrical device that increases voltage from the primary winding (input) to the secondary winding (output) while reducing the current. It follows the principle of electromagnetic induction, where the number of turns in the secondary coil is greater than the number of turns in the primary coil.

Key Features of a Step-Up Transformer:

• Increases Voltage: The output voltage is higher than the input voltage.
• Decreases Current: As per the power equation P=VIP = VIP=VI, if voltage increases, current decreases (assuming constant power).
• More Turns in Secondary Coil: The secondary winding has more turns than the primary winding, which leads to a higher induced voltage.

Applications of Step-Up Transformers:

1. Power Transmission: Used in electrical grids to increase voltage for long-distance power transmission, reducing energy loss.
2. X-Ray Machines: Provides the high voltage needed for X-ray generation.
3. Microwave Ovens: Steps up voltage for magnetron operation.
4. Electric Vehicle Charging Stations: Helps deliver high voltage for fast charging.