differentialskydd

Differentialskydd is a type of protection relay used in electrical power systems, particularly in substations and power plants. Its primary function is to detect and isolate faults that occur within a specific protected zone, typically a transformer, generator, or busbar. The principle of operation relies on comparing the current flowing into the protected zone with the current flowing out of it.

Under normal operating conditions, the incoming current and the outgoing current in a healthy circuit are equal in magnitude and phase. A differential relay measures this difference. If a fault occurs within the protected zone, such as a short circuit to ground or between phases, the outgoing current will be less than the incoming current. This imbalance creates a differential current that is detected by the relay.

When the differential current exceeds a predetermined threshold, the relay operates, sending a trip signal to the circuit breakers associated with the protected zone. This action quickly disconnects the faulty equipment from the rest of the power system, preventing further damage and minimizing the impact on the electrical grid. Differential protection is highly selective and sensitive, as it only responds to faults within its defined zone, thereby avoiding unnecessary tripping. This makes it a crucial component for ensuring the reliability and safety of electrical infrastructure.