SK285827B6 - Device for triggering an overload circuit breaker - Google Patents

Abstract

A device for triggering an overload circuit breaker, such as a line safety switch, has 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 proportional to the current to be monitored. The coil (7) can be short-circuited when a predeterminable current strength is reached.

Description

The invention relates to a trip mechanism for an overcurrent tripping device, such as a line circuit breaker, comprising a trip anchor operating a 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, in principle, fuse-links are used, but they can only be used for a single trip, and on the other hand, reusable and therefore reusable 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 in parallel. In each of these circuits there are provided protective devices, which generally consist of mechanisms for the protection of persons (protective switches FI or similar) and mechanisms for protecting the devices (line protective switches, fuses or the like). These current circuits can optionally be further subdivided into further undercurrent circuits, also provided by protective mechanisms.

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 unacceptable 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 the preceding circuit breakers should remain closed. where no fault has occurred, they should remain connected to the network. Only if the resulting overcurrent is so large that it can no longer be disconnected by the undercurrent circuit breaker, does the override switch operate. Such a time-delayed opening of the upstream switch is referred to as "selectivity".

Two trigger mechanisms are generally provided in the area of line protective switches. The first trigger mechanism is intended to shut off overcurrents whose magnitude is only slightly greater than the rated current of the device and which operate over a longer period of time. The second trip mechanism, the so-called short-circuit trip mechanism, is usually constructed as a coil through which the monitored current flows, having a movable anchor causing the trip. In order to mimic the delay depending on the incandescent power and hence the current and time intensity explained on the fuses, thermal bimetallic strips are used to flow the monitored current, the bimetallic strips deforming analogously to the melting wires directly proportional to the square of the current intensity and time, this deformation permitting a time-delayed tripping of the trigger mechanism at short-circuit current.

These bimetallic strips are components which must be mechanically precisely positioned on the one hand and additional electrical connections are necessary. All in all, bimetallic tapes thus represent a considerable complication in the design of the circuit breakers and thus a deterioration in their functional reliability and 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. Thus, even at very high short-circuit currents, which must be disconnected without delay in order to protect the device, the protection device is delayed in operation.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a trigger mechanism of the kind mentioned, which will selectively switch off and which will therefore contain only a few insensitive components of a simpler embodiment relative to the known trigger coil. Furthermore, the trigger mechanism according to the invention should lose its selectivity and achieve its activation without delay if the monitored current reaches a predetermined value.

SUMMARY OF THE INVENTION

This is accomplished by a trip mechanism for an overcurrent tripping device, such as a line circuit breaker, comprising a trip anchor controlling the circuit breaker lock which is operable by a coil through which the monitored current flows, according to the invention. an electromagnet, the coil of which flows the monitored current, or a current directly proportional to the monitored current, the coil being short-circuited by a switching contact when a predetermined current intensity is reached.

Therefore, due to these simple design measures, the actuation of the trigger anchor is delayed only until the force exerted by the coil and acting on the trigger anchor exceeds the holding force of the electromagnet. In addition, selectivity automatically adapts to the current intensity of the monitored current, but by short-circuiting that results in the immediate removal of the magnetic hold, it is suddenly canceled.

According to a further preferred embodiment of the invention, the windings of the outer coil layer can be parts without insulating material, wherein 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 with respect to the expected high currents.

In this connection, according to another embodiment, the coil may be made to comprise only one winding layer, and not all the windings of that layer are provided with an insulating material. This embodiment allows each coil thread to be short-circuitable, 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-circuiting anchor, which is displaceable from a rest position to a bridge contact position with parts of the threads not provided with insulating material by the electromagnet.

Therefore, in addition to the existing electromagnet, only one contact 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, it is very easy to adjust the value at which the coil is short-circuited.

In this connection, another embodiment according to the invention can be used, in that the holding force holding the short-circuit anchor in its rest position can be effected by a resilient component connected to the short-circuit anchor and to the trigger mechanism body. Such parts have only small dimensions, so that the overall size of the construction of the trigger mechanism according to the invention increases only insignificantly.

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

According to a further particularly preferred embodiment of the triggering mechanism according to the invention, the triggering anchor can be actuated indirectly by a magnetic anchor, movable directly by the coil, the magnetic anchor being preferably connected to the triggering anchor by at least one flexible 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 triggering anchor through the coupling member 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, but with a stiffer coupling or a direct action of the coil on the starting anchor values first released and would have to go all the way to the switch lock.

According to a further embodiment of this preferred embodiment of the invention, the at least one coupling member may be a coil spring. Such couplers require little space but at the same time have good flexibility, which remains relatively constant over a long period of time.

It may be particularly advantageous if the magnetic anchor is arranged at least partially inside the coil. In 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 arranged inside the coil, the trigger anchor being made of a non-magnetic material. This provides a further possibility of reducing the overall size of the trigger mechanism.

According to a further preferred embodiment, the lowering armature may be provided with an extension, preferably arranged parallel to the longitudinal axis of the coil and the passing magnetic anchor, on which the component of the magnetic material is fixed, which is held by the electromagnet. This allows a further geometric reduction of the trigger mechanism according to the invention, which, regardless of the electromagnet holding the trigger 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 Y-shaped yoke, whose transverse rib supports 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 short-circuit armature. This achieves a particularly easy-to-construct electromagnet design, which nevertheless still satisfies the overall requirements of the electromagnet.

According to a further preferred 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 actuation mechanism can be shortened.

According to a further preferred embodiment of the invention, the short-circuit anchor is made of slats. In the short-circuit armature thus produced, there are visibly less losses due to premagnetization and eddy currents, thereby speeding up the movement of the short-circuit armature, so that the actuation time of the triggering mechanism can be reduced in the end effect.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further explained with reference to the accompanying drawings, in which: FIG. 1a, 1b show diagrammatically in front view two possible embodiments of the trigger mechanism according to the invention, FIG. 2a, 2b show in plan view a preferred embodiment of a holding magnet with two different kinds of holding force generation, FIG. 3 is an alternative perspective view of the embodiment of FIG. 2a, 2b, FIG. 4 is a schematic front view of a particularly preferred embodiment of the trigger mechanism according to the invention; and FIG. 5 shows a longitudinal section of a line circuit breaker provided with a trigger mechanism according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The triggering mechanism for the overcurrent tripping device, for example the line circuit breaker shown in FIG. 1a and 1b, it comprises a lowering armature 11 which can operate the switch lock 18 via a pin-shaped extension 27. This switch lock 18 is in communication with one or more of the moving current contacting contacts 28 and opens these contacts 28 when actuated by a pin 27. The trigger arm 11 is arranged inside the coil 6 through which the monitored current flows and can be via a magnetic field formed move the coil 6 in the direction of the switch 18 as symbolically indicated by the arrow 110, since it is made of magnetic material. The return armature 11 is brought back to its rest position, as indicated by the arrow 120, by a spring 12, the first end of which rests on a fixed part 34, indicated only symbolically, and the other end of which rests on the armature 11 itself.

The trigger arm 11 is held by the solenoid 20 in its rest position, in which the pin 27 is spaced from the switch 18, held by the solenoid 20. The solenoid 20 has a yoke 14 carrying the coil 7, the monitored current flowing through the coil 7. This is achieved by the series connection of both coils 6 and 7 shown in solid lines. The anchor bolt 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 20, a magnetic circuit, by which the explained holding of the trigger anchor in its rest position is achieved.

The purpose of holding the lower armature 11 in its rest position is thereby to achieve a lowerable start delay. Indeed, triggering can only occur if the force exerted by the coil 6 on the trigger armature 11 is greater than the resultant of the elasticity 12 and the holding force of the electromagnet 20. By the electromagnet 20 being itself excited by the monitored current, the trigger delay, also called selectivity, depending on the current current intensity, such 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 current 7 is flowing in the coil 7, which 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 dotted lines in FIG. Ia. This embodiment makes sense if the electromagnet 20 is constructed in such a way that only a part of the monitored current is sufficient to carry out the described selectivity and a complete current could cause the trigger anchor 11 to be held too intensively in its rest position. By changing the parallel resistor 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 by a galvanic current from the monitored current, but directly proportional to the monitored current, can pass through the coil.

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

This short connection can be realized in different ways. In FIG. 1, a switching contact 30 is therefore connected in parallel to the coil 7. Next to it is a control circuit 31 which detects the current current, which is shown in FIG. When the maximum permissible current intensity is reached, the control circuit 31 closes the switch contact 30, abruptly abolishing the magnetic field passing through the component 13 and the yoke 14. This releases the trigger arm 11 and can immediately operate the lock. 18 switch.

The embodiment of FIG. Ib corresponds essentially to the embodiment of FIG. 1a, but the short connection of the coil 7 is made differently here.

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

According to FIG. Ib have all windings of a single coil winding layer 7 of part 71 without insulating material. An electrically conductive bridge 17 is provided adjacent to it and can be contacted with these parts 71 when a predetermined current intensity is reached.

For the movement of the bridge 17 in the direction of the arrow 170 required for this purpose, another electromagnet is provided, comprising an anchor 32 connected to the bridge 17 and a coil 33 acting on the anchor 32. This electromagnet is built analogously to the embodiment of FIG. 1a by the control circuit 31 in the manner described. The two embodiments described so far have the disadvantage that a control circuit 31 with corresponding current measuring devices is required.

In contrast, the embodiments of FIG. 2a and 2b for the movement of the bridge 17, a magnetic field already existing and formed by the coil 7 itself and also representing a measure of the intensity of the monitored current. The bridge 17 is therefore mounted on the shorting anchor 15, the shorting anchor 15 being held in its rest position by a predetermined holding force and displaceable by the electromagnet 20 from this rest position to a position in which the bridge 17 is in contact with the parts 71 without insulating material.

Fixing or holding the short-circuit armature 15 in the rest position is necessary to maintain the electromagnetic start delay at low current intensities. The holding force of the short-circuit armature 15 is dimensioned so that, when the current intensity to be delayed is reached, it exceeds the magnetic force generated in the air gap 19 and acting on the short-circuit armature 15. This shortens the short-circuit armature, then coils 7 briefly and the trigger is executed.

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 touching the short-circuit anchor 15. According to a particularly preferred embodiment shown in FIG. 2a, there is therefore provided a resilient part 16, which is formed by a coil spring made in function of a compression spring. This spring is arranged between the fixed part 21 and the longitudinal extension 151 of the short-circuit armature 15.

In FIG. 2b shows an embodiment corresponding to the embodiment of FIG. 2a, wherein in this embodiment, a tension spring 16 mounted on the short-circuit armature 15 and on the fixed part 21 serves as the resilient part 16. The connection of the bridge 17 with the short-circuit anchor 15 is made by means of a contact spring 35.

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

In FIG. 3, a further embodiment of the electromagnet 20 is shown. 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 it is immaterial from the point of view of the electrotechnical function and can therefore have any value as required and according to design requirements.

In FIG. 4 shows another embodiment modified from the embodiment of FIG. Ia. A special feature of this embodiment is that the trigger anchor 11 is not directly controlled by the coil 6, but there is another anchor, which will hereinafter be referred to as the magnetic anchor 10. This magnetic anchor 10 is actuated by the coil 6 directly in the direction of arrow 100 and connected to the trigger armature 11c is a flexible coupling member 22 formed by a coil spring. The anchor bolt 11 therefore moves by the coil 6 only indirectly in the direction of the arrow 110. This indirect connection can, of course, be expanded by arranging between the magnetic anchor 10 and the anchor bolt 11 auxiliary anchors (not shown) with corresponding other resilient couplers.

To hold the trigger armature 11, the trigger armature 11 is analogous to the embodiment of FIG. 1a, 1b, provided with an extension 24 carrying a magnetic component 13 which passes through a corresponding opening of the magnetic anchor 10 ic 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, via the coil 6, creates a magnetic field proportional to the current intensity causing the magnetic anchor 10 to move towards the trigger anchor 11. This movement is transmitted to the trigger anchor 11 by the resilient coupler. however, it first remains 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 becomes steadily compressed, thereby decreasing the holding force acting on the trigger arm 11. At this stage of lowering represent a magnetic anchor 10 and a coupling member 22 oscillating system, which is excited by the magnetic force generated by the overcurrent. Time that magnetic

The anchor 10 needs to press the coupler 22 to the extent that the holding force is exceeded and the trigger anchor 11 is deflected from its rest position, resulting in a time delay, i.e. selectivity of the trigger mechanism according to the invention.

If the overcurrent force exceeds the holding force, the second phase of lowering occurs. In this case, the trigger arm 11 suddenly starts to move, whereby the switch lock 18 is actuated and, as a result, the contacts 28 open. At this start-up phase, the masses of the magnetic armature 10 and the trigger armature 11, in cooperation with the return spring 12, are now an oscillating system. This oscillating system operates as a known magnetic actuation mechanism consisting only of a coil and an anchor, the excitation force being generated by the resultant of the force caused by the current and the holding force.

The lowering, generally speaking, is therefore not triggered by the overcurrent-controlled armature, but is realized indirectly by the movement of the magnetic armature 10 connected via the resilient coupler 22 to the trigger armature 11a moved indirectly by the coil 6.

A delay is created essentially in the first start-up 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 and the stroke of the magnetic anchor 10 and the force exerted 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 10. Therefore, the delay is also directly proportional to the square of the current intensity, as in the known electrothermal delay devices mentioned in the introduction.

In FIG. 5 is a longitudinal sectional view of a line circuit breaker provided with a triggering device according to the invention in the closed state. The current path leads 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 trigger mechanism according to the invention is in principle made according to FIG. 2a.

The design details that serve to mention and which contribute to the reduction of the overall design size are:

The magnetic anchor 10 as well as the trigger anchor 11 are arranged in a rest state partially inside the coil 6. In order to prevent the trigger anchor 11 in this arrangement from moving by the magnetic field of the coil 6, it has to be made of a non-magnetic material such as plastic.

The magnetic anchor 10 is formed as a tubular member enclosed on one side and a trigger anchor 11 is located at least partially within its cavity 11. In the illustrated embodiment, no resilient coupling member 22 is provided between the magnetic anchor 10 and the trigger anchor 11, with the closed end of the tubular member 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 10.

As in the embodiment of FIG. 4, the anchor 24 extends through the magnetic anchor 10 and again carries a component 13 of magnetic material 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 height of the circuit breaker can be substantially reduced, but according to the invention it is also possible to arrange the electromagnet 20 at any angle against the longitudinal axis 26 of the lowering armature 11.

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

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

Claims (15)

Trigger mechanism for an overcurrent tripping device, such as a line circuit breaker, comprising a trigger armature (11) controlling a switch lock (18) operable by a coil (6) through which a monitored current flows, characterized in that the trigger armature ( 11) is held in its rest position by a spring (12) and an electromagnet (20) whose coil (7) flows a monitored current or a current directly proportional to the monitored current, the coil (7) being short-circuitable a predetermined current intensity. Trigger mechanism according to claim 1, characterized in that the winding of the outer winding layer of the coil (7) has portions (71) without insulating material, wherein an electrically conductive bridge (17) is provided which, when reaching a predetermined current intensity, contacting these parts (71). Trigger mechanism according to claim 2, characterized in that the coil (7) has only one winding layer, all windings of this winding layer having parts (71) without insulating material. Trigger mechanism according to claim 3, characterized in that the electrically conductive bridge (17) is mounted on a short-circuit armature (15) which is movable by the electromagnet (20) from a resting position to a position in which the bridge (17) is in contact. with parts (71) without insulating material, the shorting anchor (15) being held in its rest position by a predetermined holding force. Trigger mechanism according to claim 4, characterized in that the holding force holding the short-circuit armature (15) in the rest position can be formed by a resilient member (16) connected to the short-circuit armature (15) and the fixed part (21) of the trigger mechanism. Trigger mechanism according to claim 5, characterized in that the spring part (16) is formed by a coil spring, in particular a compression spring. Trigger mechanism according to one of the preceding claims, characterized in that the trigger armature (11) is operable by a magnetic armature (10) which is indirectly controllable by a coil (6) and which is connected to the trigger armature (11) in particular by at least one flexible coupler (22) and optionally one or more auxiliary anchors. Trigger mechanism according to claim 7, characterized in that the at least one resilient coupling member (22) is formed by a coil spring. Trigger mechanism according to claim 7 or 8, characterized in that the magnetic armature (10) is arranged at least partially inside the coil (6). Trigger mechanism according to claim 9, characterized in that the trigger armature (11) is also arranged inside the coil (6), wherein the trigger armature (11) is made of a non-magnetic material. Trigger mechanism according to claim 10, characterized in that the magnetic armature (10) is formed as a tubular part closed on one side, wherein the trigger armature (11) and the at least one coupling member (22) are arranged at least partially within a cavity formed in the cavity. a magnetic anchor (10). Trigger mechanism according to claim 9, 10 or 11, characterized in that the trigger armature (11) is provided with an extension (24), arranged in particular parallel to the longitudinal axis of the coil (6) and the magnetic armature (10) passing therethrough. a part (13) of magnetic material, which is held by an electromagnet (20), is fastened to the adapter (24). Trigger mechanism 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), the pair of first arms (141, 142) acts through the component (13) on the lowering armature (11), and whose pair of second legs (143, 144) acts on the shorting armature (15). Trigger mechanism 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 trigger armature. Lowering mechanism according to one of Claims 4 to 14, characterized in that the short-circuiting anchor (15) is made of slats.