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: A circuit breaker having a contact movable between open and closed positions, includes a closing spring assembly having a closing spring and first and second brackets. The closing spring assembly is chargeable when in a reset position in which the first bracket is hooked by a first hook. The closing spring is charged, manually or electrically, with support of the second bracket being transferred to a second hook. The closing spring is discharged to close the circuit breaker, with the closing spring assembly moving from the reset position to a discharged position in the process. The closing spring assembly is then moved as an integral unit, back to the reset position, with the closing spring again being charged, enabling the circuit breaker to immediately reclose in the event of a trip due to a transient condition. An improved breaker operating mechanism and power operated charging mechanism, are also disclosed.

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 chassis, an electrical contact structure, and a shock absorber mechanism. The contact structure includes a movable first electrical contact and a second electrical contact. The first contact has a first movement range. The shock absorbing mechanism, which absorbs energy from the movement of the first contact, includes a metallic bar pivotally mounted on the chassis, and first and second limit members fixed to the chassis. The first and second limit members define a second movement range which overlaps the first movement range. A spring weakly biases the metallic bar towards the second limit member. The first contact, during movement thereof to an open position, strikes the metallic bar. Kinetic energy is removed from the first electrical contact by the metallic bar without bounce of the electrical contact, and the metallic bar pivots against the first limit member, transferring the shock of stopping the first contact to the chassis.

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.