EP1805776B1

EP1805776B1 - Mechanism for safety switch

Info

Publication number: EP1805776B1
Application number: EP05851050A
Authority: EP
Inventors: Aloysius Gerardus Majella Hemmer
Original assignee: Eaton Industries Netherlands BV
Current assignee: Danfoss Power Solutions II BV
Priority date: 2004-10-26
Filing date: 2005-10-26
Publication date: 2011-12-14
Anticipated expiration: 2025-10-26
Also published as: EP1805776A2; ES2378891T3; WO2006046869A2; ATE537546T1; WO2006046869A3; NL1027340C2; SI1805776T1; PL1805776T3

Abstract

Mechanism for switching on and off a switch (50) provided with a primary switching Junction and at least one safety function. The mechanism comprises a movable contact (T) and a fixed contact (35), wherein the movable contact (7) is fixed by fixing means (6) in the switch (50) such that it can execute a turning and translational movement. An ON/OFF switch toggle (4) engages at a first engagement point (51) on the movable contact (7). The mechanism also comprises a spring (3) that engages at a second engagement point (56) on the movable contact (7). The fixing means (6), the first engagement point (51) and the second engagement point (56) are so positioned with respect to one another that, when the switch (50) is switched on, turning of the ON/OFF switch toggle (4) beyond a predetermined position of the ON/OFF switch toggle (4) results in a reversal of themoment acting on the movable contact (T).

Description

Field of the invention

The present invention relates to a mechanism for a switch provided with a primary switching function and at least one safety function, such as a safety switch, and to a safety switch containing such a mechanism. More particularly, the present invention relates to a mechanism for switching on and off a switch, such as a safety switch, comprising a movable contact that can be moved with respect to a fixed contact from a first position to a second position, the switch being switched on or, alternatively, switched off, wherein the movable contact is fixed by fixing means in the switch such that it can execute a turning and translational movement, an ON/OFF Switch toggle to operate the switch, wherein the ON/OFF switch toggle is connected via an actuator arm to the movable contact, wherein the actuator arm engages at a first engagement point on the movable contact, and a spring that engages at a second engagement point on the movable contact in order to exert a force thereon.

State of the art

Such a mechanism, as described in the preamble of claim 1, for switching on and off a switch is known from the publication WO 92/21134 . This mechanism for an automatic switch ensures that the switch is quickly switched off if a protective device is actuated. This mechanism is provided with a spring, a locking device, an operating toggle and a moving contact, wherein the moving contact is provided with a slot for accommodating a fixed pivot point. In the event that the mechanism is switched off by release of the lock, the slot ensures that the tension in the spring causes the moving contact to move away from the fixed contact in a quick and controlled manner. However, switching on the switch via the operating toggle occurs such that the speed and force with which switching on takes place depend on the person operating the operating toggle. The slot in the moving contact ensures in this case only that the spring tension holds the moving contact firmly against the fixed contact.
A further switching mechanism is known from German Patent Application DE-A 199 33 166 . This publication describes a switch for a phase conductor or a neutral conductor, wherein a moving contact is brought into contact with a fixed contact by means of rotation about a pivot point Limited translational movement of the movable contact can also take place as a result of a slot in the movable contact A spring engages the movable contact at a location on the movable contact between the translational pivot point and the place where contact is made with the fixed contact. This spring stores energy when the switch is switched on, which energy is used to move the contacts quickly apart when the switch is switched off. The moving contact is operated from the outside via a toggle which is connected to the movable contact via an actuator arm. The actuator arm comprises an intermediate piece that is attached to the toggle such that it can turn and a pressure piece that is attached at one end to the intermediate piece such that it can turn and attached at the other end to the moving contact such that it can turn. As a result of the switch on movement (rotation) of the toggle, the movable contact is moved towards the fixed contact via the actuator arm. Because of the slot in the movable contact, the movable contact can be locked against the pressure of the spring by a locking device on the actuator arm, as a result of which the contacts are forcibly pressed against each other. The speed and force with which the switch-on process takes place depends on the force and speed with which the toggle is moved. Switching on therefore does not always take place with the same force and speed.
Switching on the switch depending on the way in which it is operated, as known from the abovementioned state of the art, can result in fusion of the contacts whenever high load currents are applied, causing a reduction in the service life of the switch.

Summary of the invention

The present invention seeks to provide a mechanism for a switch wherein switching on and off takes place independently of the person operating the switch.
According to the present invention, a mechanism of the type defined in the preamble is provided wherein the fixing means, the first engagement point and the second engagement point are so positioned with respect to one another that when the switch is switched on turning of the ON/OFF switch toggle beyond a predetermined position of the ' ON/OFF switch toggle results in a reversal of the moment acting on the movable contact. Consequently, when the switch is switched on, the spring suddenly works in the opposite direction, as a result of which switching on of the switch takes place independently of the person, in other words always with the same force and speed.
In one embodiment of the present mechanism the fixing means, the first engagement point and the second engagement point form a triangle on the movable contact, as a result of which the forces acting on the movable contact generate a moment about a momentary pivot point of the movable contact, and a force exerted by the actuator arm on the first engagement point results in a reactive force from the fixing means, wherein the reactive force at the predetermined position results in a translational movement of the movable contact, as a result of which the direction of the moment reverses. This permits the desired functionality of the mechanism (person-independent ON/OFF switching) to be achieved with a minimum of components. A switch in which such a mechanism is used can therefore be further miniaturised.
In a further embodiment the fixing means are made up of a spindle that is fixed to the moving contact such that it can turn, and the spindle can perform a translational movement in a slot in the switch. This permits better definition of the translational movement of the moving contact, and the reversing moment can be better defined. In this embodiment the switch geometry and timing do not depend on the position of the moving contact as in the state of the art.
The object of the invention is also to provide a mechanism that, in addition to its primary switching function, is also suitable in a simple yet effective and reliable manner for operating the protective functions against short-circuit currents, overload currents and earth fault currents separately or in combination. To that end, the mechanism comprises in a further embodiment a trip lever, which, by means of the fixing means, is connected to the movable contact by the fixing means such that it can turn and is provided with a locking surface on a first side, by means of which the actuator arm is locked when the switch is in the ON position. The trip lever can be rotated by means of a switching off actuator in such a way that the locking surface no longer locks the actuator arm. The mechanism is switched off by rotation of the trip lever, which causes the locking device to withdraw and the contact to be broken. The trip lever can be actuated by all the possible protective devices in a switch, such as a short circuit protective device, an overload protective device or an earth fault protective device. If the ON/OFF switch toggle is provided with its own reset spring, the mechanism is known as a trip-free type; the mechanism can switch the switch off even if the ON/OFF switch toggle is mechanically blocked.
In one embodiment the trip lever has a projection that can be moved by a switching off actuator via a trip pawl, wherein the trip pawl is spring-mounted in the switch and resets the switching off actuator. This ensures the automatic resetting of the trip system of the earth leakage protective device and the overload protective device.
In a further embodiment the trip lever is mechanically connected via a projection to a coupling part fixed in the switch such that it can slide. This makes it possible to transfer the mechanism's status to further mechanisms (external coupling) or to operate the mechanism by an external mechanism.
In a further aspect the present invention relates to a switch for switching on and off an electrical circuit with a phase side and a neutral side which comprise respective fixed and movable contacts, wherein the phase side and the neutral side are both provided with a mechanism according to the present invention, wherein the mechanism on the phase side is mechanically connected to the mechanism on the neutral side by means of the coupling part, which is mechanically connected to projections on the respective trip levers.
In one embodiment the mechanism on the phase side and the mechanism on the neutral side are so constructed that, when the switch is switched off, the contacts on the phase side open before the contacts on the neutral side and, when the switch is switched on, the contacts on the neutral side close before the contacts on the phase side. This can be achieved, for example, by making the appropriate choice regarding the location and geometry of the mechanism.
In a further aspect the present invention relates to a switch for switching on and off an electrical circuit, wherein the switch is provided with a mechanism according to the present invention, a housing and at least one safety device, wherein the at least one safety device is equipped to protect the switch against short-circuit current, overload current and/or earth fault currents, and wherein the mechanism and each of the safety devices present are installed in the housing in a modular manner. Because all the functions of the switch (also known as a safety switch) are installed in a single housing in a modular manner, a more reliably operating switch is obtained that is also easier to build.

Brief description of the drawings

The present invention will now be discussed in greater detail on the basis of a number of illustrative embodiments, with reference to the appended drawings, in which

Fig. 1 shows a plan view of a phase side of a safety switch according to one embodiment of the present invention;
Fig. 2 shows a plan view of a neutral side of the safety switch in Fig. 1;
Fig. 3 shows an enlarged view of the mechanism on the phase side according to one embodiment of the present invention;
Figs 4 and 5 show simplified representations of the forces that play a role in switching off the mechanism illustrated in Fig. 3, just before and just after being switched off; and
Fig. 6 shows an enlarged view of the mechanism on the neutral side according to one embodiment of the present invention.

Detailed description of illustrative embodiments

Fig. 1 shows a plan view of a safety switch 50 according to one embodiment of the present invention. The safety switch 50 combines four functions in one:

the primary switching function to make or break an electrical circuit;
the protection against short-circuit current;
the protection against overloads; and
the protection against earth fault currents.

These functions are combined in the housing of switch 50 in the form of modules together with the mechanism which is also made as a stand-alone module. Consequently, for different functions, separate elements or modules (switch, earth leakage protective device, etc.) do not have to be installed next to each other in separate housings and electrically and/or mechanically connected. As a result of the special modular design and build of the various components of the switch 50 according to the present invention, it is not only possible to implement the abovementioned functions inside the standardised DIN module housing with a height of 90 mm and a depth of 50 mm, but it is even possible to reduce the width of the switch 50 further, certainly in comparison with existing products. In one embodiment the height of the switch is 90 mm and the width 18 mm, giving a total volume of 87 cm³. Existing switches, such as the Alamat III range of double-pole switches with an automatic earth leakage protective device made by the applicant, have a total volume of 168 cm³. Another type of automatic, single-pole earth leakage circuit breaker from a known manufacturer has a volume of 106 cm³.
The safety switch 50 as shown in Fig. 1 has a housing 31 in two parts. In the plan view in Fig.1, one part of the housing on the phase side of the switch 50 has been omitted. In the plan view in Fig. 2, which shows the neutral side of the switch 50, the part of the housing 31 on the neutral side has been omitted. A support element 32 has been installed on the inside of the housing 31. The various components of the switch 50 are fixed to the support element 32, as a result of which automated stacked assembly is also possible. The support element 32 additionally constitutes a separation (electrical and mechanical) between the phase side and the neutral side of the switch 50. Only in the places where there are relatively thick elements, or elements that are present on both the phase and the neutral side (such as detector coil 9 and ON/OFF switch toggle 4, see below), is there a cut-out in the support element. If there are relatively thick elements on, for example, only the phase side, such as short-circuit contact breaker 2 or explosion chamber 15 (see below), a recess can then have been made in the support element 32. The support element also has contact areas where electrical connections which are easy to fit and remove again can be made between the various components by means of a compression spring or a clip connection, as described in greater detail below.
On the phase side (see Fig. 1) there is an incoming phase terminal 1 for attaching an electrical conductor. In the embodiment shown, this terminal 1 is of the box terminal type with captive screw in which a connecting wire can be firmly fixed electrically and mechanically. A conductor 60 (see the description for Fig. 3 below) connects the terminal 1 to a short circuit contact breaker 2. The other terminal 61 of the short circuit contact breaker 2 supports the fixed contact 35 of the switch 50. The movable contact 7 (or phase contact) is connected via a wire 36 to an overload contact breaker 11 in the form of a bimetal strip. If too high a current passes through the bimetal strip 11 for a long time (for example in the event of a sustained current above the rated level), this will bend as a result of the heat generated and activate a trip mechanism (see below). The phase is conducted further from the bimetal strip to an outgoing phase terminal 12, to which an electrical conductor can be connected analogously to incoming phase terminal 1.
On the neutral side (see Fig. 2) there is an incoming neutral terminal 17 for attaching an electrical conductor. This terminal 17 is connected via a conductor to a fixed neutral contact 37. The movable neutral contact 19 is connected via a conductor 38 to an outgoing neutral terminal 21, to which in turn an electrical conductor can be connected. The neutral terminals 17, 21 are made as box terminals with captive screw just like the phase terminals 1,12.
For earth leakage protection, use is made of a detector coil 9 that is connected to an earth leakage circuit breaker 10 on a printed circuit board 26. Both the conductor 36 from the phase circuit and the conductor 38 from the neutral circuit run through the detector coil 9.
The mechanism for operating the switch 50 is designed such that it fits optimally in a small space with a minimum of components. The most important components are the ON/OFF switch toggle 4, with which the switch 50 can be manually operated. The movable contact 7 is brought into contact with the fixed phase contact 35 via a mechanism consisting of the phase trip lever 5, spring 3 and moving contact 7 when the ON/OFF switch toggle 4 is turned anticlockwise (in Fig. 1). The spring 3 also ensures that a contact force is exerted on the movable phase contact 7 whenever this makes contact with the fixed phase contact 35. In corresponding manner, the ON/OFF switch toggle 4 on the neutral side of the switch 50 (see Fig. 2) operates a neutral trip lever 18 and moving neutral contact 19. This enables a connection to be made between the moving neutral contact 19 and the fixed neutral contact 37. With regard to the neutral side, a separate spring 3' is provided which engages the neutral trip lever 18. Both the phase trip lever 5 and the neutral trip lever 18 can turn about a respective displaceable pin 6, 6' which can move over a short distance, for example in slots (not shown) made in the housing 31.
As a result of the mechanism according to the present invention, it is possible for the switch 50 to be switched on in a person-independent manner. By this is meant that the movable contact 7 will always be moved at the same predetermined speed and with the same predetermined force towards the fixed contact 35, irrespective of how quickly and with what force the ON/OFF switch toggle 4 is operated. This prevents the contacts 7, 35 from fusing when the switch is switched on at high load currents, resulting in a longer service life for the switch 50.
Fig. 3 shows a detailed view of the mechanism on the phase side of the switch 50 when switched off (the movable contact 7 is not making a connection with the fixed contact 35). The movable contact 7 can move in the switch between an ON position (the movable contact 7 cannot move any further to the right because of the fixed contact 35) and an OFF position (the movable contact 7 cannot move any further to the right (sic) because of a stop 58, formed by the trip pawl 14). Furthermore, movement of the movable contact 7 is restricted by a spindle 6 and a rotatable connection 51 (first engagement point) from the movable contact 7 to the ON/OFF switch toggle 4, via a link 42 and a pressure piece 41 (that form an actuator arm). The link 42 and pressure piece 41 are attached to each other such that they can rotate at connecting point 52, and the pressure piece 41 is attached to the perimeter of the ON/OFF switch toggle 4 such that it can turn. The ON/OFF switch toggle 4 is fixed in the switch 50 (to housing 31 or support element 32) such that it can turn, and a spring 47 ensures a clockwise moment, as a result of which the ON/OFF switch toggle is forced towards the OFF position.
The contact spring 3 engages the movable contact 7 at the engagement point 56. The spindle 6 is fixed in the switch 50 such that it can not only rotate but can also execute a limited translational movement. This can be achieved, for example, by means of a slot in the housing 31 or support element 32.
In Figs 4 and 5 the forces and moments which play a role in the person-independent switching on (moment-on function) of the present switch 50 are illustrated in a line diagram. The movable contact 7, the contact spring 3 and the assembly comprising the switch toggle 4 and switch arm (pressure piece 41 and link 42 in Fig. 3) are illustrated with lines in a highly simplified manner. Also shown are the fixed contact 35 and the stop 58. The spindle 6 and the slot 48 in which the spindle 6 can execute translational movement are shown as well. Figs 4 and 5 illustrate the reversal point of the mechanism, where the ON/OFF switch toggle 4 is turned only through 0.5 degrees (anticlockwise) from Fig. 4 to Fig. 5.
In Fig. 4 a number of forces and a moment are drawn by means of lines with an arrow. The spring 3 exerts a force Fv at the engagement point 56 on the movable contact 7. The force Fb is exerted by the switch arm. Fr is the force on the spindle 6 arising from Fb. This results in a momentary pivot point M. The forces Fv and Fr generate a moment about this momentary pivot point M, indicated by the circular line. As long as this line is clockwise (Fr*Xr > Fv*Xv, where Xr and Xv are the respective moment arms), the movable contact 7 remains in the open state. As soon as the moment is anticlockwise (Fr*Xr < Fv*Xv), the spindle 6 will execute translational movement to the right in the slot 48, and the movable contact 7 will rotate about the pivot point M as far as the fixed contact 35, as shown in Fig. 5.
The time at which reversal takes place is determined by the geometry (including the moment arms of spring force Fv and she resultant force Fr on the spindle) and the coefficient of friction of the spindle 6 in the slot 48. Turning the ON/OFF switch toggle 4 changes the direction of the switch arm and thus the direction and magnitude of the force Fb. There is also an effect on the normal force of the spindle 6 on the slot 48. The magnitude of the force Fr is influenced, among other things, by the friction between the spindle 6 and the slot 48. This is in turn a function of the angle made by the slot 48 with reference to the geometry of the mechanism. This angle can be better defined by enabling a translational movement of the movable contact 7 by providing the slot 48 in the housing instead of a slot in the movable contact itself
The switch 50 is switched off manually by moving the ON/OFF switch toggle 4 from the ON position to the OFF position (clockwise in Fig. 3). As a result, the normal force on the pressure piece 41 moves in front of the pivot point of the ON/OFF switch toggle at a given moment, as a result of which this flips back again to the situation shown in Fig. 3.
The operation of the mechanism is further controlled by a (phase) trip lever 5 which is also fixed around the spindle 6 such that it can turn. At the end facing the fixed contact 35 the trip lever 5 is provided with a stop and a compression spring 53, as a result of which the relative movement of the trip lever 5 with respect to the movable contact 7 is limited to a small angle of rotation. At the end of the trip lever 5 facing the ON/OFF switch toggle 4 there is a locking surface 59. In the ON position the link 42 is restrained by this, as a result of which the trip lever 5, movable contact 7 and link 42 together form, as it were, a rigid entity, and the switch is locked in an ON position.
The phase trip lever 5 now also permits the switch 50 to be switched off in the event that one of the protective devices is actuated. When the phase trip lever 5 is turned slightly in a clockwise direction with the switch 50 in an ON position, the locking surface 59 will be displaced relative to the link 42 until the link 42 is released. The normal force on the pressure piece 42 then ceases, as a result of which the movable contact 7 is pulled from the fixed contact 35 by means of the force of the spring 3. At the same time the ON/OFF switch toggle 4 ceases to be blocked, as a result of which it is then pulled into its OFF position by the spring 47. It may be noted that this construction means that the switch 50 can be switched off by one of the protective devices even if the ON/OFF switch toggle 4 were to be blocked for one reason or another in the ON position, which guarantees effective and reliable operation of the protective devices.
One of the protective devices (or switching off actuators) which can operate the trip lever 5 is the short circuit contact breaker 2. The core of the overload module 2 moves to the middle of the coil when the current in the circuit exceeds a particular value. In doing so, the core presses against the end of the phase trip lever 5 facing the fixed contact 35. As a result, the phase trip lever 5 turns (clockwise in Fig. 3), and the switch 50 is switched off. The short circuit contact breaker 2 thus ensures rapid opening of the contacts 7, 35.
The two other protective devices (or switching off actuators) of the switch 50 (overload circuit breaker and earth leakage circuit breaker) act on the trip lever 5 via a single trip pawl 14. The trip pawl 14 is mounted in the housing 31 (see Fig. 1) such that it can turn and is provided with an inclined side that can make contact with a projecting leg 25 of the phase trip lever 5. Whenever the trip pawl 14 moves to the right (in Figs 1 and 3), the phase trip lever 5 will consequently rotate clockwise and switch off the switch 50. Because two protective devices are making use of the same trip pawl 14 to make the phase trip lever 5 move, there is a saving in components and in the space required for the safety switch 50.
The trip pawl 14 can be moved by means of a trip system 10 that is powered by the earth leakage contact breaker in the event that it detects an (excessive) earth leakage current. In addition, the trip pawl 14 can be moved by a pawl 39 whenever the bimetal strip 11 bends as a result of too high a current for too long a period. When the switch 50 is switched off, the trip pawl 14 (and, with it, the trip system 10 and the pawl 39) is returned to its initial position, as a result of which the actuator (trip system 10 from the earth leakage circuit breaker and pawl 39 from the overload circuit breaker) are automatically reset
The trip pawl 14 is made of a stiff material, and the spring force of the trip pawl 14 ensures that it returns to a stop position. The trip system 10 and the pawl 39 are also reset by this means, in part because the trip lever 5 pushes these back via the projection 25 and the inclined side of the trip pawl 14. A direct resetting action by the movable contact 7 would cause too high a load on the trip pawl 14. Because the trip pawl 14 lies against a stop at rest, the forces that are exerted by the spring 3 via the movable contact 7 are fed back via the housing.
In an alternative embodiment the trip pawl 14 is not mounted on the support element 32 such that it can turn at the bottom, but is mounted such that it can turn at a location on the support element 32 above the trip system 10 (for example, immediately adjacent to the detector coil 9). The inclined side of the trip pawl 14 which can make contact with the movable contact 7 to reset it is the same. However, the trip pawl 14 is now provided with a further projection which just fails to touch the projection 25 of the trip lever 5 when the switch is in the ON position. As soon as the trip system 10 or the overload circuit breaker causes the trip pawl 14 to move via the pawl 39, the projection 25 on the trip lever will be turned, and the switch 50 will switch off.
In a specific embodiment, as described above with reference to Fig. 1 and Fig. 2, the switch 50 is equipped with a phase side and a neutral side. The neutral side has a similar type of actuating mechanism to that on the phase side. This mechanism on the neutral side is shown in enlarged form in Fig. 6.
The mechanism on the neutral side shares a number of components, such as the ON/OFF switch toggle 4 and support element 32, which are common to the mechanism on the phase side. Furthermore, there are a number of elements with a comparable function, such as the movable neutral contact 19 (comparable to moving phase contact 7, and mounted on the same spindle 6), the neutral trip lever 18 (comparable to the phase trip lever 5, but without provisions for actuating (tripping) the overload, continuous current and earth leakage contact breakers) and the fixed neutral contact 37 (comparable to the fixed phase contact 35). There are also further similar components such as compression spring 58 and contact spring 3' (see the description of Figs 1 and 2 above), as well as similar components which form the actuator arm between ON/OFF switch toggle 4 and the moving contact 19, i.e. link 46 (comparable to pressure piece 41) and intermediate piece 43, which are connected to each other (comparable to link 42) about respective pivot points 57 and 55.
The mechanism is designed such that the neutral contact 19, 37 runs ahead of (makes contact before) the phase contact 7, 35 when the switch is switched on and that the phase contact 7, 35 opens first when the switch is switched off. This can be achieved, for example, by positioning the spindles 6, 6' slightly differently and by providing different engagement points for the various components in the mechanism. Consequently, the phase side of the switch 50 will always switch a load current on and off, as a result of which switch-off facilities, such as the explosion chamber 15, are only necessary on the phase side. This is possible by means of the mechanical link between the neutral trip lever 18 and the phase trip lever 5 via a mechanical connection in the form of a coupling slider 30. This coupling slider 30 can move in a slot in the support element 32 and is driven by a projection 59a on the phase trip lever 5 (and/or projection 18a on the neutral trip lever 18) in conjunction with a bridges (sic) 30b against which the projection 59a can press.
With the aid of a spring 30c and a further bridge 30a, the coupling slider 30 is forced into a rest position which corresponds to the OFF position of the switch 50. As soon as the phase trip lever 5 is rotated on the phase side by one of the protective devices in the switch 50, the neutral trip lever 19 will also be rotated by the coupling slider 30 (anticlockwise in Fig. 6), as a result of which the link 43 is released, and the neutral contact is broken. At the same time, this coupling ensures that the switch 50 cannot be switched on if the neutral side or the phase side are not in the reset position.
The coupling slider 30 also enables external coupling of the switch 50 with another switch 50 (for example, in a coupling circuit) via an opening in the housing 31.
The embodiment of the switch shown in Figs 1 and 2 contains in modular form the functions described above of switch mechanism, short circuit protective device, overload protective device and earth leakage protective device. The modular design makes assembly of the switch simple and reliable functioning of the switch is obtained. However, embodiments are conceivable in which only one or two of the specified protective functions are included in the switch in the single housing 31.

Claims

Mechanism for switching on and off a switch (50) provided with a primary switching function and at least one safety function, comprising
- a movable contact (7) that can be moved with respect to a fixed contact (35) from a first position to a second position, the switch (50) being switched on or, alternatively, switched off, wherein the movable contact (7) is fixed by fixing means (6) in the switch (50) such that it can execute a turning and translational movement,

- an ON/OFF switch toggle (4) to operate the switch (50), wherein the ON/OFF switch toggle (4) is connected via an actuator arm (41, 42) to the movable contact (7), wherein the actuator arm (41, 42) engages at a first engagement point (S1) on the movable contact (7),

- a spring (3) that engages at a second engagement point (56) on the movable contact (7) in order to exert a force thereon,
characterised in that
the fixing means (6), the first engagement point (1) and the second engagement point (56) are so positioned with respect to one another that, when the switch (50) is switched on, turning of the ON/OFF switch toggle (4) beyond a predetermined position of the ON/OFF switch toggle (4) results in a reversal of the moment acting on the movable contact (7).
Mechanism according to Claim 1, wherein the fixing means (6), the first engagement point (51) and the second engagement point (56) form a triangle on the movable contact (7), as a result of which the forces acting on the movable contact (7) generate a moment about a momentary pivot point (M) of the movable contact (7) and a force exerted by the actuator arm (41, 42) on the first engagement point (51) results in a reactive force from the fixing means (6), wherein the reactive force at the predetermined position results in a translational movement of the movable contact (7) as a result of which the direction of the moment reverses.
Mechanism according to Claim 1 or 2, wherein the fixing means (6) are made up of a spindle that is fixed to the movable contact (7) such that it can turn and the spindle (6) can execute translational movement in a slot (48) in the switch (50).
Mechanism according to any one of the preceding claims, wherein the mechanism further comprises a trip lever (5), which, by means of the fixing means (6), is connected to the movable contact (7) such that it can turn and is provided with a locking surface (59) on a first side, by means of which the actuator arm (41, 42) is locked when the switch (50) is in the ON position.
Mechanism according to Claim 4, wherein the trip lever (5) can be rotated by means of a switching off actuator (2; 10; 39) in such a way that the locking surface (59) no longer locks the actuator arm (41, 42).
Mechanism according to Claim 5, wherein the trip lever (5) has a projection (25) that can be moved via a trip pawl (14) by a switching off actuator (10; 39), wherein the trip pawl (14) is spring-mounted in the switch (50) and resets the switching off actuator (10; 39).
Mechanism according to any one of the preceding claims, wherein the trip lever (5) is mechanically connected via a projection (59a) to a coupling part (30) fixed in the switch (50) such that it can slide.
Switch for switching on and off an electrical circuit with a phase side and a neutral side, which comprise respective fixed and movable contacts (7,35; 19,37), wherein the phase side and the neutral side are both provided with a mechanism according to Claim 7 and the mechanism on the phase side is mechanically coupled to the mechanism on the neutral side by means of the coupling part (30), which is mechanically connected to projections (59a; 18a) on the respective trip levers (5; 18).
Switch according to Claim 8, wherein the mechanism on the phase side and the mechanism on the neutral side are so constructed that, when the switch (50) is switched off, the contacts (7, 35) on the phase side open before the contacts (19, 37) on the neutral side and, when the switch (50) is switched on, the contacts (19, 37) on the neutral side close before the contacts (7, 35) on the phase side.
Switch for switching on and off an electrical circuit, wherein the switch (50) is provided with a mechanism according to one of Claims 1 to 7, a housing (31) and at least one safety device (2,10,11), wherein the at least one safety device (2, 10, 11) is equipped to protect the switch (50) against short-circuit current, overload current and/or earth fault currents and wherein the mechanism and each of the safety devices (2, 10, 11) present are installed in the housing (31) in a modular manner.