Commutating circuit breaker
A commutating circuit breaker that progressively inserts increasing resistance into a circuit via physical motion of a shuttle that is linked into the circuit by at least one set of sliding electrical contacts on the shuttle that connect the power through the moving shuttle to a sequence of different resistive paths with increasing resistance; the motion of the shuttle can be either linear or rotary. At no point are the sliding stator electrodes separated from the matching stationary stator electrodes so as to generate a powerful arc, which minimizes damage to the sliding stator electrodes. Instead, the current is commutated from one resistive path to the next with small enough changes in resistance at each step that arcing is suppressed. The variable resistance can either be within the moving shuttle, or the shuttle can comprise a commutating shuttle that moves the current over a series of stationary resistors.
1. A commutating circuit breaker for use in an electrical circuit that defines an electrical path wherein current flows through the commutating circuit breaker when it is in an on state, the commutating circuit breaker comprising:
a stator having one or more stator electrodes;
a shuttle having one or more shuttle electrodes, the shuttle movable with respect to the stator and configured such that during such motion the shuttle electrodes slide against the stator electrodes;
wherein at least one of the stator and shuttle has an increasing resistivity along its length, with a higher graded resistivity on at least a trailing edge that comprises a portion of one electrode that last touches another electrode when the shuttle moves relative to the stator; and
a launching system arranged to move the shuttle relative to the stator between an on state position where the commutating circuit breaker presents a relatively low electrical resistance in the electrical circuit, and an open position where the commutating circuit breaker presents a very high electrical resistance in the electrical circuit;
wherein as the shuttle moves between the on state position and the open position, the current flowing through the commutating circuit breaker is shunted into paths of increasing resistance.
2. The commutating circuit breaker of claim 1 wherein at least some of the shuttle and stator electrodes are substantially surrounded by insulating material such that there are no gaps between the shuttle electrodes and the stator electrodes as the shuttle moves relative to the stator.
3. The commutating circuit breaker of claim 2 wherein all of the shuttle and stator electrodes are substantially surrounded by insulating solids.
4. The commutating circuit breaker of claim 1 further comprising a pressurized electrically insulating fluid surrounding the shuttle.
5. The commutating circuit breaker of claim 1 wherein power passes onto the shuttle through a first series of stator electrodes that define a series of paths with increasing resistance as the shuttle moves, to a shuttle electrode that is on the outside surface of the shuttle, through an insulated path to a second shuttle electrode on a different portion of the shuttle, but surrounded by insulation at the surface of the shuttle, and then off the shuttle from said second shuttle electrode to a second series of stator electrodes that connect the power through a series of paths with increasing resistance as the shuttle moves.
6. The commutating circuit breaker of claim 1 wherein the breaker is arranged in a parallel power circuit with a fast commutating switch that is used to perform a first commutation of the current to the breaker at an initial resistance level that is able to control the inrush of current in a dead short.
7. The commutating circuit breaker of claim 1 wherein the shuttle comprises a plurality of stages which are electrically coupled in series and mechanically move together as a rigid body.
8. The commutating circuit breaker of claim 1 wherein the stator further comprises a low friction high dielectric strength material that creates force against the shuttle by an elastic member.
9. The commutating circuit breaker of claim 1 further comprising a shuttle latching mechanism that comprises piezoelectric actuators that relieve force on an interface of high modulus materials to achieve very rapid actuation of the onset of movement of the shuttle.
10. The commutating circuit breaker of claim 1 further comprising correlated magnetic domains on the shuttle and the stator that are constructed and arranged to hold the shuttle in position relative to the stator.
11. The commutating circuit breaker of claim 1 wherein the shuttle moves in a linear fashion with power coming onto the shuttle through one connection, then off the shuttle through a shuttle electrode that connects with a series of stator electrodes that connect the power through a series of paths with increasing resistance as the shuttle moves.
12. The commutating circuit breaker of claim 11 wherein the shuttle is generally cylindrical with a longitudinal axis, and there are a plurality of commutation zones along the longitudinal axis of the shuttle.
13. The commutating circuit breaker of claim 1 wherein the shuttle moves in a circular rotary fashion, with power coming onto the shuttle through a first electrical connection, then off the shuttle through a second electrical connection that is electrically connected to said first electrical connection, but surrounded by insulation at the surface of the shuttle, and which connects with a series of stator electrodes as the shuttle rotates.
14. The commutating circuit breaker of claim 13 wherein the shuttle moves in a circular arc of less than 180 degrees, and commutates the power through a plurality of series-connected sequences of resistors.
15. The commutating circuit breaker of claim 1 in which at least some of the shuttle and stator electrodes comprise molybdenum on their surface.
16. The commutating circuit breaker of claim 15 in which at least some of the molybdenum-surface electrodes touch against porous metal electrodes derived from sintered particles of copper, nickel, silver, chromium, or tungsten that contain liquid metal in the pores between the sintered particles such that the liquid metal wets out the facing molybdenum electrode.
17. The commutating circuit breaker of claim 1 wherein the graded resistivity is accomplished with a plurality of adjacent layers of increasing resistivity.
18. The commutating circuit breaker of claim 17 comprising at least 12 layers, each with different resistivity.
19. The commutating circuit breaker of claim 1 wherein the graded resistivity is accomplished at least in part with a transition plug that defines a graded resistivity and is adjacent to and behind a shuttle electrode as the shuttle electrode is moved between the on state position and the open position.