Transformers Basics Quiz

Transformers Basics

• A transformer's function is to change the level of AC voltage.
• A transformer is a type of machine that produces a static induced emf.
• It is a main flux device.

Transformer Operation

• A transformer works only on AC voltage.
• The rating of a transformer is expressed in kVA (kilovolt-amperes).
• A transformer steps up or down AC voltage.
• The transformer equation V1I1 = V2I2 is a manifestation of the law of energy conservation.

Step-up and Step-down Transformers

• In a step-up transformer, the number of turns in the secondary (Ns) is greater than the number of turns in the primary (Np).
• In a step-down transformer, the number of turns in the secondary (Ns) is less than the number of turns in the primary (Np).
• The magnitude of the induced emf in the primary winding will be almost equal but opposite to the applied voltage.

Transformer Characteristics

• The resistance between the primary and secondary windings of a transformer is infinite.
• A transformer converts voltage and current levels without changing the power.
• The changes in voltage levels in a power system are provided by using a transformer.

Insulation in Transformers

• Insulating oil and insulating paper are used as insulation mediums in a transformer.

Three-Phase Transformers

• The advantages of a single three-phase transformer bank over three single-phase transformer banks include lower cost, less weight, and less space occupied for the same rating.
• In a three-phase transformer, it has a three-limbed core, takes less space, is cheaper, and is slightly more efficient.

Transformer Types

• An electric transformer is a device that consists of two or more multi-turn coils wound on a common core.
• Compared to the secondary of a loaded step-up transformer, the primary has lower voltage and higher current.

Transformer Limitations

• If the AC supply to the transformer is replaced by DC, the primary winding will burn.
• A transformer, as compared to an amplifier, cannot increase power.
• A transformer does not possess the property of changing frequency.

Transformer Design

• The HT winding of a 3-phase step-down transformer is wound with more number of turns of relatively thin wire.
• In a power transformer, the low voltage winding is always wound with fewer turns of thicker wire.
• The winding of a step-up transformer with more turns is the high voltage winding.

Transformer Applications

• Distribution transformers have a rating of up to 200 kVA.
• For higher voltage ranges, autotransformers are used.
• For low voltage and large kVA, shell-type transformers are used.

Transformer Construction

• Core type transformers are more suitable for high voltage and high output.
• There are two magnetic paths in the core type transformer.
• The use of higher flux density in the transformer design is to decrease the weight/kVA.
• Rectangular frame laminations are formed to build the interior of the transformer, which are cut in L-shape strips to avoid high reluctance at joints.

Transformer Station

• A switching station is a substation that has no transformer and operates only at a single voltage level.
• The vertical position on which the coil is wound in a transformer is called the limb.

Transformer Characteristics

• A transformer has very high efficiency, it has no moving parts, and is rugged in construction.
• The degree of mechanical vibrations produced by the laminations of a transformer depends on the tightness of clamping, gauge of laminations, and size of laminations.
• The material used while making the core of the transformer to reduce hysteresis loss is silicon steel.

This quiz covers the basics of transformers, including their function, operation, and types. It tests your knowledge of transformers and their applications.