How Current Differential Protection Detects Ground Faults💡#transformer #currenttransformer

Added: 2026-05-25

[00:00:00]One wire passes in through P1, while the other exits through P2. So, when current flows in only one direction, the secondary current flows out from the left side S1 terminal and returns through the right side S1 terminal. In this condition, no current passes through the current relay. However, when a ground fault occurs in the middle of the line, current flows inward from both sides. At this moment, the secondary currents of the two current transformers both flow out from their S1 terminals.

[00:00:28]The current relay detects this imbalance and immediately sends a signal to trip the circuit breakers on both sides of the line. This is the basic working principle of current differential protection.