US1722444A - Connecting transformer of the shell type - Google Patents

Description

July 30, 1929. w. REICHE 1,722,444

CONNECTING TRANSFORMER OF THE SHELL TYPE Filed Oct. 21. 1926 I izz/612$): mm M,

Patented July 30, 4 4 It i UNITED {STATES WI LI: REICHE, or. DRESDEN, GERMAN PA NT QF-F 4 v 4 connsc'rme TRANSFORMER 01' THE snELLirYPE.

"Application filed Qete b e r 21, 41 9 2e,,ser ia1 11 143,074, and in G erm any octoberfis, 1925,

The present invention relates to connect ing transformers of the shell type with.

equipotential winding. Transformers of this class, particularly for measuring purposes, have been brought to a certain atgree of perfection, although, at greater 1n- .tensities of the prlmary current, a cons1derable errorgexists' dueto the lack of uniform-4 ends of the core, which :is unavoidably due again to the fact that the primary conductor arranged vertically to the plane of.

the core and embracingthe connecting piece of the latter extends at one 511116 more through one window of the core 4 than through the other, asjindicated by the draw- Vith the direction of current of Wind ing of theprimary conductor as shown, which embraces the connecting p1ece b the left end a of the core is magnetitzed more than the rightfend 0. I If only one winding is:

used as shown, the 'error is particularly; large, but even if several windings are provided, it is quite considerable and trouble some. In literature, the error of such transformers isreferred to as a peculiar charac teristic without any attempt being made to remedy it. The present invention has for its object to provide this remedy in the form of the equipotential winding known and used for other purposes in the construction of transformers. The accompanying illustration shows such a self-contained permanently closed winding A. Thesecondary winding S, concentric with theprimary winding P, 18 wound on the connectingpiece b of the 4 core. If both outer legs of the core are magnetized equally,the compensating winding will be inactitveif there are equalnuin j44 4 4 bers of turns on boththe outer legs. Since, 3

' will, therefore, notbe magnetized to equal; strength. The winding A is, therefore, 4 necessary and is always active.

- of this property of the equipotential windhowever, the primary conductor P passes through one of the openings of the core more than the other, b'othjlegs of the 4core On account 4 4 ing the invention eliminates the lack of uni- 4. formlty 1n 'magnetlzation and the error in current in so far as it isndue to this cause. Furthermore, the wind ng used by the 1nvention eliminates a second source'oi': error consisting in the inducing reaction of a return of current or another conductor of larger intensities of current. This is for instance important if in connecting transformers for three-phase current the transformers coresponding to the three phases are arranged side by side. 4 l l a In ordmarycases the equipotentlal wlnding according to themventlon consists of one winding or several windings of copper-.

band attached to the outer free ends, both windings being connected in opposition, but under certaln circumstances the invention may be extended to comprlse any number ofwindings arranged on a conductor of reldefinite form of the curve of errors owing to the relative great resistance. For the same purpose, the number of wmdmgs on both free ends may vary or an equipotentialwinding uniformly embracing both free ends may carry anotherl equipotential winding possessing diiferent qualities to tune ofl'the 4 effect.

The turns of the windings of the coilfA being in opposition on the two legs of the core, when one leg of the core is magnetized more than the other an unbalanced current .is generated in-the section of the coil A on that leg. This current passing through the turns of the same winding on the other leg increasesthe magnetization thereof to the required extent to make the magnetic strength in both legs of the core equal as required by the object of this invention. When the transformer is in operation the primary winding 1P produces the effect of one more conductor. 1n the; space at the left of themiddlepart b of the core; as

shown in the drawing than in the space at the right of this part 6.. Hence the magnetization may be a little stronger in the left part a of the closed core than in the right part 0. By the presence of the windings of the coil A which forms in effect two coils,

one on each of the sides a ends, the two 4 coilsbeing closed upon one another andeach comprising an equal number of turns, this the two sides a and 0 isequalized. If the 4 primary winding should develop an.Npole at 'the front ofthe core as presented to the 4 the opposite side 0, the turns of the winding w will be. wound in such a direction that the i effect is obviatedland the magnetization in Y induced current therein will not oppose but Will add to the magneticleffectdue to the primary P in the side 0 of the core. Thus the magnetization of the core wi-l-l tend to become equal. The Winding A is particularly useful when the primary P has both its terminals on the same side of the central connecting piece bfas shown in the 7 drawing.

The turns of the windings on the part a are equal to the number of turns on the part a; but, as appears from the drawing, the arrangement is suCh that there'is one more coil or conductor on the outer face of one ofthe legs, such as the leg c than upon the outer face of the leg a. g

I claiInF- t 1. Acurrent transformerhaving an annu lar closed core with a central leg and two nectechto each other, I v

2. A current transformer accordlng to equally numbered.

claim 1, in which the coils of theWi-nding on l the outside faces of the core legs are vun- In testimony thatI claim the foregoing as my invention, I have signed my nanie here- WILLIREHDHE.

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