Abstract: A so-called blow-off type current limiting circuit breaker is provided with an elongated movable contact arm that is pivotally mounted at one end thereof on a pin that projects from opposite sides of a support. The contact arm is constructed of parallel sections that are biased toward one another, by spring means disposed remote from the support, with the support being resiliently clamped between the sections to provide a good electrical connection between the support and contact arm. The pivot pin extends through aligned enlarged pivot apertures in the parallel sections to facilitate weld breaking. A wall of each pivot aperture is disposed to cooperate with the pivot pin to achieve a camming action that moves the contact arm slightly lengthwise after initial butting engagement of the circuit breaker main contacts to wipe the engaged contacts with respect to one another.

Abstract: A warning feature for a high voltage controller or the like. A lamp is mounted on the controller cabinet, and connected to an interlock circuit so as to be illuminated whenever line voltage is being supplied to a contactor assembly, regardless of the open or closed status of the contactor itself.

Abstract: A high voltage isolator switch of the double end break type including a central, rotatable insulator carrying a switch blade and a pair of opposed insulators bearing contact assemblies for engaging the ends of the blade. The contact assemblies include pivoted saddles mounted on cantilevered studs and detents to hold the assemblies in an open position.

Abstract: An improved switch head for engaging and making electrical contact between first and second stationary electrical conductors. The switch head comprises lower and upper insulating head sections, biasing means and a contact slug contained within the lower insulating head section for contacting and making electrical connection with the first and second stationary conductors, and clamping means for holding the lower and upper insulating head sections together. The clamping means places the lower and upper insulating head sections in compression when the switch head engages the first and second stationary conductors. The clamping means also applies a force to the lower head section to disengage the switch head from the first and second stationary conductors.

Abstract: A circuit breaker having an automatically adjusting magnetic armature is provided. The magnetic armature includes a spring-biasing means to automatically maintain one end of the armature in the contact with the electromagnet and the other end away from an adjacent electromagnet. The magnetic armature includes a pair of slightly curved arms which are disposed about a pivot guide post. When current through the circuit breaker exceeds a predetermined amount, the end of the armature normally biased away from the adjacent electromagnet is suddenly attracted to the electromagnet. The force from the spring-biasing means is overcome, and the slightly curved arms of the armature pivot about the pivot guide post so that the armature contacts the adjacent electromagnet. A latch holder at the end of the armature becomes disengaged from a latch means to cause the circuit breaker to open.

Abstract: A contactor of the high-voltage type utilizing an arc chute and aligned magnetic pole pieces for urging an arc into the chute for quenching. A pair of rigid bus bars extend upon either side of the arc chute assembly, and are projected along the edges of the pole piece to supplement the arc displacement capability of the pole pieces, particularly at higher current values.

Abstract: A motor control center of the high voltage type which includes a set of three vertically-disposed cubicles. The two lower cubicles house a pair of contactor assemblies, the lowermost contactor assembly being longer than the upper one. The cubicle enclosing the upper contactor is provided with a partition behind which is a compartment containing vertical bus bars. The lowermost cubicle extends beneath this compartment so that the bus bars drop directly down to engage a set of connectors which are also engaged by the lowermost contactor assembly.

Abstract: A current-limiting electrical apparatus is provided including a housing with first and second electrical terminals contained therein. A pair of electrical contacts is disposed within the housing and electrically connected in series with the first and second terminals. A biasing means applies a biasing force to the pair of electrical contacts to bias them to a closed position. The pair of electrical contacts is configured to cause the contacts to electromagnetically repel each other and to overcome the biasing force and open when the current flowing through the contacts exceeds a predetermined value. A mechanism is provided responsive to the current flowing through the pair of electrical contacts for decreasing the biasing force as the current flowing in the electrical contacts approaches the predetermined value, to thereby decrease the predetermined value causing the electrical contacts to immediately open.

Abstract: An inexpensive power supply for an electconic control system or the like which is capable of converting a wide range of applied AC voltages into a regulated output voltage. A thyristor is coupled in series with an input terminal and a threshold device, such as a Zener diode, placed across the input terminals and paralleled by an RC circuit coupled to the thyrisor gate. Another capacitor is coupled to the thyristor cathode. A ramp-like voltage impressed on the thyristor gate effects triggering at a phase angle which varies in accordance with output voltage. The electronic control system outputs a uniform train of pulses which serve to disable a circuit interrupter. Termination or disruption of the pulse train causes the interrupter to open the protected circuit.

Abstract: An improved drawout carriage assembly for the contactor of a high voltage controller. The controller carriage is fabricated from a pair of sheet metal sides, interconnected at their lower edge by formed sheet metal cross members. The upper portions of the sides are comprised of planar sheets of insulating material. A series of insulative cross members are bolted between the opposed faces of the carriage side pieces and locate elements of the contactor mechanism.

Abstract: An improved method of joining insulated conductors and providing a water-tight seal. The area about the joined conductors is filled with a putty-like insulation filler material and an O-ring placed on the conductor insulation, some distance from the joint. The joint, including the O-ring, is overtaped with resin-rich insulation tape and the tape is surrounded by a shrinkable polyester film. Heat is applied to partially cure the insulation tape, and to cause the polyester film to contract tightly about the joint.

Abstract: An electric distribution panel is constructed with an insulating base formed by extrusion. Also extruded with the base are two rows of circuit breaker mounting ledges, hook formations for each of the mounting ledges to mechanically secure circuit breakers at the load ends thereof, and channel defining formations to slidably receive neutral bars disposed outboard of each of the mounting ledges. A tie bar extends transverse to the neutral bars and provides an electrical connection therebetween. Wiring guide elements are slidably received by appropriate formations of the base and in particular the base is provided with elongated apertures to receive annular embossments of one of the wiring guides elements so as to permit expansion of the base without buckling thereof even though the mounting surface for the distribution device does not expand at the same rate as the base.

Abstract: A lever-type handle for operating a racking mechanism and providing an interlock for a cabinet enclosing electrical equipment. The handle is comprised of two sections which are linked together by a throughbolt. A cover assembly retaining and enclosing a portion of the handle is provided with an opening oriented so that the bolt is only accessible when the handle is in an "on," or energized, position. By removing the through bolt the handle sections are disengaged so that one portion can be moved to a non-locking position and access gained to the cabinet interior.

Abstract: Aromatic aminosulphonic acids which have a reduced content of discoloring by-products are obtained when aromatic amines are reacted with a sulphonating agent in a reaction medium at least some of which consists of tetramethylene sulphone.

Abstract: A cabinet enclosing high voltage electrical apparatus is formed of a deformable, alignable framework made of structural steel or the like, and comprises at least one compartment for receiving a contactor carriage assembly. A rigid subchassis is separately constructed and mounted within each cubicle. The subchassis forms a high-integrity structure which supports and engages the contactor carriage, and maintains alignment of interengaging parts despite distortions of the cabinet framework.

Abstract: A control is provided for an AC circuit protection system or the like which is capable of monitoring either single phase or polyphase current flow. The composite current is periodically sampled at a frequency f.sub.s which is not a harmonic frequency of circuit current. The current sample values are converted into digital form and processed, then stored in an accumulator stage. When an overcurrent condition occurs the accumulator stage overflows and trips a circuit interrupter.

Abstract: An improved housing structure for a circuit interrupter. The interrupter mechanisms are mounted upon the upper surface of a platform which serves to divide the housing into upper and lower, high- and low-voltage compartments. The platform is provided with a series of vertically-depending bracing plates which carry a cross shaft for operating the interrupters. An operator mechanism is coupled to the cross shaft and hangs downwardly from the platform so that forces generated in opening and closing the interrupters are not transmitted to the housing structure but rather are contained within the platform assembly.

Abstract: An electrical circuit is provided for actuating the trip mechanism of a circuit interrupter and includes a current sensor having a pair of output terminals and designed to cooperate with at least one electrical power conductor to sense the amount of current flowing in that conductor. The circuit further includes a circuit neutral terminal. A power supply is provided having input terminals with one of the input terminals being connected to one of the output terminals of the current sensor for receiving the sensed current signal therefrom, the other of the input terminals being connected to the circuit neutral terminal. The power supply produces output power at a first voltage level during a first mode of operation of the electrical circuit and produces output power at a second voltage level during a second mode of operation of the electrical circuit, with the second voltage level being substantially higher than the first voltage level.

Abstract: An improved mechanism for racking a contactor mechanism within an enclosure. The mechanism is urged into a fully-engaged position by an arm extending from a rotatable cross shaft which in turn is operated by a pair of complementary four-bar linkages. The first linkage in effect consists of a handle, connecting rod and bellcrank, the second consisting of the bellcrank and another arm, affixed to the cross shaft. An improved spring-loaded detent arm assists in holding the handle in the "racked on" position and a pivoted interlock engages the bellcrank in two positions.

Abstract: A control for an AC circuit protection system which is capable of monitoring either single phase or polyphase current flow. The composite current envelope is periodically sampled and the sample values converted into digital form. Succeeding current signals are tested to determine whether they deviate from previous samples by a given amount. Non-deviant samples increment a first counter, while deviant samples increment a second counter. The ratio of the counts is used to recognize current imbalance and control system parameters are adjusted to compensate for the imbalance.