Class 12 Electronics Chapter 6 Installation of a Switchboard 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 6 Installation of a Switchboard Question Answer and select need one. Class 12 Electronics Chapter 6 Installation of a Switchboard Notes Download PDF. AHSEC Class 12 Elective Electronics Question Answer English Medium.
Class 12 Electronics Chapter 6 Installation of a Switchboard
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 a Switchboard
Chapter: 6
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A. Multiple choice questions:
1. Which of the following is not a type of switchboard?
(a) SB1.
(b) SB2.
(c) SB3.
(d) SB4.
Ans: (d) SB4.
2. Which of the following is a type of switchboard?
(a) SB1.
(b) SB2.
(c) SB3.
(d) All of the above.
Ans: (d) All of the above.
3. In which switchboard is a service section is deeper than the distribution section?
(a) SB1.
(b) SB2.
(c) SB3.
(d) SB2 and SB3.
Ans: (a) SB1.
4. Which of the following components are used in switchboards?
(a) Frame.
(b) Overcurrent protective devices.
(c) Buses.
(d) All of the above.
Ans: (d) All of the above.
5. The most commonly used switchboard size is ___________.
(a) 90 inches high and 38 inches wide.
(b) 100 inches high and 40 inches wide.
(c) 150 inches high and 50 inches wide.
(d) 60 inches high and 45 inches wide.
Ans: (a) 90 inches high and 38 inches wide.
6. Handle extension is used with ___________.
(a) busbar.
(b) busway.
(c) MCB trip.
(d) switchgear.
Ans: (c) MCB trip.
7. Which of the following switchboard is front and rear aligned?
(a) SB1.
(b) SB2.
(c) SB2.
(d) All of the above.
Ans: (b) SB2.
B. Fill in the blanks:
1. Switchboards are generally accessible from the ___________________ as well as the _________________.
Ans: Front, rear.
2. A typical switchboard frame is _________________ high and _________________ wide.
Ans: 90 inches, 38 inches.
3. Horizontal buses are used to distribute power to each _________________ section.
Ans: Switch board.
4. Vertical buses are used to distribute power via overcurrent devices to the _________________.
Ans: Load devices.
5. A bus duct entrance can be used when _________________ is used instead of cables.
Ans: Metal bus.
C. State whether the following statements are True or False:
1. A handle extension allows more leverage to be applied to the circuit breaker handle.
Ans: True.
2. SB1 switchboards are designed to be used in an application where space is a consideration.
Ans: True.
3. SB2 switchboards may be mounted against a wall.
Ans: False.
4. SB3 switchboards are front and rear aligned.
Ans: False.
5. A switchboard is a large single panel, frame, or assembly of panels.
Ans: True.
6. Splice plates are used to join the horizontal busbars and switchboard sections.
Ans: True.
D. Short answer questions:
1. What is a switchboard?
Ans: A switchboard is a large single panel, frame, or assembly of panels.
2. How is a switchboard different from a panel board and load centre?
Ans: Switchboard: A switchboard is a large assembly that distributes electrical power to several circuits. It contains busbars, protective devices, switches, and instruments.
Used for handling high current and installed in industrial/commercial buildings.
Panel Board: A panel board is a small distribution board that divides the main supply into subsidiary circuits. Contains protective devices (fuses/circuit breakers) and is mounted flush or on the surface. Commonly used in residential and small commercial applications.
Load Centre: A load centre is similar to a panel board but is specifically designed for residential/light commercial use. It has limited capacity and provides easy access for branch circuits. Offers protection and distribution in low-voltage systems.
3. Explain in brief the construction of a switchboard.
Ans: There are several components that make up a switchboard. They consist of a frame, overcurrent protective devices, buses, instrumentation and outer covers. Switchboards are generally accessible from the front as well as the rear. A typical switchboard frame is 90 inches high and 38 inches wide. Horizontal buses are used to distribute power to each switchboard section. Vertical buses are used to distribute power via overcurrent devices to the downstream circuits. Splice plates are used to join the horizontal busbars and switchboard sections.
4. What is the specification that has to be kept in mind while feeding the cable into the switchboard?
Ans: Cables may be brought to the top of the switchboard through a conduit:
(a) If the cable has a large diameter and requires more room, extra space of 10” to 30” height can be added.
(b) A bus duct entrance can be used when a metal bus is used instead of cables.
5. Define SB1, SB2 and SB3 type of switchboard
Ans: There is a variety of switchboards and the selection is determined by factors, such as space, load and environment. SB1, SB2 and SB3 switchboards can be found in industrial plants, hospitals and commercial buildings.
(a) SB1 switchboards are designed to be used in an application where space is a consideration. SB1 switchboards are rear aligned and are accessible from the front. The service section can be deeper than the distribution section. By aligning the rear, the switchboard can be installed against a wall.
(b) SB2 switchboards have standard rear alignment. Both front and rear alignment options are available. SB2 switchboards are front accessible and front connected. SB2 switchboards may be mounted against a wall.
(c) SB3 switchboards are front and rear aligned. SB3 switchboards are designed for special configurations, such as incoming and outgoing busway connections. The switchboard is designed as a service entrance switchboard. When the main service disconnects, the distribution devices are contained in a single unit.
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