US1331625A - Flexible connection for electric furnaces - Google Patents

Description

1.11. CRITCHETT. FLEXIBLE CONNECTION FOR ELECTRIC FURNACES.

APPLICATION FILED JULY I9, 1919- I Patented Feb. 24,1920.

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JAMES CRI'I'CHETT, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO ELECTED METALLURGICAL COMPANY, OF NIAGARA FALLS, NEW YORK, A CORPORA- TION OF WEST VIRGINIA.

FLEXIBLE CONNECTION FOR ELECTRIC FURNACES.

Specification of Letters Patent.

Patented Feb. 24, 1920.

Application filed July 19, 1919. Serial No. 312,044.

To all whom it may concern:

Be it known that 1, JAMES H. Carronnrr, a citizen of the United States, residing at Niagara Falls, in the county of Nia ara and State of New York, have invente certaln new and useful Improvements in Flexible Connections for Electric Furnaces, of which the following is a specification.

The present invention relates to electric furnaces and more particularly to electric connections for conducting the current to the electrodes.

In the construction of electric furnaces it is necessary to provide a flexible connection between the electrode and source of power in order to allow movement of the electrode to take care of changes in the level of the furnace and wear of the electrode. This flexibility is usually obtained by the introduction of a short section of conductor made up of the necessary number of flexible copper cables. In small furnaces which require moderate currents no difficult is found in providing flexible cables of S11 cient current carrying capacity, but in the modern large plantswhich require a very large current, difficulties are encountered due to the mutual inductive effect of these cables. The addition of more cables does not increase the current carrying capacity, of the system in proportion to the cop r added owing to the increased inductive e ect mentioned.

The mutual inductive effect in other parts of the circuit may be reduced by interlacing the outgoing and return conductors, but it is difficult to interlace bars of differentoint where the fl xible connection starts. T

this non-interlaced condition in the flexible connection.

It is the principal object of this invention to provide means for reducin the mut ual inductive efl'ect and converse y increasing the power factor of the system.

I accomplish this object by so disposing the elements of the flexible connection relatively toeach other that the electro-ma etic effect upon each other is considerab y reduced.

In order to more fully explain the principle u on which the invention is based and to in icate one way in which the invention the power factor due to may be advantageously carried into practice, I refer to the accompanying drawings in which- Figure 1 is a diagrammatic view of a device of ordinary construction representing the prior art;

F i 2 is a similar view of a device embodymg the invention;

Fig. 3 is a diagrammatic view of the usual electrical connections between a singlephase furnace and a source of supply; and

Fig. 4 is a similar view embodying the invention.

In Fig. 1-10 represents a source of alternating current as for instance a transformer, 11 a set of rigid 'busbars, 12 a flexible; connection composed of a number of flexible cables and 13 the movable electrode. f

The busbars, as has been previously Inch tioned, are in practice interlaced, i. e. a bar of one polarity is adjacent a bar of relatively opposite polarity, whereby the mutual inductive eflect is neutralized. However, theinterlacing' cannot be practically continued beyond the point 11' where the flexible connection beglns. At this point the flexible cables making connection between the bus bar or bus bars of one polarity and the movable electrode separate from connectors of opposite polarity and form aseparate group. Under these conditions the magnetic lines surrounding one cable continuously out each or most of the other cables and thereby set up, as is well understood in these other cables an electromotive which in its effect neutralizes paflhof the current flowing therethrough and this effect increases progressively with the number of cables.

InFig. 2 is shown a simple arrangement for reducing this mutual inductive effect. One half of the cables of the flexible connection 12' are carried on an insulated support 14 which is yieldingly held in spaced position relatively to the remainin cables by means of a rope or cable 15 running over gulleys 15 and a suitable counter weight 17.

y this arrangement the one set of cables is aintained in proper relation to the other set. of cables and yet allowed freedom of movement. I

It is understood that the flexible connection may be divided in more than two groups and that the yielding spacing rela-v tion may be effected in other ways and by other means. I have referred to the counter weight-operated support merely as one simple and convenient means for carrying out the object and contemplate the use of all means whereby one cable or group of cables is maintainedin spaced relation relatively to another cable or other cables in such a way that the normal function of the flexible connection as a whole is not materially impeded.

In Fig. 3, which represents the prior art, the bus bars 20 and 20 of relativelv opposite polarity are interlaced in the usual manner between the transformers 21 and the flexible connections. At the end of the bus bars the flexible connection 22 leads from the bus bars 20 to the electrode 23 and the flexible connection 22 leads from the bus bars 20 to the electrode 23, 24 representing the furnace shell.

Fig. 4 shows a similar arrangement to which the invention is applied. By means of the counter weights 25 and ropes or cables 26 one group of cables of the flexible connections and 22 respectively is held yieldingly in spaced relation from the other group.

I claim:

1. In an electric furnace havin a movable electrode, a flexible connection composed of a plurality of flexible conductors and means for minimizing the effect of mutual inductance between said conductors.

2. In an electric furnace havin a movable electrode, a flexible connection composed of a plurality of flexible conductors and means for yieldingly holding some of said conductors in spaced relation relatively to others of said conductors.

3. In an electric furnace having a movable electrode, a flexible connection composed of a plurality of flexible conductors having their end portions fixed relatively to each other and means for yieldingly holdin the said intermediate portions in spaced re ation.

4. In an electric furnace having a mov-- able electrode, a flexible connection composed of a plurality of flexible conductors and yielding means connected to some of said conductors and operative to draw them in a direction away from others of said conductors.

5. In an electric furnace having a movable eleetrode, a flexible connection composed of a plurality of flexible conductors. and means including a pulley, rope and counterwei ht for yieldingly spacing some of the said conductors from others of said conductors.

In testimony whereof, I aflix my signature.

JAMES H. CRITCHETT.

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