Operating mechanism for a circuit breaker

Abstract

An operating mechanism for a circuit breaker comprises a knob 102 disposed on and rotatable about a first protrusion 104, and a linking member 106 disposed on and rotatable about a second protrusion 1

Description

Field This relates to an operating mechanism for a circuit breaker, and a circuit breaker 5 comprising said operating mechanism. A method of assembling the operating mechanism is also described. Background Miniature circuit breakers (MCBs) and residual current circuit breakers with 10 overcurrent protection (RCBOs) are examples of circuit protection devices which are installed at end locations (i.e. at the final distribution of power, such as within a residential home). Such circuit protection devices comprise an operating mechanism which allows the circuit breakers to be switched on and off under normal operating conditions, as well as to trip (i.e. switch off automatically) in case of a fault. 15 Existing operating mechanisms for circuit protection devices can require a large number of components and can have a complex construction which is difficult to assemble. Such complex, multi-component mechanisms are not suitable for automated manufacturing, making the manufacturing process longerand more 20 expensive. It is therefore desirable to provide an operating mechanism for a circuit breaker which is simplerand easier to construct than existing designs, and which can be more easily manufactured. 25 Summary In a first aspect, there is provided an operating mechanism as set out in independent claim 1. In a second aspect, as an alternative solution, there is provided an operating mechanism as set out in independent claim 8. A circuit breaker comprising said 30 operating mechanism of the first or second aspect is also described herein. Described herein is an operating mechanism for a circuit breaker. The operating mechanism comprises a knob configured to be disposed on a first protrusion and configured to rotate around the first protrusion. The operating mechanism comprises 35 a linking member configured to be disposed on a second protrusion and configured to rotate around the second protrusion, wherein the first and second protrusions are parallel, the linking member comprising a third protrusion, a fourth protrusion and a fifth protrusion. The operating mechanism comprises a contact holder arranged to carry a movable contact, the contact holder disposed on the third protrusion. The operating mechanism comprises a first latch disposed on the fourth protrusion, the contact holder arranged between the linking member and the first latch. The operating mechanism comprises a second latch disposed on the fifth protrusion and 5 configured to rotate around the fifth protrusion. The operating mechanism comprises a pin coupling the second latch to the knob. The first and second latches are configured to engage such that rotation of the knob around the first protrusion causes rotation of the linking member around the second protrusion and thus a rotation of the contact holder. The first latch is configured to pivot around the fourth protrusion in 10 response to an application of force so as to disengage the first latch from the second latch and enable rotation of the knob independently of the first latch. In this way, a modular operating mechanism can be provided, in which each component can be placed within the mechanism in turn during an assembly process. 15 For example, each component can be placed, or dropped, in the mechanism in sequence. Due to the structured, layer based, arrangement, quick and easy manufacturing of the mechanism is possible, including the use of automated manufacturing processes. Moreover, the number of components are reduced as compared to existing mechanism designs, reducing cost and complexity of the 20 mechanism. The mechanism can also be assembled as a standalone component and assembled within the circuit breaker later, providing a modular arrangement which is easy to retrofit. The use of the first and second latches allows for manual closing / making and 25 opening / breaking of a circuit by manual actuation of the knob by a user. In addition, because the first latch is configured to pivot around the fourth protrusion in response to an application of force, so as to disengage the first latch from the second latch and enable rotation of the knob independently of the first latch, the mechanism also allows for rapid opening / breaking of the circuit during a trip or fault event. This latching 30 arrangement can facilitate reliable operation of the mechanism. Optionally, the first and second latches are formed of plastic. This plastic-to-plastic latching further facilitates reliable operation of the mechanism. The modular arrangement described herein can also eliminate the need for brass rivets through the 35 use of plastic-plastic or metal-plastic interfaces (i.e. avoiding the need for brass rivets to reduce friction wear, as is needed in conventional designs with metal-metal interfaces). Optionally, in example, the operating mechanism further comprises a first torsion spring configured to be disposed around the first protrusion. The knob is disposed between the torsion spring and the pin. The first torsion spring is coupled to the knob and configured to contact the first latch. The first torsion spring is also configured to 5 contact a fixed component, such as a housing of the circuit breaker. In other words, an end of the torsion spring is fixed. This first torsion spring provides resistance during rotation of the knob to close / make the circuit, thereby reducing accidental making of the circuit, and also provides a biasing force to the first latch to maintain the first latch in a correct position during a tripping event and thereby control the 10 movement of the linking member. This arrangement provides a bi-functional spring, allowing the elimination of at least one spring as compared to conventional arrangements (which can have separate latch and knob springs); the number of components can therefore be reduced. By providing a first torsion spring in this way, the resistance and biasing force can be controlled through the choice and parameters 15 of the first torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. In other optional examples, the operating mechanism comprises a first torsion spring 20 configured to be disposed around the first protrusion. The knob is disposed between the torsion spring and the pin. The first torsion spring is coupled to the knob and configured to contact a fixed component, such as a housing of the circuit breaker (but does not contact a moveable component of the operating mechanism). This first torsion spring provides resistance during rotation of the knob to close / make the 25 circuit, thereby reducing accidental making of the circuit. By providing a first torsion spring, the resistance force can also be independently controlled through the choice and parameters of the first torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. 30 Optionally, the contact holder is configured to pivot around the third protrusion in response to an application of force at the moving contact. In other words, the contact holder can pivot with respect to the linking member. Optionally, the operating mechanism further comprises a second torsion spring disposed around the third 35 protrusion, the contact holder arranged between the linking member and the second torsion spring, where the second torsion spring is coupled to the contact holder and configured to contact the linking member. The second torsion spring provides a force to the contact holder to ensure a good contact between the moveable contact and another electrical component when making the circuit. In this way, the second torsion spring can hold the moving contact in electrical and physical contact with the circuit as the linking member moves underneath (i.e. as the contact holder pivots with respect to the linking member around the third protrusion). By providing a second torsion 5 spring, the contact force can be independently controlled through the choice and parameters of the second torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. 10 Optionally, the operating mechanism further comprises a third torsion spring, the third torsion spring coupled to the first latch and configured to contact the linking member. In other examples, the third torsion spring can instead be coupled to the linking member and configured to contact the first latch. This third torsion spring provides a biasing force to the first latch to maintain the first latch in a correct position during a 15 tripping event and thereby control the movement of the linking member. By providing a third torsion spring, the spring force of the first latch can be independently controlled through the choice and parameters of the third torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. 20 Optionally, the moving contact is arranged eccentrically to the third protrusion. This eccentric arrangement of the moving contact and pivot point of the contact holder facilitates a wiping action between the moving and other electrical contacts, thereby helping to ensure lower contact resistance. This wiping action can be further 25 facilitated by the eccentric offset in the pivot points of the contact holder and the first latch. Optionally, the mechanism further comprises a spring in contact with the linking member, the spring configured to extend and compress as the linking member rotates 30 around the second protrusion. The spring can be an extension or compression spring, or any other suitable spring. Optionally, the spring is configured to rotate the linking member around the second protrusion when the first latch disengages from the second latch. The spring drives the linking member, and therefore the contact, while the pivoting second latch and pin drives the knob towards the open position. This 35 provides a rapid breaking of the circuit in case of a trip event. By providing a separate spring in this way, the velocity and breaking force can be independently controlled through the choice and parameters of the spring. This enables the spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. Optionally, the third, fourth and fifth protrusions extend in a same direction as the 5 first and second protrusions. Optionally, the third, fourth and fifth protrusions are parallel to the first and second protrusions. This can facilitate quicker and easier manufacturing of the operating mechanism. Optionally, the third, fourth and fifth protrusions are integral to the linking member. 10 Alternatively, the third, fourth and fifth protrusions are coupled to or otherwise extend from a plane of the linking member. In some implementations, the second and fourth protrusions are co-axial, optionally, wherein the fourth protrusion is an extension of the second protrusion. In other words, the linking member comprises an aperture through which the second protrusion extends, thereby forming the fourth protrusion. 15 Optionally, the operating mechanism further comprises a contact indicator. The contact indicator can indicate a position of the moving contact to a user, for example through a window or aperture in a housing of the circuit breaker in which the mechanism is installed. In some examples, the contact indicator is integral with the 20 linking member. This can provide fora reliable indication of the contact position through integration of the contact holder and the indicator via the linking member, as well as reducing the number of components. In other examples, the contact indicator is coupled to the linking member, optionally rotatably coupled. This can allow the contact indicator to operate separately to the linking member, as well as allowing the 25 contact indicator to be changed, for example depending on jurisdiction specific requirements, without having to redesign any other components of the mechanism. Optionally, the operating mechanism further comprises a first plate, the first plate comprising the first and second protrusions, and a second plate. The pin is disposed 30 between the knob and the second plate, the first and second plates coupled together. In this way, the entire operating mechanism can be assembled onto the first plate, secured with the second plate, and then placed as a stand-alone, modular component within a circuit breaker. This can facilitate retrofitting of the operating mechanism, as well as replacement of the mechanism if needed. 35 Optionally, the first and second protrusions are co-planar and are offset within said plane. Optionally, the first and second latches are co-planar. Described herein is an alternative operating mechanism fora circuit breaker. The operating mechanism comprises a knob configured to be disposed on a first protrusion and configured to rotate around the first protrusion. The operating mechanism comprises a linking member configured to be disposed on a second protrusion and 5 configured to rotate around the second protrusion, wherein the first and second protrusions are parallel, the linking member comprising a third protrusion. The operating mechanism comprises a contact holder arranged to carry a movable contact, the contact holder coupled to the linking member. The operating mechanism comprises a latch disposed on the third protrusion, the contact holder arranged 10 between the linking member and the latch. The operating mechanism comprises a pin coupling the linking member to the knob. The pin and latch are configured to engage such that rotation of the knob causes rotation of the linking member around the second protrusion and thus a rotation of the contact holder. The latch is configured to pivot around the third protrusion in response to an application of force so as to 15 disengage the latch from the pin and enable rotation of the knob independently of the latch. In this way, a modular operating mechanism can be provided, in which each component can be placed within the mechanism in turn during an assembly process. 20 For example, each component can be placed, or dropped, in the mechanism in sequence. Due to the structured, layer based, arrangement, quick and easy manufacturing of the mechanism is possible, including the use of automated manufacturing processes. Moreover, the number of components are reduced as compared to existing mechanism designs, reducing cost and complexity of the 25 mechanism. The mechanism can also be assembled as a standalone component and assembled within the circuit breaker later, providing a modular arrangement which is easy to retrofit. The use of the latch and pin arrangement allows for manual closing / making and 30 opening / breaking of a circuit by manual actuation of the knob by a user. In addition, because the latch is configured to pivot around the third protrusion in response to an application of force, so as to disengage the latch from the pin and enable rotation of the knob independently of the latch, the mechanism also allows for rapid opening / breaking of the circuit during a trip or fault event. This pin latching 35 arrangement can facilitate reliable operation of the mechanism. Optionally, the second latch and pin are formed of plastic. This plastic-to-plastic latching further facilitates reliable operation of the mechanism. The modular arrangement described herein can also eliminate the need for brass rivets through the use of plastic-plastic or metal-plastic interfaces (i.e. avoiding the need for brass rivets to reduce friction wear, as is needed in conventional designs with metal-metal interfaces). 5 Optionally, the operating mechanism further comprises a first torsion spring configured to be disposed around the first protrusion. The knob is disposed between the torsion spring and the pin. The first torsion spring is coupled to the knob and configured to contact a fixed component, such as a housing of the circuit breaker. In 10 other words, an end of the torsion spring is fixed. This first torsion spring provides resistance during rotation of the knob to close / make the circuit, thereby reducing accidental making of the circuit. By providing a first torsion spring, the resistance force can also be independently controlled through the choice and parameters of the first torsion spring. This enables the torsion spring parameters to be optimised for 15 one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. Optionally, the contact holder is disposed around the third protrusion and configured to pivot around the third protrusion in response to an application of force at the 20 moving contact. In other words, the contact holder can pivot with respect to the linking member. Optionally, the operating mechanism further comprises a second torsion spring disposed around the third protrusion, the contact holder arranged between the linking member and the second torsion spring, where the second torsion spring is coupled to the contact holder and configured to contact the linking member. 25 The second torsion spring provides a force to the contact holder to ensure a good contact between the moveable contact and another electrical component when making the circuit. In this way, the second torsion spring can hold the moving contact in electrical and physical contact with the circuit as the linking member pivots underneath (around the third protrusion). By providing a second torsion spring, the 30 contact force can be independently controlled through the choice and parameters of the second torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. 35 Optionally, the mechanism further comprises a spring in contact with the linking member, the spring configured to extend and compress as the linking member rotates around the second protrusion. The spring can be an extension or compression spring, or any other suitable spring. Optionally, the spring is configured to rotate the linking member around the second protrusion when the latch disengages from the spin. The spring drives the linking member, and therefore the contact, while the pin drives the knob towards the open position. This provides a rapid breaking of the circuit in case of a trip event. By providing a separate spring in this way, the velocity and breaking 5 force can be independently controlled through the choice and parameters of the spring. This enables the spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. Optionally, the operating mechanism further comprises a third torsion spring, the third 10 torsion spring coupled to the linking member and configured to contact the latch. This third torsion spring provides a biasing force to the latch to maintain the latch in a correct position during a tripping event and thereby control the movement of the linking member. By providing a third torsion spring, the spring force of the latch can be independently controlled through the choice and parameters of the third torsion 15 spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. Optionally, the third protrusion is integral to the linking member. Alternatively, the third protrusion is coupled to or otherwise extends from a plane of the linking 20 member. In some implementations, the second and third protrusions are co-axial, optionally, wherein the third protrusion is an extension of the second protrusion. In other words, the linking member comprises an aperture through which the second protrusion extends, thereby forming the third protrusion. 25 Optionally, the operating mechanism further comprises a contact indicator. The contact indicator can indicate a position of the moving contact to a user, for example through a window or aperture in a housing of the circuit breaker in which the mechanism is installed. In some examples, the contact indicator is integral with the linking member. This can provide fora reliable indication of the contact position 30 through integration of the contact holder and the indicator via the linking member, as well as reducing the number of components. In other examples, the contact indicator is coupled to the linking member, optionally rotatably coupled. This can allow the contact indicator to operate separately to the linking member, as well as allowing the contact indicator to be changed, for example depending on jurisdiction specific 35 requirements, without having to redesign any other components of the mechanism. Optionally, a system is provided comprising the operating mechanism. The system further comprises a first plate, the first plate comprising the first and second protrusions, and a second plate. The pin is disposed between the knob and the second plate, the first and second plates coupled together. In this way, the entire operating mechanism can be assembled onto the first plate, secured with the second plate, and then placed as a stand-alone, modular system within a circuit breaker. This 5 can facilitate retrofitting of the operating mechanism, as well as replacement of the mechanism if needed. Also provided is a circuit breaker comprising an operating mechanism as described herein. 10 In some examples, the circuit breaker comprises the system. In other words, the system comprising the first and second plates and the assembled operating mechanism can be provided within the circuit breaker. In other examples, the circuit breaker can further comprise a housing having the first and second protrusions. In 15 other words, the first and second protrusions can be formed or provided within the circuit breaker itself. This can allow the operating mechanism to be directly assembled, in a modular manner, within the circuit breaker. Also described herein is a method of assembling an operating mechanism of a circuit 20 breaker in accordance with the first aspect. The method comprises: disposing a knob on a first protrusion, the knob configured to rotate around the first protrusion; disposing a linking member on a second protrusion, the linking member configured to rotate around the second protrusion, wherein the first and second protrusions are parallel, the linking member comprising a third protrusion, a fourth protrusion and a 25 fifth protrusion; disposing a contact holder on the third protrusion, the contact holder arranged to carry a movable contact; disposing a first latch on the fourth protrusion, such that the contact holder is arranged between the linking member and the first latch; disposing a second latch on the fifth protrusion, the second latch configured to rotate around the fifth protrusion; providing a pin, the pin coupling the second latch to 30 the knob, wherein the first and second latches are configured to engage such that rotation of the knob around the first protrusion causes rotation of the linking member around the second protrusion and thus a rotation of the contact holder, and wherein the first latch is configured to pivot around the fourth protrusion in response to an application of force so as to disengage the first latch from the second latch and enable 35 rotation of the knob independently of the first latch. Also described herein is a method of assembling an operating mechanism of a circuit breaker in accordance with the second aspect. The method comprises: disposing a knob on a first protrusion, the knob configured to rotate around the first protrusion; disposing a linking member on a second protrusion, the linking member configured to rotate around the second protrusion, wherein the first and second protrusions are parallel, the linking member comprising a third protrusion; coupling a contact holder, 5 arranged to carry a movable contact, to the linking member; disposing a latch on the third protrusion, such that the contact holder is arranged between the linking member and the latch; providing a pin, the pin coupling the linking member to the knob, wherein the pin and latch are configured to engage such that rotation of the knob causes rotation of the linking member around the second protrusion and thus a 10 rotation of the contact holder, and wherein the latch is configured to pivot around the third protrusion in response to an application of force so as to disengage the latch from the pin and enable rotation of the knob independently of the latch. Features described herein in relation to the operating mechanism of the first aspect 15 may be combined with the operating mechanism of the second aspect, and vice versa, provided said combination is not functionally incompatible. List of Figures The following detailed description is with reference to the following figures, in which: 20 FIG. 1A shows a side on, exploded, schematic of a first example circuit breaker operating mechanism in accordance with the first aspect, and FIG. IB shows a side on, exploded, schematic of a second example circuit breaker operating mechanism in accordance with the first aspect; 25 FIG. 2A shows a side on, exploded, schematic of a first example circuit breaker operating mechanism in accordance with the second aspect, and FIG. 2B shows a side on, exploded, schematic of a second example circuit breaker operating mechanism in accordance with the second aspect; FIG. 3 shows a schematic block diagram of a circuit breaker comprising an operating 30 mechanism in accordance with the first or second aspect; FIGs. 4A, 4B, 4C and 4D show perspective views of an example implementation of a circuit breaker operating mechanism in accordance with the first aspect; FIG. 5 shows a perspective view of another example implementation of a circuit breaker operating mechanism in accordance with the first aspect; 35 FIG. 6 shows a perspective view of an example implementation of a circuit breaker operating mechanism in accordance with the second aspect; FIG. 7A shows an open / break position of an example circuit breaker operating mechanism in accordance with the first aspect, and FIG. 7B shows a closed / make position of the example mechanism of FIG. 7A; FIG. 8A shows an open / break position of another example circuit breaker operating 5 mechanism in accordance with the first aspect, and FIG. 8B shows a closed / make position of the example mechanism of FIG. 8A; FIG. 9A shows an open / break position of an example circuit breaker operating mechanism in accordance with the second aspect, and FIG. 9B shows a closed / make position of the example mechanism of FIG. 9A; 10 FIG. 10 is a flow chart showing example operations for assembling an operating mechanism in accordance with the first aspect; and FIG. 11 is a flow chart showing example operations for assembling an operating mechanism in accordance with the second aspect. 15 Like reference numerals refer to like features. Detailed Description In accordance with FIG. 1A, IB, an operating mechanism 100 for a circuit breaker is now described. 20 The operating mechanism 100 comprises a knob 102 configured to be disposed on a first protrusion 104. The knob is configured to rotate around the first protrusion. The rotation is around the axis of the first protrusion, axis 160. The knob is configured to rotate in response to user (or manual) actuation of an engagement portion of the knob 25 (not shown). The engagement portion can extend from a housing of a circuit breaker containing the operating mechanism 100 to facilitate actuation of the knob. The knob can also be configured to rotate independent of user actuation in the event of a fault (trip), as discussed in more detail below. 30 The operating mechanism 100 comprises a linking member 106 configured to be disposed on a second protrusion 108. The linking member 106 is configured to rotate around the second protrusion. The rotation is around the axis of the second protrusion, axis 162. Optionally, the operating mechanism further comprises a contact indicator (not shown here). The contact indicator can indicate a position of 35 the moving contact to a user, for example through a window or aperture in a housing of the circuit breaker in which the mechanism is installed. In some examples, the contact indicator is integral with the linking member. In other examples, the contact indicator is coupled to the linking member; the contact indicator can be rigidly coupled to the linking member, or rotatably coupled, or coupled in any other suitable manner. As shown here, the first and second protrusions are parallel. Optionally, the first and 5 second protrusions 104, 108 are co-planar. In other examples, the first and second protrusions 104, 108 may be arranged in separate planes offset from one another along axis 160. The first and second protrusions are offset from one another, as shown in FIG. 1A, such that the linking member 106 and the knob 102 can be arranged substantially co-planar with one another. This can provide for a more io compact operating mechanism. The linking member 106 comprises a third protrusion 110, a fourth protrusion 112 and a fifth protrusion 114. Optionally, one or more of the third, fourth and fifth protrusions are integral to the linking member 106. Optionally, one or more of the 15 third, fourth and fifth protrusions are coupled to or otherwise extend from a plane of the linking member 106. Optionally, the third, fourth and fifth protrusions extend in a same direction as the first and second protrusions. Optionally, as shown in FIG. 1A, the third, fourth and fifth protrusions are parallel to the first and second protrusions; this can facilitate quicker and easier manufacturing of the operating mechanism. In 20 some implementations, the second 108 and fourth 112 protrusions are co-axial (along axis 162). In some specific implementations (not shown here) the fourth protrusion 112 is an extension of the second protrusion 108; in other words, the linking member comprises an aperture through which the second protrusion 108 extends, thereby forming the fourth protrusion 112. 25 The operating mechanism 100 comprises a contact holder 116 arranged to carry a movable (or moving) contact 118, the contact holder disposed on the third protrusion 110. The contact holder 116 can be rigidly coupled to the third protrusion 110, or can be configured to pivot around the third protrusion 110. In some examples, the 30 contact holder 116 is configured to pivot around the third protrusion 110 in response to an application of force at the moving contact 118. In other words, the contact holder can pivot with respect to the linking member 106. The operating mechanism 100 comprises a first latch 120 disposed on the fourth 35 protrusion 112, the contact holder 116 arranged between the linking member 106 and the first latch 120. In this way, the contact holder can be retained within the operating mechanism between other components, reducing the likelihood of movement or bending of the contact holder 116, and thus of the moveable contact 118. The first latch 120 is configured to pivot around the fourth protrusion 112 in response to an application of force; in the example of FIG. 1A, the first latch is arranged to pivot around axis 162, but it will be understood that when the fourth protrusion 112 is offset from the second protrusion 108, the pivot axis of the first latch 5 will be different. The operating mechanism 100 comprises a second latch 124 disposed on the fifth protrusion 114 and configured to rotate around the fifth protrusion. Rotation is around the axis of the fifth protrusion, 164. The first and second latches 120, 124 are io in this arrangement substantially co-planar, and are configured to engage with one another in at least some positions, as discussed below in more detail. The operating mechanism 100 also comprises a pin 126. The pin 126 couples the second latch 124 to the knob 102. The pin can be a U shaped pin, as shown in FIG. 15 1A, but any other suitable pin 126 may be used. The first and second latches are configured to engage such that rotation of the knob around the first protrusion causes rotation of the linking member around the second protrusion and thus a rotation of the contact holder, where the rotation of the knob is transferred by the pin 126. The first latch is also configured to pivot around the fourth protrusion in response to an 20 application of force so as to disengage the first latch from the second latch and enable rotation of the knob independently of the first latch; this can facilitate a rapid breaking of a circuit comprising the movable contact 118 in the event of a fault (during a trip). In this way, a modular operating mechanism can be provided, in which each 25 component can be placed within the mechanism in turn during an assembly process. For example, each component can be placed, or dropped, into the mechanism in sequence. Due to the structured, layer based, arrangement, quick and easy manufacturing of the operating mechanism 100 is possible, including the use of automated manufacturing processes. Moreover, the number of components are 30 reduced as compared to existing mechanism designs, reducing cost and complexity of the mechanism 100. The operating mechanism 100 can also be assembled as a standalone component and assembled within the circuit breaker later, providing a modular arrangement which is easy to retrofit. 35 The use of the first and second latches allows for manual closing / making and opening / breaking of a circuit by manual actuation of the knob by a user. In addition, because the first latch is configured to pivot around the fourth protrusion in response to an application of force, so as to disengage the first latch from the second latch and enable rotation of the knob independently of the first latch, the mechanism also allows for rapid opening / breaking of the circuit during a trip or fault event. This latching arrangement can facilitate reliable operation of the mechanism. 5 Further examples of the operating mechanism of FIG. 1A will now be discussed with reference to FIG. IB. In some implementations, the operating mechanism 100 further comprises a first torsion spring 130 configured to be disposed around the first protrusion 104. The io knob 102 is disposed between the torsion spring 130 and the pin 126. The first torsion spring 130 is coupled to the knob 102 and configured to contact the first latch 120 (this contact is not shown here). The first torsion spring is also configured to contact a fixed component, such as a housing of the circuit breaker (not shown here). 15 This first torsion spring 130 provides resistance during rotation of the knob 102 to close / make the circuit, thereby reducing accidental making of the circuit, and also provides a biasing force to the first latch to maintain the first latch in a correct position during a tripping event and thereby control the movement of the linking member 106. This arrangement provides a bi-functional spring, allowing the elimination of at least 20 one spring as compared to conventional arrangements (which can have separate latch and knob springs); the number of components can therefore be reduced. By providing a first torsion spring in this way, the biasing force can also be independently controlled through the choice and parameters of the first torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the 25 mechanism, increasing the flexibility of the mechanism. In other examples, not shown here, the first torsion spring 130 of FIG. IB can be replaced by the first torsion spring 130' and / or the third torsion spring 136' described below with references to FIG. 2B. In some implementations, the operating mechanism further comprises a second 30 torsion spring 132 disposed around the third protrusion 110, the contact holder 116 arranged between the linking member 106 and the second torsion spring 132. The second torsion spring is coupled to the contact holder and configured to contact the linking member (this contact is not shown here). The second torsion spring 132 provides a force to the contact holder 116 to ensure a good contact between the 35 moveable contact and another electrical component of the circuit breaker when making the circuit. In this way, the second torsion spring 132 can hold the moving contact in electrical and physical contact with the circuit as the contact holder 116 pivots around the third protrusion (i.e. as the linking member moves underneath the contact holder 116, whilst the contact holder is stopped from moving further by the contact force at the movable contact 118). By providing a second torsion spring 132 in this way, the contact force can be independently controlled through the choice and parameters of the second torsion spring 132. This enables the torsion spring 5 parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. In some implementations, as shown here, the pivot point of the contact holder 116 (and thus the pivot point of the moveable / moving contact 118) is arranged io eccentrically to the pivot point of the first latch 120. This eccentric arrangement of the moving contact and first latch 120 facilitates a wiping action of the moving contact 118, thereby helping to ensure lower contact resistance. In some implementations, the operating mechanism 100 further comprises a spring 15 134 in contact with the linking member 106. The spring 134 is configured to extend and compress as the linking member 106 rotates around the second protrusion 108. The spring can be an extension or compression spring, or any other suitable spring. Optionally, the spring 134 is configured to rotate the linking member 106 around the second protrusion 108 when the first latch 120 disengages from the second latch 124. 20 The spring 134 drives the linking member 106, and therefore the moveable contact 118, while the pivoting second latch 124 and coupled pin 126 drives the knob 102 towards the open position. This provides a rapid breaking of the circuit in case of a trip event. By providing a separate spring 134 in this way, the breaking velocity and breaking force can be independently controlled through the choice and parameters of 25 the spring. This enables the spring parameters to be optimised for one or more performance criteria of the operating mechanism, increasing the flexibility of the mechanism 100. Optionally, a system 200 is provided. The system comprises the operating mechanism 30 100. The system 200 further comprises a first plate 140, the first plate comprising the first 104 and second 108 protrusions. The system 200 can further comprise a second plate 142. The pin 126 is disposed between the knob 102 and the second plate 142. The first and second plates 140, 142 can be coupled together (not shown) to retain the operating mechanism 100. In this way, the entire operating mechanism 100 can 35 be assembled onto the first plate 140, secured with the second plate 142, and then placed as a stand-alone, modular component within a circuit breaker (not shown). This can facilitate retrofitting of the operating mechanism, as well as replacement of the mechanism if needed. In other examples, the operating mechanism 100 can be assembled directly into a circuit breaker (without the first and second plates). In accordance with FIG. 2A, 2B, an alternative operating mechanism 100'for a circuit 5 breaker is now described. This operating mechanism 100' can be understood to be an alternative solution to mechanism 100 described above. Where features of the two implementations are not functionally incompatible, they can be combined in any suitable manner. io The operating mechanism 100' comprises a knob 102' configured to be disposed on a first protrusion 104'. The knob is configured to rotate around the first protrusion. The rotation is around the axis of the first protrusion, axis 160'. The knob is configured to rotate in response to user (or manual) actuation of an engagement portion of the knob (not shown). The engagement portion can extend from a housing of a circuit breaker 15 containing the operating mechanism 100'to facilitate actuation of the knob. The knob can also be configured to rotate independent of user actuation in the event of a fault (trip), as discussed in more detail below. The operating mechanism 100' comprises a linking member 106' configured to be 20 disposed on a second protrusion 108'. The linking member 106' is configured to rotate around the second protrusion. The rotation is around the axis of the second protrusion, axis 162'. Optionally, the operating mechanism further comprises a contact indicator (not shown here). The contact indicator can indicate a position of the moving contact to a user, for example through a window or aperture in a housing 25 of the circuit breaker in which the mechanism is installed. In some examples, the contact indicator is integral with the linking member 106'. In other examples, the contact indicator is coupled to the linking member 106'; the contact indicator can be rigidly coupled to the linking member 106', or rotatably coupled, or coupled in any other suitable manner. 30 As shown here, the first and second protrusions are parallel. Optionally, the first and second protrusions 104', 108' are co-planar. In other examples, the first and second protrusions may be arranged in separate planes offset from one another along axis 160'. The first and second protrusions are offset from one another, as shown in FIG. 35 2A, such that the linking member 106' and the knob 102' can be arranged substantially co-planar with one another. This can provide for a more compact operating mechanism. The linking member 106' comprises a third protrusion 110'. Optionally, the third protrusion is integral to the linking member 106'. Optionally, the third protrusion is coupled to or otherwise extends from a plane of the linking member 106'. Optionally, the third protrusion 110' extends in a same direction as the first and second 5 protrusions. Optionally, as shown in FIG. 2A, the third protrusion is parallel to the first and second protrusions; this can facilitate quicker and easier manufacturing of the operating mechanism. In some implementations, the second 108' and third 110' protrusions are co-axial (along axis 162'). In some specific implementations (not shown here) the third protrusion 110' is an extension of the second protrusion 108'; in io other words, the linking member comprises an aperture through which the second protrusion 108' extends, thereby forming the third protrusion 110'. The operating mechanism 100' comprises a contact holder 116' arranged to carry a movable (or moving) contact 118'. The contact holder 116' is coupled to the linking 15 member 106'. The operating mechanism 100' comprises a latch 120' disposed on the third protrusion 110'. The latch 120' is configured to pivot around the third protrusion 110' in response to an application of force; in the example of FIG. 2A, the latch is arranged to 20 pivot around axis 162', but it will be understood that when the third protrusion 110' is offset from the second protrusion 108', the pivot axis of the first latch will be different. The contact holder 116' is arranged between the linking member 106' and the latch 120'. In this way, the contact holder can be retained within the operating mechanism 100' between other components, reducing the likelihood of movement or bending of 25 the contact holder 116', and thus of the moveable contact 118'. The operating mechanism 100' comprises a pin 126'. The pin 126' couples the latch 120' to the knob 102'. The pin can be a U shaped pin, as shown in FIG. 2A, but any other suitable pin 126' may be used. The pin and latch are configured to engage such 30 that rotation of the knob 102' causes rotation of the linking member 106' around the second protrusion 108' and thus a rotation of the contact holder 116'. The latch is configured to pivot around the third protrusion 110' in response to an application of force so as to disengage the latch 120' from the pin 126' and enable rotation of the knob 102' independently of the latch; this can facilitate a rapid breaking of a circuit 35 comprising the movable contact 118' in the event of a fault (during a trip). In this way, a modular operating mechanism can be provided, in which each component can be placed within the mechanism in turn during an assembly process. For example, each component can be placed, or dropped, in the mechanism in sequence. Due to the structured, layer based, arrangement, quick and easy manufacturing of the mechanism is possible, including the use of automated manufacturing processes. Moreover, the number of components are reduced as 5 compared to existing mechanism designs, reducing cost and complexity of the mechanism 100'. The mechanism 100' can also be assembled as a standalone component and assembled within the circuit breaker later, providing a modular arrangement which is easy to retrofit. io The use of the latch and pin arrangement allows for manual closing / making and opening / breaking of a circuit by manual actuation of the knob by a user. In addition, because the latch is configured to pivot around the third protrusion in response to an application of force, so as to disengage the latch from the pin and enable rotation of the knob independently of the latch, the mechanism 100' also allows for rapid 15 opening / breaking of the circuit during a trip or fault event. This pin latching arrangement can facilitate reliable operation of the mechanism. Further examples of the operating mechanism of FIG. 2A will now be discussed with reference to FIG. 2B. 20 In some implementations, the operating mechanism 100'further comprises a first torsion spring 130' configured to be disposed around the first protrusion 104'. The knob 102' is disposed between the torsion spring 130' and the pin 126'. The first torsion spring 130' is coupled to the knob 102' and configured to contact a fixed 25 component of the circuit breaker (this contact is not shown here). This first torsion spring 130' provides resistance during rotation of the knob 102'to close / make the circuit, thereby reducing accidental making of the circuit. By providing a first torsion spring 130' in this way, the resistance force can be independently controlled through the choice and parameters of the first torsion spring. This enables the torsion spring 30 parameters to be optimised for one or more performance criteria of the mechanism 100', increasing the flexibility of the mechanism. Optionally, as shown in FIG. 2B, the contact holder is coupled to the linking member 106' by way of being disposed around the third protrusion 110'. The contact holder 35 116' is configured to pivot around the third protrusion 110' in response to an application of force at the moving contact 118'. In other words, the contact holder can pivot with respect to the linking member 106'. In some implementations, the operating mechanism further comprises a second torsion spring 132' disposed around the third protrusion 110', the contact holder 116 arranged between the linking member 106 and the second torsion spring 132. The second torsion spring 132' is coupled to the contact holder 116' and configured to 5 contact the linking member 106' (this contact is not shown here). The second torsion spring 132' provides a force to the contact holder 116' to ensure a good contact between the moveable contact 118' and another electrical component of the circuit breaker when making the circuit. In this way, the second torsion spring 132' can hold the moving contact 118' in electrical and physical contact with the circuit as the linking io member pivots around the third protrusion 110' underneath the contact holder 116'. By providing a second torsion spring 132' in this way, the contact force can be independently controlled through the choice and parameters of the second torsion spring 132'. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the 15 mechanism. In some implementations, as shown here, the pivot point of the contact holder 116' (and thus the pivot point of the moveable / moving contact 118') is arranged eccentrically to the pivot point of the latch 120'. This eccentric arrangement of the 20 moving contact and latch 120'facilitates a wiping action of the moving contact 118', thereby helping to ensure lower contact resistance. In some implementations, the operating mechanism 100' further comprises a spring 134' in contact with the linking member 106'. The spring 134' is configured to extend 25 and compress as the linking member 106' rotates around the second protrusion 108'. The spring can be an extension or compression spring, or any other suitable spring. Optionally, the spring 134' is configured to rotate the linking member 106' around the second protrusion 108' when the latch 120' disengages from the pin 126'. The spring 134' drives the linking member 106', and therefore the moveable contact 118', while 30 the pin drives the knob towards the open position. This provides a rapid breaking of the circuit in case of a trip event. By providing a separate spring 134' in this way, the breaking velocity and breaking force can be independently controlled through the choice and parameters of the spring. This enables the spring parameters to be optimised for one or more performance criteria of the operating mechanism, 35 increasing the flexibility of the mechanism 100'. Optionally, the operating mechanism 100' further comprises a third torsion spring 136'. The third torsion spring 136' is coupled to the linking member 106' and configured to contact the latch 120' (this contact is not shown here). This third torsion spring 136' provides a biasing force to the latch 120' to maintain the latch in a correct position during a tripping event and thereby control the movement of the linking member 106'. By providing a third torsion spring 136', the spring force of the latch 5 120' can be independently controlled through the choice and parameters of the third torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. io Optionally, a system 200 is provided. The system comprises the operating mechanism 100'. The system 200 further comprises a first plate 140, the first plate comprising the first 104' and second 108' protrusions. The system 200 can further comprise a second plate 142. The pin 126' is disposed between the knob 102' and the second plate 142. The first and second plates 140, 142 can be coupled together (not shown) 15 to retain the operating mechanism 100'. In this way, the entire operating mechanism 100' can be assembled onto the first plate 140, secured with the second plate 142, and then placed as a stand-alone, modular component within a circuit breaker (not shown). This can facilitate retrofitting of the operating mechanism, as well as replacement of the mechanism if needed. In other examples, the operating 20 mechanism 100 can be assembled directly into a circuit breaker (without the first and second plates). In some implementations, as discussed with reference to FIG. 3, a circuit breaker 300 is provided. The circuit breaker 300 comprising the operating mechanism 100, 100' 25 described above. The circuit breaker also comprises a housing 350. In some examples, the circuit breaker 300 comprises the system 200 described above. In other words, the system 200 comprising the first and second plates 140, 142 and the assembled operating mechanism 100, 100' can be provided within the circuit 30 breaker 300. In other examples, the first 104, 104' and second 108, 108' protrusions are formed from, or otherwise provided within, the housing 350 of the circuit breaker 300 itself. This can allow the operating mechanism to be directly assembled, in a modular manner, within the circuit breaker. 35 Optionally, the circuit breaker 300 comprises a first window or aperture 352 in the housing 350. In implementations where the operating mechanism 100, 100' comprises a contact indicator, the contact indicator can indicate a position of the moving contact 118, 118' to a user, for example through the window or aperture 352 in housing 350 of the circuit breaker 300 in which the mechanism is installed. Optionally, the circuit breaker 300 comprises a second window or aperture 354 in the 5 housing 350. An engagement portion of the knob 102, 102'of the operating mechanism 100, 100' can extend through said second window 354, thereby allowing for user (or manual) actuation of the engagement portion of the knob (not shown). In this way, the knob 102, 102' can be actuated from outside of the circuit breaker 300. In some examples, first window 352 and second window 354 form a single window or io aperture. A specific example arrangement of the operating mechanism 100 is now described in more detail with reference to FIGs. 4A, 4B, 4C, 4D and FIGs. 7A, 7B. 15 In accordance with FIGs. 1A, IB and 3, the operating mechanism 100 is provided between two plates, first plate 140 and second plate 142. The first and second plates 140, 142 can be coupled together (as shown in FIG. 4A) to retain the operating mechanism 100 between the plates. In this way, the entire operating mechanism 100 can be assembled onto the first plate 140, secured with the second plate 142, and 20 then placed as a stand-alone, modular component within a circuit breaker (not shown). This can facilitate retrofitting of the operating mechanism, as well as replacement of the mechanism if needed. The operating mechanism comprises a knob 102 configured to rotate around a first 25 protrusion 104 formed from or extending from the first plate 140. The knob is configured to rotate in response to user (or manual) actuation of an engagement portion of the knob 102a (e.g. through aperture or window 354 of circuit breaker 350, as shown in FIG. 7A, 7B). The operating mechanism 100 comprises a linking member 106 configured to be disposed on a second protrusion. The second protrusion (not 30 shown) extends from or is formed from the first plate 140. The linking member 106 and the knob 102 are offset from one another but arranged to be substantially coplanar with one another. This can provide for a more compact operating mechanism. The linking member 106 comprises a third protrusion 110, a fourth protrusion 112 and 35 a fifth protrusion 114. In this example, each of the third, fourth and fifth protrusions are formed integral to the linking member 106. These protrusions allow additional components to be disposed on the linking member, allowing for a modular, step by step assembly of the operating mechanism. The operating mechanism further comprises a contact indicator 470 which, in this specific example, is formed integral with the linking member. The contact indicator 470 indicates a position of the operating mechanism, and can be seen by a user 5 through a hole, aperture or window 352 in housing 350 of circuit breaker 300, as shown in FIG. 7A, 7B. The operating mechanism 100 comprises a contact holder 116 arranged to carry a movable (or moving) contact. The contact holder 116 is disposed on the third io protrusion 110 and configured to pivot around the third protrusion 110 in response to an application of force at the moving contact. In other words, the contact holder 116 can pivot with respect to the linking member 106. The operating mechanism 100 also comprises a first latch 120 disposed on the fourth 15 protrusion 112, where the contact holder 116 is arranged between the linking member 106 and the first latch 120. In this way, the contact holder can be retained within the operating mechanism between other components, reducing the likelihood of movement or bending of the contact holder 116. Moreover, the pivot point of the contact holder 116 (and thus the pivot point of the moveable / moving contact) is 20 arranged eccentrically to the pivot point of the first latch 120. This eccentric arrangement of the moving contact and first latch 120 facilitates a wiping action of the moving contact 118, thereby helping to ensure lower contact resistance. The operating mechanism 100 also comprises a second latch 124 disposed on the fifth 25 protrusion 114 and configured to rotate around the fifth protrusion. The first and second latches 120, 124 are arranged to be substantially co-planar, and are configured to engage with one another in at least some positions, as discussed below with reference to FIGs. 7A, 7B. 30 The operating mechanism 100 also comprises a pin 126. The pin 126 is disposed between the knob 102 and the second plate 142. The pin 126 couples the second latch 124 to the knob 102. The pin is in this example a U shaped pin, as shown in FIG. 4C. The first and second latches are configured to engage such that rotation of the knob around the first protrusion causes rotation of the linking member around the 35 second protrusion and thus a rotation of the contact holder, where the rotation of the knob is transferred by the pin 126. The first latch 120 is also configured to pivot around the fourth protrusion 112 in response to an application of force so as to disengage the first latch from the second latch 124 and enable rotation of the knob 102 independently of the first latch; this can facilitate a rapid breaking of a circuit comprising the movable contact in the event of a fault (during a trip). In an open position, as shown in FIG. 7A, the latches are touching but not engaged. 5 As the engagement portion 102a of the knob 102 is rotated anti-clockwise (in the view of FIG. 7A), the first latch rotates anti-clockwise (due to the coupling via the pin 126). The second latch 124 then engages with the first latch 120. In particular, it can be seen that both the first and second latches 120, 124 comprise stepped or notched surfaces which engage with each other, thereby preventing rotation of the first latch io 120 towards the second latch 124, and vice versa. As a result, continued rotation of the knob towards the closed position of FIG. 7B causes a corresponding rotation of the first latch 120 and thus of the linking member 106 and contact holder 116. This engagement is maintained during a manual opening action, i.e. in which the knob is manually rotated from the position of FIG. 7B to the position of FIG. 7A. 15 As shown in FIGs. 4A to 4D, the operating mechanism 100 further comprises a first torsion spring 130 configured to be disposed around the first protrusion 104. The knob 102 is disposed between the torsion spring 130 and the pin 126. The first torsion spring 130 is coupled to the knob 102 and configured to contact the first latch 20 120 (see FIGs. 4A, 4C). The first torsion spring is also configured to contact a fixed component, such as a housing of the circuit breaker. This first torsion spring 130 provides resistance during rotation of the knob 102 to close / make the circuit, thereby reducing accidental making of the circuit, and also provides a biasing force to the first latch to maintain the first latch in a correct position during a tripping event and 25 thereby control the movement of the linking member 106. This arrangement provides a bi-functional spring, allowing the elimination of at least one spring as compared to conventional arrangements (which can have separate latch and knob springs); the number of components can therefore be reduced. By providing a first torsion spring in this way, the biasing force can also be independently controlled through the choice 30 and parameters of the first torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. The operating mechanism further comprises a second torsion spring 132 disposed 35 around the third protrusion 110, the contact holder 116 arranged between the linking member 106 and the second torsion spring 132. The second torsion spring is coupled to the contact holder and configured to contact the linking member (see FIG. 4B). The second torsion spring 132 provides a force to the contact holder 116 to ensure a good contact between the moveable contact and another electrical component of the circuit breaker when making the circuit. In this way, the second torsion spring 132 can hold the moving contact in electrical and physical contact with the circuit as the contact holder 116 pivots around the third protrusion (i.e. as the linking member 5 moves underneath the contact holder 116, whilst the contact holder is stopped from moving further by the contact force at the movable contact 118). By providing a second torsion spring 132 in this way, the contact force can be independently controlled through the choice and parameters of the second torsion spring 132. This enables the torsion spring parameters to be optimised for one or more performance io criteria of the mechanism, increasing the flexibility of the mechanism. The operating mechanism 100 also comprises a spring 134 in contact with the linking member 106. In this specific example the spring is a compression spring. At the other end of the spring from the linking member 106, the spring is configured to 15 contact the first plate 142, i.e. the first plate provides the resistance that causes the spring to compress when the linking member rotates in a clockwise direction (as viewed from the side on perspective of FIG. 4C). The spring 134 is configured to extend and compress as the linking member 106 rotates around the second protrusion 108, and is arranged so as to rotate the linking member 106 around the second 20 protrusion 108 when the first latch 120 disengages from the second latch 124. This provides a rapid breaking of the circuit in case of a trip event. By providing a separate spring 134 in this way, the breaking velocity and breaking force can be independently controlled through the choice and parameters of the spring. This enables the spring parameters to be optimised for one or more performance criteria of the operating 25 mechanism, increasing the flexibility of the mechanism 100. In particular, during a tripping action, a force F is applied to the first latch, as shown in FIG. 7B. The first latch 120 is configured to pivot around the fourth protrusion 112 in response to this application offeree on one side of the pivot; in this specific 30 example, when the force F is applied to the first latch 120 at an opposite side of the pivot to the second latch 124, the first latch rotates away from the second latch. This disengages the latches and allows rotation of the second latch 124 in either direction around the fifth protrusion 114. The compressed spring 134 then drives the linking member, and thus the contact holder 116 and the second latch towards the open 35 position of FIG. 7A; due to the coupling of the pin, the knob 102 also moves towards the open position. This can facilitate a rapid breaking of a circuit comprising the movable contact in the event of a fault (during a trip). Another specific example arrangement of the operating mechanism 100 is now described in more detail with reference to FIG. 5 and FIGs. 8A, 8B. In accordance with FIGs. 1A, IB and 3, the operating mechanism 100 is provided 5 between two plates, first plate 140 and second plate (not shown). The first and second plates can be coupled together to retain the operating mechanism 100 between the plates. In this way, the entire operating mechanism 100 can be assembled onto the first plate 140, secured with the second plate, and then placed as a stand-alone, modular component within a circuit breaker (not shown). This can io facilitate retrofitting of the operating mechanism, as well as replacement of the mechanism if needed. The operating mechanism comprises a knob 102 configured to rotate around a first protrusion formed from or extending from the first plate 140. The knob is configured 15 to rotate in response to user (or manual) actuation of an engagement portion of the knob 102a (e.g. through aperture or window 354 of circuit breaker 350, as shown in FIG. 8A, 8B). The operating mechanism 100 comprises a linking member 106 configured to be disposed on a second protrusion. The second protrusion (not shown) extends from or is formed from the first plate 140. The linking member 106 and the 20 knob 102 are offset from one another but arranged to be substantially co-planar with one another. This can provide fora more compact operating mechanism. The linking member 106 comprises a third protrusion 110, a fourth protrusion 112 and a fifth protrusion 114. In this example, each of the third, fourth and fifth protrusions 25 are formed integral to the linking member 106. These protrusions allow additional components to be disposed on the linking member, allowing for a modular, step by step assembly of the operating mechanism. The operating mechanism further comprises a contact indicator 470 which, in this 30 specific example, is coupled to the linking member. The contact indicator 470 can be rigidly coupled to the linking member, or rotationally coupled around a pivot point (not shown). The contact indicator 470 indicates a position of the operating mechanism, and can be seen by a user through a hole, aperture or window 352 in housing 350 of circuit breaker 300, as shown in FIG. 8A, 8B. 35 The operating mechanism 100 comprises a contact holder 116 arranged to carry a movable (or moving) contact. The contact holder 116 is disposed on the third protrusion 110 and configured to pivot around the third protrusion 110 in response to an application of force at the moving contact. In other words, the contact holder 116 can pivot with respect to the linking member 106. The operating mechanism 100 also comprises a first latch 120 disposed on the fourth 5 protrusion 112, where the contact holder 116 is arranged between the linking member 106 and the first latch 120. In this way, the contact holder can be retained within the operating mechanism between other components, reducing the likelihood of movement or bending of the contact holder 116. Moreover, the pivot point of the contact holder 116 (and thus the pivot point of the moveable / moving contact) is io arranged eccentrically to the pivot point of the first latch 120. This eccentric arrangement of the moving contact and first latch 120 facilitates a wiping action of the moving contact 118, thereby helping to ensure lower contact resistance. The operating mechanism 100 also comprises a second latch 124 disposed on the fifth 15 protrusion 114 and configured to rotate around the fifth protrusion. The first and second latches 120, 124 are arranged to be substantially co-planar, and are configured to engage with one another in at least some positions, as discussed below with reference to FIGs. 8A, 8B. 20 The operating mechanism 100 also comprises a pin 126. The pin 126 is disposed between the knob 102 and the second plate 142. The pin 126 couples the second latch 124 to the knob 102. The pin is in this example a U shaped pin, as shown in FIG. 5. The first and second latches are configured to engage such that rotation of the knob around the first protrusion causes rotation of the linking member around the 25 second protrusion and thus a rotation of the contact holder, where the rotation of the knob is transferred by the pin 126. The first latch 120 is also configured to pivot around the fourth protrusion 112 in response to an application of force so as to disengage the first latch from the second latch 124 and enable rotation of the knob 102 independently of the first latch; this can facilitate a rapid breaking of a circuit 30 comprising the movable contact in the event of a fault (during a trip). In an open position, as shown in FIG. 8A, the latches are touching but not engaged. As the engagement portion 102a of the knob 102 is rotated anti-clockwise (in the view of FIG. 8A), the first latch rotates anti-clockwise (due to the coupling via the pin 126). 35 The second latch 124 then engages with the first latch 120. In particular, it can be seen that both the first and second latches 120, 124 comprise stepped or notched surfaces which engage with each other, thereby preventing rotation of the first latch 120 towards the second latch 124, and vice versa. As a result, continued rotation of the knob towards the closed position of FIG. 8B causes a corresponding rotation of the first latch 120 and thus of the linking member 106 and contact holder 116. This engagement is maintained during a manual opening action, i.e. in which the knob is manually rotated from the position of FIG. 8B to the position of FIG. 8A. 5 The operating mechanism 100 further comprises a first torsion spring 130' configured to be disposed around the first protrusion 104. The knob 102 is disposed between the torsion spring 130' and the pin 126. The first torsion spring 130' is coupled to the knob 102 and configured to contact the first plate 140 (see FIG. 5) such that an end of io the torsion spring 130' is fixed. In other examples, the first torsion spring can be configured to contact another fixed component, such as a housing of the circuit breaker. This first torsion spring provides resistance during rotation of the knob to close / make the circuit, thereby reducing accidental making of the circuit. By providing a first torsion spring, the resistance force can also be independently controlled through 15 the choice and parameters of the first torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. The operating mechanism further comprises a second torsion spring 132 disposed 20 around the third protrusion 110, the contact holder 116 arranged between the linking member 106 and the second torsion spring 132. The second torsion spring is coupled to the contact holder 116 and configured to contact the linking member 106, as shown in FIG. 5. The second torsion spring provides a force to the contact holder to ensure a good contact between the moveable contact and another electrical component when 25 making the circuit. In this way, the second torsion spring can hold the moving contact in electrical and physical contact with the circuit as the linking member moves underneath (i.e. as the contact holder pivots with respect to the linking member around the third protrusion). By providing a second torsion spring, the contact force can be independently controlled through the choice and parameters of the second 30 torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. The operating mechanism of this example further comprises a third torsion spring 35 136', the third torsion spring 136' coupled to the first latch 120 and configured to contact the linking member 106. This third torsion spring provides a biasing force to the first latch to maintain the first latch in a correct position during a tripping event and thereby control the movement of the linking member. By providing a third torsion spring, the spring force of the first latch can be independently controlled through the choice and parameters of the third torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. 5 The operating mechanism 100 also comprises a spring 134 in contact with the linking member 106. In this specific example the spring is a compression spring. At the other end of the spring from the linking member 106, the spring is configured to contact the first plate 142, i.e. the first plate provides the resistance that causes the io spring to compress when the linking member rotates in a clockwise direction (as viewed from the perspective of FIG. 5). The spring 134 is configured to extend and compress as the linking member 106 rotates around the second protrusion 108, and is arranged so as to rotate the linking member 106 around the second protrusion 108 when the first latch 120 disengages from the second latch 124. This provides a rapid 15 breaking of the circuit in case of a trip event. By providing a separate spring 134 in this way, the breaking velocity and breaking force can be independently controlled through the choice and parameters of the spring. This enables the spring parameters to be optimised for one or more performance criteria of the operating mechanism, increasing the flexibility of the mechanism 100. 20 In particular, during a tripping action, a force F is applied to the first latch, as shown in FIG. 8B. The first latch 120 is configured to pivot around the fourth protrusion 112 in response to this application offeree on one side of the pivot; in this specific example, when the force F is applied to the first latch 120 at an opposite side of the 25 pivot to the second latch 124, the first latch rotates away from the second latch. This disengages the latches and allows rotation of the second latch 124 in either direction around the fifth protrusion 114. The compressed spring 134 then drives the linking member, and thus the contact holder 116 and the second latch towards the open position of FIG. 8A; due to the coupling of the pin, the knob 102 also moves towards 30 the open position. This can facilitate a rapid breaking of a circuit comprising the movable contact in the event of a fault (during a trip). A specific arrangement of the operating mechanism 100' is now described in more detail with reference to FIG. 6 and FIGs. 9A, 9B. In accordance with FIGs. 2A and 2B, 35 the operating mechanism 100' is provided. The mechanism can be assembled between two plates (not shown) or directly into a circuit breaker. The operating mechanism 100' comprises a knob 102' configured to rotate around a first protrusion 104'. The knob is configured to rotate in response to user (or manual) actuation of an engagement portion of the knob 102a. The engagement portion can extend from a housing of a circuit breaker containing the operating mechanism 100' to 5 facilitate actuation of the knob (e.g. can extend through aperture or window 354 of circuit breaker 350, as shown in FIG. 9A, 9B). The knob can also be configured to rotate independent of user actuation in the event of a fault (trip), as discussed in more detail below. io The operating mechanism 100' comprises a linking member 106' configured to rotate around a second protrusion 108'. The linking member 106' comprises a third protrusion 110'. The linking member 106' and the knob 102' are offset from one another and are arranged substantially co-planar with one another. This can provide for a more compact operating mechanism. 15 The operating mechanism further comprises a contact indicator 470. The contact indicator can indicate a position of the moving contact to a user, for example through a window or aperture in a housing of the circuit breaker in which the mechanism is installed (e.g. the indicator 470 can be seen by a user through a hole, aperture or 20 window 352 in housing 350 of circuit breaker 300, as shown in FIG. 9A, 9B). In this example, the contact indicator is integral with the linking member 106'. This can improve reliability of the indicator. The operating mechanism 100' comprises a contact holder 116' arranged to carry a 25 movable (or moving) contact. The contact holder 116' is coupled to the linking member 106'. The contact holder 116' can be rigidly coupled to the linking member 106'. However, in this example, the contact holder is coupled to the linking member 106' by way of being disposed around the third protrusion 110'. The contact holder 116' is configured to pivot around the third protrusion 110' in response to an 30 application of force at the moving contact. In other words, the contact holder can pivot with respect to the linking member 106'. This can improve the contact force applied at the moving contact, ensuring a good electrical connection to the rest of the circuit breaker. 35 The operating mechanism 100' comprises a latch 120' disposed on the third protrusion 110'. The latch 120' is configured to pivot around the third protrusion 110' in response to an application of force. The contact holder 116' is arranged between the linking member 106' and the latch 120'. In this way, the contact holder can be retained within the operating mechanism 100' between other components, reducing the likelihood of movement or bending of the contact holder 116', and thus of the moveable contact. The pivot point of the contact holder 116' (and thus the pivot point of the moveable / moving contact) is arranged eccentrically to the pivot point of the 5 latch 120'. This eccentric arrangement of the moving contact and latch 120'facilitates a wiping action of the moving contact, thereby helping to ensure lower contact resistance. The operating mechanism 100' comprises a pin 126'. The pin 126' couples the latch io 120' to the knob 102'. The pin is a U shaped pin, as shown in FIG. 6. The pin and latch are configured to engage in at least some positions, as discussed with reference to FIGs. 9A, 9B. In an open position, as shown in FIG. 9A, the pin 126' and latch 120' are engaged. In 15 particular, the latch 120' comprises a notch or recess which is configured to engage with the pin 126' such that rotation of the knob 102'causes rotation of the linking member 106' around the second protrusion 108' and thus a rotation of the contact holder 116'. As a result, rotation of the knob from the open position of FIG. 9A towards the closed position of FIG. 9B causes a corresponding rotation of the latch 20 120' and thus of the linking member 106' and contact holder 116'. This engagement is maintained during a manual opening action, i.e. in which the knob is manually rotated from the position of FIG. 9B to the position of FIG. 9A. The operating mechanism 100' further comprises a first torsion spring 130' configured 25 to be disposed around the first protrusion 104'. The knob 102' is disposed between the torsion spring 130' and the pin 126'. The first torsion spring 130' is coupled to the knob 102' and configured to contact a fixed component of the circuit breaker (this contact is not shown here). This first torsion spring 130' provides resistance during rotation of the knob 102' to close / make the circuit, thereby reducing accidental 30 making of the circuit. By providing a first torsion spring 130' in this way, the resistance force can be independently controlled through the choice and parameters of the first torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of the mechanism 100', increasing the flexibility of the mechanism. 35 The operating mechanism further comprises a second torsion spring 132' disposed around the third protrusion 110', the contact holder 116 arranged between the linking member 106 and the second torsion spring 132. The second torsion spring 132' is coupled to the contact holder 116' and configured to contact the linking member 106' (this contact is not shown here). The second torsion spring 132' provides a force to the contact holder 116' to ensure a good contact between the moveable contact and another electrical component of the circuit breaker when making the circuit. In this 5 way, the second torsion spring 132' can hold the moving contact in electrical and physical contact with the circuit as the linking member pivots around the third protrusion 110' underneath the contact holder 116'. By providing a second torsion spring 132' in this way, the contact force can be independently controlled through the choice and parameters of the second torsion spring 132'. This enables the torsion io spring parameters to be optimised for one or more performance criteria of the mechanism, increasing the flexibility of the mechanism. The operating mechanism 100' further comprises a spring 134' in contact with the linking member 106'. In this specific example the spring is a compression spring. At 15 the other end of the spring from the linking member 106', the spring is configured to contact a fixed component (for example part of the housing of the circuit breaker, not shown) to provide the resistance that causes the spring 134' to compress when the linking member rotates in a clockwise direction (as viewed from the perspective of FIG. 6). The spring 134' is configured to extend and compress as the linking member 20 106' rotates around the second protrusion 108', and is arranged so as to rotate the linking member 106' around the second protrusion 108' when the latch 120' disengages from the pin 126'. This provides a rapid breaking of the circuit in case of a trip event. By providing a separate spring 134' in this way, the breaking velocity and breaking force can be independently controlled through the choice and parameters of 25 the spring. This enables the spring parameters to be optimised for one or more performance criteria of the operating mechanism, increasing the flexibility of the mechanism 100'. In particular, during a tripping action, a force F is applied to the latch 120', as shown 30 in FIG. 9B. The latch is configured to pivot around the third protrusion 110' in response to this application of force; in this specific example, when the force F is applied at an opposite side of the third protrusion 110' from the notch, the latch 120' rotates / pivots away from the pin. This disengages the latch 120' from the pin 126' and enables rotation of the knob 102' independently of the latch. The compressed 35 spring 134' then drives the linking member, and thus the contact holder 116' and the towards the open position of FIG. 9A; due to the coupling of the pin, the knob 102' also moves towards the open position. This can facilitate a rapid breaking of a circuit comprising the movable contact in the event of a fault (during a trip). The operating mechanism 100' further comprises a third torsion spring 136'. The third torsion spring 136' is coupled to the linking member 106' and configured to contact the latch 120' (as shown in FIG. 6). This third torsion spring 136' provides a biasing 5 force to the latch 120' to maintain the latch in a correct position during a tripping event and thereby control the movement of the linking member 106'. By providing a third torsion spring 136', the spring force of the latch 120' can be independently controlled through the choice and parameters of the third torsion spring. This enables the torsion spring parameters to be optimised for one or more performance criteria of io the mechanism, increasing the flexibility of the mechanism. In accordance with FIG. 10, described herein is a method of assembling an operating mechanism 100 of a circuit breaker 300, the operating mechanism in accordance with the first aspect. 15 The method comprises at step 1002 disposing a knob on a first protrusion, the knob configured to rotate around the first protrusion. The method comprises at step 1004 disposing a linking member on a second protrusion, the linking member configured to rotate around the second protrusion, wherein the first and second protrusions are 20 parallel, the linking member comprising a third protrusion, a fourth protrusion and a fifth protrusion. The method comprises at step 1006 disposing a contact holder on the third protrusion, the contact holder arranged to carry a movable contact. The method comprises at step 1008 disposing a first latch on the fourth protrusion, such that the contact holder is arranged between the linking member and the first latch. The 25 method comprises at step 1010 disposing a second latch on the fifth protrusion, the second latch configured to rotate around the fifth protrusion. The method comprises at step 1012 providing a pin, the pin coupling the second latch to the knob. Optionally, the method comprises disposing a first torsion spring on the first 30 protrusion before step 1002. Optionally, the method comprises disposing a second torsion spring on the third protrusion between steps 1006 and 1008. Optionally the method comprises providing a spring contacting the linking member. As described herein, the first and second latches are configured to engage such that 35 rotation of the knob around the first protrusion causes rotation of the linking member around the second protrusion and thus a rotation of the contact holder. Moreover, the first latch is configured to pivot around the fourth protrusion in response to an application of force so as to disengage the first latch from the second latch and enable rotation of the knob independently of the first latch. In accordance with FIG. 11, described herein is a method of assembling an operating 5 mechanism 100' of a circuit breaker 300, the operating mechanism in accordance with the second aspect. The method comprises at step 1102 disposing a knob on a first protrusion, the knob configured to rotate around the first protrusion. The method comprises at step 1104 io disposing a linking member on a second protrusion, the linking member configured to rotate around the second protrusion, wherein the first and second protrusions are parallel, the linking member comprising a third protrusion. The method comprises at step 1106 coupling a contact holder, arranged to carry a movable contact, to the linking member. The method comprises at step 1108 disposing a latch on the third 15 protrusion, such that the contact holder is arranged between the linking member and the latch. The method comprises at step 1110 providing a pin, the pin coupling the linking member to the knob. As described herein, the pin and latch are configured to engage such that rotation of 20 the knob causes rotation of the linking member around the second protrusion and thus a rotation of the contact holder. Moreover, the latch is configured to pivot around the third protrusion in response to an application of force so as to disengage the latch from the pin and enable rotation of the knob independently of the latch.

Claims

1. An operating mechanism (100) for a circuit breaker, comprisinga knob (102) configured to be disposed on a first protrusion (104) and5 configured to rotate around the first protrusion (104);a linking member (106) configured to be disposed on a second protrusion (108) and configured to rotate around the second protrusion (108), wherein the first (104) and second (108) protrusions are parallel, the linking member (106) comprising a third protrusion (110), a fourth protrusion (112) and a fifth protrusion (114);io a contact holder (116) arranged to carry a movable contact (118), the contactholder (116) disposed on the third protrusion (110),a first latch (120) disposed on the fourth protrusion (112), the contact holder (116) arranged between the linking member (106) and the first latch (120);a second latch (124) disposed on the fifth protrusion (114) and configured to15 rotate around the fifth protrusion (114); anda pin (126) coupling the second latch (124) to the knob (102), wherein:the first (120) and second (124) latches are configured to engage such that rotation of the knob (102) around the first protrusion (104) causes rotation of the linking member (106) around the second protrusion (108) and thus a rotation of the 20 contact holder (116), andthe first latch (120) is configured to pivot around the fourth protrusion (112) in response to an application of force so as to disengage the first latch (120) from the second latch (124) and enable rotation of the knob (102) independently of the first latch (120).

252. The operating mechanism (100) of claim 1, further comprising:a first torsion spring (130) configured to be disposed around the first protrusion (104), the knob (102) disposed between the torsion spring (130) and the pin (126),30 wherein the first torsion spring (130) is coupled to the knob (102) andconfigured to contact the first latch (120).

3. The operating mechanism (100) of claim 1 or claim 2,wherein the contact holder (116) is configured to pivot around the third35 protrusion (110) in response to an application of force at the moving contact (118), the operating mechanism (100) further comprising a second torsion spring (132) disposed around the third protrusion (110), the contact holder (116) arranged between the linking member (106) and the second torsion spring (132), where thesecond torsion spring (132) is coupled to the contact holder (116) and configured to contact the linking member (106).

4. The operating mechanism (100) of claim 3, wherein the moving contact (118)5 is arranged eccentrically to the third protrusion (110).

5. The operating mechanism (100) of any preceding claim, further comprising a spring (134) in contact with the linking member (106), the spring (134) configured to extend and compress as the linking member (106) rotates around the secondio protrusion (108),wherein the spring (134) is configured to rotate the linking member (106) around the second protrusion (108) when the first latch (120) disengages from the second latch (124).15 6. The operating mechanism (100) of any preceding claim, wherein the third(110), fourth (112) and fifth protrusions (114) extend in a same direction as the first (104) and second (108) protrusions.

7. The operating mechanism (100) of any preceding claim, wherein the second 20 (108) and third protrusions (112) are co-axial, optionally, wherein the third protrusionis an extension of the second protrusion.

8. An operating mechanism (100') for a circuit breaker, comprisinga knob (102') configured to be disposed on a first protrusion (104') and25 configured to rotate around the first protrusion (104');a linking member (106') configured to be disposed on a second protrusion (108') and configured to rotate around the second protrusion (108'), wherein the first (104') and second (108') protrusions are parallel, the linking member (106') comprising a third protrusion (110');30 a contact holder (116') arranged to carry a movable contact (118'), the contactholder (116') coupled to the linking member (106'),a latch (120') disposed on the third protrusion (110'), the contact holder (116') arranged between the linking member (106') and the latch (120'); anda pin (126') coupling the linking member (106') to the knob (102'), wherein:35 the pin (126') and latch (120') are configured to engage such that rotation ofthe knob (102') causes rotation of the linking member (106') around the second protrusion (108') and thus a rotation of the contact holder (116'), andthe latch (120') is configured to pivot around the third protrusion (110') in response to an application of force so as to disengage the latch (120') from the pin (126') and enable rotation of the knob (12') independently of the latch (120').5 9. The operating mechanism (100') of claim 8, further comprising:a first torsion spring (130') configured to be disposed around the first protrusion (104'), the knob (102') disposed between the torsion spring (130') and the pin (126'),wherein the first torsion spring (130') is coupled to the knob (102') and an end io of the torsion spring is fixed.

10. The operating mechanism (100') of claim 8 or claim 9, wherein the contact holder (116') is disposed around the third protrusion (110') and configured to pivot around the third protrusion (110') in response to an15 application of force at the moving contact (118'), optionally, the operating mechanism (100') further comprising a second torsion spring (132') disposed around the third protrusion (110'), the contact holder (116') arranged between the linking member (106') and the second torsion spring (132'), where the second torsion spring (132') is coupled to the contact holder (116') and20 configured to contact the linking member (106').

11. The operating mechanism (100') of any of claims 8 to 10, further comprising a spring (134') in contact with the linking member (106'), the spring (134') configured to extend and compress as the linking member (106') rotates around the second25 protrusion (108'),wherein the spring (134') is configured to rotate the linking member (106') around the second protrusion (108') when the latch (120') disengages from the pin (126').30 12. The operating mechanism (100') of any of claims 8 to 11, further comprising athird torsion spring (136'), the third torsion spring (136') coupled to the linking member (106') and configured to contact the latch (120').

13. The operating mechanism (100, 100') of any preceding claim, further35 comprising a contact indicator (470), wherein:the contact indicator (470) is integral with the linking member (106, 106'); or the contact indicator (470) is coupled to the linking member (106, 106'), optionally rotatably coupled.

14. A system (200) comprising the operating mechanism (100, 100') of any preceding claim, the system (200) further comprising:a first plate (140), the first plate (140) comprising the first (104, 104') and5 second (108, 108') protrusions; anda second plate (142), the pin (126, 126') disposed between the knob (102, 102') and the second plate (142), the first (140) and second (142) plates coupled together.io 15. A circuit breaker (300) comprising the operating mechanism (100, 100') of any of claims 1 to 12, the circuit breaker further comprising a housing (350), the housing comprising the first (104, 104') and second (108, 108') protrusions.

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