Abstract: A method for interrupting current is provided wherein substantially all current is conveyed through a normal current carrying path in a circuit interrupter. A movable element is displaced for interruption of the current, and a balance is struck between the normal current carrying path and a parallel alternative or transient current carrying path. The transient current carrying path includes at least one variable or controllable resistance element. The transient current carrying path presents a substantially open circuit during normal operation. The variable resistance elements have a lower resistance during initial phases of circuit interruption, favoring transition of all current from the normal current carrying path to the transient path. Thereafter, the variable resistance elements increase in resistivity, producing additional back-EMF to drive the fault current to a zero level and to limit let-through energy.

Abstract: A technique is provided for enhancing performance of a circuit interrupter by deionizing arc plasma developed during an interruption event. A source material is disposed in a secondary current carrying path parallel to a primary current carrying path through the device. Upon movement of a movable contact in the primary current carrying path, current begins to flow through the source material, causing surface ablation of a material which deionizes arc plasma, resulting in greater voltage investment in the arc and more rapid extinction.

Abstract: An electrical circuit interrupter includes a primary or normal current carrying path and a transient or alternative current carrying path. The normal current carrying path is established by a movable spanner extending between stationary contacts during normal operation. The transient current carrying path includes at least one variable resistance element which transitions from a lower resistance to a higher resistance during interruption. The transient current carrying path forms an open circuit in parallel with the normal current carrying path during normal operation. Upon interruption, the transient current carrying path is favored for the fault current, completely interrupting the normal current carrying path. The variable resistance elements increase their resistivity during this phase of operation to aid in providing high levels of back-EMF for complete interruption of fault current through the device and limitation of let-through energy.

Abstract: A method for interrupting current is provided wherein substantially all current is conveyed through a first current carrying path in a circuit interrupter. A movable element is displaced for interruption of the current, and current is directed through both the first current carrying path and a second current carrying path in parallel with the first path The second current carrying path includes at least one variable or controllable resistance element. Both current carrying paths conduct current during interruption, with resistance of the paths driving the current to a null level. Current through the first current carrying path may be terminated prior to current through the second path. The variable resistance element draws current into the second current carrying path once an arc in the first path reaches a resistance sufficient to transition a portion of the current to both paths.

Abstract: A technique for reducing arc retrogression in a circuit interrupter includes providing a source material in a parallel current carrying path in the interrupter. The source material and parallel current carrying path support no current during normal operation. Upon interruption of a primary current carrying path, current flows through the source material, causing surface ablation of material which enhances the dielectric of the arc plasma, permitting more rapid entry of the arc into a dissipating structure such as a splitter plate stack. The source material transitions to a higher resistance level by heating to limit current flow during interruption.

Abstract: A technique is provided for forcing greater voltage investment in an arc developed during interruption of a current carrying path. A source element is provided in a secondary current carrying path parallel to a primary path through the device. Upon interruption of the primary current carrying path, an arc is forced to migrate towards a dissipating structure under the influence of an electromagnetic field. The source material then begins to carry current and undergoes surface ablation, releasing gas which is directed towards the migrating arc. The arc is thus caused to expand further, increasing voltage investment and resulting in more rapid extinction and reduction in let-through energy.

Abstract: An electrical circuit interrupter includes a primary or normal current carrying path and a transient or alternative current carrying path. The normal current carrying path is established by a movable spanner extending between stationary contacts during normal operation. The transient current carrying path includes at least one variable resistance element which transitions from a lower resistance to a higher resistance during interruption. The transient current carrying path forms an open circuit in parallel with the normal current carrying path during normal operation. Upon interruption, the transient current carrying path is favored for the fault current, completely interrupting the normal current carrying path. The variable resistance elements increase their resistivity during this phase of operation to aid in providing high levels of back-EMF for complete interruption of fault current through the device and limitation of let-through energy.

Abstract: A method for interrupting current is provided wherein substantially all current is conveyed through a normal current carrying path in a circuit interrupter. A movable element is displaced for interruption of the current, and a balance is struck between the normal current carrying path and a parallel alternative or transient current carrying path. The transient current carrying path includes at least one variable or controllable resistance element. The transient current carrying path presents a substantially open circuit during normal operation. The variable resistance elements have a lower resistance during initial phases of circuit interruption, favoring transition of all current from the normal current carrying path to the transient path. Thereafter, the variable resistance elements increase in resistivity, producing additional back-EMF to drive the fault current to a zero level and to limit let-through energy.

Abstract: In a plural phase overload relay, a pivot lever (12) is mounted to the ambient compensator deflector (9), and a second pivot lever (34) is mounted to both driver and follower slide bars (36 and 38) and driven thereby to engage and pivot the first lever on the ambient compensator deflector to trip a cut-out switch. The ambient compensator deflector adjusts both the three phase current trip threshold and the loss of phase current trip threshold, and also affords ambient compensator of each. A constant ratio relationship between these two thresholds is provided throughout the entire range of current trip threshold settings. The driver bar moves a first distance for three phase trip and a second shorter distance for loss of phase trip. The ratio of these distances is constant notwithstanding adjustment by the ambient compensator deflector changing the length of such distances.

Abstract: Improved response in an ambient temperature compensated thermal overload relay is obtained by providing a bimetal element (2) wherein the main bimetal section (4) is coupled through a reversed compensating bimetal section (6) to a heat sink mounting base (8) either directly or through a heat transfer control member (18) and placing the heater (10) that is energized by the overload current only adjacent the main bimetal section (4). With this arrangement, the main bimetal section (4) bends in the switch tripping direction and the compensating bimetal section (6) bends in the subtractive direction in response to temperature change therein to reduce the net deflection for ambient temperature compensation under normal operating conditions and gradual small overload conditions.

Abstract: A reduced-size thermal overload relay having a housing (2) that includes three narrow compartments (2k, 2l, 2m) in which are mounted three connector brackets (16,18,20) supporting three flat bimetal members (16j, 18j, 20j). Three narrow cassette heaters (6,8,10) are mounted at the upper part of the housing and held in by a snap-in hold-down device (12) that engages pairs of hooks (6b, 7b) at the lower portions of the heaters. A pushbutton (12a) on the hold-down device extends through a hole (3c) in the front wall of the housing for manual depression to release the heaters for removal. Each bracket (16) is H-shaped having legs (16c, 16d) for mounting it in a housing compartment (2k) and arms (16a, 16b) connected by a platform (16e) to which the upper terminal clip (6d) of the cassette heater is clamped with a screw (16q), the small angles of this platform and terminal clip automatically drawing the flat heater element (6c) into desired spacing with the bimetal member.

Abstract: A constant load and constant contact force snap-action switch having a normally-closed movable operate contact on a flipper blade which has a compression strip that snaps through an S-curvature to a reverse buckled state to trip the operate contact open. The flipper blade is coupled through an insulating cap to the leaf spring mounted movable alarm contact to close the latter at the same time. A return spring biased reset lever resets the operate contacts on depression down a first amount, opens the operate contact without closing the alarm contacts on depression down a second amount for stop purposes, and trips the operate contacts open on lifting upwards for test purposes. On reset, lost motion in the coupling cap knocks the alarm contact open if welded. A selector is settable to select any of three functions for the reset lever, (1) reset-stop-test, (2) auto reset stop, or (3) reset test.

Abstract: A pneumatic timer translating the external force of an electromagnetic relay or the like into rotational movement of a camshaft to actuate a set of switch contacts. The rotation of the camshaft is retarded in one direction by an adjustable pneumatic one-way time delay mechanism. The timer is capable of two modes of operation, on delay and off delay, according to choice of camshaft configuration and orientation.