How the residual current transformer works

A residual current transformer is a device used to detect earth faults in power systems. Its working principle is based on the principle of current transformer.
In power systems, when a ground fault occurs, current flows through the ground path back to the ground. Residual current transformers are installed at the neutral point of the power system or in the earth current loop. It works by sensing the residual current caused by a ground fault and converting it into a low current signal proportional to the fault current.
The core component of a residual current transformer is an iron core coil. When the current through the coil changes, a magnetic field is created in the coil. This magnetic field induces an electromotive force in the coil, producing an output signal proportional to the residual current.
The output signals can be monitored and analyzed by connecting to measuring instruments or protective devices. Typically, the output signal of a residual current transformer is amplified, filtered and processed to better identify and locate ground faults.
The residual current transformer senses the residual current caused by the ground fault and converts it into a measurable low current signal, thereby realizing the monitoring and protection of the ground fault in the power system. This equipment plays an important role in improving the safety and reliability of power systems.