CZ297249B6 - Device for triggering overload circuit breaker - Google Patents

Abstract

The present invention relates to a device for triggering an overload circuit breaker, such as a line safety switch, having a triggering armature (11), which actuates a switch latch (18) and can be actuated by a coil (6) through which flows the current to be monitored. The triggering armature (11) is retained in its rest position by a spring (12) and an electromagnet (20) through the coil (7) of which flows the current to be monitored or a current directly proportional to the current to be monitored. The coil (7) can be short-circuited when a predetermined current intensity is reached.

Description

Technical field

The invention relates to an actuating device for an overcurrent tripping device, such as a line circuit breaker, comprising an actuating anchor controlling the circuit breaker lock which is operable by a coil through which the monitored current flows.

BACKGROUND OF THE INVENTION

In the case of overcurrent tripping devices, essentially fuse-type fuses are used, which can, of course, be used for a single trip only and, on the other hand, can be reclosed and therefore reusable, and therefore can be used several times, by automatic machines. In an electrical device, an overload protection of this kind is normally provided in the supply line before the supply line is divided into a plurality of parallel circuits connected to one another. In each of these circuits there are provided their own protective devices, which generally consist of personal protection devices (FI safety switches or the like) and 20 devices (line protective switches, fuses or the like). These current circuits can optionally be further subdivided into further undercurrent circuits, also protected by protective devices.

With such a wiring structure, the protective devices of the supply line, the current circuit and the undercurrent circuit are often connected in series. If an inadmissibly high current is now flowing in the undercurrent circuit, it is necessary to switch off the protective switch assigned only to this undercurrent circuit and thereby separate the undercurrent circuit from the mains, but all pre-protective circuit breakers are to remain closed. that have no faults, should remain connected to the network. Only when the overcurrent generated is so large that it can no longer be disconnected by the undercurrent circuit breaker, does the upstream switch operate. Such a time-delayed opening of the upstream switch is referred to as "selectivity".

As a rule, two actuating devices are provided in the area of the line protective switches. The first trigger device is intended to switch off overcurrents, the magnitude of which is only slightly greater than the rated current of the device, and which has been operating for a longer period of time. The second actuator, the so-called short-circuit actuator, is usually designed as a coil flowing through the monitored current, having a movable anchor causing it to trip. In order to mimic the delay depending on the heating power and hence on the current and time intensities explained above on the fuses 40, thermal bimetallic strips flowing through the monitored current are used, the bimetallic strips deforming analogously to the melting wires directly proportional to the square of intensity This distortion allows a time-delayed tripping of the triggering device at short-circuit current.

These bimetallic strips are components that must be mechanically precisely positioned and additional electrical connections are required. In summary, bimetallic tapes thus represent a significant complication in the design of the circuit breakers and hence their deterioration in their functional reliability and their manufacture. A further disadvantage of such designs is that the time delayed shutdown caused by the bimetallic elements remains independent of the magnitude of the monitored current. This results in a delayed operation of the protective device even at very high short-circuit currents, which must be disconnected without delay to protect the device.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a triggering device of the kind mentioned above which will selectively switch off and for this purpose will comprise only a few insensitive components of a simpler design compared to the known trigger coil. Further, the trigger device according to the invention should lose its selectivity and achieve its activation without delay when the monitored current reaches a certain predetermined value.

SUMMARY OF THE INVENTION

This object is achieved by a triggering device for an overcurrent tripping device, such as a line circuit breaker, comprising a triggering anchor controlling the circuit-breaker lock operable by a coil through which the monitored current flows according to the invention. and an electromagnet whose coil is flowing through the monitored current, or a current directly proportional to the monitored current, the coil being short-circuiting when a predetermined current intensity is reached.

Due to these simple constructional measures, the actuation of the trigger armature is only delayed until the force exerted by the coil and acting on the trigger armature exceeds the holding force of the electromagnet. In addition, the selectivity automatically adapts to the current intensity of the monitored current, but a short circuit that results in the immediate release of the magnetic hold is canceled abruptly.

According to a further advantageous embodiment of the invention, the winding of the outer coil layer can be parts without insulating material, and an electrically conductive bridge is provided, which is brought into contact with these parts when a predetermined current intensity is reached. This makes it possible to save a short-circuit contact connected in parallel to the coil, which would have to be dimensioned as relatively large in relation to the expected high currents.

In this connection, according to a further embodiment, the coil may comprise only one winding layer and all the windings of the winding layer are not provided with an insulating material. This design allows each coil thread to be short-circuited, thereby guaranteeing a particularly rapid magnetic field cancellation.

According to a further particularly preferred embodiment of the invention, the electrically conductive bridge is mounted on a short-circuit armature, which is displaceable from the rest position to the bridge contacting position with the parts of the threads not provided with insulating material by the solenoid, the short armature being held in its rest position by a predetermined holding force.

Therefore, in addition to the existing solenoid, only one component, namely the short-circuit anchor, must be provided. This allows a particularly compact and functionally reliable construction. By suitably dimensioning the holding force of the short-circuiting anchor, the value at which the coil is short-circuited can be easily set.

In this context, another embodiment of the invention may be used, in that the holding force holding the shorting anchor in its rest position may be exerted by a resilient component connected to the shorting anchor and the trigger body. Such components have only a small size, so that the overall size of the design of the trigger device according to the invention increases only insignificantly.

It may be particularly advantageous in this case if the elastic component is formed by a coil spring, preferably a compression spring, since such components can be manufactured very simply with the force required for this application.

-2GB 297249 B6

According to a further particularly preferred embodiment of the lowering device according to the invention, the lowering armature can be actuated indirectly by a magnetic armature movable directly by the coil, the magnetic armature being preferably connected to the lowering armature by at least one resilient coupling member or one or more auxiliary anchors.

With this elastic coupling, the magnetic anchor can also be moved before the holding force has been reached, whereby the force acting on the trigger anchor through the coupler is continuously generated. This embodiment is particularly advantageous for overcurrents with a long rise time, since the magnetic anchor has already traveled a large part of its travel here when the switching threshold is reached, whereas with a stiffer coupling or a direct coil acting on the trigger anchor first released the values and would have to travel all the way to the circuit breaker lock.

According to another embodiment of this preferred embodiment of the invention, the at least one coupler may be a coil spring. Such couplers require little space but at the same time have good elasticity, which remains relatively constant for a long time.

It may be particularly advantageous if the magnetic anchor is arranged at least partially inside the coil. With this embodiment, the magnetic anchor is movable in a predictable manner by the magnetic force of the monitored current.

It may furthermore be advantageous if the trigger anchor is also arranged inside the coil, the trigger anchor being made of a non-magnetic material. This creates a further possibility of reducing the overall size of the actuating device.

According to a further preferred embodiment, the trigger armature may be provided with an extension, preferably parallel to the longitudinal axis of the coil and passing through the magnetic armature, on which the component of magnetic material is fixed, which is held by an electromagnet. This allows a further geometric reduction of the actuating device according to the invention, which, irrespective of the electromagnet holding the actuating anchor, depends only on the size of the coil outside of which there are no moving parts.

Another advantageous embodiment of the invention is that the electromagnet has a H-shaped yoke, whose transverse rib carries the coil, and whose first pair of arms acts through the component on the trigger armature and whose second pair of arms acts on the shorting armature. This achieves a particularly easy-to-manufacture electromagnet design, which nevertheless fully meets the requirements for it.

According to a further advantageous embodiment of the invention, the electromagnet is arranged perpendicularly to the longitudinal axis of the trigger arm by its longitudinal axis. As a result, the length of the entire actuating device can be shortened.

According to a further preferred embodiment of the invention, the short-circuiting anchor is made of slats. In the short-circuit armature thus realized, there are markedly less losses due to re-magnetising and eddy currents, thereby accelerating the movement of the short-circuit armature, so that the actuation time can be reduced in the end.

Overview of the drawings

The invention will be further elucidated by way of example with reference to the accompanying drawings, in which: FIGS. 1a, 1b show diagrammatically, in a front elevation, two embodiments of a trigger device according to the invention;

2a, 2b in plan view a preferred embodiment of a holding magnet with two different kinds of holding force generation; FIG. 3 is an axonometric view of an embodiment of a holding magnet alternative to the embodiment 5 of FIGS. 2a, 2b, FIG. 5 shows a longitudinal section of a circuit breaker provided with a trigger according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The tripping device for the overcurrent tripping device, for example the line circuit breaker shown in Figs. 15a and 1b, comprises a tripping anchor 41 which can actuate the circuit breaker lock 18 via a pin-shaped extension 27. This switch lock 18 is in communication with one or more movable contacts 28 carrying the monitored current, and opens these contacts 28 when actuated by a pin 27. The trigger armature 11 is arranged inside the coil 6 flowing through the monitored current and can be via a magnetic field generated by the coil 6 movement 20 in the direction of the switch 18 as symbolically indicated by the arrow 110, since it is made of magnetic material. The return anchor 11 is brought back to its rest position, as indicated by the arrow 120, by a spring 12, the first end of which is supported by a fixed part 34, indicated only symbolically, and the second end of which is supported by the lowered anchor 11 itself.

The trigger arm 11 is held by the solenoid 20 in its rest position in which the pin 27 is removed from the switch 18 by the solenoid 20. The solenoid 20 has a yoke 14 carrying a coil and a monitored current flows through the coil 7. This is achieved by series connection of both coils 6 and 7, shown in solid lines. The trigger armature 11 is provided with an extension 24 at the end of which a component 13 of magnetic material is fixed. This component 13 forms, with the yoke 14 of the electromagnet 30 20, a magnetic circuit by which the above-described holding of the trigger armature in its rest position is achieved.

The purpose of holding the anchor bolt 11 in its rest position is thereby to achieve a lowered start delay. Indeed, triggering can only occur when the force exerted by the coil 6 on the trigger 35 of the armature 11 is greater than the resultant of the spring 12 and the holding force of the electromagnet 20. By the electromagnet 20 itself excited by the monitored current, trigger delay, also called selectivity, adjusts automatically according to the current current intensity, so that high current intensity means great selectivity.

Of course, to achieve this selectivity adjustment property, the monitored current need not flow through the coil 7, so it is sufficient if the coil 7 is flowing through a current that is directly proportional to the monitored current. Such a current can be produced, for example, by passing a portion of the monitored current through a parallel resistor 29 connected in parallel to the coil 7, as shown in dashed lines in Fig. 1a. This embodiment makes sense when the electromagnet 20 is designed so that only a part of the monitored current is sufficient to carry out the selectivity described and complete current could cause the trigger arm 11 to be held too intensely in its rest position. By changing the parallel resistance 29, selectivity can be influenced in a particularly simple manner.

Although this embodiment entails relatively greater complexity, it is also within the meaning of the invention that a current separated galvanically from the monitored current but directly proportional to the monitored current is passed through the coil 7.

-4GB 297249 B6

At particularly high current intensities, a time-delayed switch-off is no longer desirable and, in the interest of a downstream consumer, such extra-high currents should be switched off as soon as possible. To this end, it is necessary to eliminate the delay caused by the electromagnet 20 at the generation of such high currents, which according to the invention is achieved by a short coupling of the coil 7.

This short connection can be accomplished in various ways. In FIG. 1a, a switching contact 30 is connected for this purpose and is connected in parallel to the coil 7. Next to it is a control circuit 31 which detects the current current, which is measured by measuring the voltage drop caused by the monitored current on the shunt R. reaching the maximum permissible current intensity, the control circuit 31 closes the switch contact 30, thereby suddenly canceling the magnetic field passing through the component 13 and the yoke 14. This releases the anchor bolt 11 and can immediately operate the circuit breaker lock 18.

The embodiment of FIG. 1b corresponds substantially to the embodiment of FIG. 1a, but the short connection of the coil 7 is different here.

In order to form the coil 7, it is necessary to ensure that the coil 7 is always provided with only one winding layer in the illustrated embodiments. Although this is a preferred embodiment, it is by no means a limitation, since the coil 7 can have any number of winding layers.

According to FIG. 1b, all windings of a single coil winding layer 7 have sections 71 without insulating material. In addition, an electrically conductive bridge 17 is provided, which, upon reaching a predetermined current intensity, can be contacted with these parts 71.

For the movement of the bridge 17 in the direction of the arrow 170 required for this purpose, another electromagnet is provided, comprising an armature 32 connected to the bridge 17 and a coil 33 acting on the armature 32. This electromagnet is excited analogously to the embodiment of FIG. the control circuit 31 as described above. Both variants of the embodiment described so far have the disadvantage that a control circuit 31 with corresponding current measuring devices is required.

On the other hand, the embodiments of Figures 2a and 2b do not need a magnetic field already existing and produced by the coil 7 itself to represent the intensity of the monitored current to move the bridge 17. For this purpose, the bridge 17 is fastened to the short-circuit armature 15, the short-circuit armature 15 being held in its rest position by a predetermined holding force and displaceable by the electromagnet 20 from this rest position to the position in which the bridge 17 is in contact with the parts. 71 without insulating material.

Fixing or holding the shorting armature 15 in the rest position is necessary to maintain the start delay generated by the electromagnet at low current intensities. The holding force of the short-circuit armature 15 is dimensioned so that when the current intensity from which the delayed start is to occur, it exceeds the magnetic force created in the air gap 19 and acting on the short-circuit armature 15. This shortens the short-circuit armature 15, then coils 7 and the start is performed.

The holding force that holds the short-circuit anchor 15 in its rest position may be generated in any manner, for example by frictional forces or similarly formed parts contacting the short-circuit anchor 15. According to a particularly preferred embodiment shown in FIG. 2a, a resilient member 16 is provided for this purpose, which is constituted by a coil spring in the form of a compression spring. This spring is arranged between the fixed part 21 and the longitudinal extension 151 of the shorting armature 15.

Fig. 2b shows an embodiment which corresponds in function to the embodiment of Fig. 2a, in which case a tension spring 16 mounted on a short-circuit anchor serves as a spring component 16

In this case, the connection of the bridge 17 to the short-circuit armature 15 is effected by means of a contact spring 35.

2a and 2b, the preferred construction of the electromagnet 20 can be clearly discerned. Its yoke 14 is H-shaped, whose transverse rib 140 carries a coil 7 whose pair of first legs 141, 142 act across the component 13 on the trigger armature 11, and a pair of second legs 143, 144 act on the shorting anchor 15.

FIG. 3 shows another embodiment of the electromagnet 20. The pair of first legs 141, 142 is arranged perpendicular to the pair of second legs 143, 144. This arrangement at right angle is not again limiting since the selected angle between the pairs of legs 141, 142, 143 144 is immaterial from the point of view of electrotechnical function and can therefore have any value according to need and design requirements.

Fig. 4 shows another embodiment modified from the embodiment of Fig. 1a. A special feature of this embodiment is that the trigger armature 11 is not actuated directly by the coil 6, but there is another armature, which will be referred to as the magnetic armature 10. This magnetic armature 10 is actuated by the coil 6 straight in the direction of arrow 100 and connected with an anchor bolt 11 over a resilient coupler 22 formed by a coil spring. The trigger anchor 11 therefore moves only indirectly by the coil 6 in the direction of the arrow 110. This indirect connection can, of course, be extended as desired by arranging auxiliary anchors (not shown) with corresponding other elastic couplers between the magnetic anchor 10 and the trigger anchor 11.

To hold the trigger armature 11, the trigger armature 11, analogous to the embodiment of FIGS. 1a, 1b, is provided with an extension 24 carrying a magnetic component 13 which extends through a corresponding opening of the magnetic armature 10 and is arranged approximately parallel to the longitudinal axis of the coil 6.

The triggering of such an arrangement can be divided into two phases, which will now be described. In the first start-up phase, immediately after the overcurrent has occurred, the overcurrent through the coil 6 creates a magnetic field directly proportional to the current intensity causing the magnetic armature 10 to move towards the trigger armature 11. This movement is transmitted to the trigger armature 11 by the resilient coupler. however, it will first remain in its rest position due to the holding force exerted by the electromagnet 20. As the magnetic armature 10 continues to deflect, the coupler 22 is increasingly compressed, thereby reducing the holding force on the armature H. represent a magnetic anchor 10 and a coupling member 22 oscillating system, which is excited by the magnetic force generated by the overcurrent. The time required by the magnetic anchor 10 to depress the coupler 22 to such an extent that the holding force is exceeded and the trigger anchor 11 is deflected from its rest position results in a time delay, i.e. selectivity of the trigger device according to the invention.

If the force generated by the overcurrent exceeds the holding force, the second phase of lowering occurs. In this case, the trigger arm 11 suddenly starts to move, whereby the circuit breaker lock 18 is actuated, and consequently the contacts 28 open. At this start-up phase, the mutually coupled masses now represent the magnetic anchors 10 and the trigger anchors 11 in cooperation with the return spring 12 oscillating the system. This oscillating system operates as a known magnetic triggering device consisting solely of a coil and an armature, the excitation force resulting from the resultant of the current caused by the current and the holding force.

In summary, the lowering is not triggered by an overcurrent-controlled armature, but is indirectly caused by the movement of the magnetic armature 10 connected via the resilient coupler 22 to the trigger armature 11 and moved indirectly by the coil 6.

The start time delay is essentially created in the first start phase. It is determined by the mechanical properties of the oscillating system, the mass of the magnetic anchor 10, the elasticity of the coupler 22

-6GB 297249 B6 and lifting the magnetic armature 10 and the force generated by the current. The force exerted by the current is directly proportional to the current intensity and consequently also to the movement of the magnetic armature. Therefore, the delay is also proportional to the square of the current intensity, as in the known electrothermal delay devices mentioned in the introduction.

FIG. 5 is a longitudinal sectional view of a line circuit breaker equipped with a tripping device according to the invention in the closed state. The current path extends from the first terminal 1a through the bimetal 2 and through the flexible braid 3 to the contact bridge 4, from there through the movable contact 28 and the fixed contact 36 to the carrier 5 of this fixed contact 36, further through the coil 6 to the coil 7 and from there to the second terminal lb.

The starting device according to the invention is in principle designed according to FIG. 2a.

The construction details that are worth mentioning and which contribute to reducing the overall size are:

The magnetic armature 10 as well as the trigger armature 11 are arranged partially inside the coil 6 at rest. In order to prevent the trigger armature 11 from moving under the effect of the magnetic field of the coil 6, it is required to be made of a non-magnetic material such as plastic.

The magnetic anchor 10 is formed as a tubular member closed on one side and a trigger anchor 11 is located at least partially within its cavity. In the illustrated embodiment, no resilient coupler 22 is disposed between the magnetic anchor 10 and the trigger anchor 11, the closed end of the tubular member abutting. If the coupling member 22 is to be provided in this embodiment, it will preferably also be arranged in the cavity of the magnetic anchor W.

As in the embodiment of FIG. 4, the anchor 24 extends through the magnetic anchor 10 and again carries the magnetic material component 13, which in cooperation with the electromagnet 20 causes the anchor 11 to be held in its rest position.

The electromagnet 20 has an H-shaped yoke 14 and its longitudinal axis 25 is arranged perpendicular to the longitudinal axis 26 of the trigger armature 11. Thus, the overall design height of the circuit breaker can be substantially reduced, but within the meaning of the invention relative to the longitudinal axis 26 of the anchor bolt 11.

The short-circuit armature 15 is preferably made of lamellas to reduce losses due to re-magnetization and eddy currents and thereby to guarantee a particularly fast movement of the short-circuit armature 15.

The switch lock 18 is a conventional known embodiment. Both the bimetal 2 and the pin 27 formed on the trigger arm 11 act on the contact bridge 4. This contact bridge 4 is resiliently biased so that the slight deflection caused by the two trigger mechanisms is amplified until fully swung to the off position.

Claims (15)

Trigger device for an overcurrent tripping device, such as a line circuit breaker, comprising a trigger armature (11) controlling a circuit breaker lock (18) that is operable by a coil (6) through which the monitored current flows, characterized in that the trigger armature (11) is held in its rest position by a spring (12) and an electromagnet (20), the coil (7) of which flows through the monitored current or a current proportional to the monitored current, the coil (7) being short-circuited when a predetermined current intensity. Trigger device according to claim 1, characterized in that the winding of the outer layer of the coil winding (7) has insulating material-free parts (71), wherein an electrically conductive bridge (17) is provided which can be brought into a predetermined current intensity. contact with these parts (71). Trigger device according to claim 2, characterized in that the coil (7) has only one winding layer, all windings of this winding layer having parts (71) devoid of insulating material. Trigger device according to claim 3, characterized in that the electrically conductive bridge (17) is mounted on a shorting armature (15) which is movable by the electromagnet (20) from its rest position to the position in which the bridge (17) is. in contact with the insulating material-free parts (71), the shorting armature (15) being held in its rest position by a predetermined holding force. 5. The lowering device according to claim 4, characterized in that the holding force holding the short-circuit armature (15) in its rest position can be produced by a resilient part (16) connected to the short-circuit armature (15) and the fixed armature. by means of a trigger device (21). Trigger device according to claim 5, characterized in that the spring part (16) is formed by a coil spring, in particular a compression spring. Lowering device according to one of the preceding claims, characterized in that the lowering armature (11) is actuable by a magnetic armature (10) which is indirectly controllable by a coil (6) and which is connected to the lower armature (11) in particular by means of at least one resilient coupler (22) and optionally one or more auxiliary anchors. Trigger device according to claim 7, characterized in that the at least one resilient coupling member (22) is formed by a coil spring. Trigger device according to claim 7 or 8, characterized in that the magnetic armature (10) is arranged at least in part inside the coil (6). Trigger device according to claim 9, characterized in that the trigger armature (11) is also arranged inside the coil (6), the trigger armature (11) being made of a non-magnetic material. Triggering device according to claim 10, characterized in that the magnetic anchor (10) is formed as a tubular part closed on one side, wherein the triggering anchor (11) and the at least one coupling member (22) are arranged at least partially within the cavity formed in a magnetic anchor (10). -8EN 297249 B6 Lowering device according to claims 9, 10 or 11, characterized in that the lowering armature (11) is provided with an extension (24), arranged in particular parallel to the longitudinal axis of the coil (6) and passing through the magnetic armature (10). a magnet component (13) is attached to the adapter (24) and is held by the electromagnet (20). Trigger device according to one of Claims 4 to 12, characterized in that the electromagnet (20) has an H-shaped yoke (14) whose transverse rib (140) carries a coil (7) whose pair of first legs (141, 142) acting through the component (13) on the trigger armature (11), and whose pair of second legs (143, 144) act on the shorting armature (15). The lowering device according to claim 13, characterized in that the longitudinal axis (25) of the electromagnet (20) is arranged perpendicular to the longitudinal axis (26) of the lowering armature (11). Lowering device according to one of Claims 4 to 14, characterized in that the short-circuit anchor (15) is made of slats.