DE629583C - Electrical communication cable - Google Patents

Description

GERMAN EMPIRE

ISSUED
May 15, 1936

REICH PATENT OFFICE

PATENT LETTERING

JVl 629583 CLASS 21 c GROUP 5

Patented in the German Empire on October 28th. 1932 from

The invention relates to electrical cables for communication, so to Telegraph and telephone cables.

Long distance telephone cables are generally used with either at intervals distributed Pupin coils or constantly inductively loaded. Coils are usually found on land cables Use, while both types of loads are used for submarine cables. Maritime telegraph cables, however, received almost always a constant burden.

The merit of the coil loading is based

on the fact that the cable with its coils is cheaper and faster to manufacture as a corresponding cable with constant load.

Aside from the cost of the loading material, manufacturing requires steadily loaded Cable a relatively long time and ao an extensive system to apply of the incriminating material.

In some cases a steadily loaded cable would be more beneficial, if not the price of such a cable would have to be taken into account.

It. the proposal has already been made to manufacture a cable for signaling purposes, alternating sections of a continuously loaded conductor and an unloaded conductor having, in particular as a loading material an alloy of high Permeability is used.

In this known case, the absence the load in the unloaded sections compensated by the fact that one more for the loaded sections Load or a higher quality load material used, so that, albeit the length of the conductor to be loaded is reduced, despite the cost of the loading material can be increased significantly.

The invention has set itself the task of avoiding this drawback and a Making cables that are cheaper. It has basically been found to be better is to slightly increase the amount of copper in the unloaded conductor sections than that To change the load in the loaded sections.

The theoretical relationships were examined for the following case. A consistently Stressed cable of the currently common type is regardless of the fact that the loading material is a relatively low or can have relatively high permeability, through a cable with loaded and unloaded Sections replaced that have a significantly greater specific damping than a consistently loaded; Has cable.

In this study it was assumed that the total diameter of a conductor including its load remains the same as with a cable that is loaded throughout and

that the unloaded conductor has a diameter equal to the '-' diameter of the loaded line. ters' owns.

It has been found that the attenuation of the "composite cable independent vg ⁴⁵ "'ratio of the loaded length to the unloaded length will always be greater than that of the fully loaded cable, unless the following equation is met.

ρ ρ τ-

Here, R ₁ and L ₁ mean the effective resistance and inductance per unit length of a loaded section and R ₂ and L ₂ the corresponding values for an unloaded section. G and C represent the derivative and capacitance per unit length. These values are assumed to be the same for loaded and unloaded sections.

Compared to R ₁ , the value - ^ · L _{1 is im}

general low; L ₂ is also relatively small compared to L ₁ , so that the above condition can also be written as follows:

It is evident that the transmission efficiency when replacing part of the Cable through unloaded sections does not depend on the permeability of the loading material, but depends on the resistances of the loaded and unloaded conductors, which in the first place First and foremost, it depends on the strength of the conductor and, secondly, on the frequency and properties of the load material are.

If equation (a) is fulfilled, the lowest damping results when

, _ R * - ^2L -i

G_

L ₁ L ₂

λ means the ratio of the loaded length to the total length of the cable.

According to the invention, "in a telecommunication cable whose conductors are composed of alternating, continuously inductively loaded and unloaded sections, the above equation (a) is generally satisfied by appropriately dimensioning the diameter for the loaded and unloaded conductor as well also by appropriately dimensioning the strength of the loading material and taking into account the endeavor to consistently obtain the same overall diameter Set up the length ratio of the loaded and unloaded cable in such a way that the attenuation of the assembled saber is not significantly greater or equal to or even less than the attenuation of a corresponding, consistently loaded cable. The ratio of the smallest attenuation results from the expression for λ given above.

As an example of a telephone cable according to the invention, it should be stated that the loaded conductor may have a diameter of 0.913 mm and is wrapped with a 0.203 mm thick silicon iron wire. Let the unloaded conductor have a diameter of 1.32 mm. Assuming that the loading material has a permeability of 180, if a normal value is taken for G and C , then for a cable loaded throughout and at 800 p / s an attenuation of 0.0735 neper per nautical mile would result. However, if half of the cable is replaced by unloaded conductors with a diameter of 1.32 mm, the attenuation would be 0.0731 neper per nautical mile.

If the length is not too great, a cable of this type is suitable for submarine cable telephony very well suited for the four-wire system. Lies between the transfer offices a relatively greater distance, so is a loading material with higher permeability to use, e.g. B. specially treated nickel-iron alloys.

The diameter of the conductor in the unloaded part can, although preferably is kept equal to the total diameter of the loaded conductor, from this too Slightly differ in value. An adjustment can be made by means of the .Isolation, whereby however, a readjustment of the capacity is necessary.

In this case, to evaluate equation (a), the value R ₂ is assumed to be equal to the resistance of a conductor with a diameter equal to the total diameter of the loaded conductor.

Claims (4)

Patent claims: i. Electric telecommunication cable in which the conductors consist of alternating, consistently inductively loaded and unloaded sections. characterized in that the electrical Properties of the circuits of the equation are sufficient, in which R ₁ and L ₁ stand and the inductance per unit length of a loaded section, R ₂ and L ₂ the corresponding values for an unloaded section and G and C the derivatives and capacitance per unit length, assuming the same values for loaded and unloaded sections. 2. Electrical cable according to claim i, characterized in that the electrical Properties must be of such a nature that the condition i > 2 R, is satisfied. 3 electrical cable according to claim i, characterized in that in the circuit the ratio of the loaded conductor length to the total length is less than the value of the equation R ₂ 2 L ₂ R ₁ + -pr ■ L ₁ R ₂ 4. Electrical cable according to claim 1 to 3, characterized in that the conductor and its load are the same Has the same outer diameter as the unloaded conductor.