What is Relay in Power System? Why it is necessary? How it works? #electrology explained

Summary

Protective relays play a crucial role in ensuring the safety and reliability of power systems by swiftly detecting faults and disconnecting faulty components. While fuses serve in low voltage circuits, relays, in combination with circuit breakers, protect both low and high voltage systems. By continuously monitoring key electrical quantities such as current, voltage, frequency, and phase, relays detect faults and activate circuit breakers to isolate the affected sections. Their rapid response prevents service interruptions and minimizes system damage. These unsung heroes ensure the smooth operation of power systems, safeguarding equipment and allowing normal system function to continue.

Takeaways

• 😀 Protective relays play a crucial role in Power Systems, detecting faults and isolating defective components.
• 😀 These relays are essential for minimizing service interruptions and preventing further system damage.
• 😀 Fuses can automatically detect and interrupt faults but are limited to low-voltage circuits, unlike relays and circuit breakers.
• 😀 Relays continuously measure electrical quantities like voltage, current, frequency, and phase angle to detect faults.
• 😀 Upon detecting a fault, a protective relay activates the circuit breaker to disconnect the faulty section from the system.
• 😀 The protective relay circuit has three main sections: the primary winding of a current transformer, the relay coil, and the tripping circuit.
• 😀 When a fault occurs, the current flowing through the system increases, activating the relay and triggering the breaker to open.
• 😀 The relay ensures that only the faulty section is isolated, allowing the rest of the system to continue operating normally.
• 😀 Protective relays help prevent damage to circuit equipment by acting quickly during faults, ensuring the overall safety of the system.
• 😀 The importance of protective relays is often overlooked, but they are vital for the safe and efficient operation of power systems.
• 😀 The next time you use electricity, remember the protective measures in place, including relays, that work quietly behind the scenes.

Q & A

What is the role of protective relays in a power system?

Protective relays detect faults in the power system and initiate the operation of circuit breakers to isolate the faulty element from the rest of the system, ensuring minimal damage and preventing service interruptions.

Why is it important to quickly detect and disconnect faulty parts in a power system?

Quick detection and disconnection prevent unnecessary service interruptions and minimize the damage to the system, ensuring that the fault does not spread further into the system.

How do protective relays differ from fuses in protecting power systems?

Fuses are limited to low-voltage circuits and automatically perform both detection and interruption functions. In contrast, relays work in conjunction with circuit breakers to protect both low and high voltage circuits, detecting faults and sending signals to initiate disconnection.

What electrical quantities do relays measure to detect faults?

Relays continuously measure voltage, current, frequency, and phase angle, and any significant changes in these quantities indicate the presence and type of fault in the system.

What happens when a fault occurs in a power system?

When a fault occurs, the current increases dramatically, triggering the relay to close its contacts. This activates the trip circuit of the circuit breaker, opening the breaker and isolating the faulty section of the system.

What is the role of the current transformer in the protective relay system?

The current transformer detects the current in the line intended for protection. The primary winding is connected in series with the line, and the secondary winding is connected to the relay to detect faults.

How does the protective relay circuit work in case of a short circuit?

In the event of a short circuit, the current flowing through the line increases drastically. This causes a heavy current flow through the relay coil, which activates the relay, closes its contacts, and triggers the circuit breaker to disconnect the faulty part of the system.

What types of power supplies are used in the tripping circuit of the relay?

The tripping circuit can operate on either AC or DC power sources. It includes the power supply, the trip coil of the circuit breaker, and the stationary contacts of the relay.

Why are protective relays considered the 'unsung heroes' of power systems?

Protective relays are vital for the safe and smooth operation of power systems, yet they operate quietly in the background, ensuring protection without much recognition from the public.

What is the significance of the relay in ensuring the continued operation of the healthy parts of the system?

The relay isolates the faulty portion of the system while allowing the unaffected parts to continue operating normally, preventing widespread damage to the entire system.