jäännösvirta

Jäännösvirta, also known as residual current, is the difference between the current flowing into an electrical circuit and the current flowing out of it. In a normal, healthy circuit, these two currents should be equal. The difference arises when current flows through an unintended path, such as through a person touching a faulty appliance or through a damaged cable.

This difference in current is precisely what residual current devices (RCDs), also known as Ground Fault Circuit Interrupters (GFCIs) in some regions, detect. When an RCD senses a jäännösvirta above a certain threshold, it quickly interrupts the electrical supply, preventing potentially dangerous electric shock or fire. The sensitivity of RCDs is typically set to detect very small residual currents, often in the range of tens of milliamperes, which are sufficient to cause harm.

Jäännösvirta is a critical concept in electrical safety. Its presence indicates a fault condition that needs to be addressed. Monitoring and reacting to jäännösvirta through protective devices like RCDs are essential for ensuring the safety of individuals and property in environments where electricity is used. This protective measure is standard in many modern electrical installations, particularly in areas where the risk of electric shock is higher, such as bathrooms and kitchens.