Step-by-step explanation:
b)
Circuit breakers are electrical devices that automatically interrupt the flow of current in an electrical circuit when there is a fault or overload. They are classified into different types based on their voltage rating, current rating, and operational characteristics.
The most common types of circuit breakers are thermal, magnetic, and thermal-magnetic circuit breakers.
Thermal circuit breakers use a bimetallic strip that bends when heated by current flow. This trip mechanism disconnects the circuit when the current exceeds the rated value.
Magnetic circuit breakers use an electromagnet that trips the circuit when the current exceeds the rated value.
Thermal-magnetic circuit breakers combine both thermal and magnetic trip mechanisms to provide better protection against overloads and short circuits.
The operational use of circuit breakers is to protect electrical equipment and wiring from damage due to overloads, short circuits, and ground faults. They are used in residential, commercial, and industrial applications to prevent fires, electrical shocks, and other hazards.
The benefits of circuit breakers include improved safety, reduced damage to electrical equipment, and increased reliability of electrical systems. They are more reliable than fuses, easier to reset, and can be used multiple times. They also provide better protection against electrical hazards and can be integrated with other protective devices such as surge protectors and ground fault circuit interrupters (GFCIs).
c)
One technique of achieving arc interruption in medium voltage A.C. switchgear is by using a vacuum interrupter.
A vacuum interrupter is an electrical switch that uses a vacuum to extinguish the arc generated during the interruption of an electrical circuit. It consists of two metal contacts inside a vacuum chamber, with a mechanism to separate the contacts when the switch is opened.
When the switch is closed, the contacts touch and the current flows through the vacuum between them. When the switch is opened, the contacts are separated by a mechanism that creates a gap between them. The current continues to flow through the vacuum, but the voltage across the gap increases.
As the voltage across the gap increases, the electric field in the vacuum becomes strong enough to ionize the gas molecules, creating a plasma that conducts the current. The plasma rapidly cools and extinguishes the arc, allowing the current to be interrupted.
Vacuum interrupters have several advantages over other types of circuit breakers, such as air, oil, or gas. They are more reliable, require less maintenance, and have a longer lifespan. They also have a faster interruption time, which reduces the amount of damage caused by the arc. In addition, they are environmentally friendly, as they do not contain any hazardous substances.