WO2014044735A1

WO2014044735A1 - Power switching device

Info

Publication number: WO2014044735A1
Application number: PCT/EP2013/069429
Authority: WO
Inventors: Kurt Haendler
Original assignee: Eaton Electrical Ip Gmbh & Co. Kg
Priority date: 2012-09-20
Filing date: 2013-09-19
Publication date: 2014-03-27
Also published as: DE112013004603A5

Abstract

The invention relates to a power switching device comprising a single-pole or multi-pole contact system (3a). The solution to the problem consists in safe electrodynamic isolation with little complexity involved. For this, a tensioning lever (27) which is mounted axially parallel in the switching shaft (5) is associated with each contact arm (7), wherein a contact compression spring (13) acts between the contact arm (7) and the tensioning lever (27). A latching lever (29a) mounted in the switching shaft (5) is furthermore associated with the contact arm (7), which latching lever is firstly coupled moveably to the tensioning lever (27) and is secondly latchable with the contact arm (7). The contact compression spring (13) and the latching lever (29a) act on the contact arm (7) with opposite torques, but with a total torque directed towards the fixed-contact resting area (11). In the event of electrodynamic opening of the contact arm (7), the contact arm (7) is released by the latching lever (29) and is latched with the latching lever (29) once the OFF position has been assumed again by the switching shaft (5).

Description

LEISTUNGSSCHALTGERAET

The invention relates to a power switching device with a single or multi-pole contact system. The invention finds application in circuit breakers, circuit breakers and disconnectors for switching and protecting low-voltage switchgear and electric drives.

The document DE 10 2006 059 307 B3 describes a power switching device whose contact system can be executed either as a double breaker or as an individual breaker. The contact system includes a switch shaft mounted in a switch shaft and at least one pivotally mounted in the switching shaft contact arm. The contact arm is connected in the ON position end with a fixed contact and separated in the OFF position of this. Contact arm and fixed contact act together via corresponding contact pads. A contact between spring and contact arm contact pressure spring ensures in the ON position for the required contact force between the contact pads. The contact arm is a one-armed in a designed as a single breaker contact system and executed in a running as a double break contact arm with two arms. An actuating mechanism with a pivotable actuator, a lever mechanism and an over-center spring actuates the shift shaft.

If such contact systems are loaded with short-circuit currents or high overcurrents, so-called Lorentz and Holm forces develop between contact arm and fixed contact, which lead to an electrodynamic separation between the contact arm and the fixed contact. Here, a movement stop in the switch housing limits the movement of the contact arm. The actuating mechanism may be equipped with a triggering mechanism having interfaces to various triggers. The actuating mechanism transferred in the event of tripping the contact system with contact separation in a TRIPPED position. By transferring the actuating element in a RE SET position beyond the OFF position, the actuating mechanism and so that the contact system are returned to the normal OFF position.

The German utility model DE 1 532 288 U describes a vibration-proof switch high current levels, in which also one of a contact or switching shaft moving contact lever or contact arm is pressed by an engaging between the switching shaft and contact pressure contact spring against a fixed contact. In addition, a switch-off spring is tensioned in this switch with a clamping lever via a power storage lever and this lever is held by a pawl. In order to avoid accidental tripping of this switch, especially in case of shocks, it is proposed to relieve the pawl in the closed position of the switch in that the power storage lever is held by an additional locking or clamping lever, so that the pawl is relieved in the closed position and any vibrations and movements of the pawl during operation remain on the switching state without influence.

The power switching devices and switches described above suffer from the disadvantage that the electrodynamic separation of the contact arm from the fixed contact must be made counter to the action of the contact pressure spring. As a result, under certain circumstances, a renewed contact between the contact arm and the fixed contact and a repetitive so-called pumping movement of the contact arm may occur. This leads to increased wear of the contact pads and sometimes to a welding of the same. The adjustment between contact forces and electrodynamic separation forces is associated with high design effort with limited success. Another disadvantage is that to ensure the required contact forces, the contact springs are relatively strongly dimensioned. This in turn leads to the formation of relatively high support forces in the bearings of contact arm, shift shaft and actuator mechanism, whereby the bearings must be sized sufficiently large to avoid premature wear and, if necessary, must be made of high quality materials.

The invention is therefore based on the object of specifying a concept for a power switching device with safe electrodynamic separation and with reduced design and material complexity. Starting from a power switching device of the type mentioned, the object is achieved by the features of the independent claim, while the dependent claims advantageous developments of the invention can be found.

According to the invention, the contact arm is associated with a pivoting lever which is mounted so as to be axially parallel to the contact arm pivot axis in the control shaft, the contact pressure spring acting between the contact arm and the tension lever. The contact is further associated with a mounted in the shift shaft latch lever, which is coupled on the one hand movable with the clamping lever and on the other hand verklinkbar with the contact. The contact pressure spring and the latching lever act on the contact arm with opposing torques, but with a fixed contact directed toward resulting torque, the combination of clamping lever and latch lever is only limitedly movable by two arranged in the switching shaft limit stops. In a directed away from the fixed contact relative movement of the contact arm relative to the shift shaft of the contact arm is released from the latch lever and latched after re-taking the OFF position by the shift shaft with the latch lever.

The contact pressure spring acts on both ends of the contact arm and the clamping lever. The mutual distance of the axes of the pivotal movements of the contact arm, clamping lever and rocker arm within the switching shaft and the relevant lengths of the cooperating levers of contact arm, clamping lever and latch can be matched to one another in a professional manner, that in the latched state on the contact a contact-closing resulting torque in Direction towards solid contact is exercised. This resulting torque causes the required contact force between the contact pads in the ON position. An advantage of this is that compared to conventional contact systems, the contact pressure spring can be designed with a significantly lower spring force. This is due to the fact that the acted upon by the spring force lever arms are made larger, whereby the contact force delivering resulting torque can be supplied by a correspondingly reduced spring force. As a further advantage results from the fact that the bearing of contact arm, shift shaft and actuating mechanism by reducing the male support forces smaller dimensioned and can be formed with lower quality materials.

In the ON position, in the OFF position, in any transition position between the ON and OFF positions or between the OFF and ON positions, as well as in the TRIPPED position of the contact system, the contact arm remains latched to the latch lever and is thus under the action of the contact pressure spring. In all these positions, the contact arm with respect to the shift shaft remains in the same position, apart from the slight relative movement during placement of the movable contact pad on the fixed contact pad as a result of the so-called Durchhubs to compensate for Kontaktabnutzungen.

In an electrodynamically caused pivoting movement of the contact arm away from the fixed contact due to a short-circuit current or a high overcurrent, the contact arm passes through this relative movement relative to the switching shaft from the engagement of the ratchet lever. Now, in conjunction with the limit stops by the contact pressure spring alone, the torque directed away from the fixed contact is exerted on the contact arm. Thus, there are no more forces that - in contrast to conventional contact systems - counteract the electrodynamic opening forces on the contact arm can act. In contrast, the contact pressure spring - again in contrast to conventional contact systems - supports the Lorentz and Ho Im forces when the contact arm is being whirled on, until this movement is limited by the movement stop in the switch housing. A renewed contact, ie falling back of the contact, during the short-circuit or overcurrent is effectively prevented by the means according to the invention. The now essentially independent setting between contact force and electrodynamic separation force is only connected with little design effort. The latching lever arranged between the clamping lever and the contact arm has no movement relative to the contact arm in the phase of the passage of the contact arm towards the end of the switch-on operation and in the phase of the lifting of the contact arm at the beginning of the switch-off operation. This avoids considerable wear and tear between the latch lever and contact arm. The latching lever also ensures that the decoupling of the clamping lever and the contact arm, the influence of frictional forces and dirt particles within the contact system is noticeably reduced, so that the contact arm under the action of electrodynamic opening forces can be solved safely from the latch.

In order to convert the electrodynamically opened contact arm back into its latched normal state, a relative movement of the contact arm relative to the switching shaft is again effected, and that opposite to the relative movement caused electrodynamically. For this purpose, the actuating mechanism is transferred to the RESET position, which brings the contact arm back into engagement with the latch lever in conjunction with the movement stop and the limit stops. Here, too, to increase the reliability of the arranged between the clamping lever and the contact arm latch lever ensures the greatest possible reduction of the influence of frictional forces and dirt particles within the contact system.

In power switching devices with double interrupting contact system, which has a two-armed contact arm and two fixed contacts per switching pole, it is expedient to assign each individual arm each separately a contact pressure spring, a clamping lever and a latch lever.

In an advantageous embodiment of the latch of the latch lever is formed with a nose and the contact arm with a cooperating with the nose Verklinkungsfiäche.

For this purpose, the contact arm is advantageously equipped with a directed away from the movable Kontaktaufiage boom beyond the Kontaktarmschwenkachse having the Verklinkungsfiäche end.

As an alternative to the above, the contact arm between the contact arm pivot axis and the movable contact support is provided with a recess formed for the passage of the latch lever, on the inner edge of which the latching surface adjoins.

An advantageous embodiment of the invention consists in a rotationally displaceable mounting of the ratchet lever and in a coupling between latch lever and clamping lever via a fork-shaped design, which is formed either on the latch lever or on the clamping lever. An alternative advantageous embodiment to the above consists in the coupling between the latch lever and clamping lever via a rotary joint.

For this purpose, it is to ensure a reliable, for example, shock-resisting, latching advantageous if between clamping lever and latch lever an additional spring acts, which acts on the latch lever with a Verklinkungsfläche directed towards torque.

For a reliable mounting of the contact pressure spring is advantageously provided in each case a holding element on the contact arm and clamping lever.

As a contact pressure spring, a conventional coil spring, coil spring or leaf spring can be used.

An advantageous development of the invention for reducing the number of parts results from the fact that a leaf spring combines both the function of the contact pressure spring and the clamping lever in itself. Here, a portion of the leaf spring forms the clamping lever.

In certain spatial conditions in the region of the switching shaft, it is advantageous that the clamping lever or the latch lever or both are arranged laterally offset in the direction of the Kontaktarmschwenkachse to the contact.

An advantageous development of the invention also consists in that the latching lever can be acted upon by a trigger element actuated by a trigger with a torque directed away from the latching surface. As a result, the contact system is opened directly from the trigger when faulty currents occur, whereby the delay of the actuating mechanism, which is mainly based on its inertia, is bypassed.

In a further advantageous embodiment of the above, the power switching device can now be equipped with an unaufwändigem actuating mechanism without triggering function, the only of a simple lever system with Übertotpunktfeder consists.

Further details and advantages of the invention will become apparent from the following, with reference to figures explained embodiments. Show it

Fig. 1: a partial, spatial representation of a preferred embodiment of the circuit breaker according to the invention in the ON position;

FIG. 2 shows a lateral longitudinal section of the circuit breaker according to FIG. 1 in the ON position; FIG.

FIG. 3: as in FIG. 2, but at the beginning of an electrodynamic opening; FIG.

FIG. 4: as in FIG. 2, but at the end of an electrodynamic opening; FIG.

FIG. 5: as in FIG. 2, but in the RESET position; FIG.

FIG. 6: as in FIG. 2, but in the OFF position; FIG.

Fig. 7: the side view of a second embodiment;

Fig. 8: the side view of a third embodiment;

Fig. 9: the side view of a fourth embodiment;

Fig. 10: the side view of a fifth embodiment;

Fig. 11: the side view of a sixth embodiment.

According to Fig. 1 to 6, the power switching device 1 is equipped with a contact system 3 for three switching poles. The contact system 3 includes a mounted in a switch housing switch shaft 5, not shown, per Schaltpol a pivotally mounted in the shift shaft contact arm 7 with a movable contact support 9 and a cooperating with the contact arm 7 fixed contact, of which only the fixed contact support 11 is shown. Between each contact arm 7 and the switching shaft 5 engages in each case a contact pressure spring 13 in the form of a helical tension spring. For each contact arm 7, a movement stop 15 is provided on the switch housing. Between an actuating element 17 and the switching shaft 5, an actuating mechanism 19 is arranged. The actuating mechanism 19 may have an ON position with movable contact pads 9 connected to the fixed contact pads 11, an OFF position with movable contact pads 9 separate from the fixed contact pads 11, a TRIPPED position caused by faulty currents with movable contact pads 9 also separated from the fixed contact pads 11 and a RESET position for the return of to the TRIPPED position to the OFF position. To trigger the actuating mechanism 19 is equipped with a trigger mechanism 21 which is actuated by triggers, not shown. Further details and function of the actuating mechanism 19 are described in EP 0 584 503 AI. Each movable contact pad 9 moves within an arc quenching chamber 23, of which in Fig. 1, only the one for the middle Schaltpol is shown.

According to the invention, each contact arm 7 is associated with a tension lever 27, which is mounted so as to be axially parallel to the contact arm pivot axis 25 via a tension lever axis 26 in the control shaft 5. The contact pressure spring 13 engages between contact arm 7 and clamping lever 27. Each contact arm 7 is further associated with a mounted in the switching shaft 5 latch lever 29, which is connected on the one hand via an axially parallel to Kontaktarmschwenkachse 25 arranged pivot 31 with the clamping lever 27 and on the other hand verklinkbar with the contact arm 7. Contact pressure spring 13 and latch lever 29 act on the contact arm 7 with opposing torques, but with a solid contact pad 11 directed toward resulting torque, so in the ON position shown in FIGS. 1 and 2, the movable contact pad 9 with the required contact force on the fixed contact pad eleventh lies. The combination of clamping lever 27 and latch lever 29 is limited by two arranged in the switching shaft 5 limit stops 33 and 35 in their movement, which allows that at a fixed contact pad 11 directed away pivotal movement of the contact arm relative to the switching shaft 3 (FIG Contact arm 7 is released from the latch lever 29 and, after taking the RESET position by the switching shaft 5 (Fig. 5) with the latch lever 29 is latched again.

The latch lever 29 has a nose 37 which cooperates with a latching surface 39 formed on the contact arm 7 both in the ON position (FIG. 2), in the OFF position (FIG. 6) and in any intermediate position. Contrary to the movable contact support 9, the contact arm 7 continues beyond the Kontaktarmschwenkachse 25 in a boom 41, which has the Verklinkungsfläche 39 end. On the tensioning lever 27 and on the contact arm 7, a respective holding element 43 or 45 is provided for the contact pressure spring 13. In the ON position of FIG. 2, in the OFF position of FIG. 6, in any transition position between the ON and OFF positions and between the OFF and ON positions, and in the TRIPPED position of the FIG Contact system 3, each contact arm 7 remains latched with its latch lever 29 and is thus under the action of its contact pressure spring 13. In all these positions, the contact arm 7 remains with respect to the shift shaft 5 in the same position, apart from the slight relative movement when placing the movable contact pad 9 the fixed contact pad 11 due to the so-called Durchhubs to compensate for contact wear.

In an electrodynamically caused pivotal movement of the contact arm 7 away from the fixed contact due to a short-circuit current or a high overcurrent between movable contact pad 9 and fixed contact pad 11, the contact arm 7 moves relative to the switching shaft 5. According to FIG. 3 passes through this relative movement in conjunction with the lower limit stop 35th the Verklinkungsfläche 39 of the contact arm 7 from the engagement of the nose 37 of the latch lever 29. Now, in conjunction with the upper limit stop 33 by the contact pressure spring 13 alone one of the fixed contact pad 11 directed torque exerted on the contact arm 7. There is no more torque that can act against the contact arm 7 against the electrodynamic opening forces. The contact pressure spring 7 now supports the between Lorentz and Holm forces formed between movable contact pad 9 and fixed contact pad 11 during spin-coating of the contact arm 7 until this movement is limited by the movement stop 15 as shown in FIG. Renewed contact with harmful consequences, i. a falling back of the contact arm 7 during the short-circuit or overcurrent is thus effectively prevented.

The arranged in the chain of action between clamping lever 27 and contact arm 7 latch lever 29 has in the phase of the stroke of the contact arm 7 at the end of the switch and in the phase of cancellation of the stroke of the contact arm 7 at the beginning of the switch-off no movement relative to the contact arm 7. This avoids significant wear phenomena between latch lever 29 and contact arm 7. The latch lever 29 also ensures that in the decoupling of clamping lever 27 and contact arm 7 (Fig. 3), the influence of frictional forces and dirt particles is significantly reduced within the contact system 3. As a result, the contact arm 7 reliably releases from the latching with the latching lever 29 when electrodynamic opening forces arise.

In order to convert the electrodynamically opened contact arm 7 according to FIG. 4 back into its latched normal state, a relative movement of the contact arm 7 relative to the switching shaft 5 must again be carried out, namely opposite to the relative movement caused electrodynamically. For this purpose, the actuating mechanism 19 is transferred to the RESET position shown in FIG. 5. By taking place thereby pivotal movement of the switching shaft 5 in the clockwise direction of FIG. 5, the contact arm 7 is latched in conjunction with the movement stop 15 and the upper limit stop 33 again with the latch lever 29. The latch lever 29 also ensures a significant reduction in the influence of frictional forces and dirt particles within the contact system 3. After performing the RESET process, the power switching device 1 goes back to the normal OFF position shown in FIG. It should also be noted that actuation mechanisms without tripping function, which are used in particular for disconnectors, are brought back to the OFF position without a RESET process.

Hereinafter, further embodiments of the switching device according to the invention will be described by means of the figures 7 to 11, wherein only one switching pole is shown, will be mainly dealt with the essential differences from the embodiment described above and equivalent elements are occupied despite changed geometric design with the same reference numerals.

7 shows a contact system 3a which can be actuated by a releasable actuating mechanism 19 in the ON state, in which a latching lever 29a mounted in a rotationally displaceable manner in the switching shaft 5 is used. The two-armed clamping lever 27 is coupled to the latch lever 29a via a fork-shaped formation 47 and superimposed with one formed on one of the fork ends cylinder 49 in a trough 51 at one of the arm ends of the clamping lever 27. At elektrodynamischer opening of the contact arm 7 triggers its boom 41 from the latching with the latch lever 29a and is otherwise as in the figure shown with this latched.

Fig. 8 shows an actuatable by a triggerable actuating mechanism 19 contact system 3b in the ON position with an indicated fixed contact 8 with Festkontaktaufiage 11. A contact 7b is a trained as a tension spring contact pressure spring 13 to one arm of the two-armed clamping lever 27 coupled to the other Arm on a hinge 31 a latch lever 29 is articulated. The contact arm 7b has a recess 53 between its contact arm pivot axis 25 and its movable contact support 9. Through the recess 53 reaches the latch lever 29. The latching surface 39 adjacent to the recess 53 acts in the manner described above with the nose 37 of the latch lever 29 together. Between the clamping lever 27 and the latch lever 29 engages in the vicinity of the rotary joint 31 designed as a compression spring auxiliary spring 55, which acts on the latch lever 29 with a Verklinkungsfläche 39 directed towards the torque. This ensures secure latching, e.g. Better to withstand shocks. In electrodynamic opening of the contact arm 7b this dissolves from the latch with the latch lever 29 and is otherwise latched as shown in the figure with this.

9 shows a double-armed contact system 3c in the ON position that can be actuated by a releasable actuating mechanism 19. To compensate for different burnup of the two movable contact pads 9 and fixed contact supports 11, the Kontaktarmschwenkachse 25 of the two-armed contact arm 7c superimposed on a slot-shaped axle bearing 57 in the switching shaft 5c. Each partial arm 59, 61 of the double-armed contact arm 7c is assigned in each case a contact pressure spring 13c, a one-armed tension lever 27c and a latch lever 29. The contact pressure springs 13c are formed here as helical compression springs. The pawl lever 29 are coupled via a rotary joint 31 with the associated clamping lever 27c and pass through a recess 53 of the associated arm 59 and 61 of the contact arm 7c, wherein in each case an additional spring 55 as in the embodiment described above for a reliable latch between the respective arm 59 and 61 and the associated latch lever 29 provides. In the case of electrodynamic opening of the contact arm 7c, its partial arms 59, 61 release from the latching with the latching levers 29 and are otherwise in the same manner as shown in the figure with these latched.

10 shows, analogously to that of the embodiment according to FIG. 7, a contact system 3d which can be actuated by a releasable actuating mechanism 19 in the ON position. Compared with the embodiment of FIG. 7, the embodiment of FIG. 10 differs in that the clamping lever and contact pressure spring are structurally combined in a leaf spring 63. The leaf spring 63 is fixed at one end via a trained on the contact arm 7 behind grip holding element 45 d and coupled with its other end via its trough 51 with the cylinder 49 on the fork-shaped formation 47 of the latch lever 29a. On the one hand, the leaf spring 63 has to apply the contact force between the movable contact support 9 and the fixed contact support 11 and, on the other hand, the prestressing for ensuring the latching between the arm 41 and the latch lever 29a. For this purpose, an arcuate deflection 67 formed between the ends of the leaf spring 63 presses against a pressure element 69 on the selector shaft 5. The tensioning lever here is the section of the leaf spring 63 which extends from the deflection 67 to the depression 51. In the case of electrodynamic opening of the contact arm 7, its arm 41 releases from the latching with the latching lever 29a and is otherwise latched to it as shown in the figure.

Fig. 11 shows in the ON position an embodiment with a contact system 3e, which differs from the contact system according to Fig. 9, inter alia, by the use of a one-armed contact arm 7e. Here, too, a latch lever 29e extends through a recess 53 in the contact arm 7e, the contact pressure spring 13c is subjected to pressure and an additional spring 55 between clamping lever 27c and latch lever 29e is arranged. This embodiment differs from the embodiments described above essentially in that the latching lever 29e can be acted upon by a triggering element 71 operatively connected to actuators. The trigger element 71 is held by not shown conventional spring means in the rest position shown in Fig. 11. The latch lever 29 e is directed away from the pivot 31 with a release surface 73 is provided. If the triggering element 71 is displaced in the actuating direction 75 as a result of a faulty current, for example overcurrent, it strikes the actuating surface 73 and pivots the latching lever 29e with a torque which releases its nose 37 from the latching surface 39 of the contact arm 7e. As a result, under the action of the contact pressure spring 13c in conjunction with the lower limit stop 35 for the released clamping lever 27c, the contact arm 7e separated from the fixed contact 8 and pivoted counterclockwise to the limit stop 15. In this embodiment as well, the contact arm 7e releases from the latching with the latch lever 29e when the opening is electrodynamic. After transfer of the contact system 3d in the OFF position, the contact arm 7e is again latched to the latch lever 29e. In this embodiment, a complex operating mechanism with tripping function is unnecessary. Here, an actuating mechanism 19e which merely consists of a simple lever system with an over-center spring is sufficient.

The present invention is not limited to the embodiments described above, but also includes all the same in the context of the invention embodiments. Thus, for example, the invention can be designed such that the contact pressure springs 13, 13c are designed as spiral or leaf springs or that in unfavorable spatial conditions in the region of the switching shaft 5, 5a, 5c clamping lever 27, 27c or latch lever 29, 29a, 29e or both in the direction of the Kontaktarmschwenkachse 25 laterally offset from the contact arm 7, 7b, 7c, 7e are arranged. Furthermore, all meaningful combinations of the embodiments described above are possible.

Table of reference numbers:

1 power switching device

3; 3a; 3b; 3c; 3d; 3e contact system

5; 5a; 5c switching shaft

7; 7b; 7c; 7e contact arm

8 fixed contact

9 movable contact pad

11 fixed contact support

13; 13c contact pressure spring

15 movement stop

17 B etätigungselement

19; 19e B etätigungsmechanismus

21 trigger mechanism

23 arc quenching chamber

25 contact arm pivot axis

26 clamping lever axis

27; 27c tension lever

29; 29a; 29e latch lever

31 swivel joint

33, 35 limit stops

37 nose

39 latching surface

41 outriggers

43, 45; 45d holding elements

47 fork-shaped training

49 cylinders

51 trough

53 recess

55 additional spring

57 axle mounting

59, 61 partial arms

63 leaf spring

67 deflection

69 pressure element

71 triggering element

73 trigger surface

75 B heading

Claims

claims

1. power switching device with an at least single-pole contact system (3; 3a; 3b; 3c; 3d;

3e) containing

a switching shaft (5; 5a; 5c) mounted in a switch housing,

at least one contact arm (7; 7b; 7c; 7e) pivotally mounted in the switching shaft (5; 5a; 5c) with a movable contact support (9), a fixed contact (8) cooperating therewith with a fixed contact support (11), a contact pressure spring (13; 13c) acting between contact arm (7; 7b; 7c; 7e) and selector shaft (5; 5a; 5c) and a movement stop (15) for the contact arm (7; 7b; 7c; 7e),

an actuating mechanism (19; 19e) arranged between an actuating element (17) and the switching shaft (5; 5a; 5c), which has an ON position in the case of a contact arm (7; 7b; 7c; 7e) connected to the fixed contact (8) at least one more OFF position at the contact arm (7; 7b; 7c; 7e) separated from the fixed contact (8),

characterized,

in that the contact arm (7; 7b; 7c; 7e) is associated with a clamping lever (27; 27c) which is mounted so as to be axially parallel to the contact arm pivot axis (25) and the contact pressure spring (13; 13c) is between the contact arm (7; 7b; 7c; 7e) and clamping lever (27; 27c) attacks,

in that the contact arm (7; 7b; 7c; 7e) is further associated with a latching lever (29; 29a; 29e) mounted in the switching shaft (5; 5a; 5c), which on the one hand is movably coupled to the tensioning lever (27; on the other hand, can be latched to the contact arm (7; 7b; 7c; 7e),

- that contact pressure spring (13; 13c) and latch lever (29; 29a; 29e) act on the contact arm (7; 7b; 7c; 7e) with opposing torques, but with a resultant torque to the fixed contact (8),

- that the combination of clamping lever (27, 27c) and latch lever (29; 29a; 29e) by two in the switching shaft (5; 5a; 5c) arranged limit stops (33, 35) is limitedly movable and

- That at one from the ON position of the fixed contact (8) directed away Relative movement of the contact arm (7; 7b; 7c; 7e) with respect to the switching shaft (5; 5a; 5c) of the contact arm (7; 7b; 7c; 7e) is released from the latching lever (29; 29a; 5; 5a; 5c) is reconnected to the latching lever (29; 29a; 29e).

2. Power switching device according to the preceding claim, characterized in that a two-armed contact arm (7c) are each associated with two contact pressure springs (13c), clamping lever (27c) and latch lever (29).

3. Power switching device according to one of the preceding claims, characterized in that the latching lever (29; 29a; 29e) has a nose (37) and the contact arm (7; 7b; 7c; 7e) has a latching surface (39) cooperating with the lug (37). having.

4. Power switching device according to claim 3, characterized in that the contact arm (7) of the movable contact pad (9) directed away boom (41), the end having the Verklinkungsfläche (39).

5. Power switching device according to claim 3, characterized in that the contact arm (7b;

7c; 7e) between Kontaktarmschwenkachse (25) and movable contact support (9) for the passage of the Klinkhebels (29; 29e) formed recess (53) to which the Verklinkungsfläche (39) borders.

6. Power switching device according to one of claims 1 to 5, characterized in that the latch lever (29a) rotatably mounted and the clamping lever (27) with the latch lever (29a) via a fork-shaped formation (47) is coupled.

7. Power switching device according to one of claims 1 to 5, characterized in that the latching lever (29; 29e) via a rotary joint (31) with the clamping lever (27; 27c) is coupled.

8. Power switching device according to the preceding claim, characterized in that between clamping lever (27c) and latch lever (29; 29e) an additional spring (55) engages, which acts on the latch lever (29; 29e) with a Verklinkungsfläche (39) directed towards the torque ,

9. Power switching device according to one of the preceding claims, characterized in that for the contact pressure spring (13; 13c) in each case a holding element (43, 45; 45 d) on the clamping lever (27; 27c) and on the contact arm (7; 7b; 7c; ) is provided.

10. Power switching device according to one of claims 1 to 9, characterized in that the contact pressure spring (13; 13c) is designed as a tension spring, compression spring, coil spring or leaf spring.

11. Power switching device according to one of claims 1 to 9, characterized in that the clamping lever and contact pressure spring in a leaf spring (63) are combined.

12. Power switching device according to one of the preceding claims, characterized in that the clamping lever (27; 27c) and / or the latch lever (29; 29a; 29e) in the direction of extension of the contact arm pivot axis (25) laterally offset from the contact arm (7; 7b; 7e) are arranged.

13. Power switching device according to one of the preceding claims, characterized in that the latching lever (29e) can be acted upon by a tripping member actuated by trigger (71) with a of the Verklinkungsfläche (39) directed away torque.

14. Power switching device according to the preceding claims, characterized in that the actuating mechanism (19e) consists of a simple lever system with Übertotpunktfeder.