14 Questions
What is the primary function of a transformer?
To change the voltage level of an electrical signal
What is the common core material used in a transformer?
Ferromagnetic material
What is the term for a transformer that increases the voltage of an electrical signal?
Step-up transformer
What is the term for the winding that receives energy from the supply mains?
Primary winding
What is the purpose of a step-down transformer?
To decrease the voltage of an electrical signal
Where are transformers commonly used?
In AC power systems
What is one of the primary tasks performed by transformers in electrical power systems?
Changing voltage and current levels
What is the purpose of changing the turns ratio of a transformer?
To match the impedance of the source and load
What is the primary function of an instrument transformer?
To measure voltage and current
What is the material used to make the magnetic core of a transformer?
Cold-rolled grain-oriented silicon steel sheets
What is the advantage of using silicon steel in transformer cores?
Low cost and low core loss
What is the shape of the coils used in core-type transformers?
Oval or rectangular
What is the term used to describe the vertical portions of the core in a transformer?
Limbs or legs
Why is it desirable to reduce the leakage flux in a transformer?
It improves the transformer performance
Study Notes
Transformers
- A transformer is a static device that changes one voltage level to another voltage level through a magnetic field without a change in frequency.
- It consists of two or more coils of wire wrapped around a common ferromagnetic core.
Primary and Secondary Windings
- The transformer winding that receives energy from the supply mains is called the primary winding.
- The other winding that delivers electrical energy to the load is called the secondary winding.
Types of Transformers
- Step-up transformer: when the secondary winding has more turns than the primary winding, increasing the secondary voltage.
- Step-down transformer: when the secondary winding has less turns than the primary winding, decreasing the secondary voltage.
Applications of Transformers
- Used extensively in AC power systems to generate, transmit, and distribute electrical power efficiently.
- Enable voltage stepping up for transmission over long distances and stepping down for final use.
Tasks Performed by Transformers
- Change voltage and current levels in electrical power systems.
- Match source and load impedances for maximum power transfer in electronic and control circuits.
- Provide electrical isolation between circuits.
Types of Transformers (Construction)
- Core-type transformers
- Shell-type transformers
Types of Transformers (Application)
- Step-up transformers/unit transformers
- Substation transformers/step-down transmission line voltage to distribution level
- Distribution transformers/to final used voltage
- Instrument transformers/special transformers (CT, PT)
- Single-phase/three-phase transformers
Construction of Transformers
- Magnetic core made up of stacks of thin laminations (0.35mm) of cold-rolled grain-oriented silicon steel sheets lightly insulated with varnish.
- Silicon steel has low cost, low core loss, and high permeability at high flux density (1 to 1.5T).
- Primary and secondary coils are wound on the core and are electrically insulated from each other and from the core.
Core-type Winding
- Coils are wound on a circular, oval, or rectangular core.
- Coils surround a considerable part of the steel core.
- Vertical portions of the core are called limbs or legs, and the top and bottom portions are called yokes.
- Most of the flux is confined to high permeability core.
Learn about the basics of transformers, including their function, components, and types. Understand how they work and their applications.
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