The current transformer sensors are of toroidal type mounted one per
phase on the primary studs of the circuit breaker. These transformers provide
a signal to the static-trip device proportional to the primary current.The static logic box receives the signal from the primary current transformer.
It monitors the signal, senses overloads or faults, and executes the required
action in accordance with preselected settings. The tripping actuator receives
the output signal from the static logic box and in turn causes the circuit
breaker contacts to open.