Class 12 Electronics Chapter 3 Circuit Breaker Solutions English Medium As Per AHSEC New Syllabus to each chapter is provided in the list so that you can easily browse through different chapters Class 12 Electronics Chapter 3 Circuit Breaker Question Answer and select need one. Class 12 Electronics Chapter 3 Circuit Breaker Notes Download PDF. AHSEC Class 12 Elective Electronics Question Answer English Medium.
Class 12 Electronics Chapter 3 Circuit Breaker
Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. AHSEC Class 12 Elective Electronics Textual Solutions are part of All Subject Solutions. Here we have given AHSEC Class 12 Electronics Textbook Solutions English Medium for All Chapters, You can practice these here.
Circuit Breaker
Chapter: 3
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A. Multiple choice questions:
1. How many metals are used to form a bimetallic strip?
(a) One metal.
(b) Two metal.
(c) Three metal.
(d) Four metal.
Ans: (b) Two metal.
2. Which of the following is not part of a MCB?
(a) Processor.
(b) Copper Braid.
(c) Arc chute.
(d) Magnetic coil.
Ans: (a) Processor.
3. Which of the following is not a type of fuse?
(a) Cartridge type high voltage HRC fuse.
(b) Liquid types high voltage HRC fuse.
(c) Expulsion type high voltage fuse.
(d) Stroke Fuse.
Ans: (d) Stroke Fuse.
4. Which of the following is not a type of low voltage fuse?
(a) Rewirable fuse.
(b) Cartridge fuse.
(c) Dropout fuse.
(d) Cartridge type high voltage HRC fuse.
Ans: (d) Cartridge type high voltage HRC fuse.
5. Which of the following is not a high voltage fuse?
(a) Cartridge type high voltage HRC fuse.
(b) Expulsion type high voltage fuse.
(c) Liquid type high voltage fuse.
(d) Solid type high voltage fuse.
Ans: (d) Solid type high voltage fuse.
6. The most commonly used fuse in house wiring is _________________.
(a) Rewirable fuse.
(b) D-type cartridge fuse.
(c) Dropout fuse.
(d) Link type cartridge.
Ans: (a) Rewirable fuse.
7. Which of the following principle is used in the operation of a fuse?
(a) Heating effect of current.
(b) Electromagnetic induction.
(c) Faraday’s law.
(d) Magnetic field.
Ans: (a) Heating effect of current.
8. Which of the following material is used to make the casing of a fuse?
(a) Ceramic.
(b) Glass.
(c) Plastic.
(d) All of the above.
Ans: (d) All of the above.
9. Which of the following is/are reason(s) for overcurrent in a system?
(a) Overload.
(b) Short circuit.
(c) Ground fault.
(d) All of the above.
Ans: (d) All of the above.
10. Which of the following is the basic classification of a fuse?
(a) AC.
(b) DC.
(c) AC and DC.
(d) None of the above.
Ans: (c) AC and DC.
B. Fill in the blanks:
1. A bimetallic strip is made up of ___________ and ____________.
Ans: Steel, brass.
2. In a rewirable fuse the base is made up of ____________.
Ans: Copper or aluminium.
3. A fuse is also called ______________ device.
Ans: Electromechanical.
4. A general fuse consists of a ______________ metallic wire enclosed in a non-combustible material.
Ans: Low resistance.
5. A ______________ fault occurs when electrical current f lows from a conductor to uninsulated metal that is not designed to conduct electricity.
Ans: Ground.
6. A short circuit occurs when there is a direct but unintended connection between ______________ or ______________ conductors.
Ans: Line to line or line to neutral.
7. The melting point of copper is __________________ degree Celsius.
Ans: 1090
8. In India, the rate of change of AC supply is ______________ cycles per second.
Ans: 50
9. The standard unit of frequency is ________________.
Ans: Hertz.
10. The enclosure of the HRC fuse is filled with powdered pure quartz, which acts as _______________ material.
Ans: Heat absorbing.
C. State whether the following statements are True or False:
1. Melting point of silver is 980 ˚C.
Ans: True.
2. Corona in electrical system means “the glow around a conductor at high potential”.
Ans: True.
3. Arc chute extinguishes the arc produced due to heavy current.
Ans: True.
4. The ON/OFF switch can be manually used by the user.
Ans: True.
5. A bimetallic strip uses two similar metals bonded together.
Ans: False.
6. In MCB the live/phase wire is screwed at the input terminal.
Ans: True.
7. The current from the coil goes to the bimetallic strip by means of another thick wire.
Ans: True.
8. In cartridge type high voltage HRC fuse the fuse element is wound in the shape of a helix, which avoids the corona effect at higher voltages.
Ans: True.
9. In high rupturing capacity fuse, the fuse element carries the fault current for a longer duration.
Ans: True.
10. In dropout fuse the melting of fuse causes the fuse element to drop in the lower support of fuse.
Ans: True.
D. Short answer questions:
1. What is the role of a circuit breaker in the electrical system?
Ans: The circuit breaker will interrupt the power supply when there is a current overload caused by a short circuit or by the load itself drawing more current than the rating of a circuit breaker. For example, if the circuit breaker is rated for 15 amps, it will break the circuit as soon as the circuit load draws more than 15 amps.
2. Write down the working principle of a fuse.
Ans: The working principle of a fuse is based on the heating effect of current. Whenever a short circuit or overcurrent or mismatched load connection occurs, the thin wire inside the fuse melts from the heat generated by the heavy current flowing through it. Therefore, it disconnects the power supply and electric circuit. Generally, a fuse wire is a very low resistance component and does not affect the normal operation of the system connected to the power supply.
3. What are the types of fuse?
Ans: Various types of fuses are available, classified on the basis of their parameters. Largely they are classified as DC and AC fuse on the basis of input supply voltages.
4. List the names of low voltage fuse.
Ans: Low voltage fuse can be further divided into four classes: rewirable fuse, cartridge fuse, dropout fuse and striker fuse.
5. List the names of high voltage fuse.
Ans: This type of fuse deals with high voltage. While operating with high voltage, the corona effect may occur. Therefore, high voltage fuses are specially designed to overcome the corona effect. HRC fuses are mainly classified into three types – cartridge type high voltage HRC fuses, expulsion type high voltage fuses and liquid type HRC fuses.
6. List the material used to make the case of a fuse.
Ans: The fuse consists of a fuse carrier, base body and fuse element. The base body and fuse carrier are made of ceramic, glass, plastic or moulded mica laminates.
7. Write short notes on:
(a) AC fuse.
Ans: An AC fuse operates on AC power supply. The amplitude of AC supply varies instantaneously. In India, the rate of change of AC supply is 50 cycles per second. It means that an AC signal will have 50 positive half and 50 negative half in one second. This rate of change is called frequency of AC signal. Thus, the arc produced in an AC fuse can be easily compensated as compared to the arc in a DC circuit. An AC fuse is classified further into low voltage fuse and high voltage fuse.
(b) DC fuse.
Ans: DC fuse operates on DC power supply. The amplitude of DC remains constant. The only difficulty with a DC fuse is that the arc produced by the direct current is difficult to compensate, as the DC voltage remains constant. This constant voltage produces a high arc between the electrodes of the fuse. To reduce the DC fuse arcing, the electrodes are placed further apart, due to which the size of a DC fuse is bigger as compared to an AC fuse.
(c) Link type cartridge or high rupturing capacity.
Ans: In a link type cartridge or high rupturing capacity (HRC) fuse, the fuse element carries fault current for a longer duration. If the fault is not clear, then the fuse element will melt and open the circuit. HRC fuse has high-speed operation and does not require maintenance, but, the fuse element needs to be replaced after each operation.
(d) Cartridge type high voltage HRC fuse.
Ans: In a cartridge type high voltage HRC fuse the fuse element is wound in the shape of a helix, which avoids the corona effect at higher voltages. It has two fused elements placed parallel to each other, one of low resistance and the other of high resistance. The low resistance wire carries normal current, which is blown out, thereby reducing the short circuit current during a fault condition.
(e) Liquid type high voltage HRC fuse.
Ans: Liquid type high voltage HRC fuse is filled with carbon tetra-chloride and sealed at both ends. When a fault occurs the current exceeds beyond the permissible limit and blows out the fuse element. The liquid of the fuse acts as an arc extinguishing medium for the HRC fuse. They can be used for transformer protection and as a backup protection to the circuit breaker.
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