Abstract: A shutter mechanism is provided for a motor control center of the type having a backwall with a stab opening for receiving a stab connector for making electrical contact with bus bars which are behind the panel. The shutter consists of two pieces, a stationary member which has a central opening and a vertical slit opening into the central opening and a movable member which has a guide thereon and is positioned between the motor control center and the stationary member with the guide extending through the slit and vertically movable therein. The stationary member is fastened to the motor control center with the central opening overlaying the stab opening. The movable member moves from a closed position to an open position and then from the open position to the closed position under the force of gravity alone without the use of springs.

Abstract: A multipole molded case circuit breaker has a single handle assembly contained in a first pole along with a movable contact arm assembly. A second pole has a movable contact arm assembly connected to the first contact arm assembly by a crossbar member so that the arms move in unison during normal operation. Each pole contains a tripping mechanism for tripping the breaker pole. The breaker mechanisms are connected for uniform tripping of all poles.

Abstract: A high-speed, high-current making switch is provided which has a driver which forms an air cylinder in the housing and which has movable contacts attached thereto. The driver moves the contacts to make and break the circuit. The force to move the driver is provided by pressurized air within the housing chamber which in response to the operation of a solenoid which operates a latch allows the contacts to make very rapidly. Upon operation of the solenoid, the latch is removed from abutting contact with the driver thereby allowing the driver to move in response to the air pressure and make the circuit.

Abstract: A method for producing a winding for large AC salient pole dynamoelectric machine comprising winding an array of conductors in edgewise fashion about a pole body and then securing the conductor ends such that the array forms a single layer edgewise wound conductor.

Abstract: A method and a device for monitoring instantaneous electrical parameters of a power distribution system under load utilizing digital control means. An analog signal equivalent to such a parameter is sensed and rated down for processing by solid state components. This signal is converted into a binary coded digital signal having n digits. A plurality of digital signals is sampled and squared values with a format of 2n digits are derived from each sample. The squared values of one sampling period are accumulated to a sum value composed of 2n+m digits and the square root comprising n+k digits of the sum is taken. This value is rescaled to a true root mean square value by performing k left shifts as an accurate measurement result. The core of such device is represented by a microcomputer with built-in analog-to-digital converter.

Abstract: A movable contact arm assembly is provided for a circuit breaker. The contact assembly includes a carrier which has first and second guide plates with aligned roller guides and bracket supports and a roller which has a middle portion extending between the guide plates and the end portions and engaging the roller guides. A bracket extends between the guide plates and engages the bracket supports. A spring is positioned between the bracket and roller which urges the roller along the roller guide. The contact arm has first and second cam surfaces and is positioned between the guide plates and pivotally connected thereto. The roller rides in the guide on the first and second cam surfaces and the roller moves from the first cam surface to the second cam surface as the contact arm moves from a closed position to an open position in response to preselected electromagnetic repulsion forces.

Abstract: A circuit breaker with blow open contacts is provided with a housing. Each pole of the circuit breaker has a reinforced molded housing. The walls of the housing are provided with reinforcing ribs to withstand the high pressures caused by gases generated by the arc during interruption of high short circuit currents.

Abstract: A blow open contact arm assembly is provided for a molded case circuit breaker. A ferromagnetic carrier is attached to the movable contact arm and is positioned thereabout for creating a magnetic field about the movable contact arm which attracts the contact arm to the open position during severe fault conditions. The molded case housing has reinforced walls to withstand the pressures exerted on the walls of the houses during a blow open operation of the contacts.

Abstract: A stator yoke is provided for a bulb generator or motor. The stator yoke includes a cylindrical wrapping plate with flanges connected to the ends of the wrapping plate. Yoke plates are connected to the core. Axial ribs extend through openings in the yoke plates and interconnect the wrapping plate, the yoke plates and the flanges. The flanges, yoke plate and axial ribs combine to increase the stiffness of the wrapping plate which increases the ability of the yoke to resist deformation caused by static and dynamic forces.

Abstract: A puffer-type compressed-gas circuit-interrupter is provided having a tubular stationary and at least two movable contacts which draw at least two arcs within at least two regions in the interrupter. The two regions are connected by a series of insulating flow guides, tubular contacts, and an insulating nozzle to a single fluid motor which during contact opening, after a predetermined portion of the opening travel of the interrupter, provides a blast of puffer gas extinguishing the arcs.

Abstract: An overload relay is provided which monitors current flow in a circuit and triggers an electromagnetic interrupter to open the circuit upon detection of an overcurrent condition. A train of pulses is generated and received by the electromagnetic interrupter for maintaining the circuit closed. The pulse train is terminated upon detection of an overcurrent condition.

Abstract: An improved gasket sealing motor leads which extend from the interior of an electric motor enclosure. The gasket is provided with one or more resilient, conical bushings whose diameters extend through a wide range of lead diameters. By severing the bushings at an appropriate point, round apertures are formed through which the leads can be pulled and sealed. The flat portion of the gasket which surrounds the bushings is secured to the motor enclosure in a conventional manner.

Abstract: An improved panel board construction is described, including an extruded insulative base pan which slidably engages at least one main-line bus bar and a neutral connector element and which has a plurality of electrical contact points. The base pan also prevents current flow through the base pan between any two of the contact points of the main-line bus bars. A protrusion extending from the base pan having a tortuously formed surface thereon prevents current flow through the base pan. The panel board is provided with interchangeable main-line lugs which may be used to directly contact the main-line bus bars or, alternatively, support a main-line circuit breaker between the lugs and the main-line bus bars. The base pan is symmetrically formed by an extrusion process so that it may be adaptable for use with a variety of panel board sizes simply by shearing the base pan to form the appropriate length.

Abstract: A front panel assembly for an electrical panelboard or the like. An interior trim panel is fastened within the enclosure proper, having holes through which circuit breakers may protrude and having upstanding edge flanges. A panelfront assembly includes a number of rotatable camming latches for engaging the edges of the flanges. The latches are secured in place with threaded screws extending through rabbets which are concealed by the door of the panelfront.

Abstract: A contactor having main and auxiliary contacts and an arc quenching system including a blowout coil. The blowout coil is connected in series with a first and second set of auxiliary contacts and the resulting series combination connected in shunt around the main contacts. The second set of auxiliary contacts is arranged to open after the first auxiliary closes and before the main contacts close in order to remove the blowout coil from the circuit when the main contacts are carrying load current.

Abstract: A system for controlling current flow to the actuating coil of a contactor or the like. A solid state switch is provided for gating current flow to the coil, and operated by an oscillator stage. A time delay causes the oscillator to operate at a high duty cycle when power is initially applied, allowing a relatively high current to flow to the contactor coil to operate the contacts. Subsequently the control causes the oscillator to operate at a low duty cycle, wherein the solid state switch passes a significantly lower current flow to the coil to maintain the contacts in position.

Abstract: A so-called blow-off type current limiting circuit breaker includes a stationary contact strap that is divided into three elongated closely spaced coplanar parallel arms that are connected to each other at one end of the strap. The stationary contact is mounted to the interior one of the parallel arms at the end thereof remote from the one end of the strap. A terminal portion of the strap connects exterior ones of the parallel arms to one another at the ends thereof remote from the one end of the strap. A movable contact engageable with and disengageable from the stationary contact is mounted to one end of a movable contact arm that is pivoted at its opposite end in the region of the one end of the strap, extending parallel to the arms of the strap and being aligned with the interior arm. Current in the interior arm flows in a direction opposite to the direction of current flow in the exterior arms and the movable contact arm.

Abstract: An operator is provided for a molded-case circuit breaker of the type in a motor controller where the circuit breaker is removably mounted on a pan brace which is held in place by a pan latch. The operator mounts on the breaker for opening and closing the breaker and for providing three interlocks. One interlock prevents withdrawal or insertion of the breaker with the operator handle in the "on" position. A second interlock prohibits closing or opening the control door except when the handle is off and a third interlock locks the operator handle in "off" position.

Abstract: A one-piece, slam-type latch for snap-in installation in an orifice of a door is provided for maintaining the door in a closed position relative to a door frame having an extending keeper means. The latch includes a first portion having a generally rectangular configuration, and a second portion extending normally outward from the first portion for insertion through the orifice. One end of the second portion is in integral attachment with one side of the first portion. The other end of the second portion is provided with at least one indentation for interlocking engagement with the keeper means. A leaf spring is integrally attached to the second portion and extends angularly from the second portion toward the first portion. The latch is further provided with a third portion in integral engagement with the first and second portions. The third portion extends planarly outward from the first portion.

Abstract: A so-called blow-off type current limiting circuit breaker is constructed with a contact pressure spring that also holds the contact arm in open contact position when the contacts are blown open by electrodynamic forces. A multi-section cam means transmits contact opening and closing forces produced by a spring powered overcenter toggle type operating mechanism to the movable contact arm. A follower on the latter is biased into engagement with the cam means by the contact pressure spring. The cam means is so constructed that during contact blow-off the movable contact arm requires relatively little motion to move overcenter in the opening direction. One section of the cam means is constructed so that when the contact arm moves overcenter in the opening direction during contact blowoff, speed of the contact arm is controlled to an extent that contact rebound does not become a problem.