US2847540A

US2847540A - Device for extinguishing electrical arcs

Info

Publication number: US2847540A
Application number: US621761A
Authority: US
Inventors: Pfeiffer Adolf; Fehling Heinz
Original assignee: Licentia Patent Verwaltungs GmbH
Current assignee: Licentia Patent Verwaltungs GmbH
Priority date: 1955-11-10
Filing date: 1956-11-13
Publication date: 1958-08-12
Anticipated expiration: 1975-08-12
Also published as: DE1064589B; FR1165481A

Description

g- 1958 A. PFEIFFER ETAL DEVICE FOR EXTINGUISHING ELECTRICAL ARCS 5 Sheets-Sheet 1 Filed Nov. 13, 1956 filikiw ADOLF PFE/FFER HE/IVZ FEHL we Attorneys Aug. 12, 1958 A. PFEIFFER ETAL DEVICE FOR EXTINGUISHING ELECTRICAL ARCS Filed Nov. 1a, 1956 5 Sheets-Sheet 2 lllllllllll I! ADOLF PFE/FFER HEl/VZ FEHL/NG United States Patent DEVICE FOR EXTINGUISHING ELECTRICAL ARCS Adolf Pfeilfer and Heinz Fehling, Neumunster, Holstein,

Germany, assignors to Licentia Patent-Verwaltungs- G. m. b. H., Hamburg, Germany Application November 13, 1956, Serial No. 621,761

Claims priority, application Germany November '10, 1955 8 Claims. (Cl. 200-144) This invention relates to electrical arcs.

More in particular, this invention relates to a method and an apparatus for extinguishing electrical arcs, particularly D. C. current arcs produced in electric switches.

It is known in the art to provide electric switches with an arc extinction chamber. The electrical arc is blown into this chamber by force of magnetic fields. As the high temperature plasma is deposited at the walls of the chamber the wall molecules recombine with the load carriers. The arc plasma looses energy as the arc gases are whirled, dispersed and caused to give off heat. Finally, the loss of energy reaches the critical point at which the arc is extinguished. The extinction of strong D. C. current arcs can be greatly facilitated by dividing the are into several beams. In addition, it is known to provide for copper guiding horns imparting a certain configuration to the are thus facilitating the further treatment of the are by the various magnetic fields.

Usually the arc ignition chamber on the one hand and the arc extinction chamber 'on the other hand are located parallel to each other. However, other arrangements are known wherein a chamber has orthogonally arranged ignition and extinction planes (see the patent to Latour, 2,668,890). The advantage of this arrangement resides in the fact that the apparatus can be made much smaller than according to the usual arrangement.

The course of the arc is that shown in Figure l of the drawings and assumes the shape of a solenoid A. The are is driven into the chamber either by its own or by another magnetic field B. The arrangement of the arc guiding horns first disclosed by the patent to Latour is demonstrated in Figure 3 of the drawings. In the case of A. C. current arcs every single chamber can be kept very narrow. Thereby, the proper depositing of the plasma at the material constituting the chamber is acbomplished and at the same time the chimney effect is comparatively great. In addition, the proper magnetic field C of the arc can be compared with the field of a coil, i. e. the magnetic fields C produced by the annular arc columns A neutralize each other in regard to their neutral components K, K. Consequently, there remains only the magnetic field H comprising all coils (see Fig. 1.).

The natural magnetic field of the arc plays an important part in continuing the movement of the arc. While this may be sufficient where the individual chambers are extremely small, the effect of the natural magnetic field of the arc is almost negligible with widely dispersed partial.

arcs of D. C. current. In particular, it is impossible to impart the necessary acceleration to a D. C. current are. At the same time, it is well known, that D. C. current arcs are much more stable and therefore more diflicult to extinguish than A. C. current arcs where the point of reversal at zero leads to a de-ionization of the discharge space and thus favors the process of extinguishing the are.

For these reasons, D. C. current arcs produced in high efiiciency switches can be controlled and finally extinguished'only by having a recourse to magnetic fields. This "ice is even more important where the are must be extinguished in a predetermined period, as in high voltage switches.

On the other hand the magnetic blow-out effect should not exceed a certain amount, particularly during the last stages of the treatment of the arc and before the latter breaks, in order to avoid excess voltages which could damage the installation, as, for example, the Winding of an electric apparatus etc.

In order to avoid these disadvantages, the initial blowing force is stepped up so as to blow the arc into the extinction chamber but not to participate in the extinguishing process proper. Once the arc has entered the extinction chamber, it is influenced by an additional blowing, which is quite often initiated by the arc itself by its proper effect of division. The blowing exerted upon the arc during this stage of the process must be as effective as possible while at the same time avoiding any abrupt and harsh effects.

This additional blowing process is particularly important for high voltage switching, and especially if high voltage D. C. currents (3 kv.) are to be switched oil.

In the art, dynamic effect exerted upon the arc is enhanced by a particular construction of the arc guiding horns within the individual particular chambers. In many instances U-shaped partial guiding horns are preferred. The effect of these horns is clearly demonstrated by the formation of the magnetic field at these U-shaped horns. After partition of the arc the copper conductor is now in electric connection through the arc and is alive underneath the plasma. The magnetic field produced by this current embraces the conductor and pushes the movable convection current (arc plasma) in an upward direction. The natural magnetic field of each single partial arc supports this process (see K and K). The magnetic conductor field underneath the arc is supported by the horizontal component of the natural magnetic fields.

Usually the U-shaped horns are made relatively short compared with the total wall of the chamber, in order to allow for the development of the process of prolongation of the are which sets in immediately after the process just described.

In the solenoid-chamber mentioned further above, the projection of the U-shaped horn into the transverse plane assumes the shape of a V (see Figure 3). This makes possible a deviation of the entire are after leaving the ignition chamber and upon entering the extinction chamber. Thereafter, the single partial arcs face each other in a uniformly directed and unstable manner.

Although this arrangement offers an improvement over the older known art there are still considerable disadvantages accompanying the same. In particular, the arcs of D. C. current cannot be sufficiently accelerated, because the natural magnetic field is considerably weakened once the partial arcs have been considerably drawn apart.

It is the general object of the present invention to provide for an improved device for extinguishing electrical arcs.

It is another object of the present invention to provide for an improved device for interrupting the current in high speed switches.

It is a particular object of the invention to provide for a device with which D. C. current arcs can be extinguished very quickly.

These objects and advantages are accomplished and the drawbacks and deficiencies of the known constructions are eliminated by the arc chamber of the present invention which is particularly suitable for treating and rapidly extinguishing D. C. current arcs. The peculiar feature of the present invention consists in an arrangement whereby the arcs are received in the extinction chambers as partial arcs each having an opposed direction relative to the respective adjoining partial arcs. By employing magnetic sheets producing the blow-out effect and introducing the same into every divisional wall of the extinction chamber the natural magnetic field of every two neighboring partial arcs is rectified in regard to the vertical component. It is thus possible to create a sufiiciently large stray field for the individual are within the partial extinction chamber to effect the extinction of the are when supported by the action of the natural field of the arc.

The invention will be more fully apprehended by the description of the accompanying drawings wherein like reference numerals designate like parts, and wherein Figure 1 is a diagram showing the course of the arc in devices known in the art.

Figure 2 is a diagram showing the course of the arc according to the present invention.

Figure 3 is a schematic view of the arc guiding horns known in the art.

Figure 4 is a perspective view of the arc chamber comprising the partial chambers and the arc guiding horns of the invention.

Figure 5 is a lateral view of the chamber shown in Figure 4.

Figure 6 is a front view of the chamber shown in Figure 4.

Figure 7 is a perspective view of the iron legs embracing the ignition chamber of the apparatus of the invention.

Figure 8 is a schematic view of the arc transfer by a supplemental blow-out effect.

Figure 9 is a perspective view of the integral apparatus of the invention.

Referring now to the drawings in particular, the apparatus of the invention comprises the ignition chamber 1 and the partial extinction chambers 2 arranged vertically relative to the ignition chamber. The ignition chamber 1 is embraced by two iron legs 3 and serves for producing sufiiciently strong stray fields by influencing the two

horns

4 and 5. The two connecting yokes 6 and 7 extend into the free space underneath the arc horns and are inserted into the isolating base plate 8 which is, in turn, fastened to the switch. The base plate 3 supports the Walls 9 of a casing enclosing both the ignition chamber 1 and the partial extinction chambers 2 above the former.

The switches will be mostly of the one pole type (quick-break switches) having a fixed contact K1 and movable contact K2 fulcrumed at L. Two protective plates 10 and 11 consisting of an are proof material as, for instance Micalex are arranged adjacent these two contacts. The two plates are held at a predetermined distance from each other in the base plate 8 and screen the are particularly at its originating points from the other parts of the switch. The plates 14) and 11 are thus not mounted at the chamber casing proper, but are connected with the switch and therefore enjoy a longer life time. The various separating walls 12 of the chamber consist of hollow bodies so as to allow for a mounting of the blow-out iron 16 within the same. The separating walls 12 are formed by two spacing

strips

13, 13 consisting, for example, of hard paper, resting on a lower supporting part 14 of ceramic material, and supporting spacedly two

wall plates

15, 15. These individual elements are mounted and fastened together by conventional screw or adhesive means commonly used for assembling known are chambers. The blow-out irons 16 are inserted into the separating hollow space 17 in the form of individual single sheets and can thus be arranged in layers. By omitting one or several of the sheets eventually constituting the layer forming a blow-out iron 16, the strength of the supplemental blow-out effect can be varied. Such regulation is particularly important in order to achieve an equal and uniform distribution of the are over the entire extinguishing chamber.

The are horns 19 are arranged in couples and parallel to each other on both sides of the walls of the chamber. They are mutually connected and form a U-shaped configuration. The chamber is provided with two handles 18 at its front sides. By means of these handles the chamber can be removed and replaced especially during a control of the contacts of the switch (not shown).

The partial extinguishing chambers 2 can be further subdivided in a vertical direction by intermediary metal electrodes 20 allowing for an additional de-ionization. On account of the considerable heat capacity of the intermediary metalelectrodes the arc is cooled and de-ionized faster than usually and the duration of the arc is accordingly shortened. At the same time, the arc chamber can take care of a far greater number of switching operations.

The operation The apparatus of the present invention just described in detail operates in the following manner:

As soon as the contacts K1, K2 are opened the arc plasma is blown through the ignition chamber. As the moving cathode and anode points proceed on the arc guiding horns 4 and 5 a stray field is produced in the iron legs 3. This stray field forces the arc in upward direction. Therefore it is with a suificiently accelerated speed that the arc hits the arc horns 19 embracing the separating hollow walls and serving as a sonde. At this stage the arc is split up to form various partial arcs. It is first caught by the pickup arc horns 19 and transferred to the various extinguishing chambers in the form of a plurality of partial arcs. Every single partial are now follows a direction opposed to the course pursued by the adjoining partial arcs.

Contrary to the well known solenoid chamber, the arrangement according to the present invention is of the bi-filar type and there must be a screen for every single partial arc in order to obtain a sufliciently strong stray field by the superpositioning of the vertical component of the natural magnetic fields, as will be seen from Figures 2, 4, 5, 8 of the drawings.

The advantages of the present invention are particularly apparent if the apparatus is applied to switches for interrupting D. C. current, but it is, as a matter of course, equally applicable to A. C. current.

It will be understood that this invention is susceptible to modification in order to adapt it to diiferent usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

What we claim is:

1. In a device for extingushing electrical arcs composed of an arc ignition chamber and a plurality of arc extinguishing chambers, the improvement of a plurality of are horns arranged in pairs, said are horns being connected at their respective bases to form a U-shaped configuration, each pair of horns having a direction which is opposite to the direction of the neighboring horns.

2. The improved device as described in claim 1, further comprising a couple of iron legs, said iron legs embracing the ignition chamber of the arc extinguishing device, and a couple of yoke pieces, said yoke pieces connecting said iron legs below said are horns.

3. The improved device as described in claim 1, further comprising a plurality of hollow separating walls, said hollow separating walls separating the arc extinguishing chambers and being adapted for receiving the blowout irons of said are extinguishing device.

4. The improved device as described in claim 1, further comprising a plurality of hollow separating walls, each of which separating walls comprises a pair of spacing strips, a pair of ceramic base parts supporting said strips, and a pair of wall plates, and a plurality of blow-out irons each of which is housed in one of said hollow separating Walls, said hollow separating walls separating the arc extinguishing chambers from each other.

5. The improved device as described in claim 2, further comprising a base plate bearing said iron legs, and a pair of protective plates of are proof material, said protective plates being exclusively mounted in, and connected to the base plate of the arc extinguishing device intermediate said iron legs so as to laterally confine the ignition chamber of said are extinguishing device.

6. The improved device as described in claim 1, further comprising intermediary metal electrodes, said electrodes further subdividing in a vertical direction each of 10 the extinguishing chambers of the arc extinguishing device.

7. An improved method for extinguishing electrical arcs, comprising the step of dividing the are into a plurality of partial arcs having a transverse direction relative to the course of the unidivided arc and each partial 5 ity of partial arcs and de-ionizing the subdivided portions of the partial arc.

References Cited in the file of this patent UNITED STATES PATENTS 2,564,178 Strobel Aug. 14, 1951 2,668,980 Latour Feb. 9, 1954 2,707,739 Latour May 3, 1955 FOREIGN PATENTS 253,098 Switzerland Nov. 1, 1948