Which type of relay is primarily used for detecting faults in electrical systems?

The choice of an overcurrent relay as the primary tool for detecting faults in electrical systems is based on its functionality and design. Overcurrent relays are specifically designed to monitor the current flowing through a circuit and quickly trip a circuit breaker if the current exceeds a predetermined threshold. This characteristic is crucial in protecting against various fault conditions, such as short circuits or overloads, which can lead to equipment damage or safety hazards.

When a fault occurs, it typically results in a significant increase in current flow. The overcurrent relay can sense this increase and react promptly, thereby isolating the affected section of the circuit and preventing further damage. The speed and reliability of this operation make overcurrent relays a staple in protective schemes across various electrical systems.

Distance relays, while also used in fault detection, are primarily effective for specific applications, such as line protection in transmission systems where they measure the impedance to detect faults. Directional relays help determine the direction of fault current but are often used in conjunction with other devices to provide a comprehensive protection strategy. Voltage relays primarily monitor voltage levels and are not focused on current flow, making them less suitable for directly identifying fault conditions that lead to critical disturbances in current.

In summary, overcurrent relays are