US1920903A - High tension cable - Google Patents

Description

Aug. 1, 1933. K. A. HAANEN ET AL HIGH TENSION CABLE Original Filed July 7, 1925 Patented Aug. 1, 1933 UNITED STATES HIGH TENSION CABLE Karl August Haanen,

Cologne-Mulheim, and

Hans Meurer, Cologne, Germany, assignors to Felten & Guilleaume Carlswerk Actien-Gesellschaft, Cologne-Mulheim, Germany Original application July 7, 1925, Serial No. 42,104, and in Germany December 27, 1924, now Patent No. 1,808,407, dated June 2, 1931. Divided and this application May 24, 1926.

Serial No. 111,396

1 Claim.

The insulation of` high-tension cables consists of cellulose and impregnating compound. The cellulose is used in the form of unloaded and unsized paper. The cable papers used hitherto, whether smoothed on the calendar or not, have a density of from 0.60 to 0.87, the term density signifying the quotient derived from the dry Weight per square metre in grams and the calculated volume of a square metre of pulp in cubic centimetres. This case is a division of the serial application No. 42,104 nled on the 7th July, 1925, on which a patent has been issued on 2nd June, 1931, under the No. 1,808,407.

It has now been found that, when using the same quantity of impregnating compound, the resistance `to puncture of high-tension cables increases, if by rolling or pressing the paper the volume proportion of cellulose to impregnating compound is raised to a certain favourable point. When the pressure applied exceeds a certain amount, the cellulose bres are so Weakened that the resistance to tearing of the paper is inadmissably reduced and it can no longer be Wrapped on.

The present invention relates to a new method of treating cable papers, which is to be carried out before the papers reach the wrapping machine, the method being based on the recognition of the fact that by it the resistance to puncture of the cable insulation is increased.

According to the invention the resistance to puncture of the cable paper is increased by the density of the paper being increased by rolling under great pressure or by other pressure applying means, but n'o more than the retention of the necessary tensile strength for wrapping the conductors will allow.

It has' been found that the pressures to be applied must be so great that the thickness of 0 the paper is reduced at least by 15% of its origl inal thickness. The pressure of the rollers can be raised to such an extent that the thickness ofthe paper will be reduced to about 60% and more. respond to increases of density to from 0.90 to 1.30 and more.

.In papers treated in this manner it has been found that in spite of the greater density of the paper the absorbent property is not only retained but is in most cases even increased.

The treatment by rolling under pressure or by other pressure applying means may be carried out after the paper has been impregnated with a suitable impregnating medium, for instance paraffln, cable impregnating compounds Such rolling or pressing pressures cor-V or the like. By rolling under pressure or by other pressure applying means'I the paper is given a smooth surface, which ensures the separate paper layers of the cable insulation lying particularly closely on one another. This latter point is also of great importance inobtaining high resistance to puncture.

The accompanying drawing illustrates, by way of example, a high tension cable according to the present invention. y

d shows the conductors, b the insulation provided between the conductors, c is the paper insulation obtained in the manner above referred to, and d is the sheathing.

What we claim isz- An electric cable including a conducting core and insulating-impregnated unloadedv and unsized paper covering said core, said paper having had its thickness reduced at least 15% from its original thickness by compression' thereof and having a density above 0.9 grams per cubic centimetre in its unimpregnated state and the necessary tensile strength for Wrapping it round the conducting core.

' KARL AUGUST HAANEN.

HANS MEURER.,

Images