Protection relay: what it is, ANSI functions and types

Thus, they have the function of performing shutdowns in one or more output circuits when they detect undesired conditions, ensuring the safety of the electrical system.

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What are protection relays used for?

Protection relays perform measurements of electrical quantities (such as voltage, current, power factor, among others) and compare these measurements with programmed reference values.

When any value exceeds the pre-established limits, the protection relay acts, turning off the protection devices (such as circuit breakers) and interrupting the electrical circuit.

In this way, these devices are used to protect the electrical system against a series of disturbances and faults, such as:

Therefore, they play a fundamental role in preventing damage to electrical equipment, in the safety of workers and in maintaining the continuity of the electrical power supply.

What are the types of protection relays?

There are different types of protection relays, which can be classified based on their characteristics and functions.

Thermal relays

They are devices used for the protection of power transformers and electric motors.

Thus, they monitor the temperature of the equipment and act to prevent overheating, turning off the circuit when they detect abnormal temperature conditions.

Phase protection relays

These relays detect voltage drops in one or more phases of the electrical system and trigger the protection device (such as a medium voltage or high voltage circuit breaker) to interrupt the circuit and prevent damage to electrical equipment.

Timer relays

They are widely used in industrial processes, such as motor starters, industrial ovens and control panels.

Thus, they have a timing function, allowing programmed delays to turn on or off electrical devices at specific times.

Medium voltage protection relays

These relays are specifically designed for protection in medium voltage systems.

So, they detect faults and dangerous conditions in the system and issue commands to open the circuit breakers, interrupting the power supply and preventing damage to the equipment.

Besides these, there are overcurrent protection relays, overvoltage relays, directional relays, phase loss relays, among others, each with its specific characteristics and functions.

What are the protection relays used in primary substations?

There are different types of relays that can be used in primary substations, depending on the specific needs and requirements of the electrical system.

In this way, the choice of specific relays will depend on the characteristics of the electrical system, the protection needs and the applicable standards.

So, it is important to consult electrical engineering experts and follow the relevant recommendations and technical requirements when selecting relays for a primary substation.

Are you looking for relays for primary substations?

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