US2196820A - Arrangement for extinguishing electric arcs - Google Patents

Description

April 9, 1940. H. VERSE ARRANGEMENT FOR EXTINGUISHING ELECTRIC ARCS Filed IarCh 7, 1939 Inventor: Hahsh'e'mfich Verse, b .1%

Attorn ey.

Patented Apr. 9, 1940 UNITED STATES ARRANGEMENT FOB EXTINGUISHING ELECTRIC ARCS Hanslseinrich Verse, Brunswick, Germany, aslignor to General Electric Company, a corporation of New York Application March I, 1939, Serial No. 260,458

In Germs it, March 17, 1937 4(liaims.

It is known that the arc, arising when the contacts or a switch carrying continuous-current are separated, can be extinguished only ii the arc voltage, requisite to maintain the arc, becomes 5 higher than the supply voltage of the network. In order to extinguish the arc in the case of a high voltage direct or continuous current the arc must, therefore, either be drawn out to a great length or must be subjected to an extraordinarily strong extinguishing blast.

These methods of extinguishing arcs can be materially improved by following a suggestion, according to which, in order to obtain the purpose in view, several auxiliary electrodes are provided onto which the main arc is blown with the aid of a magnetic field. But apart from undesired excessive elongation of the arc, as is necessary also with this switch, the respective arrangement suffers from the drawback that the extinguishing effect of the magnetic blow-out depends upon the strength of the arc current.

It is, furthermore, known that an arc can be extinguished by conducting through it a counterdischarge from a condenser for example, the intensity of the current of which is equal to, or greater than, the momentary intensity of the arc to be extinguished. but to produce this counterdischarge it has up to now been necessary to make use of additional switching arrangements or source of current. If, the net voltage itself is used for charging the condenser eflecting the counter discharge it is, if no additional means are employed, possible to attain at the most a strength of counter-current equal to the strength of the interrupted current, but opposite thereto, but this does not insure that the rupturing arc will be reliably and quickly extinguished.

The present invention obviates the above-mentioned disadvantages of the known arrangements by providing in an arrangement designed for extinguishing arcs with the aid of the dischargecurrent of a condenser charged from the network across a resistance, auxiliary electrodes which the arc to be extinguished touches, and which are connected to a condenser charged across high resistances in such a sense that the discharge initiated by the arc itself extinguishes this arc.

As with the arrangement constituting the present invention the electro-motive force, driving the counter-current, is always greater than the decrease of the counterelectro-motive force of the portion of the arc lying in the counter-current circuit, it is, by this invention assured that a counter-current arises which is essentially greater than the current of the arc to be extinguished.

The are current is, therefore, not only reduced to zero in the portion of the arc to be extinguished which is inserted into the counter-current circuit, but the counter-current tends to reverse the direction of the current in this position of the arc, 5 that is to say, part of the arc will be extinguished quickly and definitely where the present improved arrangement is used.

The invention is illustrated diagrammatically and by way of example on the accompanying 10 drawing on which Figure 1 is partially an elevation, partially in vertical cross section, of the entire arrangement and combination of parts constituting the invention, and Figure 2 is a horizontal cross section through some details located 15 in the uppermost portion oi Figure 1, as more fully described hereinafter.

On the drawing, L denotes a casing of noncombustible or refractory material. This casing may be termed an extinguishing chute. In the 20 lowermost portion of said casing or chute are supported two movable contact members K1 and K: which are located opposite to one another and are intended to interrupt the continuous-current high voltage circuit indicated in Figure 1 by a as heavy line. Into this circuit is inserted a continuous current generator G one pole of which can be grounded as well as a load V. In the uppermost portion of the casing L are located two stationary electrode contacts E1 and E: (Figures 1 30 and 2) which are connected in a circuit network with a condenser C across resistances R: and R4 of appropriate size. The condenser is charged to the full value of the voltage to be interrupted, in the present case the continuous current voltage 36 across resistances R1 and Rs.

If the continuous current circuit is to be interrupted, the two contacts K1 and K: are separated from one another by means of the operating mechanism denoted H. The are now arising be- 40 tween said contacts is either blown upwardiy-by a jet of compressed gas, as indicated by the flow direction arrow of Figure 1 from a pipe P connected with a source of such gas simultaneously with actuating of the said contacts in the manii ner described, or said are is subjected either to the action of a suitably arranged blowout coil or to the heat generated by the arc itself whereby the arc is driven upward in the casing or chute L. By suitably determining the strength of the action IO selected for the purpose stated it is possible to have the arc touch the electrodes E1 and E: only when the contacts K1 and E have been moved away from one another to the utmost degree, as indicated by dotted lines in Figure 1. At this 5 moment the condenser C discharges across the portion of the are located between the electrodes E1 and E2 due to the comparatively low dielectric strength of the are gases in the gap between said electrodes, and extinguishes that portion of the arc in said gap, as can be seen from the signs of polarity and the indications of the directions in Figure 1. As, owing to the charging path for the condenser C, as stated, there exists always the full operating voltage between the electrodes E1 and E2, whereas the portion of the are located between these electrodes undergoes only a decrease of voltage, the desired enforced extinguishing will always take place. The character of the counter-discharge from the capacity C is to be suitably adjusted by means of the resistances R: and R4 or, in lieu thereof, by reactances or by combinations of reactances and resistances.

After the portion of the rupturing are located between the electrodes E1 and E2 has been extinguished, the arc portions that existed between the contact K1 and the electrode E1 and between the contact K2 and the electrode E: are also extinguished if the resistances R1 and R2 (across which the condenser C has been charged) are of such high value that the current passing through them becomes so slight that it no longer sufilces to maintain an arc whereby the procedure of the self-acting extinguishing is completed The extinguishing method according to this invention obviously can also be used for other portions of the are. But also any other desired additional extinguishing methods such as fluid blast can be applied to the other portions of the arc.

After the switch has again been closed, the condenser C is again charged, whereupon the switch is again ready for use, i. e., for another interruption.

The arrangement described is not restricted for the use in connection with switches used for the single extinction of arcs, but is also applicable with suitable changes in connection with rectifier devices.

I claim as my invention:

1. An arrangement for extinguishing electric arcs in a direct current circuit comprising arcing means connected in said circuit, a pair of auxiliary electrodes arranged to form an arc gap separate from said arcing means, means for causing the arc to impinge on said electrodes, and a network including a condenser and impedance electrically connected to said circuit and to said auxiliary electrodes so that said condenser is charged from said circuit, the connections between said network, auxiliary electrodes and circuit precluding flow of current in the open circuit position, the polarity of said charge at said electrodes being opposite to the polarity at said arcing means whereby said condenser can discharge through a portion of said are in opposition to the arc current when said are impinges on said auxiliary electrodes.

2. An arrangement for extinguishing electric arcs in a direct current circuit comprising arcing means connected in said circuit, a pair oi auxiliary electrodes forming an arc gap separate and spaced from said arcing means so that an intermediate portion oi the are when extended impinges on said electrodes to bridge said gap, and a condenser electrically connected to said circuit and across said electrodes so that the condenser charge across said gap is opposite in polarity to that at said arcing means whereby said condenser may discharge through said intermediate portion of the arc in opposition to the arc current when said arc moves into the gap between said electrodes.

3. An arrangement for extinguishing electric arcs in a direct current circuit comprising separable contacts connected in said circuit, means for extending the are beyond said contacts, a pair of electrodes forming an arc gap disposed in the path of said arc so that an intermediate portion of said are can move into said gap to bridge said electrodes, and a circuit network including a con denser and resistances electrically connected to said circuit and to said electrodes so that the polarity of the condenser charge across said gap is opposite to that at said contacts whereby said condenser may discharge through said intermediate arc portion at said gap in opposition to the arc current, said network being connected with respect to said direct current circuit and electrodes so that said condenser is eii'ective to check further current flow in said circuit after interruption of arcing at said electrodes.

4. An arrangement for extinguishing electric arcs in a direct current circuit comprising separable contacts connected in said circuit, an insulating arc chute in which the arc is formed between said contacts, means for directing a fluid blast through said chute for looping said are beyond said contacts, a pair of auxiliary electrodes disposed in said chute toward the exhaust portion thereof, said electrodes being spaced to form a gap directly in the path of an intermediate portion of said arc, and a circuit network including a condenser and resistances electrically connected to said circuit and to said auxiliary electrodes so that the polarity of the condenser charge across said gap is opposite to that at said contacts whereby said condenser may discharge through said gap in opposition to the arc current when said intermediate arc portion moves into said gap, the connections of said network to said direct current circuit and auxiliary electrodes being such that said condenser precludes further flow of current in said circuit after interruption oi the are at said auxiliary electrodes.

HAN SHEINRICH VERSE.

Images