Static-trip devices are completely static; that is, there are no moving parts.
These devices use semiconductor-integrated circuits, capacitors, transformers,
and other electric components. Static-trip devices operate to open the circuit
breaker when the current–time relationship exceeds a preselected value.
The energy required to trip the breaker is obtained from the circuit being
protected. No external power, such as DC batteries, is required. The complete
static-trip system is comprised of (1) primary circuit current transformers,
(2) the static logic box, and (3) the tripping actuator (a magnetically held
latch device).