Abstract: The present invention involves a power circuit breaker that conditionally and temporarily enables instantaneous trip protection. A position sensor senses whether the breaker contacts are open or closed. When the breaker contacts are open, the circuit breaker enables the instantaneous trip protection. After the circuit breaker contacts are closed, the circuit breaker continues to enable the instantaneous trip protector for a predetermined period of time. After this time delay, the circuit breaker disables the instantaneous trip protection and the circuit breaker reverts to providing its ordinary protection, such as long-time or short-time protection.

Abstract: A low voltage electrical power circuit breaker in which an actuator in the form of a pushrod controls the separation of arcing contacts by an actuating mechanism, a force-actuated mechanical latching assembly is interposed between the pushrod and the actuating mechanism. Under fault current conditions, the current-induced force tending to open the contacts exerts sufficient force on the latch assembly to unlatch it, thereby permitting the contacts to open freely on their own, without waiting for the operation of the actuating mechanism.

Abstract: A tripping coil for a circuit breaker, wherein the circuit breaker is designed to carry high load currents. The tripping coil includes a coil having a first winding and a second winding, a permanent magnet, a return spring, an armature and an actuator rod. The first winding and the permanent magnet produce a magnetic flux to urge and hold the armature into a biased position. The second winding produces a magnetic flux which urges the armature into an unbiased position. The return spring also exerts a force on the armature urging the armature into the unbiased position. The actuator rod is fixed to the armature, and interacts with the circuit breaker such that the circuit breaker is tripped when the armature moves into the unbiased position.

Abstract: A signal voltage level sensing circuit particularly well adapted for use in a static overcurrent trip device. An operational amplifier is utilized to sense the difference between a signal voltage and a predetermined reference voltage while another operational amplifier is the memory element. Minimum duration of input signal to which the memory element responds is established by a resistor and a capacitor in conjunction with the threshhold of the memory element.