North American Philips Corporation

Philips Electronics North America Corporation

Gregory T DiVincenzo

Wen-Jian Gu

Stephen L Wong

Howard B Pein

Paulo P Caldeira

Keith A Singer

John C Lucas

Paulo Caldiera

Richard M Collevechio

Stefan Gabrielson

Digital processing of current signals allows close matching of arbitrary time delay curves for a circuit breaker. An analog signal proportional to the current is sampled and digitized. Digital samples, with or without further processing, are used to select increment values from a look-up table for accumulation in a counter. The counter is decremented periodically to simulate cooling of the circuit being protected. The values in the look-up table are determined according to the desired time delay curve. Processing of the digital samples may include squaring samples, accumulating the squared values to form a subtotal which is compared with an instantaneous trip threshold, accumulating the subtotals for a time period equal to half a cycle of AC line voltage, taking the square root of the accumulated subtotals, and using that square root as the address for looking up the increment value.

Electronic processing unit, and circuit breaker including such a unit

Current in a line is measured by passing it through a coil, having at least one turn, linking a small high permeability core; passing a measuring current through a bucking winding around the same core; and controlling the measuring current to buck the magnetomotive force of the line current so that the core flux stays below the saturation level. The measuring current may flow through a precision resistor so that a voltage across the resistor is an accurate measure of the line current. The measuring current is obtained from a high frequency switching circuit which senses the change of flux in the core. In normal operation the circuit switches when the core flux has risen to a predetermined value, such as 60% or 80% of the saturation value. If drift or extreme transients cause the flux to reach the saturation level, a sensing and correction circuit re-establishes operation between the desired points.

Isolated current sensor for DC to high frequency applications

A circuit breaker having an arc chute adjacent the arc path between a fixed and a movable contact. To aid in extinguishing the arc under short circuit conditions, an arc suppressor element is fixed on a movable surface adjacent the movable contact; and preferably on the arm itself facing the fixed contact and arc chute. The arc suppressor is made from a thermoplastic material such as nylon 6/6 which has high temperature resistance and high dissipation factor, and absorbs a relatively large amount of water. During interruption of a high current arc, heat shock liberates gases and water vapor from the suppressor material to neutralize arc ions and blow the arc toward the chute.

DC-rated circuit breaker with arc suppressor

Tripping of the poles of a multi-pole breaker requires less force from current sensing actuators, through use of a lost motion linkage including a trip link which unlatches the linkage holding one pole contact set closed before operating the inter-pole tripping elements. Preferably the breaker has a fast forcing arrangement for forcing a movable contact open under short-circuit conditions, faster than the normal contact opening spring can respond. The lost motion linkage is provided by a trip link which first releases a secondary latch to permit contact opening at normal speed, and then operates an inter-pole tripping element. Under short-circuit conditions the trip link engages the movable contact to force it open, between unlatching and engagement of the inter-pole tripping element.

Trip link latch and interpole link for a circuit breaker

Rapid extinguishing of the arc in a circuit breaker is accelerated by a booster loop which extends parallel to an arc runner, but carries current in a direction opposite to the direction of current flow in the arc runner. The booster loop and arc runner are formed from a single piece of rigid conductor material, preferably stamped to form mounting lugs and bent over into a U-shaped configuration. In a preferred embodiment, the breaker internal connections are arranged such that current flows through a thermal overload sensor when the contacts are closed, but transfers to the booster loop and arc runner after arc current termination transfers from one of the contacts to the arc runner, thus reducing short circuit current duration through the thermal sensor.

Magnetic blow-out circuit breaker with booster loop/arc runner

Adjustment of the static position of the armature of a solenoid or relay-type structure is used to adjust the trip level. An armature stop rod extends through an opening in the structure and is bent over to adjust the length of the stop rod between the frams opening an the active part of the armature. A compact structure is achieved by winding the device coil on a plastic bobbin which provides a bearing for the armature at one end, and an extension through which the adjustment portion of the stop rod extends. This permits ready adjustment after assembly, even when the device spring is arranged around the armature inside the bobbin.

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Easton, MD, United States of America

Gregory T DiVincenzo