RESIDUAL CURRENT RELAY (RCD RELAYS)
A residual current relay (RCD) is an electrical safety device designed to detect and respond to leakage currents in an electrical system. It monitors the difference between the current flowing in the live and neutral conductors. If this difference, known as residual current, exceeds a predetermined threshold, it indicates a leakage, potentially due to an insulation fault or an accidental contact. The RCD relay then triggers a protective mechanism, such as tripping a circuit breaker, to cut off the power supply, thereby preventing electric shocks and reducing the risk of fire. RCD Relays are crucial for enhancing electrical safety in residential, commercial, and industrial settings. You can buy Schneider Electric residual current relay from our eShop.
Working Principle of Residual Current Relay (RCDs)
The working principle of a residual current relay (RCD) is based on detecting the imbalance in the current between the live (phase) and neutral conductors of an electrical circuit. Here’s a detailed explanation of its operation:
1. Current Monitoring: The RCD continuously monitors the current flowing through the live and neutral conductors. In a healthy circuit, the current entering the live conductor should be equal to the current returning through the neutral conductor.
2. Detection of Residual Current: A differential current transformer (also known as a core balance transformer) is used to detect any imbalance. The live and neutral conductors pass through the core of this transformer. Under normal conditions, the magnetic fields generated by the currents in the live and neutral wires cancel each other out, resulting in zero net magnetic flux.