DE1588224A1 - Thermal and magnetic release device for an overcurrent circuit breaker - Google Patents

Description

7 //
Docket 4lD-9l
HS-Ser.No. 528.276
Convention date:
February 17,1966

General Electric Company, Schenectady, N.Y., USA

Thermal and magnetic release device for an overcurrent circuit breaker.

The invention relates to electrical control devices, in particular an automatic switch whose movable contact between the open and the closed position can be actuated * mechanism; is switchable, which contains a pawl part that with Notching through both thermal and magnetic overcurrent tripping causes the switch contacts to open automatically.

For some circuit breakers, thermal and magnetic tripping is desirable in such a way that at a certain relatively high overcurrent magnetic tripping and, in the case of certain, relatively low overcurrents, the thermal tripping takes effect. In some cases it will A transformer device is used for thermal tripping, which heats a bimetallic strip, which when it occurs

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relatively low continuous overcurrents is operated. Such a transformer! See device is in the am 7 · 1 · 65 elngerichten USA patent application serial no. 423 9 ^ 2 (inventor; George E. Gauthier) by the same applicant.

Although the various prior art devices such as e.g. according to the above-mentioned US patent application, the connected circuits against relatively high overcurrents as well as against protect relatively low continuous overcurrents, they allow im generally no protection against a sudden surge current average value, which is not sufficient to make the magnetic release effective, but is strong enough to endanger the connected devices or circuit arrangements. In fact, since small overcurrents generate little heat that is used to open the circuit under these conditions thermal release device sq. be set up that it responds to small continuous overcurrents, but not to minor ones Current fluctuations. Such thermal release devices therefore have, in order to avoid unnecessary release, a slow response and are therefore generally ineffective against sudden overcurrent surges of medium value,

The invention is therefore based on the object of creating a thermal and magnetic release device that is based on ' responds to relatively low, medium and relatively high overcurrents.

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There should be predetermined for low and medium overcurrents Two independent thermal release devices and in the case of a relatively high overcurrent, a magnetic one Release device take effect.

Pure thermal tripping at low continuous overcurrents a transformer device should be used.

To solve this problem, according to the invention, a thermal and magnetic trip device for an overcurrent circuit breaker provided with a holder on which an electrical Arranged head and an actuator for actuating the switch are movable. One on the holder close to the ladder arranged magnetic field piece forms a path for the Magnetic flux induced by the current flowing through the conductor is, and has two spaced, each forming a pole arm portions, one of which is earlier by the magnetic flux is more saturable than the other. An armature movably arranged on the holder normally becomes magnetic against the former Arm part tightened, but when a relatively strong overcurrent occurs in the conductor, this saturates of the flow path formed by the first-mentioned arm part, magnetically attractable against the other arm part. When the anchor is pulled in this way against the other arm part, detected he the actuator so that this is moved.

A first thermal trip device arranged on the holder and responsive to the flow of current in the conductor causes

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when a predetermined overcurrent mean value occurs, the armature moves away from the first-mentioned arm part towards the ' other arm part, so that the magnetic field of the other arm part can attract the armature and thereby the armature the actuator grasped and set in motion. A second thermal trip device arranged on the holder, which also responds to the flow of current in the conductor, detected when a predetermined overcurrent occurs, a relatively low value the actuator so that it is moved.

The two thermal trip devices can either be placed on the conductor or on the holder and speak for predetermined medium and low value currents. One of these two devices is supposed to trigger a trip to prevent minor current fluctuations, a relatively slow response, but speaks to small or relatively low continuous overcurrents so that it takes effect when the overcurrent persists.

The other of the two thermal release devices must, in order to prevent damage to the connected circuit, respond quickly to overcurrents of medium value. It advantageously consists of a bimetal strip arranged on the conductor, which takes effect in the event of sudden overcurrents of average value, the one before the more slowly responding thermal trip device takes effect, can cause damage, but is not sufficient to activate the magnetic release mechanism Bringing appeal.

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For the first thermal release device, a transformer Device can be used with a magnetic core, which is arranged on the holder close to the conductor, so that he provides a path for the magnetic flux induced by the current in the conductor. A secondary winding arranged on the core is through the magnetic flux in the core excitable, and one in thermal contact with this secondary winding arranged bimetallic strip can detect the actuator so that it is moved. These transformer device responds slowly because the secondary winding must first be heated before the bimetallic strip is operated. It is therefore effective at relatively low continuous overcurrents, but it is granted because of its slow speed Response normally does not provide protection against sudden overcurrents or overcurrent surges of medium value.

The first thermal trip device and the magnetic trip device detect and move the armature when it occurs a corresponding overcurrent in the sense of actuation of the actuating element * In the preferred embodiment, the Armature and the second thermal trip device set up so that when they are actuated they capture a trip rod, their movement then actuates the trigger mechanism of the switch.

Appropriately, a clamping device is arranged on the holder, which the anchor against the first-mentioned arm part of the Magnetic field piece tensions and, if no current in the conductor

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flows, holds in this its only minimal position, and the one additional Holding force supplies which must be overcome by the magnetic attraction of the other arm part before the anchor at Occurrence of a sudden high overcurrent can be drawn against this other arm part. Serves as a clamping device expediently a coil spring which is attached between the switch housing and the armature, so that they normally tensioning the armature against the first arm part of the magnetic field piece.

If a strong overcurrent occurs, the magnetic flux path formed by the first-mentioned arm part is saturated earlier than that of the other arm part, which later generates a sufficiently greater magnetic attraction force to counter the armature pulling away the holding force of the spring and the magnetic force of attraction of the first-mentioned arm part. When a mean Overcurrent overcomes the second thermal release device the holding force of the spring and the magnetic attraction force of the first-mentioned arm part, so that the armature of the first-mentioned arm part lifted off and magnetically attracted to the other arm part and thereby the actuator is moved.

Further features of the invention will become apparent from the following description with reference to the accompanying drawings. Show it:

Fig. 1 is a side view of a multipole circuit breaker, part of the switch members are shown in dashed lines and a

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Piece of the switch housing is broken away to certain switch organs to show more clearly;

Pig. 2 is a fragmentary section of the switch according to FIG. 1 on an enlarged scale, the switch switches in FIG ON positions are shown;

FIG. 3 is a fragmentary section similar to FIG. 2; the switch elements shown in phantom are shown in the OFF position; and

Fig. 4 is a fragmentary perspective view in enlarged scale of part of the organs of the switch of FIG. 1.

In the drawings, 10 generally denotes a multipole circuit breaker with the trip device according to the invention. According to the usual design, the automatic switch 10 has a housing 12 and a manually operable toggle lever 14, which switches two movable contact pieces 18 and 20 between the open and closed positions via a suitable actuating mechanism 16. The actuating mechanism 16 contains a pawl 22 which can be latched by a release mechanism 24 which automatically interrupts the flow of current in the main conductors of the switch in the event of an overcurrent due to thermal or magnetic release.

For the actuating mechanism 16, an embodiment of that in US Pat. No. 2,921,168 of 1/12/66 is preferably used

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(Inventor: Judd et al) of the same applicant type described used. A suitable latch or release mechanism 24 is disclosed in US Pat. No. 2,834,407 of April 29, 1959 (inventor: Steven et al) by the same applicant.

In Fig. 1, the movable contacts 18 and 20 of the switch 10 are shown in the ON position, in which they make contact with two fixed contacts 26 and 28 arranged on the conductor 30. The movable contacts 18 and 20 are arranged on the contact arm 32, which is pivotably mounted on the housing 12 and is electrically connected to the flexible conductor 34. The conductor strip 36 and a further conductor J3, which is guided through an opening in the triggering device 40, which is accommodated in a housing made of two molded parts 42 and 44 that fit one another, are electrically connected to the contact arm 32. The lower housing part 42 as the larger of the two parts serves as a holder for parts of the trigger mechanism 24, while the part 44 serves as a cover. The trip unit 40 causes the pawl 22 to disengage when overcurrents occur in the main conductor 30, whereupon the actuating mechanism 16 moves the contact arm 32 so that the movable contacts 18 and 20 of the switch 10 are lifted and the current is thereby interrupted.

The multi-pole switch 10 has a plurality of pole chambers and a movable contact set 18 and 20 in its housing 12 in each of these polar chambers. The operating mechanism 16 can be operated by hand by switching the rocker arm 14 so that

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that the movable contacts 18 and 20 of each pole chamber are in the ON position where they meet the corresponding fixed contacts 26 and 28, or be brought into the OFF position by turning the rocker arm 14, where they are fixed by the corresponding ones Contacts 26 and 28 are lifted in each pole chamber and thereby the individual circuits are interrupted. That Lifting the movable contacts 18 and 20 from the fixed contacts 26 and 28 can also be achieved by automatically releasing the Pawl 22 by the release mechanism 24 when actuated by the thermal or magnetic device in the Trip unit 40 take place.

In Fig. 2, the switch members are in the ON position of the Switch 10 shown in Fig. 1, wherein the pawl 22 is latched. The trip rod 46 is by means of a pivot pin 48 hinged to the lower housing part 42 so that it is via an adjusting screw 52 can be detected by a first thermally triggering bimetal strip 50. There is also 48 on the pivot pin an armature 54 is mounted, which by an adjusting screw 56 on a second thermally tripping bimetal strip 57 j which is arranged on the conductor 38 can be detected.

The conductor 38 penetrates an arrangement with an insulating part 58 and a magnetic sheet metal core arrangement 60 fastened thereon. The insulating part 58 is shaped in such a way that it is in the trip unit 40 sits and is held, and it has several openings (not shown) for the passage of the various main conductors of the multipole

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Switch, for example the conductor 38, which by suitable Screws 62 are attached to the housing.

The insulating part 58 also carries a secondary winding 64 on each of the core parts. The secondary winding 64 is preferably made from a short turn in the form of a single loop of solid copper as shown. The bimetal strip 50 is attached to the secondary winding 64.

For the magnetic trip device, there are magnetic main pole pieces 66 relatively large volume provided, the pairs on the insulating part 58 each opposite the individual ·. Magnetic core parts 60 are arranged at a distance from one another, so that there is an air gap between them which is magnetically parallel, runs to the associated core part 60. On the main pole pieces

66 , a pair of magnetic auxiliary pole pieces 68 of relatively small volumes is arranged in each case, these auxiliary poles running with their ends at a parallel distance from the ends of the main poles 66. In this way, each of the main pole pair 66 and the associated auxiliary pole pair 68 are arranged at a distance from one another; Nete pole or arm parts that can attract the armature 54 in question magnetically.

The anchor made of magnetically susceptible material ' 54 has such a length that its free end extends between the parallel ends of the pole pairs 66, 68, so that it is of the End parts of both pole pairs can be detected magnetically. The trigger rod 46 is by a coil tension spring 70, which with her

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one end is anchored on the lower housing part 42 of the trigger unit 40, tensioned in the counterclockwise direction (total in FIG. 2). The spring 7C holds the armature 54 in the normal ON position, in which it is detected by the magnetic auxiliary pole pair when no current flows in the conductor.

A current flowing through the main conductor 38 generates a Magnetic field that penetrates the magnetic core 60, the main magnetic poles 66 and the auxiliary magnetic poles 68. Since the anchor 54 is in the area the parallel magnetic flux paths through the pole pairs 66, 68 are located, a normal flow of current generates a magnetic flux which, in cooperation with the spring 70, causes the armature 54 in FIG ON position on the auxiliary magnetic poles 68 and in the stop on the Adjusting screw 56 on the second bimetal strip 57 holds. When a predetermined strong overcurrent occurs, the auxiliary magnetic poles are 68 magnetically saturated and a stronger magnetic attraction force is generated in the larger magnetic pole parts 66, so that the armature 54 against the force of the spring 70 and the magnetic force of the auxiliary magnetic poles 68 to the left (total. In Fig. 2) is drawn against the larger magnetic poles 66. At this Movement displaces or pivots the armature 54 the trip rod 46, whereby the lever or knee joint of the trigger mechanism 24 is pressed down, so that the spring-loaded The pawl 22 disengages and thereby the actuating mechanism l6 removes the movable contacts l8 and 20 from the fixed ones very quickly Contacts 26 and 28 can stand out.

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The bimetal strip 50 speaks in a similar manner to that Occurrence of overcurrents in the main conductor 38. Such a Overcurrent causes the magnetic field in the magnetic core 60 and in the secondary winding 64 formed by a short-circuit winding increases in intensity. Since the secondary winding 64 is short-circuited and made of a very good conductor material such as e.g. Copper, there are very strong eddy currents in the secondary winding generated, which heat the metal of the secondary winding 64 quickly. This heat is very quickly applied to those in direct contact therewith located bimetal strips 50 transferred. Because the bimetal strip 50 is constructed and arranged in such a way that it bends to the right (total in Fig. 2), causes it to bend, that the set screw 52 detects the trip rod 46 and pivoted clockwise, whereby the trip mechanism 24 is actuated will. Appropriate setting of the adjusting screw ensures that this bimetallic strip on a relatively small continuous overcurrent responds.

A faster-acting thermal trip is brought about by the bimetal strip 57, which is arranged directly on the conductor J58 is and is actuated by a sudden overcurrent surge of medium value, which a rapid heating of the conductor 58 as a result, but is insufficient to cause armature 54 to be pulled away from auxiliary magnetic poles 68. When through a sudden rise in temperature in conductor 38 as a result of a predetermined overcurrent mean value of the bimetal strips

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is heated, it bends to the left (total. In Fig. 2), and the set screw 56 pushes the armature 54 away from the auxiliary magnetic poles 68 away in the direction of the main magnetic poles 66 until their Sufficient magnetic field to fully attract armature 54. At his Pivoting detects the armature 54 the trip rod 46, which is the trip mechanism 24 actuated so that the pawl 22 is disengaged and the switch is thereby opened.

During operation of the device, when a small, but lasting overcurrent, the trip rod 46 through the interaction of the magnetic core 60, the secondary winding 64 and the bimetal strip 50 actuated. The main and auxiliary magnetic poles 66 and 68 act when one occurs relatively strong overcurrent surge regardless of the bimetallic strip 50 a pivoting of the trigger rod 46 by the Anchor 54. The second bimetal strip 57 is through a middle Actuated overcurrent which is insufficient for the magnetic actuation of the armature 54, but is strong enough to damage it to cause the system before the switch is triggered by the slower responding first bimetal strip 50. The second bimetal strip is set in such a way that it is affected by the low continuous overcurrent required for actuation of the first bimetal strip 50 is sufficient, is not actuated. The device thus responds to different overcurrent conditions such as that the switch is triggered in any case before any damage can occur.

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The invention thus creates a thermal and magnetic release device for an overcurrent self-holder that is set to relatively low, medium and relatively responds to high overcurrents. Pur the operation of the » The trigger mechanism in the event of overcurrent of predetermined low and medium values are two independent thermal ones Triggering devices are provided, and in addition, a magnetic triggering is provided, which in the case of relatively strong Overflow becomes effective. The device thus protects the connected devices and lines from damage in all possible overload conditions.

The special embodiment described above and shown in the drawings can be used within the scope of the invention in modify and design differently in various ways

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Claims (7)

Claims 1.) Thermal and magnetic release device for an overcurrent circuit breaker with a holder on which an electrical conductor and a movable actuator for operation of the switch are arranged, characterized by a arranged on the holder close to the conductor (58) magnetic field piece that forms a path for the magnetic flux generated by the flow of current in the conductor and two spaced apart, respectively a pole-forming arm portions (66, 68), one of which is saturable by the magnetic flux earlier than the other; one on the Holder arranged movable armature (54), which is normally magnetically attracted against one arm part (68) and at Occurrence of a relatively strong overcurrent in the conductor, which causes saturation of the flow path of this one arm part, can be magnetically attracted to the other arm part (66) in such a way, that it detects the actuating member (46) and in the sense of an actuation the switch moves; a first thermal release device (57) * which is arranged on the holder and which, when a predetermined overcurrent average value moves the armature away from one arm part against the other arm part, so that this other arm part magnetically fully attracts the armature and brings it into engagement with the actuator; and one arranged on the holder second thermal release device (60, 64, 50), which when a predetermined, relatively weak overcurrent occurs BATH ORIGINAL 009833/0338 in the head of the actuator detected and in the sense of an actuation of the switch moves. 2.) Device according to claim 1, characterized in that the first thermal release device is a is arranged on the conductor bimetallic strip (57) which detects and moves the armature (54) when it is bent. 3.) Device according to claim 1 or 2, characterized that the second thermal release device is a magnetic core part arranged on the holder close to the conductor (6o), which forms a path for the magnetic flux generated by the current flow in the conductor, one arranged on the magnetic core part Secondary winding, which can be excited by the magnetic flux in the magnetic core part, and one in thermal contact with the secondary winding arranged bimetallic strip (50), which detects the actuating member (46) when it is thermally bent and in the sense an actuation of the switch moves contains. 4.) Device according to one of the preceding claims, characterized in that the actuating member a trip rod (46) articulated on the switch housing (12), which is triggered by the movement of the armature (54) and by the deflection of the bimetallic strip (50) of the second thermal release device in the sense of an actuation of the release mechanism (24) of the switch can be pivoted. 5.) Device according to one of the preceding claims, characterized by an attached to the holder 009833/0338 arranged tensioning device (70), which the anchor (54) against the one Arm part (68) tensions and provides an additional force which is overcome by the magnetic attraction of the other arm part (66) must be before the armature is fully attracted by this other arm part when a corresponding overcurrent occurs can. 6.) Device according to claim 5 * characterized in that that the tensioning device is a helical spring (70) fastened between the holder and the armature. 7.) Device according to one of the preceding claims, characterized in that the switch a movable and a fixed contact, which are on the Holder are arranged, an actuating mechanism arranged on the holder for switching the movable contact between the open and closed position with a latch part, which causes an automatic contact opening when notched, and a release mechanism disposed on the holder which, when actuated, disengages the pawl member. 009833/0338