Dual trip circuit for circuit breaker
AssigneeSiemens Energy & Automation, Inc.
InventorsDavid A. Leone, William A. King
Life of this patent
Estimating the term…
Abstract
A trip circuit for tripping a circuit breaker has a first coil having a relatively large number of turns and therefore a relatively slow reaction time and a second coil having a relatively small number of turns and therefore a relatively fast reaction time. The first coil is responsive to a relatively low current level through a circuit breaker for tripping the circuit breaker at the rated tripping current. The second coil is responsive to a higher current through the circuit breaker for tripping the circuit breaker with great rapidity in case the higher level is reached before the first coil has an opportunity to react.
Claims16
A circuit breaker trip circuit comprising:
- first trip means for tripping a circuit breaker within a first reaction time upon detection of a first current level being carried by the circuit breaker;
- and
- second trip means for tripping the circuit breaker within a second reaction time which is quicker than the first reaction time, upon detection of a second current level being carried by the circuit breaker, wherein the second current level is greater than the first current level and wherein said first trip means has a first conductive coil, having a first inductance, for carrying a first coil actuation current upon detection of the first current level;
- and
- said second trip means has a second conductive coil having a second inductance less than the first inductance, for carrying a second coil actuation current upon detection of the second current level;
- and wherein both the first and second conductive coils form electromagnets within an electromagnetic solenoid.
A circuit breaker trip circuit comprising:
- an electromagnetic solenoid having:
- an actuator movable between a first position which maintains a circuit breaker in a closed, current-carrying status and a second position which opens the circuit breaker;
- a permanent magnet forming a magnetic field having an orientation which biases the actuator into the first position;
- and
- first and second conductive coils, having first and second inductances, respectively, with the second inductance being less than the first inductance, the coils being oriented with respect to the permanent magnet such that carrying of a respective coil actuation current in either of said coils alters the magnetic field of the permanent magnet, so that the actuator moves to its second position;
- a current transformer for sensing current being carried by a circuit breaker;
- first trip means, coupled to the current transformer and including the first conductive coil, for tripping the circuit breaker within a first reaction time upon detection of a first current level being carried by the circuit breaker by energizing the first conductive coil with coil actuation current;
- and
- second trip means, coupled to the current transformer and including the second conductive coil, for tripping the circuit breaker within a second reaction time which is quicker than the first reaction time, upon detection of a second current level being carried by the circuit breaker, wherein the second current level is greater than the first current level, by energizing the second conductive coil with coil actuation current.
Dependencies are inferred from the claim text.