Function of distance relay

A distance relay is a type of protection relay most often used for transmission line protection. Distance relays measure the impedance from the installation side to the fault location and operates in response to changes in the ratio of measured current and voltage.

1. What is the purpose of distance relay?
2. What are the advantages of distance relay?
3. What is the distance of relay?
4. Which relay is used as a distance relay?
5. What is the working principle of relay?
6. Why do we need distance protection?
7. What is the difference between distance relay and impedance relay?
8. What is the basic principle of distance protection?
9. What is the difference between distance relay and differential relay?
10. What is the disadvantage of distance relay?
11. What is a phase distance relay?
12. What is the purpose of relay in aircraft?
13. What is the reason of relay?
14. What is the purpose of a relay physics?
15. What is the purpose of relay in automotive?
16. What is difference between relay and switch?
17. What is the difference between a fuse and a relay?
18. What happens if a relay fails?

What is the purpose of distance relay?

Distance relays are generally used for phase-fault primary and back-up protection on subtransmission lines, and on transmission lines where high-speed automatic reclosing is not necessary to maintain stability and where the short time delay for end-zone faults can be tolerated.

What are the advantages of distance relay?

The relay gets operated when the ratio of voltage and current is set to a predetermined value or less than the relay. This type of relay is used for backup protection, fault protection, phase protection, and main protection of transmission and distribution lines.

What is the distance of relay?

Distance relays are the protecting equipment that functions based on the distance of the fault point on the transmission line. The distance is calculated from the generating unit. Based on the distance, the impedance is calculated by evaluating the fault voltage and fault current.

Which relay is used as a distance relay?

A mho relay is a voltage-controlled directional relay. These relays are used for long-distance transmission line. MHO relays are least affected by the voltage surges.

What is the working principle of relay?

It works on the principle of electromagnetism. The electromagnetic field that creates the temporary magnetic field is energised when the relay's circuit detects the fault current. This magnetic field moves the relay armature to open or close connections.

Why do we need distance protection?

Distance protection schemes are commonly employed for providing the primary or main protection and backup protection for AC transmission line and distribution line against three-phase faults, phase-to-phase faults, and phase-to-ground faults.

What is the difference between distance relay and impedance relay?

As the ratio of voltage to current is nothing but impedance so a distance relay is also known as impedance relay. The operation of such relay depends upon the predetermined value of voltage to current ratio. This ratio is nothing but impedance.

What is the basic principle of distance protection?

The basic principle of distance protection involves the division of the voltage at the relaying point by the measured current. The apparent impedance so calculated is compared with the reach point impedance.

What is the difference between distance relay and differential relay?

Distance Protection is for Transmission Lines and works on the principle of calculating the impedance up to the point of fault. It needs both Voltage Input & Current Input. Differential Protection operates on the principle of calculating the difference between two currents inputted to the relay.

What is the disadvantage of distance relay?

One of the main disadvantages of a distance relays is the limited fault resistance measurement capability. There are currently more than 20 relay types applied as transmission line protection on the ESKOM's transmission network with the most common types of characteristic being mho and polygonal characteristics.

What is a phase distance relay?

The phase distance relays provide directional control of the phase overcurrent relays and also allow for increased relay loadability on the lines. Directional ground overcurrent relays are applied for ground fault protection.

What is the purpose of relay in aircraft?

Airborne radio relay is a technique employing aircraft fitted with radio relay stations for the purpose of increasing the range, flexibility, or physical security of communications systems. The aircraft may be manned or unmanned aerial vehicles.

What is the reason of relay?

Relays can reduce the need for high-amperage wiring and switches, which are expensive and take up space. Therefore, switching to relays in your electronic systems can reduce the size or weight of a casing, for instance, or allow manufacturers to fit more functionality into a space of the same size.

What is the purpose of a relay physics?

Relays are used to protect the electrical system and to minimize the damage to the equipment connected in the system due to over currents/voltages. The relay is used for the purpose of protection of the equipment connected with it.

What is the purpose of relay in automotive?

Relays are used throughout the vehicle's electrical systems, allowing low-current switches to control higher-current components. Think of all the small-gauge wiring circuits found throughout a modern vehicle, and then consider the high-current loads that these circuits control.

What is difference between relay and switch?

You are correct that a relay is basically just a switch, but it's a switch operated via remote control, so to speak. A regular switch controls electrical current by connecting or breaking the path of either the positive side of a circuit (most common) or the negative side of a circuit.

What is the difference between a fuse and a relay?

If too much current flows through the circuit, the fuse will blow -- interrupting the circuit and halting the flow of electricity, protecting the components further down the circuit. Relays are remote switches that open or close an electrical circuit.

What happens if a relay fails?

If the relay fails it will cut off power to fuel pump and ignition system, which will result in a no power, and therefore no start condition. You may find that turning the key may power on the accessories, and may even crank the engine.