Which device is commonly used to detect ground faults in electrical circuits, providing rapid disconnection if a fault occurs?

Which device is commonly used to detect ground faults in electrical circuits, providing rapid disconnection if a fault occurs?

• A. Ground fault relay or residual-current device.
• B. Isolation transformer.
• C. Voltage regulator.
• D. Rupture disk.

Answer: (A)

Detecting leakage current to earth and disconnecting the circuit quickly is the job of a ground fault protection device. A ground fault relay, or residual-current device (RCD), monitors live and neutral currents and looks for any imbalance. If current leaks to ground—through a person or a faulty path—the return current is not equal to the supply current, and the device trips in milliseconds to cut power. This rapid disconnection greatly reduces electric shock risk and potential equipment damage. The other devices don’t perform this function. An isolation transformer provides galvanic separation but doesn't detect faults or automatically disconnect the circuit. A voltage regulator maintains steady voltage but again doesn’t detect leakage. A rupture disk is used for overpressure relief in piping systems, not for electrical fault protection.

Detecting leakage current to earth and disconnecting the circuit quickly is the job of a ground fault protection device. A ground fault relay, or residual-current device (RCD), monitors live and neutral currents and looks for any imbalance. If current leaks to ground—through a person or a faulty path—the return current is not equal to the supply current, and the device trips in milliseconds to cut power. This rapid disconnection greatly reduces electric shock risk and potential equipment damage.

The other devices don’t perform this function. An isolation transformer provides galvanic separation but doesn't detect faults or automatically disconnect the circuit. A voltage regulator maintains steady voltage but again doesn’t detect leakage. A rupture disk is used for overpressure relief in piping systems, not for electrical fault protection.