US1021252A - Bell-ringing transformer. - Google Patents

Description

Patented Mar. 26, 1912.

WTNESSE'S: ZAZVENTDR WQ( .5J/END Ef JHNNESEN y. im MM 'BM y i TTY 30 formers of this character so that if vthe-sec- UNTTED STATES PATENT ormon- SVEND E. JOHANNESEN, OF \PITTSFIELD,. MASSACHUSETTS, ASSIGNIOR T GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

BELL-itineraire TRANsrom/LER.

Specication of Letters Patent. V Patented Mar. 26, 1912.

Application sied August 14, 1909. serial No. 512,8'14.

y and useful Improvementsl in Bell-Ringing `value, andthe transformers will be able to stand this short circuit for a long period of Transformers, of which the following is a specification.

My invention relates to electrical insformers. A i

Although it is" not limited in its appli- `cation, it is more particularly adapted for use in connection with those transformers which are employed for ringing electric bells.

One of'the chief requisites of bell ringing transformers is that they shall be constructed as cheaply and at the same time asdurably as possible, as they are used for the energization of electricalA circuits of comparatively minor importance. In such circuits there is a great possibility of the bell, the wiring, or other devices in series with the secondary of the transformer, being short circuited, which would cause a large current to flow in the secondary winding, unless some precautions are taken to prevent it. Because of the size of these transformers, it is hot convenient to connect the protective` device in series with them. It is therefore customary to design transondary winding .becomes short Circ/suited, the short circuited current-will be limited in time. In order to reduce as far as possible the size, and, therefore, the costofsuch transformers, the short circuited currentA must be made as small as possible, as by so doing the size ofy wire used for both primary and secondary 'winding may be made aminimum, and'hence the cost ofthe transformers may be made a minimum. The object of my' invention then .is the construction of a transformer which will givea smaller short circuited currentthan is given by those transformers .at present in use, and thusI effect a considerable saving in the cost of such-4 transformers. In the past, ltransformers of this character with a large magnetic leakage between/ the primary and secondary sh'ort circuited currentA will be greatly 1n excess of the current'which is required unwinding is used,l

der normal operating conditions. .I have found that by a special construction and arrangement of the transformenwindings, I

am enabled to reduce the short circuited current sothat it will not be greatly in eX- cess of the normal load current, and I am therefore able to -decrease thesize of the wire used for the windings and thus d ecrease the' cost of a transformer without impairing its abil-ity tostand ashortcircuit fora long peri0d.

For a further understandingof my inventilon, reference Vmay be hadto the accompanying drawing, whichI shows diagrammatically the core and windings of atransformer.

l is the core which may be constructed in the usual manner of laminae of magnetic material, and as shown in the drawing consists of three legs withl suitable end pieces connecting the legs. The primary winding 2 surrounds a part of the central leg of the core, .and the .main portion of the secondary winding 3 surrounds another part of the same leg; these windings being shown as wound upon different parts of the core,I

so that there will be a large magnetic leak- `age between the two windings. A second portion of Vthe secondary winding 4 is wound upon the same pa'rtof the core as the primary winding and in1 close `proximity thereto, and this portion of lthe secondary winding is so connectedk that` the electro-` motive force generated in it will be in opposition t0 or will buck the electro-motiveforce 'generated in the mainp'ortion of the secondary winding. 'Ihe y'main portion of the secondary winding may have taps 5, so that thel voltagesupplied to the load l may be varied the well-knownl manner. If it is desired to obtain a large" range of voltages so that onlyl a small portion of this- .the opposing action of winding 4 may become greater than desirable, and therefore this winding I have shown as provided with an intermediate tap 6, to which the. load may be connected.

It will, be Y understood that while for clearness I have illustrated the windings as consistingof a -small number ofturns, and the secondary as having a small number'bf taps. conneotedthereto, that I do not limit myself to .the Y particular arrangement shown. The primary winding may be connectd by conductors 7 and. 8 to a suitable source of supply, which is: not shown, and

the secondary winding may lee connected signed that the desired secondary voltage will be obtained, and taps 5 and 64 may also* be arranged to give suitable lesser voltages. It a short circuit occurs when the secondary winding is connected so as to give either its whole, or a portion of. its whole voltage, greater leakage will occu'r between the primary and the main portion of the secondary winding, and this greater leakage 01' itself would tend to cut down the short circuit current in the secondary inthe well understood manner. The' opposing portion of the secondary dwill have a greater amount of'iux proportional to the flux in the main portion flowing through it for a short circuit than for normal load, and will, hence, have more effect in opposing the main voltage than for normal load and itsy action will therefore still further decrease the secondary current. It will also tend to decrease the primary flux. If the secondary winding is connected so that only aportion -of it be used, the short circuited current in this portion will still'loe low, as the opposing portion 4L of the secn ondary winding ywill have a proportionately greater effect upon this portion of the main winding than it does if the entire main winding is. used.

While I have shown my invention em- Vloodied in a particular form and arrangement of parts, l do not limit myself vto this form or arrangement, but seek in the appended claims to cover all'forms and arrangements which willvhe within the scope of my invention and will loe obvious -to those -skilled in the art.

vWhat I claim' as new and desire to secureby Letters Patent of the United States, is,-

l. ln an electricalapparatus, a core, an

mary winding inducing" windin g surrounding the coreand awinding in inductive relation thereto having a portion wound so that there will he large magnetic leakage between it and the inducing winding, and a' second portion reversely connected to the irst portion and 1n closer proximity to the inducing winding' than the'said first portion.

2. ln an electrical transformer, a core, a primary winding surrounding. the core, and a secondary winding having a portion wound on 4a diii'erent part of the core, and a 'second portion reversely connected to the thereof and upon the same part of the core;

asthe primary winding.

4. In an electrical transformer, a corea` primary winding surrounding the core., andE a secondary winding having a portion pro vided. with taps wound upon a dilterent: part of the core and second portion `re versely connected to the balance thereof. and

upon the same part of the core as thelpri'.-

5. In an electrical transformer, a core, a` primary winding su rounding the core, andf a secondary winding having a portionwound upon a diiierent part ofthe core and provided with taps, and a second-portion reversely connected to the first portion, wound' upon the same part of the core vas the prie mary winding andprovidedwith taps. op lfnwitness whereof, l .have hereunto set my hand this 11thy day of Jaugust, 1909.

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l/Vitnesses WnlLrs A. lsLiiLnR, Genuss l1. Lien.

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