Jäännösvirtalähde

Jäännösvirtalähde, often referred to as residual current device (RCD) or ground fault circuit interrupter (GFCI) in English, is an electrical safety device that automatically disconnects an electrical circuit when it detects an imbalance between the outgoing and incoming current. This imbalance indicates that an electrical current is flowing through an unintended path, such as a person or a faulty appliance.

The primary function of a jäännösvirtalähde is to protect individuals from electric shock. When a fault occurs, the device senses the difference in current between the live and neutral conductors. If this difference exceeds a predetermined threshold, typically 30 milliamperes (mA) for personal protection, the jäännösvirtalähde rapidly interrupts the power supply to the circuit. This rapid disconnection significantly reduces the risk of serious injury or fatality from electric shock.

Jäännösvirtalähteitä are commonly installed in residential, commercial, and industrial settings, particularly in areas where the risk of electric shock is higher, such as bathrooms, kitchens, outdoor outlets, and areas with damp conditions. They can be implemented as individual socket outlets or as circuit breakers that protect multiple outlets and lighting circuits. Regular testing of jäännösvirtalähteitä is recommended to ensure their continued proper operation.