Class 12 Electronics Chapter 1 Electrical Power 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 1 Electrical Power Question Answer and select need one. Class 12 Electronics Chapter 1 Electrical Power Notes Download PDF. AHSEC Class 12 Elective Electronics Question Answer English Medium.
Class 12 Electronics Chapter 1 Electrical Power
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.
Electrical Power
Chapter: 1
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A. Multiple choice questions:
1. The most efficient way to transmit electrical energy using a transmission line is ________________.
(a) Increase voltage and current.
(b) Increase voltage and reduce current.
(c) Decrease voltage and increase current.
(d) Decrease voltage and current.
Ans: (b) Increase voltage and reduce current.
2. Which of the following meter is used to measure the amount of power consumed in residence?
(a) Voltmeter.
(b) Ammeter.
(c) Barometer.
(d) Energymeter.
Ans: (d) Energymeter.
3. A protecting device used in an electric circuit to protect against electric shock is ________________.
(a) TPS.
(b) PROFIBUS.
(c) GFCI.
(d) GMI.
Ans: (c) GFCI.
4. The voltage rating for medium voltage equipment is ______________.
(a) 480 volts.
(b) 1000 volts or less.
(c) Greater than 1000 to 100,000 volts.
(d) Greater than 100,000 to 230,000 volts.
Ans: (c) Greater than 1000 to 100,000 volts.
5. The voltage rating for high voltage equipment is ________.
(a) 480 volts.
(b) 1000 volts or less.
(c) greater than 1000 to 100,000 volts.
(d) greater than 100,000 to 230,000 volts.
Ans: (d) greater than 100,000 to 230,000 volts.
6. The voltage rating for low voltage equipment is ________.
(a) 480 volts.
(b) 1000 volts or less.
(c) greater than 1000 to 100,000 volts.
(d) greater than 100,000 to 230,000 volts.
Ans: (b) 1000 volts or less.
7. The voltage rating for extra high voltage equipment is ______________.
(a) 2,40,000 volts to 8,00,000 volts.
(b) greater than 1000 to 100,000 volts.
(c) greater than 100,000 to 230,000 volts.
(d) for 1000 volts or less.
Ans: (a) 2,40,000 volts to 8,00,000 volts.
8. Which of the following units is used for the safety, reliability, flexibility of an electrical system?
(a) Busway.
(b) Transformer.
(c) Load centre.
(d) Switchgear.
Ans: (c) Load centre.
9. Which of the following units acts as a medium for transmitting electrical signals from one machine to another?
(a) Transformer.
(c) Busway.
(b) Load centre.
(d) Circuit breaker.
Ans: (c) Busway.
10. The electrical device that converts electrical energy to mechanical energy is called ______________.
(a) Generator.
(b) Motor.
(c) Switch.
(d) Switchgear.
Ans: (b) Motor.
B. Fill in the blanks:
1. GFCI protects us from ___________ and ___________.
Ans: Short circuit and ground faults.
2. To protect the load from these sudden fluctuations ___________ is used.
Ans: Surge arrester.
3. Load centre consists of an enclosure, interior, and ___________.
Ans: Trim.
4. Three phase transformers are used in ___________ station, transmitting station, and ___________ station of an electrical system.
Ans: Generating, distributing.
5. A transformer is a ___________ unit.
Ans: Static.
6. Sudden fluctuation in electric power is called __________.
Ans: Surge.
7. Coal, oil, and uranium are fuels used to convert water into steam, which in turn drives a ___________.
Ans: Turbine.
8. GFCI stands for ground ___________ circuit ___________.
Ans: Fault, interrupter.
9. AFCI stands for ________________ circuit _________.
Ans: Arc, fault, interrupter.
10. In an electrical system, the unit which performs the operation of routing of power cables, controlling the equipment and safety of individuals is known as ___________.
Ans: Switchgear.
C. State whether the following statements are True or False:
1. Armature is the rotating part of a motor or generator.
Ans: True.
2. A brush is a stationary or fixed part of a generator.
Ans: False.
3. According to Faraday’s law of electromagnetic induction, whenever a conductor moves in a magnetic field, EMF gets induced across the conductor.
Ans: True.
4. An AC generator is also known as alternator.
Ans: True.
5. Circuit breakers provide over current protection of a circuit.
Ans: True.
6. A generator converts mechanical energy into electrical energy.
Ans: True.
7. Switchgear is used in substation.
Ans: True.
8. GFCI is designed for protection of a person against electric arc.
Ans: False.
9. AFCI is designed for protection of a person against electric shock.
Ans: False.
10. Load centre is a term used for the panel board in industry.
Ans: True.
D. Short answer questions:
1. Write down the classification of a distribution system.
Ans: Electrical power distribution can be classified as:
(i) Residential application.
(ii) Commercial application.
(iii) Industrial application.
2. Write down the manufacturing steps of a three- phase transformer.
Ans: Visit a transformer manufacturing site and illustrate how a three-phase transformer is manufactured.
Material required: Writing material
Procedure: Observe the following steps in a transformer manufacturing site.
Step 1: Observe the cutting of core. Note that a three-phase transformer is used in a generating station, transmitting station, and distributing station of an electrical system.
Step 2: Observe the manufacturing of primary and secondary winding.
Step 3: Observe the formation of a conservator.
Step 4: Observe the assembling of coils into the core.
Step 5: Observe the coil connection in a star or delta configuration.
Step 6: Observe the fitting of high voltage and low voltage bushing on the main tank of the transformer.
Step 7: Observe the placing of the core assembly into the main tank of a three-phase transformer.
Step 8: Observe the testing of transformer.
3. Discuss the concept of a three-phase transformer. How it is different from a one-phase transformer?
Ans: In addition to single-phase connections, transformers can also be used to supply power to three or more phase connections. Transformers that can supply voltage to three or more phases are known as poly phase transformers. These transformers can be used to generate or supply power on a large scale, such as for industrial or commercial use. Compared to single phase transformer, a three phase transformer has many advantages. It provides a more economical approach by using less material. The three phases carry equal current and voltage. However, these three phases are 120 degree apart from each other. Three phase transformers require a total of six coils. Three coils are used in the primary side of the transformer, while the remaining three are used in the secondary side. All the six coils can be connected in either a star or a delta configuration.
4. Discuss the scenario of power source available in India.
Ans: Power Sources: India’s electricity sector is dominated by fossil fuel. For example, in 2017-18, coal produced about three fourth (¾th) of the electricity. There are several other sources used to produce power. For example, coal, oil and uranium fuels are used to convert water into steam to drive a turbine. The output shaft of the turbine is connected to an alternating current (AC) generator. The AC generator is rotated by the turbine, which converts mechanical energy into electrical energy.
5. What is the role of a generator in the electric power station?
Ans: The role of a generator is to convert mechanical energy into electrical energy. This generated energy is transmitted to consumers via transmission lines. The most efficient way to transmit energy is by increasing the voltage and reducing the current. This task is performed by the transformer.
6. List out the different parts of a transformer.
Ans: Low voltage bushing can be easily distinguished from high voltage bushing. Low voltage bushings are usually smaller in size compared to the high voltage bushing.
(i) Cooling Fins or Radiators: They help to dissipate the heat of a transformer, which is absorbed by oil insulation. They are placed on the outer body of a transformer.
(ii) Cooling Fans: They can be usually found attached to the cooling fins. Cooling fans help to raise the transformer capacity when the load increases to a larger value.
(iii) Conservator Tank: It is an oil preservation system in which the oil in the main tank is isolated from the atmosphere.
(iv) Drain Valve: It is usually found at the bottom of the transformer tank, depending on the manufacturer. It is used whenever oil replacement is necessary.
(v) Dehydrating breathers: They are used to prevent the transformer from being adversely affected by the moisture present in the air. It helps to maintain the insulation capability of the oil.
(vi) Oil Temperature or Pressure Gauges: They are used to monitor the internal characteristics of the transformer. These gauges help to check the level of temperature of winding and the pressure of oil inside the transformer.
(vii) Control Panel: It is the monitoring device of the transformer. It can be used to monitor pressure gauge, oil temperature and auto cooling fans.
7. Write short notes on:
(a) Load centre.
Ans: Panel boards are the power control unit in industry. Load centres used for residential application are typically rated at 225 amps or less and 240 volts maximum. A load centre consists of an enclosure, interior, and trim. Circuit breakers are mounted in the interior to provide circuit protection and control for light, heat, and power circuits.
(b) Switchgear.
Ans: An electrical network includes generation, transmission and distribution of electric power. While dealing with electrical circuit, equipment and load, it is important to monitor the control over the operation of the electrical system and its safety. In an electrical system, the unit which operates the routing of power cables, controls the equipment and safety of individuals, is known as a switchgear. Switchgear includes switches, which can be disconnected, fuses or circuit breakers. The basic function of a switchgear is to protect from faulty current, overload, surge and short circuit. Switchgears are responsible for the safety, reliability, and flexibility of an electrical system. For example, in a house, the domestic electric panel boards at the entrance of the service line act as switchgear, which has a fuse or miniature circuit breaker.
(c) Service entrance.
Ans: The service entrance is the point from where electric power enters a residential area. The service entrance in a residence is commonly thought of as a breaker or fuse box. In large commercial or industrial area electrical systems, the service entrance may be a main disconnect panel and thereby called the main panel. For industrial or commercial purpose, outdoor feeder busway is used. This involves routing the electrical power inside the premises of a commercial building or industry. This can be done using a transformer outside the premises of the industry or commercial building. For distribution of electrical power inside the building or campus, indoor feeder or plug-in busways are used.
(d) Busway.
Ans: Busway is the path or route through which power will be transferred from one section to another. Busway is the medium through which electrical signals can travel from one machine to another. There are two methods to route power into a building or distribute power throughout a building, through a conduit or a busway. The distribution system in a building consists of a combination of busway and conduit. Busway is a prefabricated electrical distribution. Busway consists of uncovered copper conductors supported on insulators. This system consists of busbars in a protective enclosure. Busbars are the electrical conductors that carry power. The bars are individually insulated and enclosed in houses.
(e) Circuit breaker.
Ans: Circuit breakers provide manual means of energising and de-energising a circuit. In addition, circuit breakers provide automatic overcurrent protection of a circuit. Residential circuit breakers are available with current ratings from 15–125 amps and a voltage rating of 220/440 volts. In residential applications, single-pole breakers protect 220 volt circuits; two-pole breakers protect 440 volt circuits.
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