What is the main function of protective devices in a power system?

To isolate faults and affected components to ensure safety.

Fill in the blank: The percentage probability of a Single Line to Ground Fault in a power system is ______.

85%

True or False: The 2012 blackout in India affected only a small portion of the population.

False. The blackout affected over 620 million people, about 9% of the world population.

Riddle: I can sense a fault and trigger a breaker, but I'm not an operator. What am I?

A protective relay

Which of the following is NOT a cause of power system failure? A) Transformer breakdown B) Bird contact C) Lightning D) Overcurrent protection

D) Overcurrent protection

Fill in the blank: The protective system's reliability is often measured by the formula % Reliability = (_______).

(No. of correct trippings X 100) / (No. of desired trippings + No. of incorrect trips)

What is the role of backup protection in a power system?

To act when primary protection fails, ensuring the fault is cleared.

True or False: Ground-fault neutralizers are used to enhance the mechanical strength of electrical equipment.

False. Ground-fault neutralizers are designed to limit the magnitude of short-circuit currents.

Riddle: I protect against high currents and ensure safety, but I'm not a fuse. What am I?

An overcurrent relay

What principle does differential protection rely on?

Kirchhoff's Current Law, comparing incoming and outgoing currents.

Fill in the blank: The time multiplier setting (TMS) for an inverse time relay is defined as T = ______.

Required time of operation / Time obtained from the relay characteristics

Which type of relay is sensitive to phase angles and is used for directional protection?

Mho relay

True or False: The breaker failure relay operates when the primary circuit breaker fails to trip.

True.

Riddle: I'm the speed of response in circuits, measured in milliseconds, what am I?

Operating time of a relay

Which type of protection scheme is specifically designed for long overhead lines?

Carrier-current protection

Fill in the blank: A distance relay operates based on the ______ of the transmission line.

Impedance

What is the primary purpose of circuit breakers in an electrical grid?

To switch lines during normal operation and disconnect power in case of overloads or short circuits.

True or False: SF₆ is a highly flammable gas used in circuit breakers.

False. SF₆ is non-flammable and used for insulation and arc interruption.

Riddle: I’m a characteristic of a relay, designed to avoid unnecessary trips, what am I?

Sensitivity

Which component in a circuit breaker is responsible for interrupting fault currents?

The tripping relay

Fill in the blank: The device that detects abnormal operating conditions and isolates faulty sections is called ______.

Protective relay

Which type of relay operates when the current exceeds a predetermined value? A) Distance Relay B) Over Current Relay C) Differential Relay D) Voltage Relay

B) Over Current Relay

True or False: Backup protection is unnecessary if primary protection is functioning correctly.

False. Backup protection is essential in case the primary protection fails to act, preventing potential disasters.