Circuit breaker including two magnetic coils and a positive temperature coefficient resistivity element

• Main Authors: LARSON; BRETT E, CHEN; WILLIAM W
• Format: Patent
• Language: English
• Published: 01.02.2000
• Edition: 7
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SWITCHES; ELECTRICITY; EMERGENCY PROTECTIVE DEVICES; RELAYS; SELECTORS

A circuit breaker for interrupting the flow of electric current in a line includes a switch connected in series with the line, the switch having an open position and a closed position. At least one positive temperature coefficient resistivity element (PTC element) is connected in series with the line. A first magnetic coil is positioned around a yoke, for example, an iron core, and connected in parallel with the PTC element and a second magnetic coil is positioned around the yoke and connected in series with the line and the switch. A voltage limiting device, such as a metal oxide varistor, is connected in parallel with the at least one PTC element. An armature is pivotally mounted in relation to the yoke wherein the yoke and the armature form a magnetic circuit with the first magnetic coil and the second magnetic coil. A trip lever is connected to the armature and the switch, the trip lever effecting movement of the switch from a closed position to an open position wherein the flow of electric current in the line is interrupted. When the first magnetic coil or the second magnetic coil reaches a predetermined current value, the armature is pulled to trip by the magnetic circuit wherein the trip lever is pulled to a tripped position to effect the movement of the switch to an open position wherein the flow of electric current in the line is interrupted.