What is the primary role of protective relays in a 3-phase system?

Protective relays are essential components in a 3-phase electrical system, serving primarily to disconnect circuits during abnormal conditions. Their main role is to provide protection against faults or disturbances that could potentially damage equipment or jeopardize the safety of the system. When a fault occurs, such as a short circuit or an overload, the protective relay detects these abnormal conditions by continuously monitoring electrical parameters like current and voltage.

Upon detection of an anomaly, the protective relay activates, signaling protective devices (like circuit breakers) to open the circuit. This action effectively isolates the faulty section of the system, thereby preventing further damage, ensuring the safety of personnel, and maintaining system reliability. Thus, the proper function of protective relays is crucial for the overall stability and efficiency of 3-phase electrical systems.