US1882201A - Choke coil - Google Patents

Description

Oct. 11, 1932. I TAETZ 1,882,201

CHOKE con.

Filed July 51. 1930 1 V V V 7' V r INVENTOR PAUL TAETZ ATTORN EY Patented Get. 11, 1932 UNITED STATES PATENT QFFICE PAUL TAETZ, OF BERLIN, GERMANY, ASSIGNOR T0 TELEFUNKEN GESELLSCI-IAFT FUR:

DRAI-ITLOSE TELEGRAPHIE M. B. IL, OF BERLIN, GERMANY, A CGBPOBATION OF GERMANY CHOKE COIL Application filed July 31, 1930, Serial No.

In the transmission of radio frequency waves along high potential lines, recourse is had to special blocking chokes in combination with parallel condensers, which are built into the high potential conductors and which conjointly with the said parallel condensers are tuned to the carrier wave, for the purpose of preventing the scattering of radio frequency energy into other parts of the network or transmission line, and undesirable reactions in case of switch operations or circuit chan es.

These choke coils must be designed so as to measure up to the high loads of the working current and the extraordinarily high stresses attendant upon short circuits.

According to prior practice it has been customary to design these coils in such a way that the Winding was made from flat copper strip, that insulating layers were interposed between the constituent turns, and that the winding was firmly held together by means of longitudinal bolts and terminal disks.

On a construction of this kind the copper cross-section must be made relatively large since, due to current displacement the active or effective copper cross-sectional area is markedly diminished, and since the cooling conditions are relatively unfavorable.

To be sure, by subdividing the winding in a way usual in the construction of power transformers, the active copper cross-sectional area can be increased; but the conditions of cooling, owing to the necessary insulation of the constituent current conductors, become still more unfavorable, with the re sult that a saving in the volume of copper is not attainable in a form of construction of this kind. In the case of transformer building, it is possible to proceed along these lines inasmuch as by the aid of artificial cooling means it is possible to carry away such heat as may be developed (and for reasons of efiiciency the amount of heat thus dissipated should be minimized). However, in the case of blocking chokes similar cooling devices are technically unfeasible since the accommodation of choke coils in special oil tanks furnished with suitable high potential 472,013, and. in Germany July 18, 1929.

lead-ins or bushes would mean an inadmissible technical compllcation.

'Now, the present invention consists in i1nf proving the cooling conditions by providing,

on the outside of the winding of copper,'

tion i is further suggested, according to the present invention, to provide sheets or plates adapted to act as cooling ribs, and which are fitted between the turns or into the turns of the coil. This makes it possible to use cop per conductors of standard shape and profile.

In the accompanying drawing embodiments of the basic idea of this invention are illustrated by way of example.

Figure 1 is a partial vertical cross-section of a choke coil illustrating the conductor, cooling means on both sides of the insulation.

Figure 1 is a partial vertical cross-section of a choke coil illustrating the conductor cooling means on only one side of the insulation.

Figure 2 illustrates cooling elements inserted in the turns of a coil, and

Figure 3 illustrates an elevation of a neferred form of the cooling element.

Figure 3 illustrates how the cooling ele-, ment as shown in Figure 3, is bent, as ill be described below.

Figure l. illustrates an elevation of a cooling element shown in Figure 3, which has been perforated.

Figure 4? illustrates an elevation of a cooling element having a serrated edge.

In the embodiment shown in Figure 1, sheets I), say, made of copper, are laid between the copper turns a preferably of roughly square cross-sectional form, and the insulation layers 0, said sheets I) being thermally associated with the copper turns a so that the cooling surface of the latter is increased. The material and nature of these cooling sheets is governed by various factors and viewpoints, such as high heat conductivity, mechanical stability and ruggedness, and low weight.

In the embodiment shown in Fig. 1, the sheets I) are between the turns of the copper conductors a and the insulation 0 said sheets 6 being to the left of only one s1 de of the conductor a for cooling as mentloned above, this latter form being employed 1n a circuit where the current is less than in the embodiment shown in Fig. 1.

In order that these sheets may be free from current flow, the constituent sheets may be made of sheet rings split at right angles as at S, Figure 3 to the direction of flow of current, say, radially. Figure 3 illustrates a sheet section, and Figure 3* illustrates a turn formed therefrom by bending at an angle to conform with the pitch of the conductor winding. It is also possible to make these sheets from segmental pieces more or less separated radially.

The sheets inserts b may be disposed either only on one side of the copper turns as in Figure 1 or upon both sides thereof as illustrated in Figure 1.

Figure 2 illustrates another scheme n which cross-sectional U-shaped copper pieces a are employed into the incisions or slots of which the cooling sheets Z) are fitted.

The drawing further shows that towards the ends of the choke coil the diameter of the cooling rings may be graduated in order to diminish corona arising at high working potentials. In order to improve the conditions of air circulation, the cooling sheets 6 may be perforated as at 29, Figure 4, or be provided with a serrated edge or outwardly open notches as at a, Figure 4*.

V hat I claim is:

1. A high frequency coil comprising a helically wound conductor of large cross-sectional area, a tape-like cooling fin thermally and electrically associated with the conductor substantially throughout its length and extending radially outward from the coil, the width of the tape increasing from the ends toward the mid section of the coil.

2. A high frequency coil comprising a helically wound conductor of large cross-sectional area, a tape-like cooling fin having a serrated edge thermally and electrically associated with the conductor substantially throughout its length and extending radially outward from the coil, the width of the tape increasing from the ends toward the mid section of the coil.

3. A high frequency coil comprising a helically wound conductor of large cross-sectional area having a slot, a tape-like cooling fin located in said conductor slot and thermally and electrically associated with the conductor substantially throughout its length and extending radially outward from the coil, the width of the tape increasing from the ends toward the mid section of the coil. PAUL TAETZ.

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