Protective relays are electrical devices used to monitor and protect electrical circuits against faults and anomalies.
Thus, they have the function of shutting down one or more output circuits when they detect unwanted conditions, ensuring the safety of the electrical system.
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What are protection relays 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 a 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 failures, such as:
- voltage drops;
- system overload;
- overvoltages;
- undervoltages;
- short circuit;
- lack of phase;
- phase inversion;
- between others.
Therefore, they play a fundamental role in preventing damage to electrical equipment, ensuring worker safety and maintaining the continuity of the electricity 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.
Discover some of them right now.
Thermal relays
These are devices used to protect transformers of power 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 or high voltage circuit breaker) to break the circuit and prevent damage to electrical equipment.
Timing relays
They are widely used in industrial processes, such as motor starters, industrial furnaces and control panels.
Thus, they have a timing function, allowing programmed delays to turn electrical devices on or off at specific times.
Medium voltage protection relays
These relays are specifically designed for protection in medium voltage systems.
They then 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.
In addition to these, there are overcurrent protection relays, overvoltage relays, directional relays, phase failure relays, among others, each with its own specific characteristics and functions.
What protection relays are used in primary cabinets?
There are different types of relays that can be used in primary cabins, depending on the specific needs and requirements of the electrical system.
Therefore, the choice of specific relays will depend on the characteristics of the electrical system, protection needs and applicable standards.
Therefore, it is important to consult electrical engineering experts and follow relevant technical recommendations and requirements when selecting relays for a primary cabinet.
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