Abstract: Current-limiting device having a movable contact vigorously moved in the open circuit position by an electromagnetic repulsion device at the appearance of a short-circuit current. A retarding member is mechanically linked to the movable contact to delay the reclosing of the contact and to prevent a reclosing before tripping of the circuit breaker.

Abstract: The contact structure for a puffer-type compressed-gas circuit interrupter comprises a pair of elongated aligned axially separable contacts one of which is hollow and has an end portion provided with a plurality of axially extending, circumferentially spaced-apart contact fingers adapted to resiliently grip the other contact in telescoping relation therewith. The fingers are surrounded by a snugly sleeve ending short of the tips of the fingers permitting the puffer mechanism to direct a radial (cross-blast) jet of arc-extinguishing gas through the interstices between said tips exhausting subsequently through the interior of the tubular contact. The sleeve screens off the residual, major part of the length of the fingers to prevent a radial flow of gas therebetween at this level. It has been found that this arrangement provides an unexpected increase in the breaking power of the apparatus as compared to contact structures having sleeves covering the total length of the contact fingers or no sleeves at all.

Abstract: Air-break circuit interrupter having a plurality of stacked plates of insulating material straddled at the lower edge thereof by electrodes including diverging wing portions extending between the plates to permit the initial arc to be divided by the base portion of the electrodes into a number of elementary arcs extending between the plates to define a helical current path. Inserts of ferromagnetic material are sandwiched between the upstanding legs of the base portion of the electrodes interconnecting the wings thereof in order to enhance the migration of the arc roots along the base portion preventing their stagnation thereon.

Abstract: High-current, current-limiting circit interrupter having arcing contacts connected in parallel with the main contacts. Impetus means open the main contacts strikingly to switch the short-circuit current to the high-resistance arcing circuit. Electrodynamic means cause the arcing contacts to remain closed a short lapse of time after the transfer of the short-circuit current to the arcing circuit. Further electrodynamic means cause the arcing contacts to open sequentially.

Abstract: Circuit interrupter having a magnetic circuit energized by the current flowing through the interrupter and an induction plate that is movable with the movable contact of the interrupter. The abrupt rising of a fault current induces secondary currents in the induction plate which is located in the air gap of the magnetic circuit as long as the interrupter is in the closed-circuit position. The secondary currents tend to expel the induction plate from the air gap thereby moving the movable contact vigorously away from the magnetic circuit.

Abstract: A gastight dynamic seal sealing the pressurized enclosure of a compressed-gas circuit interrupter to a rotatable through control shaft. Radial partition walls of a sleeve surrounding the shaft define a plurality of liquid-filled gas-trap chambers separated by small throttle passageways causing the gas leaking through elastomer joints disposed in some of said chambers to be dissolved in the liquid in degressive concentration, going from the pressurized side of the seal towards the atmospheric side thereof.

Abstract: An arc-extinguishing device having a pair of separable electrodes to draw an arc therebetween. A permanent magnet is associated with each electrode and the magnetic fields produced by the magnets are additive to rapidly transfer the arc to diverging parts of the electrodes thereby causing the arc to be lengthened and subsequently quenched. Advantageously the electrodes comprise a pair of offset contact rings.

Abstract: A rack-mounted electronic equipment module having plug-in normal-service contacts for engagement with the connector panel of a cabinet. The module comprises, preferably on the front edge of the module card, a plurality of aligned test contacts cooperating with a removable plug-in test bar. A single test bar may be provided to test the operation of several modules.

Abstract: Gas-blast circuit interrupter of the puffer type comprising sealed compressed-gas filled arc-extinguishing chambers and support insulators. The enclosures of the chambers and of the support insulator thereof are traversed by control rods which operate the contacts and which are assembled in situ through a door managed in a junction housing which secures the enclosures together and accomodates the confronting end portions of the rods. The junction housing is gastight and may be filled with the same gas as the enclosures so as to avoid pressure differentials across the seals causing leakage of gas. A fluid communication is established between the enclosures after mounting thereof on the junction housing.