US1036696A - Transformer cut-out for alternating-current circuits. - Google Patents

Description

CURRENT GIRQUTS.

PPLIGILTO l-LBD JULY 15, `1909.

T FOR LLTERN UNITED STATES PATENT o JOHN SEDG'WIICKy PECX, 0F TRAFFORD IARK, MANCHESTER, ENGLAND, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A GORPORATION OF PENNSYLVANIA.

TRANSFORMER CUT-OUT lFOB. ALTERNATING-QURRENT CIRCUITS.

, Patented Ang. 27,1912. serial No. 5o7,7 5o.

Avlowing is a speciication.

My invention relates to alternating cur` rent electric distribution systems and particularly to systems in which main and auX- iliary transformers are employed.

windings,

vmain transformer to It has heretofore been proposed to provide an automatic switching device to be operated through a relayby variations inthe current supplied to, or delivered byl the transformers, for short circuiting the auxiliary transformer primary and secondary or for opening and closing the primaryv and secondary windings .of the main transformer when a parallel system is utilized.

One object of the present invention is to provide improved devices in connection with tlie relay switch which tion of the automatic switch, another object of the invention being to provide `an improved device whereby the blowing of a. fuse in the auxiliary transformer circuit when the main transformer is not in use shall cause the automatic 'switch to close and therebytransfer the load to the main trans former in order to avoid interruption in the supply of energy.

In systems where main Aand auxiliary transformers are so arranged that their secondary windings are connectedin' parallel to. `Supply has hitherto been considered necessary' to install two switches in the secondary circuit, one switch beingin the neutralI wire'wliich is connected to the middle point of themaiii transformer secondary winding, and the other being in the circuit of one outer con-` ductor-which-is connected toone end vof the said secondary winding, or a switch is employed in each outerfconductor.

A. further object of the present invention is to provide an improved arrangement for opening and closing the connections of the the circuit, in a system of the above mentioned chafa ter, ingwhich only a single switch is Arequir ed..

In the accompanying drawings, Figures 1,

when a series system is employed,

governs the operaf energy to a three-wire circuit, it`

cuit.

3 and 4 are diagrammatic views of distribution systems embodying my invention. Referring now to Fig. 1, which illust-rates a distribution system having main and auX-` iliary transformers connected in series with one another, a main transformer being indicated at 1 as .having a primary winding 3 and a secondary winding 4, and an auxiliary transformer beingsiiidicated at 2 as having a primary winding`5 and a secondary winding 6. .The primary windings 3 and 5 are connected in-series with each other between fthe conductors 7 8 of the supply circuit,

and the secondary windings 4 and 6 are similarly connected. The primary winding 5 of the auxiliary,l transformer 2 is arranged to be short circu-ited by means of a switch when the loatl on the system becomes considerable, and the secondary winding 6 of the transformer 2 is arranged to be similarly short circuited by meaiis of a switch 14 comprising lixed contact terminals 12 and 13 which are connected, respectively, to the v junction 11 of Ythe windings 4 and 6 and to a conductor :10 of the distributing circuit 9410. The 'movable bridge pieces 45 and 1G ofthe respective switches 14 and 15 are arranged to be operated by means of an electro-1nagnctically actuated member 17 which is provided with a closing coil. 18 and an opening coil 19. One terminal of the closing coil 1S is connected to the contact terminal 13 of the switch 14 and one terminal of the opening coil 19 is connected to one ofy the stationary contact terminals 20 of a switch A 21, the other stationary contact terminal. 22 of whic is connected through indicating lamps 23 to the conductor 9 of the distributing circuit. The other terminals of the Aopening' coil 19 and the closing coil 18 are connected, respectively, tothe contact termi# nals 24 and 25 of a relay switch 26 having a contact arm 27 which is electrically connected to the conductor 9 and isl arranged to be moved against the'action cfa spring 28 by means of an electro-magnet 29 in order to effect engagement with the contact tere minal 24. IThe coil of the electro-magnet 29 may be supplied with current from the secondary winding 30 of a series transformer 31, the primary winding 32 of which is connected in the conductor 8 of t-he supply cir A contact.l terminal 33 of the switch 15 is connected to an intermediate point in ico the winding -32 of the series transformer 31,

so that, when the switch 15'is closed, a portion of the turns of the winding 32 are short circuited to reduce the voltage impressed upon the coil of the electro-magnet 29 of the relay switch 26. l

The movable contact member 34 of the switch 21 is pivoted at 35 and is normally V held in engagement with'the contact terminal 20, against the act-ion of a weight 36, 'by means of a bell crank lever 37, one arm 38 of which engages a projection 39 on said contact member and the other arm '40 of which is connected to a fuse 41 'which is included in circuit with the conductor 10 of the distributing circuit. The member 17 novided with a projection 42 to be engaged by contact member 34 to move the switc es 14 and 15 into their closed positions.

The operation of the apparatus is as follows: 1When the load upon the system is light, the various' switches occupy the posi# tions illustrated in Fig. 1 and the mainand auxiliary transformers are connected in series with each other across the supply and distribution circuits. tlf, however, the load increases to a predetermined value, the'current traversing the series transformer 31 bccomes sufficient to so energize the electrovau magnetv 29 that it will move the member 27' of the relay switch26 into engagement with the cont-actterminal 24. A circuit is thereby completed through the closing coil 18 of the switches 14 and 15 whereby said switches are closed and the auxiliary transformer to the coil by over-heating is greatly re duced. If the load on the supply circuit be reduced below the predetermined value at which the electro-magnet 29 is adjusted to operate. the member 27 of the relay switch 26 will be moved by the spring 28 into engagement with the contact terminal 25 and a circuit will thereby be completed through the opening coil 19 to openthe switches 14 and 1.5. It', at any time during the opera tion under light load conditions, the current traversing the winding 6 of the auxiliary transformer 2 increases to such proportions as to blow the fuse 41, the bell crank lever 37 will release contact member 34 of the switchv21, and this contactmember willbe moved by the weight 36 to close the'switches 14 and 15 and also to break the circuit .able bridge piece 45 of the through the opening'coil 19 and complete a circuit through the indicating lamps 23. The attention of the attendant :will thus be drawn to the fact that the auxiliary transformer circuit has been interrupted, and, since it will be impossible to complete a circuit through the opening coil 19, the switches 14 and 15 will remain closed.

Referring now to Fig. 2, a modification is illust-rated as applied to a system in which the main and auxiliary transformers 1 and 2 'are connected in parallel with each other, the switches 14 and 15 bein arranged. to

open and close the circuits of t e main transformer windings. The operation of the apparatusis similar to that of the apparatus .shown in Fig. 1 `-and need not be further described.

Referring now to Fig. 3, the invent-ion is illustrated as applied to a three-wire system in which .the circuit connections of the main and auxiliary transformer 1EL and 2a are arranged to be effected by means'of, a single switch, in the manner set forth inu my application, Serial No. 489,253, tiled April 12, 1909, the arrangement of the means for controlling the closing and opening coils of the switches 14 and 15 and for preventing these switches from being opened when a fuse 41 in the secondary circuit of the main transformer has been destroyed, being similar to those already described with reference to Fig. il

Referring now to Fig. 4, a three-wire dis- `tribution system is illustrated in which main and auxiliary transformers 1a and 2l are connected. in parallel with each other, the

connections of the main and auxiliary transformers on the primary side ofthe system being similar to those illustrated. in Fig.. 2. The secondary winding of the main trans- ,former is divided at its middle point into two equal portions 42, 43 and the adjacent ends of the portions 42, 43 are connected to thev two fixed terminals 12 and 13 of the switch 14, the neutral Wire 44 of the distributin@r circuit being connected to the movswitch. The operation ofv the apparatus is as follows: When the switch 14 is open, the circuit of the main transformer is broken and the ortion 42a and 43 of the ransformer winding are also disconnected om the' neutral wire 44 of the system, whereas, when the switch is closed, the two portions 42a and 43 of the main transformer windingare connected in series and the neutral wire 44 is joined to the middle point thereof. The remainder of the connections of the system of Fig. 4 are similar to those already described and need not be more particularly referred to.

lt will be understood that any one of the systems which I have shown vand described may ybe further modified by utilizing any other known means in lieu of that specifically set forth for modi ing the action of the electro-magnet 29 o the relay switch 26 or protecting its winding from injury by the heating action of excessive currents.

I claim as my invention:

In a system of alternating currentelectrical distribution, the combination with a main and an auxiliary transformer, of means for automatically adgusting the transformer connections in accordance with the load, an electro-magnetically operated relay switch for controlling said adjusting means, and means for reducing the current supplied to the operating magnet of the relay switch.

2. In a system of alternating current electrical distribution, the combination with a main and an auxiliary transformer, mechanically connected switches for adjustin the circuit connections of the primary an secondary transformer windings, an electromagnetically operated relay switch for con` trolling the operation of said mechanically connected switches, and means for reducing the current supplied to the operating magnet of the relay switc In a system of alternating current electrical distribution, the combination of main and auxiliary transformers, of interconnected switchesfor adjusting the circuit connections of the primary and secondary windings of said transformers, means tendin to close said interconnected switches and a use in the secondary circuit of one of said trans formers which serves to prevent said switchclosing means from operating until ruptured by an excessive current.

In a system of alternating current electrical distribution, the combination with a inain and an auxiliary transformer, of mechanically connected and electro-magnetically operated switches for adjusting the primary and secondary circuits of said the actuating coil transformers, a relay switch for controlling the supply of current to the operatin coils of said mechanically connected switc es, a mechanical means tending to close said connected switches, a latch for retaining said closing means in inoperative position, and a fuse in the secondary circuit of one of said transformers for releasing said latch when traversed by an excessive current.

5. In a system of alternating current-electrical distribution, the combination with a main and an auxiliary transformer, of mechanically connected main switches for adjusting the primary and secondary circuit connections of said transformers, actuating coils for said main switches, an electro-inagnetically operated relay switch for controlling the circuits of the actuating coils of said main switches, a series transformer the main circuit for supplying current to of said relay switch, and connections to one of the main switches for short-circuiting a portion of the primary winding of said series transformer.

6. In a system of alternating current electrical distribution, the combination 'with a main and an auxiliary transformer, of means for automatically adjusting the circuit connections of said transformer in accordance with the load, an elcctrornagnetically operated relay switch for controlling said adjusting means, and means for varying the ampere turns of the operating magnet of said relay switch.

In testimony' whereof, I have hereunto subscribed my name this 23rd day of June, 1909.

JOHN SEDGWICK PECK.

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