US1420103A - Transformer - Google Patents

Description

S. HORELICK.

TRANSFORMER.

APPLICATION FILED MAY 10. 1921.

1 ,420, 1 03. Patented June 20, 1922.

3 SHEETS-SHEET 2.

V g avwe nfoz 1 (mime/1g S. HOREUCK.

TRANSFORMER.

APPLICATION FILED MAY 10, 1921.

1,420, 1 03. I Patented June 20, 1922.

3 SHEETS-SHEET 3.

UNITED STATES PATENT OFFICE.

SAMUEL HORELICK, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO PITTSBURGH TRANSFORMER COMPANY, A CORPORATION OF PENNSYLVANIA.

TRANSFORMER.

Application filed May 10,

To all whom it may concern:

Be it known that I, SAMUEL HoRELicK, a citizen of the United States, residing at Pittsburgh, in the countyof Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Transformers, of which the following is a specification.

This invention relates to transformers and particularly to furnace transformers adapted to supply electric. current to the material which is to be reduced by the passage of electric current theret-hrough. I

In beginning the reduction of the ore or mixture of material to be reduced, a'comparatively high voltage is desirable during the melting down stage, but as the reduction proceeds, the voltage applied to the material is reduced and in the refining stage of the process the voltage required is lower than in any of the prior stages. Another feature is that in' the initial stages of reduction, the flow of current is ordinarily very changeable and causes objectionable sur es of current which not only lessens the e ciency of the reducing current, but the surges are objectipnable on the apparatus and lines supplymg the electric energy. As the melting and re ning proceeds, however, the tendency to surges of current is lessened, but even in the final stage there is a tendency to pro- 4 duce some surging and irregular distribution of the current.

The main object of my invention is to produce an improved transformer so constructed that it will prevent or reduce to a minimum the surging of the current and also provide a construction whereby the voltage in the secondary may be controlled in accordance with the requirements of the reduction of the material. My invention also includes production of a transformer for this purpose which will include therein, so

as to be self contained, the means whereby the voltage control may be obtained and the surging of the current overcome by control of the primar; circuits. My improvement also permits time use of simple means for controlling the primary circuits by outside switches for changingthe voltage as desired and also regulate the circuits to suitably overcome the surging.

Specification of Letters Patent.

Patented June 20, 1922.

1921. Serial No. 468,402.

My invention will be understood from the following description and accompanying drawings, wherein Fig. 1 is a diagram showing the windings and connections of the transformer for a three phase system; and Figs. 2 and 3 are similar diagrams showing different connections of the circuits.

The transformer is preferably a three phase transformer, but three separate transformers may be used and connected as shown, enclosed in one case or tank, 'or separately enclosed. The primary winding of each phase is made up of two portions, a main winding of comparatively heavy wire and an overwindingof li hter or smaller size wire. The main winding of one phase is indicated by the numeral 1 and the overwinding of the same phase by P. The main winding has a much greater number of turns than the overwinding and I have obtained good results. by including three times the number of turns in the main winding compared with the number of turns in the overwinding. The secondary winding of this phase is ,indicated at 1.

I also provide two sets of reactance coils and one set has a considerably greater reactance than the other and may be referred to herein as the high reactance coils and the low reactance coils. The high reactance coil for the first phase is indicated at 1 and the low reactance coil for this phase is indicated at 1'. The windings and reactance coils for the second phase are correspondingly designated by 2, 2 2, 2, and 2 and for the third phase by 3,.3, 3 3 and 3 The leads from these windings and coils are carried out through the casing of the transformer, the casing being partly indicated in section, through the insulators 4 to leads from the rimary windings and react+. ancesof the third phase. Leads from secondary windings of course, also pass out delta circuit.

of the transformer casing through suitable insulating bushings, but these are not indicated as the connections of the secondary coils may be made as desired and need not be shownor described. a

The leads from bushings 4, 5, 8, 9, 12 and 13 are carried to contacts 4*, 5 8*, 9*, 12, 13 of a three pole switch 16, the three movable elements of which are electrically connected together as indicated by the connection 16. This switch when thrown to the right engages contacts 5 9 and 13* and thereby makes a common connection between those contacts. similarly connects together the contacts 4, 8 and 12*. When in mid position, the switch is open circuited. Leads from the bushings 6, 10, and 14 extend to contacts 6, 10 and 14: of a three pole switch 17. From this switch leads also extend to the incoming three phase supply lines 18, 18 and 18*. When the switch 17 is closed, it connects the supply lines with a terminal of the reactance coils 1 2 and 3, respectively. When the switch 17 is opened, it-disconnects the supply lines therefrom. The incoming lines are also connected through the line switch 19 with the leads from bushings 7, 11 and 15. which leads are connected to one terminal of the low reactance coils 3 2} and 1.

With the connections as shown in Fig. 1 and the switches in the positions indicated, the apparatus will supply the highest voltage to the furnace from the secondary windings of the transformer for the beginning of the melting down process. The primary circuits will also have a maximum reactance by reason of both the high and low reactance coils being connected in series in the respective primary circuits. 'It'will also be seen that the mainwindings of the primary coils are connected in delta with each other with both sets of reactance coils included in the This will be evident by followin the circuit from supply line 18 through the bushing 15, the low reactance coil 1, the main winding 1, the high reactance coil 1,-through bushing 14 to switch 17 to a junction point 20; to this point one supply line 18 is connected and a lead 'extends therefrom through bushing 11, low re actance coil 2, main windin 2, high reactance coil 2 through bushing 10and through switch 17 to a junction point 21; from this junction extends a supply line 18 and also a lead which passes through bushing 7, low

reactance coil 3 main winding 3, high reactance coil 3, through bushing '6 and through switch 17 to a junction point 22, to wh ch the supply line 18 is connected and also'the'l'ead extending through bushing 15,

already referred to;

It will be noted that the reactance coils are tweenthe line and a primary winding, so

When thrown to the left itv that the coils not only protect against current surges but also protect against line voltage surges.

By-the above connections, maximum reactance isimparted to the primary circuits which tends to reduce the surges of current which would otherwise be set up in the meltin down process and thereby gives a more eflicient utilization of the electric energy and protects the apparatus and lines from objectionable current surges. After the initial stage of melting down the material has progressed sufliciently, the switch 17 is opened and the switch 16 is moved to close a circuit between contacts 5, 9 and 13*, giving the connections shown in Fig. 2. The opening of switch 17 breaks the delta connectipn and also removes the high reactance coils 1, 2 and 3 from circuit. The movement of switch 16to connect contacts 5*, 9 and 13 together gives a star connection of the main windings of the primaries. This arrangement results in the low reactance coils remaining in circuit with the main windings of the primaries star connected as may be seen by tracing the circuits of Fig. 2. Thus starting from supply line 18 through switch' 19, the path continues through bushing 15 through low reactance coil 1 main winding 1, through bushing 13 to the common connection accomplished by the position of the switch 16. The circuit from supply line 18" passes through bushing 11, low reactance coil 2 main winding 2, through bushing-9 to the common connection of switch 16. The circuit from the supply line 18 passes through bushing 7, low reactance cOil 3", main winding 3, through bushing 5 to switch 16.

The star connection of the primary coils thus secured will result in a considerably lower voltage being supplied to the electric furnace from the secondary windings. Also the high reactance coils are now removed from circuit while the low reactance coils remain in circuit, the tendency to surging being so much less in this stage of the melting and refining of the material that the lower reactance is suflicient to prevent undue surging of the current.

In the connections of Fig. 1 and Fig. 2,

the over-voltage in the over-winding is not sufiicient to be dangerous, because it is only a small part of the normal voltage, being one-third of the normal voltage with the ratio of turns above referred to.

In Fig. 3 the connections are the same as in Fig. 2, except that the switch 16 is shifted to connect contacts 4 8 and 12 together. This results in connecting the over-windings 1, 2*, 3 in series with the main windings and gives a star connection of the primary circuits with the low reactance" coils remaining in circuit. This results in a further reduction of the voltage supplied by the secondary windin s to the furnace and of a proper amount or the refining stage of the process, the low reactance coils being sufficient to avoid objectionable surges durin this stage of the process.

he controlling switches may be combined so as to form a single controlling means; and

if separate switches 16 and 17 are used, they' paratus supplying the current is also self contained and well protected and afl'orcls control of the voltage and reactance by simple controlling means in the primary circuits.

ment of my invention, modifications thereof may be made without departing from the scope of the invention, and it will be understood that in using the term polyphase trans former, or polyphase winding in this specification and claims, I include the use of single phase transformers connected in polyphase relation.

I claim 1. An enclosed transformer comprising polyphase primary and secondary windings, a reactance coil for each phase respectively located within the enclosing means, leads from the primary windings and reactance coils passing through the enclosing means, and external controlling means whereby the reactance coils may first be connected in series with the primary windings respectively in the line circuits and with the primary windings connected in delta, and then the primary windings be connected in star and the reactance COllS removed from the series connection.

2. An enclosed transformer comprising polyphase primary and secondary windings, reactance coils for each phase respectively located within the enclosing means, leads from the primary windings and reactance coils passing through the enclosing means, and controllin means whereby the reactance coils may iirst-be connected in series with the primary windings respectively in the line circuits and with the primary windings connected in delta, and then the primary windings be connected in star with a portion of the reactance coils removed from the series connection;

3. An enclosed transformer comprising polyphase primary and secondary wind; ings. each of said primary windings comprising a'main winding andan over-wind- The aping, a reactance coil for each phase respectively located Within the enclosing means, leads from said primary windings and reactance coils passing through the enclosing means, and external controlling means whereby the reactance coils may first be connected in series with the main windings respectively and with the main primary .windings and reactance coils connected in delta, then the main primary windings be connected in star and the reactance coils removed from the series connection, and then be connected with the over-windings in series with the main primary windings and connected in star.

4. An enclosed transformer comprising polyphase primary and secondary windlngs, each of said primary windings comprising a main winding and an over-wind ing, reactance coils for each.phase respectively located within the enclosing means, leads from said primary windings and rep actance'coils passing through the enclos-' Although I have described one embodi ing means, and controlling means whereby all of the reactance coils may first be connected in series with the main primary windings respectively and with the primary windings connected in delta, and the main windings then be connected in star and a portion of the reactance coils removed from the series connection, and then be connected with the main primary windin and over-windings in series with each otl iir respectively and connected in star and with a portion of the reactance coils in series therewith.

5. An enclosed transformer comprising polyphase primary and secondary windings, reactance coils for each phase respectively located within the enclosing means, leads passing through the enclosing means from the primary windings and reactance coils, and controlling means outside the enclosing means for connecting the primary windings and. reactance coils in delta, and then in star with the reactance coils removed from the circuit.

6. An enclosed transformer comprising polyphase primary and secondary windings, each of said primary windings having a main winding and an over-windin ,reactance coils for each phase respective y lo cated within .the enclosing means, leads from the primary windings and reactance coils passing through the enclosing means,

- and controlling 'means outside the enclosmg means for connecting the main primary windings and reactance coils in delta, then connecting the main primary windings in star with a portion of the reactance coils in series therewith, and then connecting the main primary windings and over-windings in series with each other respectively and in star.

7. A transformer comprising polyphase connected in series'with the 'main primary windings respectively and with the main primary windings and reactance coils connected in delta, then the main primary windings connected in star and the reactance coils removed from the series con nection, and then be connected with the over-windings in series with the main primary windings and connected in star.

9. A transformer comprising polypha'se primary and secondary windings, each of said primary windings comprising a main winding and an overwinding, reactance coils for each phase respectively, and means.

whereby all of the reactance coils may first be connected in series with the primary windings respectively and with the primary windings connected in delta, and the main windings then be connected in star and a portion of the reactance coils removed from the series connection, and then be connected with the main primary windings and overwindings in series with each other respectively and connected in star and with a portion of the reactance coils in series therewith.

10. A transformer comprising polyphase primary and secondary windings, each of said primary windings comprising a main winding and an over-winding of approxi- Inately-onethird the number of turns in the main winding, and means whereby the main primary windings may be connected in delta, then in star, and then the overwindings in series with the main windings respectively.

,11. A transformer comprising polyphase primary and-secondary windings, reactance coils for each phase, and means for connecting the primary windings in delta with the reactance coils connected in detail therewith and with a reactance coil between each primary line and each portion of the primary wind1ngs, and for also connecting the primary windings 111 star with a reactance coil between each primary winding and the primary line.

SAMUEL HORELICK.

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