Transformers Basics Quiz
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Questions and Answers

Which law states that energy cannot be created or destroyed, only transformed or transferred?

  • Newton's Third Law
  • Law of Inertia
  • Law of Energy Conservation (correct)
  • Ohm's Law
  • In a transformer, when the number of turns in the secondary winding is greater than the number of turns in the primary winding, what relationship does this create?

  • Ns/Np = 0
  • Ns = Np
  • Ns < Np
  • Ns > Np (correct)
  • What is the primary reason for using insulating oil and insulating paper in a transformer?

  • To improve cooling
  • To increase efficiency
  • To provide insulation (correct)
  • To reduce weight
  • State one advantage of a three-limbed core transformer.

    <p>It takes less space</p> Signup and view all the answers

    In a transformer, the primary winding is connected to the power source and produces ________________.

    <p>flux</p> Signup and view all the answers

    What is the purpose of a transformer?

    <p>To change the voltage of an alternating current</p> Signup and view all the answers

    What principle explains how a transformer works by inducing a voltage in a secondary coil due to changes in the primary coil's magnetic field?

    <p>Faraday's Law of Electromagnetic Induction</p> Signup and view all the answers

    The function of a transformer is to:

    <p>Change the level of AC voltage</p> Signup and view all the answers

    Type of machine that produces the static induced emf is:

    <p>Transformer</p> Signup and view all the answers

    The power transformer is a constant:

    <p>Main flux device</p> Signup and view all the answers

    A transformer works on:

    <p>A.C.only</p> Signup and view all the answers

    The rating of a transformer is expressed in:

    <p>kVA</p> Signup and view all the answers

    A transformer steps up or down:

    <p>Both AC and DC</p> Signup and view all the answers

    The transformer equation V1I1 = V2I2 is the manifestation of:

    <p>Law of energy conservation</p> Signup and view all the answers

    In a step-up transformer:

    <p>Ns &gt; Np</p> Signup and view all the answers

    In a step-down transformer:

    <p>Ns &lt; Np</p> Signup and view all the answers

    The magnitude of the induced emf in the primary winding will be ______ but opposite to the applied voltage:

    <p>Lower</p> Signup and view all the answers

    Study Notes

    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.

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    Description

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

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