DE2501717A1 - OVERCURRENT CIRCUIT BREAKER - Google Patents

Description

T KTAKWALT HOLZEE DIPIi. R. BUKG GS LdEH-dil'llASSE 14 • pTHTTT.TF U ₁ £ 1373 1.*", • ATE) ING. ATJ 'PINE

W. 720

Augsburg, January 14, 1975

Westinghouse Electric Corporation, Westinghouse Building, Gateway Center, Pittsburgh, Allegheny County, Pennsylvania 15222, V.St.A.

overcurrent circuit breaker

The invention relates to an overcurrent circuit breaker with a contact arrangement and a switching mechanism.

To protect circuit breakers and other equipment in electrical distribution systems from damage caused by excessive

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large currents due to the mechanical inertia of the self-switching mechanism between the perception of the Overcurrent through the circuit breaker and the actual time of contact separation occurring time delay it has become common practice to connect circuit breakers in series with current-limiting protective fuses, which instantaneously respond to overcurrents and limit these currents to a level that triggers the circuit breaker is sufficient, but cannot destroy it. However, such current-limiting protective fuses have the disadvantage that they are no longer reusable after a single response to an overcurrent.

A circuit breaker that itself has a current-limiting capability and, in contrast to protective fuses can be reset and reused after each triggering process is known from US Pat. No. 3,517,356, "Das there The switching device described has two pairs of contact arms, each of which is rotatable about one end of its contact arm is mounted and carries a contact at its other end, and the contact arms are arranged and electrically so connected that in the closed position the two contact arms of each contact arm pair in the longitudinal direction with each other align and the two contact arm pairs essentially

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are arranged parallel to one another and flowed through them in opposite directions. As a result, it causes when a strong overcurrent occurs, the electromagnetic Repulsion that the contact arms of each contact arm pair in the direction of the contact arms of the respective other contact arm pairs are pivoted away about their axes of rotation, so that thereby the contacts are opened and the current flowing through the electromagnetic tripping mechanism of the switching device is limited. The trigger mechanism causes rectilinear movement of one of the two pairs of contact arms as a whole from the other Contact arm pair away into a contact open position. Since the overflows of this type act on the contact arms Repulsive forces decrease exponentially with increasing distance between the opening contacts, are the Contact arms of the pair of contact arms that can move as a whole to compensate for this undesirable weakening of the driving forces each equipped with a spring, which during the pivoting movement of the associated contact arm takes effect and accelerates the same in the direction of its fully open position and it up to a later resetting in the closed position in this furnace division holds.

The invention has for its object to be a

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To improve over the troms protection switch of the general type set out at the beginning so that it can limit strong overcurrents very reliably and without the need for assistance from acceleration springs and still be compact, simple in construction and very reliable, _etc.

In terms of solving this problem, such an overcurrent circuit breaker according to the invention is characterized in that the contact arrangement has two fixed contacts and one in a straight line in a closed position and an open position movable bridge contact, that further the switching mechanism a magnetic release device contains, which forms a magnetic flux conducting path and a part of the bridge contact receiving has open-ended groove that a holding device is also provided, which in the closed position of the Switch exerts a holding force acting in Schlxeßrichtung on the bridge contact, and that the arrangement is made is that in the case of an overcurrent of a certain strength flowing across the bridge contact, such a large magnetic one Flux is induced in the magnetic trip device that the bridge contact is contrary to the holding force in the sense a quick contact separation and current limitation is drawn into the said groove in the opening direction.

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The arrangement according to the invention represents a switching device with double interruption, in which an overcurrent of a certain magnitude causes a straight movement of the bridge contact by pulling it quickly into the groove of the magnetic release device, roughly in the same way in which the windings are drawn into the armature slots in an electric motor. Because the width of the groove of the magnetic release device in the entire range of motion of the bridge contact remains constant, the driving force acting on the bridge contact also remains constant, so that the bridge contact with undiminished speed in its completely Open position is driven and consequently no special acceleration springs to ensure a complete Contact opening required.

The magnetic trip device is layered and preferably from a large number of approximately U-shaped metal sheets composed of soft magnetic material, which so are aligned that the between their U-legs located spaces together form the said groove. The bridge contact is in one through the magnetic Triggering device guided through opening in a straight line movable.

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The holding device, which holds the bridge contact in its closed position at permissible currents, is preferably a magnetic arrangement with a permanent magnet, the pole pieces with one between them Has gap-forming parts. A movable armature mechanically connected to the bridge contact is bridged, when the bridge contact is in its closed position, the gap between the two pole pieces and thus closes the magnetic circuit of the permanent magnet, so that the bridge contact is in its closed position is magnetically locked. If desired, the The bridge contact can be made unlockable by hand using an auxiliary anchor pretensioned in an inoperative position is provided, which is brought into contact by hand with the two pole pieces of the magnetic holding device can be, creating a magnetic shunt to the one running through the movable locking armature magnetic circuit is formed and consequently the bridge contact is unlocked.

The magnetic holding device can advantageously be designed for a mode of operation according to the flux transfer principle, i.e. it can be a fixed Anchor, which is so with respect to the two pole pieces

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is arranged that he has one with the permanent magnet forms another magnetic circuit, which, however, has a higher magnetic resistance than that caused by the moving one Has armature extending closed magnetic circuit, and an electrical coil can be provided, which such with respect to the two magnetic circuits is arranged that an excitation of the coil when the moving Armature is in its locked position, the relative magnetic resistances of the two magnetic Circles changes so that a flux shift from the magnetic circuit passing through the movable armature in the magnetic circuit running through the fixed armature is caused into it. This will make the bridge contact unlocked for a contact separation movement, which is independent of the magnetic release due to the action of suitable means, for example one that biases the movable armature in the contact opening direction Compression spring takes place, the spring force being less than is the magnetic force normally holding the movable armature in its locked position. This arrangement has the advantage that it is suitable for triggering the circuit breaker even when overcurrents occur less powerful than that used to operate the magnetic

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Trip device required overcurrents. the Design of the overcurrent circuit breaker for such a Trip mode only requires switching on current-sensitive switching elements in the excitation circuit of the mentioned electrical coil, which this excitation circuit when one of the response current strength of the relevant Circuit breaker corresponding overcurrent closes'. Desired if the said excitation circuit can also have a manually operated trigger switch for closing the Coil circuit included.

The bridge contact can be made from its Offensteliung by manual or other resetting of the movable Armature in its armature locking division in its closed position to be led back. In the above-mentioned embodiment, which has the additional trigger option offers, the can on one below the response current the magnetic release device lying overcurrent appealing additional triggering device independent of the movable one connected to the bridge contact Anchors can be made resettable by an additional, relatively movable relative to the first-mentioned movable armature and between the same and those associated with the permanent magnet Pole shoes arranged armature is provided, and

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in that the bias voltage acting on the bridge contact in the switch opening direction is applied to the said additional anchor the first-mentioned movable armature acts. With this arrangement it is possible to use the additional release device by resetting the additional anchor against the action acting on it Reset bias when the pole pieces as well as the bridge contact and consequently the first-mentioned armature below the influence of a magnetic induced by the occurrence of an overcurrent in the magnetic trip device The force of the river.

Some preferred embodiments of the invention are described below with reference to the accompanying drawings, for example. Show it:

Fig. 1 is a plan view of an over

current protection switch according to the invention with removed housing cover,

Fig. 2 is a vertical section along

the level II-II in Fig. 1,

Fig. 3 is a vertical section through a

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modified construction of the bridge contact shown in FIG ,

Fig. 4 is a vertical section through a

further embodiment of the invention,

5 along a vertical section

the plane V-V in Fig. 2,

Fig. 6 is a horizontal section in

Plane VI-VI in Fig. 4, and

Fig. 7 is a circuit diagram of some of the

overcurrent circuit breaker according to Fig. 4 included elements.

With the overcurrent circuit breakers shown in the drawings it is a single-pole switchgear. It is clear, however, that the invention does not apply limited single-pole switching devices, but can be used in the same way on multi-pole switch arrangements.

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The circuit breaker shown in FIGS. 1 and 2, generally designated by, has an insulating housing 13 with a base 15, side walls 20, end walls 17 and a cover 19, the cover being suitably
for example by means of screws 21a screwed into threaded bores 21 in the side walls 20, removably attached to the rest of the housing.

The overcurrent circuit breaker also has a. magnetic release device 23, which can be referred to as a magnetic groove motor and contains a layered yoke with a substantially rectangular outline and a groove 63, which on the housing base 15 facing surface 65
is open and at its other end 67 is closed. That
layered yoke consists of relatively thin
Sheets 59 made of soft magnetic material, for example made of iron or cold-rolled steel. The sheets 59 are in
essentially U-shaped and in a suitable manner, for example by means of screws or rivets 61 so with one another
connected that the cutouts delimited by the U-legs in the essentially U-shaped metal sheets with one another
align and together form the groove 63 of the magnetic release device. In the fiction, contemporary switching device
it is a switch with double interruption,

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which two fixed contacts 33 arranged on both sides of the magnetic release device and one through the Groove 63 has protruding bridge contact area 27, which the latter in a straight line within the groove 63 in a closed position with the fixed contacts 33 and an open position is movable. A resilient pad 69 made of suitable material such as nylon and serves as a buffer for the bridge contact arm 27, the groove 63 is attached to the bottom 67. According to FIG. 2, the carries Bridge contact arm 27 two movable contact pieces 31 interacting with the two stationary contacts 33 The stationary contacts 33 are arranged on conductor strips 35 and 37, which pass through openings in the housing end walls 17 protrude and connectable by means of terminals 39 to power and load lines, not shown are. When the switch is closed, i.e. when the linearly movable bridge contact arm 27 with the stationary Contacts 33 has connection, the circuit according to FIG. 2 runs from the conductor strip 35 on the left-hand side via the pair of contacts 33 »31» the bridge contact arm 27 and the pair of contacts 31, 33 on the right-hand side to the conductor strip 37

The bridge contact arm 27 is generally of one

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rait 29 designated arrangement held, which in a in the direction of movement of the bridge contact arm through the magnetic release device 23 through η Opening 49 is guided movably in a straight line. In addition, a lining 79 is located in the opening 49 non-conductive material, which preferably has a low coefficient of friction, for example polytetrafluoroethylene. the Liner 79 of opening 49 extends substantially from the open end 65 of the groove 63 to a point 81 slightly above the layered yoke and has two diametrically opposite incisions 83, which with the groove 63 of the magnetic release device align and in which the bridge contact arm 27 is movable.

The holding arrangement 29 for the bridge contact arm 27 of the preferred embodiment shown in FIG. 2 has a contact arm carrier 73 which has a recess for receiving the contact arm 27 and on which the contact arm is rotatably attached by means of a pin 77. To a limited tilting movement of the contact arm 27 for the purpose of allowing self-alignment when the switch is closed with respect to contacts 33 is the. Surface of the recess receiving the contact arm

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Contact arm support 73 is arched, as indicated at 87. The contact arm support 73 has a holding element to which one end of a compression spring 75 is attached, the other end of which is attached to a peder holding element 71 is appropriate. The spring 75 is used to generate a contact pressure force between the contact pairs 31 and 33, if these are closed and locked in a manner still to be described. The contact arm support 73 and the spring retaining element 71 are made of insulating material, which preferably has a low coefficient of friction, ie for example made of polytetrafluoroethylene, since both the contact arm support and the spring retaining element are inside the lining 79 should slide relatively easily "

The overcurrent circuit breaker also has a general with 41 designated holding device which, when the switch is closed, the contact arm 27 in normal, permissible currents in contact with the fixed contacts 33 holds. In the embodiment shown in FIG this holding device has a permanent magnet 43 with pole pieces 45 (see also Fig. 1), which latter on opposite sides of the Permanent magnets 43 are arranged and extend over the opening 49 of the magnetic release device 23.

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In addition, the holding device contains an armature arrangement 47, 53 interacting with the two pole pieces protruding over the opening 49, the armature 53 of which is attached to one end of a shaft 51 which protrudes through the space between the two pole pieces and into the opening and at the other end End is connected to the spring holding element 71. The upper end of the shaft is accommodated together with the armature arrangement 47, 53 ^for protection in a hat-shaped insulating part 55 placed on the housing cover 19.

If the individual parts of the switch are in the positions shown in Fig. 2 with solid lines, i.e. when contacts 31, 33 are closed, they are bridged the armature 53 the two pole shoes 45 and is consequently in the magnetic containing the permanent magnet 43 Circle. This has the consequence that the bridge contact arm 27 is magnetically locked in the contact closed position and remains locked in this position as long as the strength of the current flowing through it is normal is. In the event that the current rises above a certain Given the current intensity this current induces in the magnetic release device 23 but such a large one magnetic flux, as indicated by arrows 89 in FIG

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is that the holding force of the permanent magnet 43 is overcome and the bridge contact arm 27 is drawn into the groove 63 of the trip device (see the diagram in Pig * 2 Contact arm position indicated by dashed lines), so that the movable contacts 31 quickly move away from the stationary ones Contacts 33 are separated and the current flow is effectively limited before the switch is fully opened. In the illustrated Each contact pair 31, 33 is a suitable embodiment Spark extinguishing device assigned to facilitate complete power interruption.

The overcurrent protection switch can be reset to its closed position by depressing the shaft 51 is until the bridge contact arm 27 again with the. fixed contacts 33 has contact and the armature 53 again bridged the two pole shoes 45 and the contact arm holds magnetically locked in its closed position. Depression of the shaft 51 can be accomplished by inserting a suitable tool, not shown, through an opening 57 and formed in the hat-shaped cover part 55 Pressure is exerted on the armature 53 with this tool.

Fig. 3 shows a modification of the overcurrent circuit breaker described above, which is based on the shape of the

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rectilinearly movable bridge contact arm 93 with the movable contacts 95 and a simpler design the conductor strip 99 with the fixed contacts 97 relates.

Another embodiment of the invention is shown in FIG. There are only those from the so far The embodiments described have been given different parts with new reference numerals. The release mechanism of this The switch version has two trigger mechanisms, namely one for lower overcurrents and the other for high overcurrents.

The circuit breaker shown in Fig. 4 has a Conductor 101 with a vertical part 103, a bimetallic element 105, an electromagnet generally designated 107 and one enclosed by a coil 111 Anchor 109 on. The lower end of the bimetal element 105 is at 113 on the vertical part 103 of the conductor 101

attached. The upper end of the bimetal element 105 carries a contact piece 115, which with a corresponding Contact piece 118 at the upper end of a conductor 117 interacts. The top of the conductor 117 is rigid attached. The lower end of the conductor 117 carries one

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Armature 119 and a contact piece 121, which is connected to a contact piece 123 fastened on a U-shaped core 125 cooperates. The core 125 is in turn on a part of the conductor 101 fastened and encloses the vertical part 103 of this conductor 101. An increase in the current to a low overcurrent magnetizes the core so strongly, that it attracts the armature 119, whereby an electrical contact between the contact pieces 121 and 123 is made will.

There is also a switch 129 for manual opening of contacts 95 and 97 are provided.

As shown in more detail in FIG. 6, when the armature 47 is locked, most of the magnetic flux of the permanent magnet from one pole piece through the armature 47 to the other pole piece. However, another path for the magnetic flux is formed by the armature 109, which as a result of arranged between the armature 109 and the pole pieces 45, Spacers 131 made of insulating material (Fig. 6) one has higher magnetic reluctance. If the coil 111 is energized, it reduces the holding force by a

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Magnetic field builds up »whose direction of action is opposite runs to that of the permanent magnetic field. Through this the armature 47 is released. This mechanism is on has a very fast triggering ability, which, however, is due to the inertia of the bridge contact arm 27 and the generation the required acceleration in a spring 133 The amount of energy that can be stored is limited »The flux transfer j coil 111 is shown in FIG. 7 by closing the contacts 121 and 123 of the electromagnetic device 107 or by Closing the contacts 115 and 118 of the bimetal element IO.5 excited. The supply voltage is supplied by a full wave bridge rectifier 135 and leads 137 supplied. The contact pairs II5, 118 and 121, 123 and the switch 129, which can be operated either by remote control or by means of a push button 130 are connected in parallel, see above that the overcurrent protection switch is activated when one of these switching arrangements is closed triggered by energizing the coil 111 will. Since the bimetal element 105 and the electromagnet 107 are not used directly to trigger the switch, they can only close auxiliary contacts. regarding Size and mass in the sense of a considerable increase the working speed must be reduced.

According to FIG. 4, an armature 134 is resiliently mounted in such a way that

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• οι © ·

that he normally has no contact with the pole pieces the flux transmitter assembly has. However, when the pin I36 connected to the armature is depressed, it closes he briefly part of the magnetic flux and the armature is released due to its spring preload, so that the switch opens. In this way, the switch can be triggered manually. The switch is activated by depressing a Reset button 139 reset, which when open The switch protrudes through the opening 57 of the housing part 55.

Since the reset mechanism including the push button 139 and the armature 47 closes the switch in the presence do not allow an overcurrent, a further armature 141 is provided according to FIG. That other anchor is placed on the armature 47, which in the locked state most of the energy to trigger the Spring 133 stores. The armature 47 is first reset by means of a lever mechanism, not shown, then the armature 141 is reset and only requires a small holding force, about 2.7 kg for a 100 amp switch. If a large overcurrent occurs, the armature 141 is released first, since the bridge contact arm 93 is accelerated by the yoke 59. With smaller ones

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overflow, the armature 47 is released first and takes the anchor l4l and the bridge contact arm 193 with.

The switching device according to the invention thus has a Number of advantages, in addition to which a lower forward current and a lower energy loss, a greater one Number of trips at high overcurrents than at Switches with single interruption, a better utilization of the yoke material for generating a driving force and an increased rate of rise of the arc voltage with the same acceleration of the contact arm as belong to a single break switch. Finally, the switch according to the invention has a Peak switching capacity of up to 100,000 amperes effectively with symmetrical current and through integration of the switch and the current limiting assembly into a single unit there are considerable cost advantages and a remarkable reduction in overall dimensions,

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Claims (12)

Claims / 1.! Overcurrent circuit breaker with a contact arrangement and a switching mechanism, characterized in that the contact arrangement has two fixed contacts (33) and one in a straight line in a closed position and an open position movable bridge contact (27) that further the switching mechanism is a magnetic release device (23) which forms a path which conducts the magnetic flux and which forms part of the bridge contact receiving open-ended groove (63) that further a holding device (41) is provided, which in the closed position of the switch one in the closing direction acting holding force exerts on the bridge contact, and that the arrangement is made so that in the event of an over The bridge contact flowing overcurrent of certain strength such a large magnetic flux in the magnetic release device what is induced is that the bridge contact counteracts the holding force in the sense of rapid contact separation and current limiting is drawn into said groove in the opening direction. 2. Overcurrent protection switch according to claim 1, characterized - 22 -509831/0234 characterized in that the magnetic release device (23) has a layered yoke (25) which consists of a Large number of approximately U-shaped metal sheets (59) made of soft magnetic material Material consists, which are aligned so that the spaces between the U-legs together form said groove (63), 3. Overcurrent protection switch according to claim 1 or Z _3, characterized in that an opening (49) extends in the direction of movement of the bridge contact (27) through the magnetic release device (23) and that a contact holder (29) carrying the bridge contact is slidably arranged in this opening . 4. Overcurrent protection switch according to claim 2, characterized characterized in that the bridge contact (27) can be tilted on Contact holder (29) is arranged so that the Eontaktarm for the purpose of self-alignment with the fixed Contacts (33) can perform a limited tilting movement in the closed position, 5 · Overcurrent protection switch according to one of claims 1 to 4, characterized by means (75) for production a contact pressure between the bridge contact (2?) and - 23 5Q9831 / 0234 the fixed contacts (33) with the switch closed,. . 6. übers tr oms ch ut zs ch al ter according to one of claims to 5, characterized in that said holding device ( ¹ Jl.) Has a permanent magnet (43) and a movable armature connected to the bridge contact (27) ( 53), the arrangement being such that the armature closes the magnetic circuit of the permanent magnet when the bridge contact is in its closed position and thereby magnetically locks the bridge contact in its closed position. 7 * overcurrent protection switch according to claim 6, characterized by a further manually operated armature (134), which is shown in Direction of its inoperative position is biased and so in cooperation with the magnetic circuit of the Permanent magnets (43) can be brought that he has this magnetic Circuit as a magnetic shunt short-circuits and thereby the bridge contact (27) is unlocked. 8 «overcurrent protection switch according to claim 6 or 7» characterized in that the holding device (41) has a has additional fixed anchor (109), which - 24 509831/0234 is arranged such that it has a further magnetic circuit parallel to said magnetic circuit higher magnetic resistance than the first mentioned, passing through the movable armature (47) magnetic circuit closes, and that an electrical coil (111) is arranged and polarized such that it when excited, the magnetic resistance further magnetic circuit changed so that a flux shift from the first-mentioned magnetic circuit to the others magnetic circuit takes place, whereby the movable armature is released, 9. Overcurrent protection switch according to claim 8, characterized characterized in that the holding device has a second movable armature (47, Fig. 4) between the the former movable armature (141) and the magnetic Circle of the permanent magnet (43) is arranged that further Biasing means (133) the second movable armature and pretension the first-mentioned movable armature via this in the opening direction of the bridge contact (27), and that the first-mentioned movable armature independent of the second movable armature in the opening direction of the bridge - 25 ■ - 509831/0234 contact and the second movable armature independent of the the first-mentioned movable armature from an unlocked position relative to the permanent magnetic circuit into a magnetic one locked position is movable. 10. Overcurrent protection switch according to claim 8 or 9, characterized by triggering means for separating the bridge contact (27) of the fixed contacts (33) when an overcurrent occurs with a lower current intensity than the specified current strength, and that this triggering means a switching element (121) for closing the Excitation circuit of said electrical coil (111) at the overcurrent with said lower current intensity exhibit. 11 «overcurrent protection switch according to claim 10, characterized characterized in that the triggering means a second switching element (115) for closing the excitation circuit for the electrical coil (111) have at overcurrents, the current strength of a further, also lower than that the former value exceeds the current strength. 12. Overcurrent protection switch according to claim 10 or 11, - 26 509831/0234 characterized in that said triggering means also a hand-operated switch (129) for closing of the coil excitation circuit. 509831/0234 Blank page