Class 12 Electronics Chapter 4 Installation of Residential Control Panel 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 4 Installation of Residential Control Panel Question Answer and select need one. Class 12 Electronics Chapter 4 Installation of Residential Control Panel Notes Download PDF. AHSEC Class 12 Elective Electronics Question Answer English Medium.
Class 12 Electronics Chapter 4 Installation of Residential Control Panel
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.
Installation of Residential Control Panel
Chapter: 4
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A. Multiple choice questions:
1. A label does not contain which of the following information?
(a) Load centre’s catalog number.
(b) Current rating.
(c) Voltage rating.
(d) Number of circuit breakers.
Ans: (d) Number of circuit breakers.
2. Which of the following meters is used to measure the amount of power consumed by the loads in a house?
(a) Energy meter.
(b) Ammeter.
(c) Voltmeter.
(d) Multimeter.
Ans: (a) Energy meter.
3. Neutral can be grounded at _________________.
(a) Service entrance.
(b) Downstream equipment.
(c) Upstream equipment.
(d) Anywhere in the premises.
Ans: (a) Service entrance.
4. Which of the following components is not involved in the interior of a load centre?
(a) Busbars.
(b) Neutral bars.
(c) Circuit breakers.
(d) Light arrester.
Ans: (d) Light arrester.
5. A load centre is also called _________________ unit.
(a) Control.
(b) Processing.
(c) Logical.
(d) Panel.
Ans: (a) Control.
6. Which of the following is the reason for heating effect in a wire?
(a) Due to high voltage.
(b) Due to high power.
(c) Due to thick conductor.
(d) Due to high current.
Ans: (d) Due to high current.
7. Which of the following are load centre rating methods?
(a) Full rating.
(b) Series rating.
(c) Full and series rating.
(d) Parallel rating.
Ans: (c) Full and series rating.
8. Which of the following material is used to manufacture enclosure of load centre?
(a) Iron.
(b) Copper.
(c) Wood.
(d) Galvanised steel.
Ans: (d) Galvanised steel.
9. Which of the following methods are not used for distribution of electric power?
(a) Residential distribution.
(b) Commercial distribution.
(c) Industrial distribution.
(d) Household distribution.
Ans: (d) Household distribution.
10. Which of the following places can be earthed?
(a) Domestic level.
(b) Power distribution level.
(c) Substation.
(d) High tension line.
Ans: (c) Substation.
B. Fill in the blanks:
1. A _________________ system distributes electrical power throughout a building.
Ans: Power distribution.
2. Load centres are covered by _________________.
Ans: Trim assembly.
3. The two types of load centres are main ______________ and main _________________ only.
Ans: Breaker, lug.
4. Main lug only load centres are sometimes referred to as _________________ or _________________ panels.
Ans: Secondary or downstream panel.
5. The _________________ rating method is to select circuit protection devices with individual ratings equal to or greater than the available fault current.
Ans: Series.
6. The enclosure of the outer box is made up of _________________.
Ans: Galvanised steel.
7. Holes on an enclosure are known as _________________.
Ans: Knockouts.
8. In earthing, coal and salt increases the _________________ of soil.
Ans: Moisture.
9. The interior of an enclosure is covered by _________________ assembly.
Ans: Trim.
10. High current rating of a circuit breaker is known as _________________.
Ans: Amperage.
C. State whether the following statements are True or False:
1. Load centre as a single unit placed in a cabinet or enclosure can be mounted on the wall.
Ans: True.
2. Current flow in a conductor always generates heat.
Ans: True.
3. The trim assembly is the back portion of the load centre that covers the interior.
Ans: False.
4. When overload occurs circuit breaker breaks the circuit.
Ans: True.
5. Excessive current in a circuit is prevented by the use of overcurrent safety devices.
Ans: True.
6. Earthing protects us from getting electric shock.
Ans: False.
7. In overload conditions, circuits draw less current.
Ans: False.
8. Neutral buses are present in a main busbar.
Ans: True.
9. Enclosures protect the box from external damage.
Ans: False.
D. Short answer questions:
1. What is a load centre?
Ans: In an electrical system, ‘load’ means ‘appliance, machinery, equipment, which consume electric power’ and centre means ‘the point from where an activity or process is directed’. Therefore, load centre is the point from where an activity or process of electrical appliance can be controlled. Load centre is the control unit.
The electric power distribution network, installed in our houses, is an example of residential power distribution system. Electric power from a substation enters the house through a metering device called energy meter. The incoming power then goes to a residential control panel or load centre. This load centre provides circuit control and overcurrent protection. From there, power is distributed to various rooms of the house through branch circuits.
2. What are the types of load centre?
Ans: Load centres are divided into two, main breaker load centre and main lug load centre, on the basis of circuit breaker use in the load centre.
3. Explain the construction of a load centre.
Ans: A load centre can be a single panel or a group of panels that can be assembled to form a single panel. A load centre includes a busbar, circuit protection devices, equipped switches for the control of light, fan, machinery, power circuit, etc. A load centre as single unit in a cabinet or enclosure can be mounted on the wall and can be accessible only from the front.
Some of the major components of a load centre are enclosure, interior and trim.
An enclosure is an outer box, constructed of galvanised steel. It houses the other components and is designed to provide component and personnel protection. The box has hole for cable and conduit connection. These holes are called knockouts.
The interior consists of several components, including busbars, neutral bars and circuit breakers. The busbar serves as a common connection for two or more circuits. The electrical current returns to the load centre through the neutral circuit wire.
Circuit breakers can be a weak link because at the time of over current it breaks the path and hence protects the circuit from damage.
The trim assembly is the front portion of the load centre that covers the interior. The trim includes a door and an adjustable upper pan.
4. How does the rating of a load centre affect the electrical distribution?
Ans: Load Centre Ratings: When selecting load centres and overcurrent protection devices, it is extremely important to know both the maximum continuous amperes and available fault current. There are two ways to meet this requirement, by full rating, and series rating.
Full rating: In this method, all the circuit breakers including the main and branch circuit breakers must have a rating equal to or greater than the available fault current. For example, in case of a building using the full rating method, it will have every circuit protection device rating at, at least, 22,000 amperes.
Series rating: In this method, main and branch circuit breakers of different ratings can be connected in series. The main circuit breaker will limit the fault current and protect the branch circuit breaker. Series rating reduces the cost as compared to the full rating method.
5. Explain the concept of service entrance grounding.
Ans: Service Entrance Grounding: The neutral is grounded only at the service entrance, never at any downstream equipment., the neutral is grounded by connecting neutral to a grounding electrode. The enclosure is also connected to the ground through the grounding electrode connector.
6. Write down the difference between earthing and grounding.
Ans:
| Earthing | Grounding |
| Earthing is more commonly used in Britain, European and most of the Commonwealth countries’ standards (IEC, IS). | Grounding is the word used in North American standards (NEC, IEEE, ANSI, and UL) |
| Earthing means connecting the metallic part of a machine that does not carry current under normal conditions to the earth. | Grounding means connecting the live part, means the part which carries current under normal conditions to the earth. Grounding refers to the current carrying part of the system, such as neutral of the transformer or generator. |
| It is done for the protection of electrical equipment and to provide a least resistive path from the equipment to the earth. | It is done for the protection of power system equipment and to provide an effective return path from the machine to the power source. |
| For example, electrical equipment frames, enclosures, supports, etc. | For example, grounding of neutral point of a star connected transformer. |
| It is done at the domestic level. | It is done at the power distribution level. |
| Earthing is to ensure safety or protection of electrical equipment and humans by discharging electrical energy to the earth. | Because of lighting, line surges or unintentional contact with other high voltage lines, dangerously high voltages can develop in the electrical distribution system wires. Grounding provides a safe, alternate path around the electrical system of your house, thus, minimising damage from such occurrences. |
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