Which type of relays use in HT side?

Answer 1

On the HT side (High Tension side), where voltage levels are typically above 11kV, protective relays are used to ensure the safety and reliability of the power system. Common relay types include:

Overcurrent Relays (OCR)

Protect against excessive current due to faults or overloads.

Differential Relays

Used for transformer and generator protection by detecting differences between input and output currents.

Distance Relays

Measure impedance between the fault point and relay location; widely used in transmission line protection.

Earth Fault Relays (EFR)

Detect ground faults to prevent equipment damage and hazards.

Under/Over Voltage Relays

Protect equipment from voltage fluctuations beyond safe limits.

Directional Relays

Identify the direction of power flow or fault current, especially in interconnected systems.

These relays are critical for high voltage substations, transmission lines, and industrial power systems to minimize downtime and equipment damage.

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Answer 2

In the high-tension (HT) side of electrical systems, electromagnetic relays, such as air-insulated and oil-insulated relays, are commonly used for protection and control. Additionally, microprocessor-based relays are increasingly utilized for their advanced functionality, including fault detection and communication capabilities. These relays help ensure system reliability and safety by monitoring various parameters and isolating faults.