Abstract: Operation of a medium voltage spring powered circuit breaker having an operating mechanism is analyzed by a test unit. The test unit includes a potentiometer having an input and a rotary shaft. A voltage source energizes the input of the potentiometer. A rotary wheel engages a driven part, such as a spring crank or a closing cam, of the operating mechanism to adjust the rotary shaft of the potentiometer and produce a variable output voltage thereof. The potentiometer tracks angular movement of the driven part and the output voltage corresponds to the variable angular movement of the driven part. A processing unit or an oscilloscope monitors the output voltage with respect to time in order to monitor the angular movement of the driven part with respect to time.

Abstract: Operation of a medium voltage spring powered circuit breaker is analyzed by determining the linear position of a selected driven part of the circuit breaker operating mechanism. When the charged closing springs of the operating mechanism are released, the selected driven part, such as a vacuum interrupter stem or push rod, moves to a new linear position as actuated by the release of the charged closing springs. Linkages are provided to the driven parts. LVDT sensors engage each of the linkages to determine the linear positions of the driven parts. A processing unit collects operation data for the operating mechanism when the charged closing springs are released to actuate and produce linear movement of the driven parts. The operation data includes a plurality of the linear positions of the driven parts. A microprocessor-based routine and interface outputs the operation data.

Abstract: Operation of a medium voltage spring powered circuit breaker is analyzed by applying a recording medium in the form of an adhesive backed tape to a selected driven part of the operating mechanism. A marking instrument is held in contact with the recording medium at a fixed point by a fixture in the form of a template secured to the circuit breaker frame. When the charged closing springs of the operating mechanism are released, the marking instrument produces a trace on the recording medium which is then analyzed to provide a quantitative evaluation of switch operation, including overtravel of the selected driven part.

Abstract: An improved flexible connector for a circuit breaker. The flexible connector preferably, comprises a plurality of flexible sheets arranged in a stack. The stack defines an opening having an edge including at least one tab extending inwardly from the edge of the opening. The tabs are adapted to bend so that they make a secure interference fit with a movable contact so that current can flow directly from the movable contact into the flexible connector. A circuit interrupter system is also disclosed.

Abstract: A mechanical interlock device for preventing simultaneous operation of two 3-phase vacuum interrupter-type circuit breakers is provided. The device operates with the floor tripper and the Mechanism Operated Control ("MOC") driver of each vacuum circuit breaker. The device includes a retainer member mounted at the base of each circuit breaker. Each retainer member includes two levers. The first lever is a trip lever which engages the floor tripper of the associated circuit breaker. The second lever is driven by the MOC driver of the associated circuit breakers. The two levers are preferably mounted on a common pivot bar located at one end the retainer member. Cabling is provided between the trip lever on the first circuit breaker and the MOC driver lever on the second circuit breaker. Similarly, a cable is provided between the MOC driver lever of the first circuit breaker and the trip lever of the second circuit breaker.

Abstract: A circuit breaker, and method of constructing same, in which a levering-in mechanism may be added after the circuit breaker has been assembled. The circuit breaker includes a chassis having first and second side plates which define upwardly open slots, which enable the levering-in mechanism to be "dropped in" to the correct position of an assembled circuit breaker, with bottom portions of the slots functioning as half bearings. First and second retainer plates with downwardly open slots are respectively attached to the first and second side plates, to complete the half bearings and hold the levering-in assembly. The levering-in mechanism includes a threaded shaft having a traveling nut, with a bushing on the shaft being held radially, but not axially, by a bracket member, with the bushing also functioning as a non-stress stop for the traveling nut.

Abstract: A circuit breaker having a trip actuator which mechanically trips the breaker in response to an electrical trip pulse. The trip actuator includes first and second parallel magnetic circuits, with the first circuit having a lower reluctance than the second circuit. A magnet provides magnetic flux for both circuits. A pivotally mounted clapper has a first position in which it is releasably held in the first circuit by a magnetic force, and a second position. Bias springs urge the clapper towards the second position, with the bias springs providing a biasing force which is less than the magnetic force holding the clapper. The electrical trip pulse creates a magnetic flux which opposes the magnetic flux in the first circuit, switching the magnetic flux to the second circuit. The clapper member pivots to the second position, and a trip link associated with the clapper actuates a trip mechanism.

Abstract: A visually inspectable indicator for a circuit breaker interrupter apparatus is provided. The visual indicator is located on a portion of the contact wipe assembly of an operating rod assembly of a circuit breaker to provide a reading of relative movement between components of the contact wipe assembly. This reading is related to integrity of the contacts. In a preferred embodiment, the indicator is a T-shaped cut out which is positioned and dimensioned such that it provides a reading relating to compression of the contact spring of the operating rod assembly when the assembly and the circuit breaker contacts are in the closed position which, in turn, provides an indication of the condition of the contacts.

Abstract: A grounding switch device for a metal-clad switchgear is adapted to be inserted into a standard circuit breaker cell allows the bus and line conductors within the switchgear assembly to be grounded for maintenance. A plurality of fixed and selectable test ports are provided to facilitate various electrical tests. The ground switch device is disposed on a frame and contains a ground contact assembly for providing sliding contact between the ground switch device and the ground bus within the circuit breaker cell. The ground contact assembly is in electrical contact with a movable contact. The movable contact is adapted to engage a stationary contact mounted on a mounting plate, attached to the frame by way of an insulator. A selector switch assembly connects the stationary contact to either the upper bus terminals or line terminals in the metal-clad switchgear assembly. The contact portion of the movable contact is U-shaped having two spaced-apart blades.

Abstract: A drawout switchgear apparatus is characterized by a cell having a front opening through which a circuit breaker is movable on tracks into and out of the cell for engagement and disengagement with electrical terminals within the cell. A cell frame includes formed columns at outside corners members, cross-strut members, and formed horizontal members which members are of similar cross-section of a substantially U-shape with U-legs and a bight and with a laterally extending flange. Each member converges to form junction corners where they are fastened together. A track extension and interlock cooperate to facilitate removal and retention of the unit into and out of the cell.