WO2003021617A1

WO2003021617A1 - Tripping device for power switch

Info

Publication number: WO2003021617A1
Application number: PCT/EP2002/009396
Authority: WO
Inventors: Wolfgang Meyer-Haack; Axel Heitbrink; Walter Felden
Original assignee: Aeg Niederspannungstechnik Gmbh & Co., Kg
Priority date: 2001-08-22
Filing date: 2002-08-22
Publication date: 2003-03-13
Also published as: DE10141123B4; DE10141123A1

Abstract

The invention relates to a tripping device for a power switch (1). An armature (21) is magnetically induced to perform a tripping motion when a short circuit current occurs. A latch plate (50) associated with the armature (21) is provided with inclined guides and engages with the armature (21) so that the armature (21), in response to the first half-wave of the short circuit current, is guided against a stop following the inclined guides of the latch plate (50) and does not trip the power switch (1). If the short circuit persists so that the second half-wave of the short circuit current flows through the tripping device, the armature (21) is again put in a tripping movement. When the armature (21) returns from the inhibited position, it reaches a second trajectory relative to the latch plate (50), said trajectory leading past the stop. In this case, the armature (21) can pass the stop and trips the power switch (1) when the second half-wave of the short circuit current flows through. If there is no longer a short circuit, so that no second half-wave of the short circuit current acts upon the tripping device, the armature (21) returns to its initial position relative to the latch plate (50). A tripping movement occurring later on is first inhibited by the latch plate (50) and only the immediately subsequent second tripping movement allows the armature (21) to reach the tripping position.

Description

TRIP UNIT FOR CIRCUIT BREAKERS

DESCRIPTION

The invention relates to a tripping unit for a circuit breaker.

Various circuit breakers are known from the prior art which are used to protect downstream circuits in order to prevent the occurrence of excessive currents (short-circuit currents) in the downstream circuits.

However, there is basically the problem that in the case of circuit breakers connected in series, the triggering of a downstream circuit breaker should preferably take place, i.e. the upstream circuit breaker should only trip if the downstream circuit breaker does not trip in the event of a short circuit. In other words, the circuit breaker should have a tripping behavior referred to below as selective. The circuit breaker is tripped by a tripping unit, which largely determines the tripping behavior of the circuit breaker. An example of a non-selective tripping unit for a circuit breaker is explained below in anticipation of the description of the figures.

A tripping unit and a circuit breaker shown in FIG. 18 are known from German published patent application DE 199 03 911 AI. This switch 100 has a movable contact 102 which is rotatably mounted on the axis 103 of a switching shaft 104. The selector shaft 104 itself is in a pole track housing, not shown mounted and has two diametrically opposite satellite axes 105 and 106, which are rotated about the axis 103 when the control shaft 104 is rotated. The axis 105 is the point of attack for a joint mechanism 107 which is connected to a ratchet lever 108. The pawl lever 108 is pivotably mounted on an axis 110 positioned on the switch housing 109 and is released by a switch lock 111 in the event of an overcurrent or short circuit in order to enable the separated state of the contact 102 shown in FIG. 18.

The switch lock 111 can be actuated by a release lever 113 which can be pivoted about an axis of rotation 112. The trigger lever 113 is assigned to a trigger shaft 114 which is mounted on an axis 115 on the switch housing 109. At the

Trigger shaft 114 is formed a cam 116 which can be pivoted clockwise in FIG. 18 against the force of a spring (not shown) wound around axis 115.

In the lower section of the circuit breaker is on

Switch housing 109 a magnetic yoke 117 mounted, which engages around a current-carrying rail 119 connected to one of the contacts of the switch 100. The current to be monitored flows through the rail 119. An armature 121 designed as a flap is arranged opposite the magnetic yoke 117 and is connected to a fixed section of the circuit breaker or to the rail so that it can pivot about an axis 118. The armature 121 is also connected by means of a spring 122 to a fixed section of the rail 119 or the circuit breaker. The spring biases the armature 121 clockwise to a rest position against a stop portion (not shown). In its upper section in FIG. 18, the armature 121 is provided with an impact piece 123 provided, which abuts against the cam 116 by a pivoting movement of the armature 121 and rotates the trigger shaft 114. As a result, the switch lock 111 is actuated via the release lever and the circuit breaker 100 is triggered.

As can be seen from the above functional description, by coordinating the biasing force of the spring 122 with the magnetic forces occurring during the tripping current, it is possible to influence the tripping behavior of the tripping unit. However, the tripping usually takes place immediately when the tripping current occurs, so that it is difficult to achieve a desired tripping order with circuit breakers connected in series.

In contrast, it is an object of the invention to provide a tripping unit for a circuit breaker which triggers an upstream circuit breaker only when a downstream circuit breaker or circuit breaker has not tripped in the event of a short circuit.

The object is achieved with a trigger unit with the features defined in claim 1. Advantageous developments of the invention are specified in the subclaims.

The invention is explained in more detail below on the basis of preferred exemplary embodiments with reference to the drawing. In it show: 1 shows a first exemplary embodiment of a circuit breaker provided with a tripping unit according to the invention;

2 to 6 is a perspective view of a

Sequence of movements of a locking plate and an anchor similar to the arrangement shown in FIG. 1 in a release unit;

7 to 11 a schematic representation of the movement sequence of FIG. 2 to 6 belonging to the respective FIGS

Locking plate and anchor, the line of sight is perpendicular to the locking plate;

12 shows an alternative embodiment for an armature of a release unit according to the invention;

13 to 17 a sequence of movements of the armature from FIG. 12 relative to the locking plate in the same time steps as the previous FIGS. 2 to 6; and

Fig. 18 is a schematic representation of a conventional circuit breaker.

Fig. 1 shows a schematic side view of an embodiment of a circuit breaker 1, which is provided with a tripping unit further developed according to the invention. With regard to the effect of the switch lock 11 on the internal sequence of contact separation in the circuit breaker, reference is made to the description of the prior art given with reference to FIG. 18, in which the interaction of the switch lock and the elements for contact separation which are subordinate in the triggering sequence is set out. The tripping unit according to the invention can be combined with such a circuit breaker in order to implement the invention.

In other words, the following description therefore relates essentially to the tripping unit which actuates the tripping shaft 14 in FIG. 1 to trip the circuit breaker via the switch lock 11. As shown in Fig. 1, a magnetic yoke 17 is arranged to surround a current-carrying rail 19 and is opposite an armature 21 which is pivotably articulated on a joint 18 and by means of a spring 22 in its rest position, i.e. is biased counterclockwise in Fig. 1 against a stop. At the upper end of the armature 21 in FIG. 1, a locking plate 50 is shown schematically, which is articulated on the magnetic yoke 17. The blocking plate 50 interacts with the armature 21 in such a way that the armature 21 cannot turn the trigger shaft 14 when a short circuit occurs in a first half-wave of a short-circuit current, while when the second half-wave occurs the blocking plate releases the trigger path for the armature 21, so that the trigger shaft 14 can be actuated and the circuit breaker 1 is triggered via the switch lock 11.

Theoretically, it should be stated that the short-circuit current flowing through the rail 19 generates a magnetic field, which is amplified by the magnetic yoke 17 surrounding the rail 19 and directed onto the armature 21. The magnetic attraction between the magnet yoke 17 and the armature 21 is independent of the direction of flow of the short-circuit current, ie in each half-wave the armature 21 is attracted by the magnet yoke 17 against the force of the spring 22. ie rotated clockwise in Fig. 1. As will be explained in more detail below, the interaction of the locking plate 50 and the armature 21 ensures that the armature 21 does not yet reach the trigger point for the trigger shaft when it is first tightened, while it is tightened again in the second, shortly thereafter half wave and can then actuate the trigger shaft. If the second half-wave does not occur, ie there is no second triggering movement of the armature 21 immediately after the first triggering movement, the armature 21 falls back into its rest position following the force of the spring 22. If a short-circuit occurs at a later time, the first triggering movement, which is inhibited by the locking plate 50, takes place again, and if the second half-wave occurs, the second occurs

Tripping movement of the armature 21, which is no longer inhibited by the locking plate 50, so that the circuit breaker trips.

In a practical application, the circuit breaker according to FIG. 1 is connected in series in front of a number of further circuit breakers or circuit breakers connected in parallel. If a short circuit now occurs in a circuit of the downstream circuit breaker, the first half-wave of the short circuit current passes through both the circuit breaker shown in FIG. 1 and the downstream circuit breaker in whose circuit the short circuit occurs. If the downstream circuit breaker trips properly in response to the first half-wave of the short-circuit current, the second half-wave does not occur, ie the circuit breaker shown in FIG. 1 is no longer flowed through by the second half-wave of the short-circuit current, so that no tripping of the circuit breaker shown. The advantage is that if a short circuit occurs in one of the downstream circuits, not all of the downstream circuits connected in parallel are shut down. This so-called selective

Switching behavior distinguishes between the first and the second half-wave, and if the second half-wave is absent, it is recognized that the subsequent circuit breaker has tripped. However, if the second half-wave occurs in the circuit breaker shown in FIG. 1, this means that the short circuit continues in the subsequent circuit, so that the circuit breaker according to FIG. 1 then trips.

In the circuit breaker shown in Fig. 1, the

Lock plate 50 pivotally attached to the magnetic yoke 17. On the one hand, the pivotable mounting serves the interaction between the locking plate 50 and the armature 21, on the other hand the locking plate 50 can also be folded up and locked in this position, so that the selective behavior of the circuit breaker shown in FIG. 1 can be switched off. In other words, when the blocking plate 50 is folded up, the circuit breaker 1 trips as soon as the first half-wave of the short-circuit current occurs.

The interaction of armature 21 and locking plate 50 is explained in more detail in the following FIGS. 2 to 6 and 7 to 11. 7 to 11 show a view of the main plane of the locking plate in order to illustrate the relative movements of the armature and locking plate.

As can be seen in FIG. 2, the armature 21 is provided with two extensions 23 and 24, which are connected to the locking plate 50 are engaged. The locking plate 50 is pivotally and slidably received on an axis 60. As shown in Fig. 3, inclined guides 51, 52 and 53 are formed on the locking plate, which can engage with the extensions 23 and 24 of the armature 21. 2 to 6 and 7 to 11, the armature 21 is magnetically attracted when the short-circuit current occurs in each of the two half-waves from left to right, ie the extensions 23 and 24 endeavor to adapt to the magnetic force of the magnetic yoke (not shown). subsequently move to the left while the return spring 22 biases the armature 21 or the extensions 23 and 24 in FIGS. 2 to 6 and 7 to 11 to the right. 2 and 7 show the starting position, ie the armature 21 is biased into its rest position following the force of its return spring (not shown). Likewise, the locking plate 50, which is held displaceably on the axis 60, is in its rest position. As can be clearly seen in FIG. 7, the extension 24 of the armature 21 is in contact with the inclined surface 51 of the locking plate 50 in this rest position. 3, in response to the first half-wave, a

Short-circuit current a movement of the armature 21 in the direction of arrow b, while the locking plate 50 moves in the arrow direction a. According to FIG. 8, after this movement, the extension 23 of the armature 21 has slipped on the inclined surface 531 of the inclined guide 53 and lies against one in

Continuation of the inclined surface 53 trained stop. As a result, the further movement of the armature 21 in the triggering direction is inhibited. During its sliding movement on the inclined surface 531 of the inclined guide 53, the locking plate 50 was also moved synchronously in direction a. This is indicated by the distance s in FIG. 8. Starting from the position in FIGS. 3 and 8, the first half-wave of the short-circuit current now subsides, as a result of which the armature according to FIGS. 4 and 9 moves. As can be seen in FIG. 4, the armature moves in the direction of the arrow c following the decreasing magnetic force of its return spring. Due to the transverse displacement of the locking plate along the axis 60, the space between the extensions 23 and 24 engages in the second inclined guide 52 during the backward movement of the armature. In other words, the inner edge of the extension 24 of the armature 21 slides along the inclined surface 521 of the inclined guide 52 and presses the locking plate 50 further in the direction of arrow a, as a result of which the distance s to a fixed bearing point becomes almost 0. In this position, which is shown in FIG. 9, the short-circuit current passes approximately zero. After this

The short-circuit current rises again rapidly at zero crossing, so that the armature 21 is again drawn in the direction of arrow b, as shown in FIG. 5. 9 was guided into a position in which the extension 23 is no longer opposite the stop of the first inclined guide 53, so that, as shown in FIG. 10, the anchor 21 now passes this stop can and can move to the trip position where it trips the circuit breaker. 10 shows that the armature 21 has left the area of the locking plate 50. As shown in FIGS. 2 to 5 and 7 to 10, the interplay between the locking plate 50 and the extensions of the armature 21 summarizes the following sequence: When the armature 21 is tightened for the first time, it reaches the first

Inclined guide 52 to a stop formed thereon. Because the armature 21 is held on the stop, there is no triggering of the trigger movement Circuit breaker. When the short-circuit current approaches zero crossing, ie the magnetic effect of the armature decreases, the armature moves relative to the locking plate in such a way that the armature and locking plate are adjusted relative to one another by the second inclined guide, so that the movement path of the armature is free for a new trigger movement is, that is outside the range of the stop. If the second release movement actually takes place, the armature can move into the release position without being hindered by the stop.

6 and 11 show the movement sequence of armature and locking plate when no second half-wave of the short-circuit current flows through the circuit breaker, ie the second triggering movement does not take place. In this case, the armature moves in the direction of arrow c as shown in FIG. 6 following its return spring force. Following this movement, the armature bumps with its extension 24 against a third inclined guide 51, by means of which, together with an optional return spring of the locking plate, the state shown in FIGS. 2 and 7 is restored. In other words, the armature moves to the right in FIG. 11 and thereby pushes the locking plate upwards by sliding on the inclined guide 51. This procedure restores the original rest position, so that if a short circuit occurs, the device is ready to selectively trip the circuit breaker not during the first half-wave but only during the second half-wave. It should be noted that various modifications of this embodiment are possible; the inclined guides in particular are designed as positive guides, so that no spring loading or spring preloading of the locking plate in the direction of its pivot axis 60 is required. However, it is possible to provide such a spring preload, in which case damping the movements of the locking plate is useful in order to delay the movement of the locking plate compared to that of the armature. It is also possible to make the locking plate rigid and the anchor relatively slidable. Furthermore, the locking plate can also be designed to be non-pivotable but displaceable, in which case a sufficient engagement depth between the armature and the locking plate has to be provided in order to compensate for the change in length of the armature due to the pivoting movement relative to the locking plate. An alternative embodiment of the armature for cooperation with a rigid locking plate is also possible, which is explained in detail below with reference to FIGS. 12 and 13 to 17.

FIG. 14 shows an alternative embodiment of the anchor, which can replace the anchor shown in FIG. 1 essentially unchanged. This anchor 21 is pivotable about an axis 18 and has an elastically deformable extension 25, which is shown here in the form of a pin. This pin-shaped extension is preferably elastic in itself, but it can also be a rigid pin received in an elastic bearing or a correspondingly pivotably held, spring-loaded pin. It should be noted that a merely unsprung movable pin can also be used if the on the Lock plate trained oblique guides are dimensioned appropriately to form positive guides for the pin.

FIGS. 13 to 17 each show the same non-tripping states or tripping states as were explained in FIGS. 2 to 6 or 7 to 11. Fig. 13 shows the initial state in which the armature 21 is in its rest position, the pin 25 of the armature on an inclined guide

51 is present. Now the armature 21 is attracted by magnetic force when a first half-wave occurs

Short-circuit current, the armature 21 is moved to the left in FIG. 13 and slides along the second inclined guide

52 to the first inclined guide 53, which has formed the stop. This state is shown in FIG. 14, where the pin 25 of the armature 21 deflected upward in FIG. 14 abuts a stop on the inclined guide 53. The stop can additionally have a small depression, which improves the hold of the pin on the stop. The short-circuit current now approaches zero crossing, whereby the magnetic force acting on the armature decreases and the armature is moved to the right following its return spring force. In this case, as shown in FIG. 15, the pin 25 of the armature is bent or tilted downwards by the inclined guide 52 in FIG. 15 and has approximately the position shown in FIG. 15 when the current passes through zero. After the zero crossing, if the short circuit continues, the current rises again and the armature 21 is again attracted by magnetic force. In this case, the armature is cleared into the release position which, as shown in FIG. 16, it reaches following the magnetic force. The pin 25 of the anchor has passed the stop. The sequence in FIGS. 13 to 16 can therefore be summarized in such a way that the armature when activated on the first half-wave of a short-circuit current to a stop and is held there, after the magnetic force has temporarily decreased as a result of the current in the second half-wave, it is tightened again and now follows a movement path that leads past the stop, so that the armature can reach its release position ,

Fig. 17 shows the case where the second half-wave of the short-circuit current does not occur, i.e. that a downstream circuit breaker or

Circuit breaker has already switched off the current in response to the first half-wave of a short-circuit current.

In this case, as shown in FIG. 17, the armature is moved to the right following its return spring force and is brought back into the starting position according to FIG. 13 via the guide 51.

Two different exemplary embodiments of the invention have been explained in detail above. It should be noted that various modifications are possible without departing from the scope of the invention. In particular, the locking plate can also be attached to the side of the magnetic yoke, and the armature can be moved with a corresponding, displaceable, if necessary sprung

Be provided guide pin which moves, for example, the locking plate shown in FIGS. 13 to 17 during its movement. Alternatively, it is also possible to attach a corresponding extension on the side of the armature, so that a locking plate which is displaceably attached to the side of the magnetic yoke can be used in accordance with the pattern of FIGS. 2 to 6 in order to achieve the desired selective effect. It should also be noted that the trigger unit according to the invention can be provided with further trigger elements. These are in particular bimetallic elements that trip the circuit breaker in the event of an overload.

The locking plate can be a simple plastic part, so that a selective tripping unit can be achieved by making minor changes to conventional tripping units for circuit breakers.

Claims

1. Tripping unit for a circuit breaker (1) for triggering a switch-off device, with a magnetic yoke (17) which interacts with an armature (21) which actuates the switch-off device by a triggering movement into a triggering position, characterized by an armature (21) assigned Locking mechanism (23, 24, 50; 25, 50), which inhibits a first release movement starting from a rest position of the armature (21) and releases a second release movement of the armature (21) starting from a starting position that deviates from the rest position into the release position.

2. Tripping unit according to claim 1, characterized in that the first tripping movement starting from the rest position of the armature (21) is the tripping movement which takes place in response to a first half-wave of a tripping current.

3. Tripping unit according to claim 1, characterized in that the second trigger movement of the armature (21) starting from the starting position is the trigger movement which takes place in response to a second half-wave of a trigger current.

4. Release unit according to claim 1 to 3, characterized in that the locking mechanism has a locking plate (50) which engages with at least one on the armature (21) formed extension (23, 24; 25) and a first inclined guide (53rd ) has the extension of the armature during the first release movement along a first movement path against one on the locking plate (50) trained stop, and has a second inclined guide (52) to move the extension on the return movement of the armature and the second release movement along a second movement path that leads the extension (23; 25) past the stop.

5. Trip unit according to claim 4, characterized in that the locking plate has a third inclined guide (51) to guide the extension (23, 24; 25) of the armature (21) in the rest position of the armature in the first path of movement.

6. Tripping unit according to claim 1, characterized in that the armature is pivotally mounted about a pivot axis (18) and is biased into a rest position.

7. Release unit according to claim 5, characterized in that the locking plate (50) and the armature (21) are movable relative to each other in a direction perpendicular to the release movements.

8. Release unit according to claim 7, characterized in that the locking plate (50) along an axis (60) parallel to the pivot axis of the armature (21) is displaceable.

9. tripping unit according to claim 8, characterized in that the parallel axis (60) through the magnetic yoke (17) is arranged.

10. Release unit according to claim 4, characterized in that the locking plate (50) is stationary in a direction perpendicular to the release movement and the Extension (25) of the armature (21) is elastically deformable in the direction perpendicular to the release movement.

11. Trip unit according to claim 7 or 10, characterized in that the locking plate (50) is foldable to release the engagement between the locking plate and the extension of the armature to shut down the locking mechanism.

12. Release unit according to one of the preceding claims, characterized in that the locking plate (50) is made of plastic.

13. Tripping unit according to claim 1, characterized in that the magnetic yoke (17) surrounds a rail (19) guiding the tripping current and a thermal tripping element which is fastened to it and can be actuated by heating.

14. Tripping unit according to claim 13, characterized in that the thermal tripping element has a bimetallic plate which is connected to the rail at its first end section (29), while its second end forms a tripping section.