Abstract: An improved system for sensing current flow in a single phase or polyphase circuit to be protected and deriving a single signal representing composite current flow. A ramp-like reference signal is applied to one input of a comparator at sampling intervals, and the outputs of a plurality of current amplifiers coupled to the other comparator input so that the duration of a change in signal output level of the comparator is an inverse function of composite current. An accumulator stage stores portions of incoming current signals less a predetermined fraction of previous accumulator contents. In the event of circuit interruption the accumulator is decremented in a manner which reflects the inferred thermal history of the system.

Abstract: An improved anti-rebound mechanism for circuit breakers having a blow-off, current-limiting feature is provided. The improvement consists of a ferromagnetic latch which is activated by any massive current surge through the circuit breaker sufficient to cause blow-off current interruption. The latch is caused to be magnetically attracted to, and engage with, a notch on a movable arm of a circuit breaker to maintain the arm in an open position until the circuit breaker is manually reset in a closed position.

Abstract: A circuit interrupter of the type including an arc chute and separable contacts between which an arc may be drawn is provided with flash plates. The plates are disposed at either side of the region in which an arc forms and serve to protect the adjacent interrupter housing, while assisting in channeling the arc into the arc chute. The flash plates are formed of a ceramic material and are provided with a plurality of grooves running the direction generally transverse to the direction of the arc.

Abstract: A watthour meter socket assembly of the type which engages the blades of a watthour meter. The blades are frictionally held by pairs of spring-loaded conductive jaws, which form the female contacts of the socket assembly. Helper springs are provided to increase the biasing of the jaws. In order to provide a conductive bypass when the meter is removed for servicing or replacement a reciprocable, conductive blade is mounted on a slide mechanism so that it can be wedged between the jaws. The wedging action simultaneously spreads the jaws apart, allowing removal of the meter.

Abstract: An easily visible condition indicating device to signify a lack of pressure within the envelope of an electrical interrupter of the type utilizing a pressurized-gas environment. The system includes a rotatable drum contained within a housing having an aperture through which the drum is viewed. When pressure within the interrupter drops a spring-biased bellows collapses, causing the withdrawal of stops which hold the drum in place against spring tension. This allows a biasing spring to rotate the drum so that a different portion thereof, such as a different colored segment, is viewed through the housing aperture in order to provide a visual indication of a low-pressure condition.

Abstract: Means for causing the properly-polarized one of a pair of series-connected DC contactors to open before the other, depending upon the direction of load current flow. Load current is caused to link the magnetic circuit constituted by a contactor coil, frame and armature; with current flowing in a first direction, the linking has an additive effect, strengthening the MMF in the magnetic circuit. When current flows in the opposite direction, the MMF is weakened which allows the contactor to open more quickly.

Abstract: A gear motor assembly is disposed in a support structure in such a manner that it may rotate in a plane perpendicular to the output shaft thereof. Stops are provided for preventing the shaft from turning past a predetermined point. The motor assembly is located in the support structure by a resilient leaf spring which deflects when the stops are engaged.

Abstract: A direct acting undervoltage release device utilizes stored spring energy to trip a circuit breaker when the control voltage reduces to a critical level (the "undervoltage"). The device includes a solenoid that senses the undervoltage, and a charging motor that automatically resets the device after a tripping operation (provided the control voltage recovers to its normal level). The direct acting feature is achieved by providing a chargable trip spring and a trip pin in the circuit breaker which directly drives the latch bar of the breaker to trip the breaker.

Abstract: A tap changer voltage regulator permits a tap changer selector contact to engage an open circuited new tap without arcing and has a half-tap voltage auxiliary winding which permits halving the inter-tap voltage to thus double the number of steps, and an auxiliary switch with a pair of movable contacts. A first auxiliary contact initially connects a selector contact which has moved to a new tap through a circulating current limiting resistor to a load, preventing load current interruption. A second auxiliary contact is in series with a normally-closed switch through which load current and circulating current flow. A first set of inverse parallel SCR's is in series with the resistor, while the normally-closed switch is shunted by a second pair of inverse parallel thyristors. The first pair of thyristors is not gated until the first auxiliary contact has attained its new position, precluding initial arcing.

Abstract: A rotor having cast squirrel cage windings is provided with a number of spacers for interrupting or spacing the stacked rotor laminations, thus forming vents for cooling. The spacers surround the rotor bars, and have a projection at each side thereof for fitting into the adjacent laminations. The design of the spacers allows them to be narrower than those previously known, thus enhancing air flow through the rotor.

Abstract: A permanent magnet rotor configuration which produces four magnetic poles utilizing two sets of symmetrically-disposed permanent magnets. The slots carrying the magnets exhibit a truncated V-shaped configuration, extending from points on the periphery of the rotor to meet the ends of a straight, central portion which lies parallel to a tangent to the rotor shaft. A short magnetic bridge interrupts the center of each slot, the slots being disposed generally symmetrically upon opposite sides of the rotor shaft.

Abstract: A permanent magnet rotor configuration which produces two magnetic poles. Two pairs of axial slots are provided in which permanent magnets are arranged about the rotor shaft. A third, diametrically opposed pair of slots is provided which extend radially outwardly and in which permanent magnets are disposed. Off-axis magnetic bridges are formed on either side of the third slots, separating them from the first and second sets of slots.

Abstract: The rotor assembly comprises a shaft, a rim structure, and a spider for connecting the rotor rim to the shaft. The spider structure incorporates a number of rigid arms which are secured to and extend radially from the shaft. The ends of the rigid arms are secured such that free radial motion of the rotor rim is permitted with respect to the spider, but angular motion between the rotor rim and the spider is prevented. The rotor assembly further contains a plurality of flexible cross beams and associated floating arms. The cross beams extend between adjacent spider arms, while the floating arms are firmly connected between the middle section of the cross beams and the inner surface of the rotor rim. The cross beams flex in and out in radial directions as the rotor rim contracts and expands, respectively, due to centrifugal or thermal forces.

Abstract: An improved limited-travel linkage for "cracking" a gas blast valve in a circuit breaker. A projection from a portion of the circuit breaker linkage travels along an arc in interfering relationship with a spring-loaded latch on a crank. Movement in one direction engages the latch, turning the crank and cracking the valve. Arc quenching gas then flows through a conduit to the interrupter contacts to blow out the arc drawn between them.

Abstract: Bearing adaptable for use in dynamoelectric machine for preventing current from flowing through the bearing itself. A three-part layer including a base material, a ceramic layer, and an adhesion layer is applied sequentially upon the bearing shell. The last layer is then covered with a bearing material, ordinarily babbitt so that the babbitt, is electrically isolated from the bearing shell.

Abstract: An air disconnect switch incorporates a unique arrangement of an ice breaking self-polishing current transfer horn arrangement which transfers the current to a puffer-type interrupter to effect circuit interruption prior to the disconnect switch being fully opened; the puffer-type interrupter is a dielectric insulated device which has its operating mechanism disposed within the dielectric insulating medium so that the system has no fast-moving external parts and provides a direct drive with minimum maintenance of the mechanism parts. The porcelain tube serves both as the interrupter housing and as the mechanism housing.

Abstract: A tap changer voltage regulator permits a tap changer switch selector contact to engage an open-circuited new tap without arcing and has a half-tap voltage auxiliary winding which permits halving the inter-tap voltage and doubling the number of steps, and also has an auxiliary switch system. An auxiliary static switch circuit initially connects a first tap selector in series with a circulating current limiting resistor and a load to prevent load circuit interruption. An auxiliary selector switch initially coupled to a second tap selector and is in series with a normally-closed switch through which the load current and circulative current flow. The normally-closed switch is shunted by a second static switch circuit. The first static switch is not gated until the first tap selector has attained its new position, precluding initial arcing.

Abstract: A shielding arrangement for preventing the buildup of ice on the contacts of an outdoor high-voltage switch structure. The shield includes one or more flexible members which overlie the contacts and are in the path of the travel of a switch element.

Abstract: A vertical electric motor embodying the invention has a housing including a cylindrical frame enclosing a stator, a rotor and a shaft affixed to the rotor and mounted for rotation about a vertical axis, upper and lower end frames, a heat generating thrust bearing supported on the top end frame and rotatably supporting shaft and rotor, and a lubricant-receiving reservoir within the motor enclosure above the top end frame and enclosing the thrust bearing. Liquid lubricant within the reservoir is in heat absorbing and lubricating relation with the thrust bearing. A plurality of finned heat transfer heat pipes are supported within the reservoir with their evaporator end submerged in the lubricant and their condenser end exposed to air within the motor housing above the top surface of the lubricant and enhance heat transfer from the lubricant to the atmosphere.

Abstract: Arc suppressing gas in a high voltage circuit breaker system is collected, filtered and compressed. The compressed gas is passed through a series of oil and desiccant filters and returned to a high pressure vessel for storage. The oil and desiccant filtering system is combined in a single, separable casing including baffles and a check valve.