DE3005877A1 - DEVICE FOR EXTINGUISHING THE ARC OF ELECTRICAL SWITCHGEAR - Google Patents

Description

BROWN, BOVERI & CIE AKTIENGESELLSCHAFT Mannheim February 14, 1980

Mp.no. 507/80 ZFE / P4-Ft / Ht

Device for extinguishing the arc of electrical switchgear ...

The invention relates to a device for extinguishing the arc for electrical switching devices, in particular for low-voltage AC contactors higher rated current, with at least one contact point and one arranged parallel to it Secondary electrode arrangement, this being assigned a semiconductor arrangement which is connected to the auxiliary electrode arrangement switches off the flowing current during its zero crossing.

Low-saving AC contactors for switching high outputs are used in large numbers in electrical power engineering. When switching off under load, switching arcs occur, which continue to maintain the flow of current after opening the contact pieces and only allow a final interruption of the circuit after they have migrated to an extinguishing system. The service life of the contact and extinguishing system in which ^: 35

mostly arc-splitter stacks assigned to each contact point is decisively influenced by the thermal effects of the switching arcs.

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So-called hybrid switching systems are therefore proposed on various occasions in order to reduce the amount of arcing work carried out. in which the load current commutates to a secondary path after opening the main contacts and through semiconductor valves installed there is switched off in the natural zero crossing. The valve is then fitted with mechanical devices By-pass after the current has zeroed from the main circuit (see. DE-OS 27 30 726).

These previously known so-called hybrid switching systems have the disadvantage that they either require controllable semiconductor valves, or alternatively, when using uncontrolled semiconductors, synchronous switching drives were required.

The object of the invention is to create a device of the type mentioned at the outset which has a simple mechanical structure using semiconductor elements, a simultaneous reduction in the arc work for the main contact points or · for the main contact point of a double or single sub-2Q breaking system and inrush current peaks from the Keeps semiconductor elements away.

According to the invention, this object is achieved in that in parallel in addition to the contact point, a further secondary electrode arrangement

" _T. It is provided that both secondary electrode arrangements are formed from two secondary electrodes each, that means are also provided for generating a constant magnetic field which drives the arc to one or the other secondary electrode arrangement, depending on the polarity, and that in series with the secondary electrodes

2Q trode each secondary electrode arrangement one as a rectifier acting semiconductor arrangement is provided.

In other words: the space between the opening contact pieces is interspersed with a magnetic constant field, which the developing alternating current arc through magnetic Forces away from the contact pieces and depending on the direction of current flow on one of each contact point of the Double break or single break system associated Secondary electrode pairs drives. At least one at a time

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Secondary electrode of each secondary electrode pair (or arrangement) is connected to a rectifier, the polarity of which is selected so that it conducts the current up to the end of the respective alternating current half-cycle from the secondary electrode of one contact point, which is connected to the load circuit via the arc, and one after the zero crossing of the alternating current prevents further current flow. _{In the case of a double-break system, the semiconductors are polarized so that they can ro} the current up to the end of the respective alternating current half-oscillations from the secondary electrode connected to the load circuit via the arc of one contact point £ <u of the corresponding secondary electric.

de the other contact point and in the same way a further current flow after the zero crossing of the alternating current prevented.

A renewed flow of the alternating current in the half-wave following the blocking time of the rectifier is thereby prevents the arc gaps between the secondary electrodes from deionizing during the rectifier blocking time and thus lose their conductivity. A mechanical opening of this circuit is therefore unnecessary.

In the arrangement according to the invention, the secondary electrode arrangements are Formed by stationary secondary electrodes, which prevents synchronously switching drives.

In the normal case, simple diodes can be provided as semiconductor arrangements; for certain purposes, for example to achieve a high current limitation, controlled semiconductor valves can also be provided through which the load current is no longer switched off in the natural zero crossing, but current-limiting after reaching a certain current value.

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With the device according to the invention are preferred Way provided AC contactors; There is also the possibility of using every circuit breaker according to the teaching to train the invention.

Based on the drawing, in which some examples of embodiments of the invention are shown, the invention and others are intended advantageous refinements and improvements of the invention are explained and described in more detail.

It shows

Figure 1 is a schematic representation of a first embodiment of the device according to the invention, in one -J5 first operating state with two contact points,

FIG. 2 shows the device according to FIG. 1 in a second operating state,

Figure 3 shows a further embodiment of the invention similar to Figure 1,

Figure 4 is a perspective view of the device according to Figures 1 and 2,

FIG. 5 shows a perspective illustration of the arrangement according to FIG

of Figure 3,

FIG. 6 shows a perspective illustration of a further embodiment the invention,

Figures 7 and 8 a device according to the invention with only

a contact point, in the closed or open state,

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Figures 9 and 10 with a further device according to the invention

only one contact point in the closed and open state.

Reference is made to FIG. 1. The switch, which is referred to as a "hybrid switch", has a double contact system with a first fixed contact piece 2 connected to a connection terminal 1, to which a contact bridge 4 is attached, first movable contact piece 3 is assigned. A second movable contact piece is also located on the contact bridge 4 5 attached, which is also connected to a terminal 7 electrically-galvanically connected to the second fixed Contact piece 6 cooperates.

To the contact point formed by the two contacts 2 and 3 and is therefore called the first contact point, a first secondary electrode arrangement (also a secondary electrode pair) is assigned, which is formed from the secondary electrodes 10 and 11 and the two further secondary electrodes 10a and 2o. The two Secondary electrodes Io and 11 as well as lüa and 2o are on opposite sides Sides of the contact point arranged. In the same way, each of the contacts 5 and 6 are also formed from the second Contact point assigned to two pairs of secondary electrodes, consisting of secondary electrodes 14 and 15 and the secondary electrodes 14a and 18 are formed. The sub-electrode 11 is connected to the sub-electrode 15 via a line 11a in which a diode 16 is arranged, which is connected to the secondary electrode 15 in the forward direction. The secondary electrodes 18 and 20 are connected to one another by means of a further line 18a, the line 18a having a diode 21 which faces in the direction is switched from the secondary electrode 18 to the secondary electrode 20 in the forward direction.

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The first and second contact point 2/3 and 5/6 is a magnetic one Constant field 9/13 (or several magnetic constant fields) associated with generating element. The constant magnetic field 9 runs perpendicular to the plane of the picture panel and into it, and the constant magnetic field 13 is perpendicular to the plane of the picture panel and out of this. The ^ generated by the two equal fields Forces exerted on the electric arc through which current flows are directed in the same direction according to the Amper's rule, what is indicated by the arrows 9a and 13a.

In the event of a switching operation, an arc 8 or 12 is drawn between the two contact points 2/3 and 5/6. In the case of a positive half-oscillation of the load circuit (see. Fig. 1), the current enters the terminal in the direction of arrow F ₁ when the switch is closed, flows over the fixed and movable contact pieces 2/3 in the direction of arrow F-, over the contact bridge 4 in Arrow direction F, and over the two contact pieces 5 and 6 in arrow F or F, - to terminal 7. When lifting the contact bridge 4 with the movable contact pieces 3 and 5 in the direction of the arrow F is located between the contact pieces 2, 3 is commutated by the forces exerted by the constant magnetic field 9 in the direction of arrow 9a away from the contact pieces to the secondary electrodes 10, 11 and the arc forming between the contact pieces 5 and 6 is commutated by the constant magnetic field 13 in the direction of arrow 13a on the secondary electrodes 14 and 15. The current is thus commutated from the contact bridge 4 to the rectifier or to the diode 16 and flows there in the direction of the arrow F, and is interrupted by the rectifier 16 at the end of the current half-cycle. In the negative half-oscillation of the load current (cf. over. When the contact bridge with the movable contact pieces 3 and 5 is lifted off in the direction of arrow F, the will be located between the contact pieces

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5 and 6 forming arcs 17 by the electromagnetic forces exerted by the constant magnetic field 13 in the direction of the arrow 13b away from the contact pieces onto the secondary electrodes 14a, 18 driven and the one between the contact pieces 2 and 3 resulting arcs 19 due to the forces exerted by the constant magnetic field 9 in the direction of arrow 9b on the Secondary electrodes 20, 10a. The current flow is thus commutated from the contact bridge 4 to the rectifier 21 and is interrupted by the rectifier 21 at the end of the current half-oscillation.

Fig. 3 shows an arrangement which is similar to that of Figs. 1 and 2. The secondary electrodes 11 and 18 are above a line 50 and the secondary electrodes 20 and 15 are connected to one another via a line 52. The two lines 5 0 and

52 are themselves in turn bridged via a line 5 4, with 15

In the line 5 4 a rectifier diode 22 is switched on, which only a current flow from the line 5 0 to the line 52 allows. The mode of operation of the arrangement is otherwise the same as that in FIGS. 1 and 2, respectively.

FIG. 4 shows a possible embodiment of the double break system according to the principle shown in Figure 1 with the two rectifiers 16 and 21 and the two secondary electrodes 11 and 20 or 15 and 18. The constant magnetic field 9

or 13 is held by a permanent magnet 23 between the two 25

Contact points generated; the magnetic return is achieved by means of a C-shaped iron core 24.

Fig. 5 shows a spatially constructive embodiment of the

Arrangement according to FIG. 3 with the rectifier 22

Purposes are the two secondary electrodes 11 and 18 through a secondary electrode 26, which is both integrated into itself, and the two Sub-electrodes 20 and 15 formed by a sub-electrode 25. Otherwise, the arrangement is then the same as that according to FIG. 4.

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Another embodiment of the invention with two rectifiers 21 and 16 is shown in FIG. 6. The secondary electrodes 29 and 31 as well as 30 and 32 are arranged on both sides to form a contact piece 27 and 28 made of erosion-resistant conductor material, with between the Secondary electrodes and the fixed contact pieces each have a half-ring gap 27a, 27b or 28a and 28b left free. Of the Arc 8 and arc 12 then burn in half-ring gaps 27a and 28b, respectively; otherwise the arrangement is the same as that according to FIG. 4.

The variants that work with only one rectifier allow the generated by the permanent magnet to be amplified in a simple manner DC magnetic field after commutation, in which with the rectifier 22 according to FIG additional blowing coil is connected in series. At all

The permanent magnet can also design options shown in J5 be arranged at other points of the facility; it should provide the required constant field between the contact pieces and the Set up secondary electrodes. The use of a common permanent magnet for multi-phase contact systems is possible.

In the figure 7 is a device according to the invention with only one Contact point shown. The two opposite contacts have the reference numerals 50 and 52 and are in Surround the area of the contact point with an erosion ring 54 and 56, which erosion ring is made of arc-proof material. A pair of secondary electrodes 58 and 60 is arranged on both sides of the contact point, which are made up of the secondary electrodes (or also briefly called electrodes) 62 and 64 or 66 and 68 are formed. The sub-electrodes 62 and 64 are wired to each other 70 and the secondary electrodes 66 and 68 are connected to one another via a line 72, the lines each having a rectifier diode 74 and 76, which are switched for a current flow in the forward direction. Between the secondary electrodes 62 and 64 or 66 and 68 and in the area of the contact point, there is the magnetic constant field 78, which is transverse to the contact point and runs transversely to the secondary electrodes.

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(Direction of current flow Figure 7 shows the device in the closed state. When the movable contact piece (here the contact piece 50) moves away from the fixed contact piece (here the contact piece 52), then the current commutates in the selected direction from the current and magnetic field into the gap between the contact piece 50 or the consumable electrode 54 and the secondary electrode and burns there, as does the arc between the secondary electrode 68 and the consumable ring 56.

V (according to arrow direction Py) .jQ The further current flow ty as can be seen from FIG. 8 _; Via the line 72, the diode inserted in the forward direction towards the fixed contact piece. If the polarity of the current changes, then the current wants to flow through the diode 76 in the reverse direction; this is not possible and in the area between the

.,. Secondary electrodes 62 and 64 and the associated consumable rings 54 and 56 ignition cannot occur, so that with this polarity there is no arc and no further current flow he follows. When the next half-wave comes, in which the diode 76 would again be applied in the forward direction, has the space between the consumable electrode 54 and the secondary electrode 66 or the consumable electrode 5 6 and the secondary electrode 68 deionized to the point that reignition is no longer possible. For the reverse current polarity, the the processes described analogously to that in FIGS. 7 and 8

pe left side of the arrangement.

FIGS. 9 and 10 show an arrangement similar to that in FIGS. 7 and 8; here, however, are the secondary electrodes 66 and 68 or 62 and 64 not connected to each other,

but the secondary electrode 66 with the secondary electrodes 64 and 30

the secondary electrode 62 with the secondary electrode 68 via lines 80 and 82, respectively. These two bridging lines 80 and 82 are connected to each other via a connecting line, in which a diode 86 is turned on, such that im

In the event of a switching operation, the diode 86, as shown in FIG. 10 35

can be seen, is flowed through in the forward direction. The mode of action is the same as in the device according to Fig. 8 j

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_{/ 3} 300587?

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In the case of a contact opening, the arc commutates in the first half period after the contacts have opened into the gap between the consumable piece and the secondary electrode 66, flows via the line 80, the diode 86 _and the line 82 to the secondary electrode 68, where a second arc is formed between the latter and the burnout ring 56. After the zero crossing, the polarity is reversed, so that the diode 86 is now acted upon in the reverse direction. An arc cannot form between the secondary electrodes 62 and 64 and the associated erosion rings on the contact pieces; with a further reversal of polarity, the diode 86 would again flow through the current in the forward direction; Since the gap between the dp-r electrode 66 and the consumable ring 54 as well as the electrode 68 and the consumable 56 is deionized, the arc can no longer be reignited.

Because of the greatly reduced arc work according to the invention, the contact pieces can be made small and light; In addition to the reduced use of precious metals, the expenses for the mechanical drive are reduced, and arcing chambers are not required. The rectifiers used do not need to carry any inrush currents and are separated from the load circuit at both poles, except during the disconnection process; they are also not subject to any mechanical stress. The secondary electrodes are easily exchangeable and, depending on the desired service life, can consist of material that is as resistant to erosion as possible or as inexpensive as possible. After the arc has been extinguished, the load streamer-Fifä-fVanisch is disconnected. The direction of the arrow of the flowing current is indicated in the illustration according to FIGS. 9 and 10

Fg.

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Claims (11)

. Mp, no. 507/80 Feb. 14, 1980 ZFE / P4-Ft / Ht Claims e \
lj device to extinguish the arc for electrical switching devices, higher in particular for low-voltage alternating current contactors rated current, with at least one contact point and arranged in parallel therewith side electrode assembly, said a semiconductor device is associated which switches off the current flowing through the secondary electrode arrangement stream during its Nulldiarchgang, characterized characterized ge characterizing in that additionally parallel to the contact point a Another secondary electrode arrangement is provided that both secondary electrode arrangements are formed from two secondary electrodes each, that means are also provided for generating a constant magnetic field, which depending on the polarity of the arc on the 25th drives one or another secondary electrode arrangement, and that in series with the secondary electrodes of each woven electrode arrangement a semiconductor arrangement acting as a rectifier is provided. 2. Device according to claim 1, characterized in that that the secondary electrodes assigned to the same load current polarity are operated in the forward direction for this load current polarity Rectifiers are connected to each other. 130036/0089 3. Device according to one of claims 1 or 2, characterized characterized in that the secondary electrodes associated with the unequal load current polarity are each by means of a bypass line are interconnected and that both bridging lines with the interposition of a rectifier, which in Forward direction is switched for the load current polarity of both secondary electrodes, are connected to each other. 4. Device according to one of claims 1 to 2, characterized in that each secondary electrode of the one secondary electrode arrangement with one of the secondary electrodes of the additional secondary electrode arrangement via the one acting as a rectifier Semiconductor arrangement is connected so that the current flows through one or the other semiconductor arrangement and depending on polarity is switched off in the zero crossing.
15th 5. Device according to one of the preceding claims, in particular for switching devices with a double contact point, characterized characterized in that two secondary electrode arrangements are assigned to each contact point. 6. Device according to one of the preceding claims, characterized in that in a double contact arrangement between the contact points a permanent magnet is provided for generating the magnetic constant field, its north-south direction runs parallel to the connecting line of the contact points, v / obei the secondary electrodes transversely to the constant field on both sides of the Contact point run. 7. Device according to claim 6, characterized in that that in order to achieve a magnetic return path, an approximately C-shaped core extending outside the contact points is made ferromagnetic material is arranged such that the magnetic lines of the constant field between the ones facing each other Leg ends of the core through the permanent magnet in FIG. 35 lie on one level. 130036/0089 300587? 8. Device according to one of the preceding claims, characterized in that on both sides and at a distance from each fixed contact piece each with a strip-like secondary electrode attached is such that the arcs associated with each load current polarity between the fixed contact piece and the secondary electrode burn in the gap formed between the two. 9. Device according to claim 8, characterized in that the fixed contact piece in the area in which the arc burns, is at least partially formed from an arc-proof conductor material. 10. Device according to one of claims 1 to 6, characterized in that each secondary electrode arrangement consists of two secondary electrodes arranged parallel to one another are formed 15 is, the distance from each other is chosen so that reignition after the arc has been extinguished. 11. Device according to claim 8, characterized in that the constant magnetic field is substantially between the two secondary electrodes. 130036/0089