Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
  • H01H71/10—Operating or release mechanisms
  • H01H71/12—Automatic release mechanisms with or without manual release
  • H01H71/24—Electromagnetic mechanisms
  • H01H71/26—Electromagnetic mechanisms with windings acting in opposition
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
  • H01H71/10—Operating or release mechanisms
  • H01H71/1081—Modifications for selective or back-up protection; Correlation between feeder and branch circuit breaker

Definitions

• the invention relates to a tripping device for an overcurrent shutdown device, such as Miniature circuit breaker, comprising a trigger armature which actuates a switch lock and which can be actuated by a coil through which a current to be monitored flows.
• an overcurrent shutdown device such as Miniature circuit breaker
• Fuses are essentially used on overcurrent switch-off devices - they can only be used for a single switch-off process - and on the other hand reusable circuit breakers that can therefore be used several times are used.
• an overload protection of the above-mentioned designs is normally provided in the supply line before this supply line is divided into a plurality of circuits connected in parallel with one another.
• Each of these circuits has its own protective devices - usually consisting of personal protection (RCCBs or the like) and system protection (circuit breakers, fuses or the like). If necessary, these circuits can in turn be subdivided into further sub-circuits that are also protected by protective devices.
• Such a circuit structure results in a series connection of the protective devices of the feed line, circuit and sub-circuit.
• this selectivity is determined by the heating power required for melting the fuse wire, which is proportional to the square of the current and the duration of the overcurrent.
• a first device is provided for switching off overcurrents which are only slightly above the nominal system current and act over longer periods of time.
• the second, so-called short-circuit current triggering is usually implemented by a coil through which the current to be monitored flows and with a movable armature which effects the shutdown.
• thermal bimetal strips through which the current to be monitored flow are used, which bimetal strips deform analogously to the fuse wires in proportion to the square of the current and the time and by this deformation enable the switching action of the short-circuit current release with a time delay.
• bimetallic strips are components that on the one hand have to be mechanically adjusted precisely and on the other hand require additional electrical connections. In summary, they result in a significant complication of the circuit breaker structure and thus a deterioration in the functional reliability and a more complicated manufacture.
• Another disadvantage of such designs is that the time-delayed shutdown achieved by the bimetal elements is maintained regardless of the level of the current to be monitored. This results in a time-delayed response of the protective device even with very high short-circuit currents, which should be switched off without any delay to protect the system.
• the object of the invention is to provide a triggering device of the type mentioned at the outset, which has a selective triggering behavior, but for this only has a few, insensitive and easy-to-install components to be added to the conventional triggering coil.
• the triggering device according to the invention should lose its selectivity and respond without delay when the current to be monitored reaches a certain, predeterminable value.
• this is achieved in that the trigger armature is held in its rest position by a spring and by an electromagnet, the coil of which is traversed by the current to be monitored or a current proportional to the current to be monitored, and that the coil when a predeterminable is reached Current strength can be short-circuited.
• the response of the trigger armature is delayed by simple design measures until the force exerted by the coil on the trigger armature exceeds the holding force of the electromagnet.
• the selectivity is also automatically adapted to the current strength of the current to be monitored, but is abruptly reduced by short-circuiting, which leads to an immediate reduction in the holding magnetism.
• turns of the outermost winding layer of the coil have sections kept free of insulating material and that an electrically conductive bridge is provided which can be brought into contact with these sections when a predeterminable current intensity is reached.
• the coil has only one winding layer and that all turns of this winding layer have sections kept free of insulating material.
• This design allows each turn of the coil to be short-circuited, which ensures a particularly rapid breakdown of the magnetic field.
• the electrically conductive bridge is fixed on a short-circuit armature, which short-circuit armature is moved from the electromagnet from a rest position into the bridge Contact with the positions free of insulating material is movable, this short-circuit armature is held in its rest position with a predetermined holding force.
• a further feature of the invention can be that the holding force holding the short-circuit armature in its rest position can be generated by an elastic component connected to the short-circuit armature and the housing of the release device.
• Such components are small in size, so that they only slightly increase the overall size of the triggering device according to the invention.
• the elastic component is formed by a helical spring, preferably a compression spring, since such components can be manufactured very easily with the forces required for this application.
• the release armature can be moved indirectly by a coil, preferably by means of at least one elastic coupling member and optionally one or more auxiliary anchors connected to the release armature by the coil can be actuated.
• the elastic coupling allows the magnet armature to be moved even before the holding force is reached, this movement continuously building up the force acting on the release armature via the coupling member. This is particularly advantageous in the case of overcurrents with a long rise time, since the magnetic armature has already covered a large part of its path here when the switching threshold is reached, with rigid coupling or when the coil acts directly on the trigger armature when it reaches the Switching threshold is only released and must travel the entire way to the switching lock.
• the at least one elastic coupling member is formed by a helical spring.
• Coupling links of this type require little space, but at the same time have good elasticity which remains relatively constant over time.
• the magnetic armature is arranged at least in sections inside the coil.
• the magnetic armature can thus be moved in a precisely predictable manner by the magnetic forces of the current to be monitored.
• the trigger armature is also arranged in the interior of the coil, the trigger armature being formed from non-magnetizable material.
• the release armature has a shoulder which extends through the magnet armature and preferably runs parallel to the longitudinal axis of the coil, on which shoulder a component made of magnetizable material is fixed, which component is held by the electromagnet.
• the electromagnet has an H-shaped yoke, the crossbar of which carries the coil, the first pair of legs acts on the release armature via the component and the second pair of legs acts on the short-circuit armature.
• the electromagnet is arranged with its longitudinal axis normal to the longitudinal axis of the release armature.
• the longitudinal extent of the entire triggering device can thus be kept small.
• the short-circuit armature is laminated.
• the tripping device for an overcurrent shutdown device such as e.g. Miniature circuit breaker, has a tripping armature 11, which can actuate a key switch 18 via a pin-shaped extension 27.
• This switch lock 18 is operatively connected to one or more movable contacts 28 carrying a current to be monitored and opens them when actuated by the pin-shaped extension 27.
• the trigger armature 11 is arranged inside a coil 6 through which the current to be monitored flows and can, because it is made of a magnetizable material, through which the magnetic field generated by the coil 6 is moved in the direction of the switching mechanism 18, as symbolically represented by the arrow 110.
• the reset armature 11 is returned to its rest position - represented by arrow 120 - by a spring 12, the first end of which is supported on a symbolically illustrated, fixed component 34 and the second end of which is supported on the release armature 11 itself.
• the release armature 11 is held in its rest position, in which the pin-shaped extension 27 is lifted from the switching mechanism 18, by an electromagnet 20.
• This electromagnet 20 comprises a yoke 14 carrying a coil 7, the current to be monitored flowing through the coil 7. This is achieved by the series connection of the two coils 6 and 7 shown with strong lines.
• the trigger armature 11 is provided with a projection 24, at the end of which a component 13 made of magnetizable material is fixed. This component 13 forms with the yoke 14 of the electromagnet 20 a magnetic circuit, by means of which the above-mentioned retention of the release armature 11 is achieved in its rest position.
• the purpose of setting the trigger armature 11 in the rest position is the trigger delay that can be achieved thereby. Tripping can only take place if the force acting on the release armature 11 from the coil 6 is greater than the result of the spring force of the spring 12 and the holding force of the electromagnet 20.
• the electromagnet 20 excites itself from the current to be monitored , the tripping delay, also referred to as selectivity, is automatically set as a function of the current current, in such a way that a high current results in a high selectivity.
• the current to be monitored does not itself have to flow through the coil 7; it is sufficient to apply a current proportional to the current to be monitored to the coil 7.
• a current proportional to the current to be monitored to the coil 7. can be generated, for example, by passing a portion of the current to be monitored past the coil 7 via a parallel resistor 29, as shown in broken lines in FIG. 1a.
• This can be useful if the electromagnet 20 is designed so that only part of the current to be monitored is sufficient to implement the selectivity described, but the full current would cause the release armature 11 to be held too intensely in its rest position.
• the parallel resistor 29 the selectivity can be influenced in a particularly simple manner.
• This short circuit can be implemented in various ways.
• a switching contact 30 connected in parallel to the coil 7 is provided in FIG. 1a.
• a control circuit 31 which detects the current strength, which, according to FIG. 1a, is carried out by measuring the voltage drop caused by the current to be monitored at a shunt resistor R.
• the control circuit 31 closes the switch contact 30, as a result of which the magnetic field passing through the component 13 and the yoke 14 suddenly breaks down.
• the release armature 11 is thereby released and can immediately actuate the switch lock 18.
• FIG. 1b essentially corresponds to that according to FIG. 1a, but here the short-circuiting of the coil 7 is realized differently.
• the coil 7 it should be noted that this is always equipped with only one winding layer in the embodiments of the drawings. Although this is a preferred embodiment, it is in no way to be understood as limiting, rather this coil 7 can be equipped with any number of winding layers.
• all turns of the single winding layer of the coil 7 now have sections 71 which are kept free of insulating material.
• an electrically conductive bridge 17 is provided, which can be brought into contact with these sections 71 when a predeterminable current intensity is reached.
• a further electromagnet is provided, consisting of an armature 32 connected to the bridge 17 and a coil 33 acting on this armature 32.
• This electromagnet is controlled analogously to the embodiment according to FIG. 1a by a control circuit 31 in the manner already explained above.
• FIGS. 2a, b use the magnetic field for the movement of the bridge 17 that is already present and generated by the coil 7 itself and thus represents a measure of the strength of the current to be monitored.
• This bridge 17 is fixed to a short-circuit armature 15, which short-circuit armature 15 is held in its rest position with a predeterminable holding force and from Electromagnet 20 can be moved from this rest position into a position bringing the bridge 17 into contact with the sections 71 that are kept free of insulating material.
• the holding force of the short-circuit armature 15 is dimensioned such that when the current intensity, from which an instantaneous tripping is to take place, it is exceeded by the magnetic force acting on the short-circuit armature 15 and built up in the air gap 19. The short-circuit armature 15 is thus released, the coil 7 is short-circuited in a further sequence and the triggering is carried out.
• the holding force defining the short-circuit armature 15 in its rest position can be obtained in any way, e.g. can be generated by components generated by the short-circuit armature 15 contacting frictional forces or the like.
• an elastic component 16 is provided for this purpose, which is provided by a helical spring, which is functionally designed as a compression spring. It extends between a stationary housing part 21 and an elongated extension 151 of the short-circuit armature 15.
• FIG. 2b shows an embodiment which corresponds to the function of FIG. 2a, wherein a tension spring fixed on the short-circuit armature 15 and on a housing part 21 serves as an elastic component 16.
• the connection of the bridge 17 to the short-circuit armature 15 takes place via a contact spring 35.
• FIGS. 2a, b A preferred structural design of the electromagnet 20 can also be clearly seen from FIGS. 2a, b.
• Its yoke 14 is H-shaped, the cross bar 140 carrying the coil 7, its first pair of legs 141, 142 via the component 13 on the release -Anchor 11 and its second pair of legs 143, 144 acts on the short-circuit anchor 15.
• FIG. 3 Another embodiment of the electromagnet 20 is shown in FIG. 3: the first pair of legs 141, 142 stands normally on the second pair of legs 143, 144.
• the arrangement at right angles is again not to be understood as limiting, the selected angle between the pair of legs is irrelevant to the electrotechnical function and can therefore be selected as desired or depending on the design requirements.
• FIG. 1a A development of the embodiment according to FIG. 1a is shown in FIG.
• the special feature here is that the release armature 11 cannot be actuated directly by the coil 6, but that a further armature, hereinafter referred to as a magnet armature 10, is provided.
• This magnet armature 10 can be actuated by the coil 6 directly in the direction of the arrow 100 and is connected to the trigger armature 11 via an elastic coupling member 22 formed by a helical spring.
• the trigger armature 11 is thus only moved indirectly by the coil 6 in the direction of arrow 110.
• This indirect coupling can of course be expanded as desired by providing additional auxiliary anchors with corresponding further elastic coupling elements between the magnet armature 10 and the tripping armature 11, but these are no longer shown in the drawings.
• the triggering process of such an arrangement can be divided into two triggering phases, which are described below.
• the overcurrent In a first tripping phase immediately following the occurrence of the overcurrent, the overcurrent generates a magnetic field proportional to its strength via the coil 6, which moves the magnet armature 10 in the direction of the tripping armature 11. This movement is transmitted via the elastic coupling member 22 to the release armature 11, which for the time being, however, remains in its rest position due to the holding force exerted on it by the electromagnet.
• the coupling member 22 is increasingly biased, as a result of which the force acting on the release armature 11 increases.
• magnet armature 10 and coupling element 22 represent an oscillation system which is excited by the magnetic force generated by the overcurrent.
• the time it takes for the magnet armature 10 to pretension the coupling member until the holding force is exceeded and the trigger armature 11 can be deflected from its rest position results in the time delay, the selectivity of the triggering device according to the invention.
• the second tripping phase occurs.
• the tripping armature 11 suddenly starts to move, as a result of which the switching lock 18 is actuated and the contacts 28 are subsequently opened.
• the now coupled masses of magnet 10 and tripping armature 11, in cooperation with the return spring 12, represent the vibration system.
• the triggering is not initiated by an armature that is actuated directly by the overcurrent, but takes place indirectly by the movement of the magnetic armature 10 that is directly movable by the coil 6 and that is connected to the trigger armature 11 by the elastic coupling element 22.
• the time delay for triggering is essentially created in the first trigger phase. It is determined by the mechanical properties of the vibration system - magnet armature mass, spring rate of the coupling member 22 and magnet armature stroke - and by the current force. As is known, the current force is proportional to the current square, and consequently also the movement of the magnet armature 10. The delay is therefore also proportional to the current square, just as in the known, electrothermally functioning delay devices mentioned at the beginning.
• FIG. 5 shows a longitudinal section through a circuit breaker which is equipped with a short-circuit current tripping device according to the invention and is in the switched on state.
• the current path leads from the first connection terminal 1 a via the bimetal 2 via a flexible conductor cable 3 to the contact bridge 4, from there via the movable contact 28 and the fixed contact 36 to the fixed contact carrier 5, via the coil 6 to the coil 7 and from there to the second Terminal 1b.
• the triggering device according to the invention is constructed in principle according to the embodiment according to FIG. 2a.
• the magnetic armature 10 and the trigger armature 11 are arranged in sections inside the coil 6 in the idle state. So that the trigger armature 11 is not moved by the magnetic field of the coil 6 in such an arrangement, it is necessary to make it from non-magnetizable material, such as Plastic, to manufacture.
• the magnet armature 10 is designed as a tube piece closed on one side and at least partially accommodates the release armature 11 within its cavity.
• no elastic coupling member 22 is provided between the magnet armature 10 and the trigger armature 11, the closed tube end lies directly on the trigger armature 11. If such a coupling member 22 is to be installed, it is advantageously also arranged in the cavity of the magnet armature 10.
• the extension 24 of the release armature 11 extends through the magnet armature 10 and again carries a component 13 made of magnetizable material, which in cooperation with the electromagnet 20 causes the release armature 11 to be held in its rest position .
• the electromagnet 20 has an H-shaped yoke 14 and is arranged with its longitudinal axis 25 normal to the longitudinal axis 26 of the release armature 11.
• the overall height of the circuit breaker can thus be significantly reduced, nevertheless it is possible in the sense of the invention to arrange the electromagnet 20 at any other angle to the longitudinal axis 26 of the tripping armature 11.
• the short-circuit armature 15 is preferably designed laminated in order to reduce magnetic reversal and eddy current losses and thus to ensure a particularly rapid movement of the short-circuit armature 15.
• the switch lock 18 is carried out in a conventional construction known per se. Both the bimetal 2 and the pin 27 formed on the release armature 11 act on the contact bridge 4. This is spring-loaded, whereby the slight deflection caused by the two release mechanisms is amplified into a complete pivoting into the off position.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Breakers (AREA)
• Emergency Protection Circuit Devices (AREA)
• Electronic Switches (AREA)
• Keying Circuit Devices (AREA)

Applications Claiming Priority (3)

Publications (2)

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ID=3506060

Family Applications (1)

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• 1997
  • 1997-06-20 AT AT0107597A patent/AT406099B/de not_active IP Right Cessation
• 1998
  • 1998-06-18 TN TNTNSN98103A patent/TNSN98103A1/fr unknown
  • 1998-06-19 DE DE59801535T patent/DE59801535D1/de not_active Expired - Lifetime
  • 1998-06-19 AR ARP980102955A patent/AR011485A1/es active IP Right Grant
  • 1998-06-19 WO PCT/AT1998/000154 patent/WO1998059354A1/de active IP Right Grant
  • 1998-06-19 SK SK1760-99A patent/SK285827B6/sk not_active IP Right Cessation
  • 1998-06-19 EP EP98929114A patent/EP0990247B1/de not_active Expired - Lifetime
  • 1998-06-19 AT AT98929114T patent/ATE205960T1/de active
  • 1998-06-19 ES ES98929114T patent/ES2165169T3/es not_active Expired - Lifetime
  • 1998-06-19 AU AU78975/98A patent/AU734007B2/en not_active Ceased
  • 1998-06-19 CZ CZ0453199A patent/CZ297249B6/cs not_active IP Right Cessation
  • 1998-06-20 MY MYPI98002798A patent/MY120450A/en unknown
• 1999
  • 1999-11-22 NO NO19995717A patent/NO317124B1/no not_active IP Right Cessation

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