Abstract: Provided is a spring drive cam for a spring drive of a circuit breaker including a disc-like shape configured for rotating around a rotation axis in the spring drive, whereby the disc-like shape comprises a radius (R) that changes depending on an angle (?) of the radius (R) relative to a base angle (?0), and whereby a rate (dR/d?) defined by a change of the radius (R) per change of the angle (?) is ?0.3 mm/°.

Abstract: Provided is a spring drive cam for a spring drive of a circuit breaker including a disc-like shape configured for rotating around a rotation axis in the spring drive, whereby the disc-like shape comprises a radius (R) that changes depending on an angle (?) of the radius (R) relative to a base angle (?0), and whereby a rate (dR/d?) defined by a change of the radius (R) per change of the angle (?) is ?0.3 mm/°.

Abstract: The invention describes a spring arrangement for spring drive unit, which spring arrangement comprises a spring, a pullrod connected at a first pullrod end to a first spring end of the spring and connected at an opposite second pullrod end to a rotary shaft of the spring drive unit, a frame plate against which a second spring end of the spring is mounted and the frame plate being provided with an opening through which the pullrod extends to be connected to the shaft. Further, the first spring end of the spring, to which the pullrod is connected, is unguided, and the parameters of the spring are chosen in response to the operating conditions of the spring drive unit such that the spring is stable during operation.

Abstract: The invention relates to spring protection device for a spring drive unit and adapted to surround a spring of the spring drive unit, the protection device comprising a frame plate, against which a first end of the spring rests, and the frame plate being provided with an opening passage for a pullrod connected to the spring. The spring protection device comprises bars with first end parts that are connected to the frame plate, externally of the first end of the spring, and which bars are arranged to extend externally of and along the sides of the spring and externally of a second end of the spring, thereby forming an open cage surrounding the spring. The invention also relates to a spring drive unit comprising a spring protection device.

Abstract: The invention describes a spring arrangement for spring drive unit, which spring arrangement comprises a spring, a pullrod connected at a first pullrod end to a first spring end of the spring and connected at an opposite second pullrod end to a rotary shaft of the spring drive unit, a frame plate against which a second spring end of the spring is mounted and the frame plate being provided with an opening through which the pullrod extends to be connected to the shaft. Further, the first spring end of the spring, to which the pullrod is connected, is unguided, and the parameters of the spring are chosen in response to the operating conditions of the spring drive unit such that the spring is stable during operation.