Showing papers by "General Cable published in 1966"

Apparatus to measure continuously corona inception and extinction voltages in movinginsulated cable cores

Abstract: 1,201,801. Testing cable insulation. GENERAL CABLE CORP. Sept.14, 1967 [Sept.20, 1966], No.41904/67. Heading G1U. A cable testing apparatus is of the type where the cable 1 is passed through an elongate fluid bath probe 11, and potential gradients are established along the probe between a central electrode 8 supplied with high alternating voltage and earthed end electrodes 10, two detector electrodes 12, 13 being situated symmetrically relative to the central electrode near each end of the probe. The ratio of the output pulse amplitudes obtained at the two detector electrodes indicates the position along the probe at which a corona discharge occurs within the cable, and this position indicates the corona inception voltage. To render the result independent of pulse shape, &c., the detector electrodes are coupled by a capacitor stack C5 whose electrical centre is connected to the central electrode 8, and the signals derived from the detectors are passed through the filter rectifier-amplifier chains 25A- 28A, 25B-28B, that from one electrode 14 being inverted, and applied to opposite ends of a multitapped resistor R5. The particular tapping at which zero amplitude voltage occurs along this resistor is determined and represents the corona inception voltage. To determine the position along the multi-tapped resistor where zero volts occurs, trigger circuits 33 are attached to repective tappings. The number of these which are triggered indicates the required position. This number is determined by parallelling the trigger output currents to flow through a resistor 36, the voltage across this indicating the number. This voltage, representing the corona voltage, may be displayed on an oscilloscope 40, or used to control an alarm 42 and a recorder 43.

Manufacture of bare or pre-insulated metal clad sodium conductor

Abstract: 1,188,544. Casting composite electric conductors; casting processes. GENERAL CABLE CORP. 15 May, 1967 [7 July, 1966], No. 22316/67. Heading B3F. [Also in Divisions H1 and H2] A metal-clad sodium conductor is made by filling a conducting tube 12 with molten sodium. The sodium is melted in a container 24 under an inert gas such as nitrogen, and is sucked into the helical tube 12 which is connected through a trap 50 to a vacuum line 46. When the tube is completely filled, valves 44 and 48 are shut and the ends of the tube are hermetically sealed by screw-on caps (68). During the filling. the tube 12 is maintained at a temperature above the melting point of sodium (97.5‹ C.), e.g. at between 110‹ and 120‹ C. by being enclosed in an oven 51 heated by steam coils 52 and/or by electrical heating from a power line 54. Tube 12 may be covered with insulation (16) before being filled and more than one tube may be wrapped around core 20. The inert gas may be supplied under pressure through pipe 34 with valve 40 in the outlet pipe 38 almost or entirely closed if extra pressure for filling the tube 12 is required. The tube may be made of aluminium, copper or steel and a weighing system 64 may be used to monitor the process.

Wire coiling apparatus

Abstract: 1,170,508. Winding and reeling. GENERAL CABLE CORP. 28 Feb., 1967 [28 Feb., 1966], No. 9373/67. Heading B3E. Wire coiling apparatus includes a capstan on which the wire is wound by a feed roll mounted on a carrier, one of the capstan and the carrier rotating with respect to the other, the said other being capable of turning in response to tension in the wire, under restraint. Wire 24 from a driven capstan 16 passes over guide sheaves 68 and down a hollow rotating shaft 38 to the lower end of which is secured a flyer 40. The wire then passes over rolls 92, 88, 94 and 90 on the flyer 40 to a V- groove in a capstan 70 to lie therein for an arc of 90 degrees, the wire then passing over a roll 98 and under a casting roll 100 on the flyer 40 back into the groove in the capstan 70 to lie therein for an arc of 270 degrees the last 90 degrees of which it lies under the previous 90 degrees lay of wire. The wire then falls in coils on to a receiver 116. The flyer 38, 40 is driven by a pulley 42, variable pulley 46, pulley 60 and pulley 64 on the capstan 16, the variable pulley being so adjusted by screw means 53 that the speed of the shaft 38 exceeds the speed of the capstan 16. The resultant tension in the wire being coiled produces a turning moment on the capstan 70 which rotates slowly in response, being secured to a brake drum 74 engaged by a brake band 78, coils smaller than the capstan 70 thus being produced. The speed of the shaft 38 and flyer 40 can be varied cyclically, to produce a bundle containing cyclically varying coil sizes, by turning the screw 53 by electromechanical means to vary the pitch of the pulley 46. In a modification, Fig. 8 (not shown) the coil receiver may be adjusted eccentrically and be rotated slowly from the braked capstan to produce a patterned bundle. In another modification, Fig. 9, a flyer 340 carries straightening rolls and the coils are directed by an eccentric guide 400, slowly rotated by a braked capstan 370, to a receiver 316. Coil catcher fingers 420 provided on the guide 400 retain a coil temporarily while a full receiver 316 is replaced by an empty one.

Laboratory Evaluation of 345-kY Cable 2 High-Pressure Oil-Filled Pipe-Type After Field Testing at Cornell University

Abstract: Upon completion of the 345-kV field test at the Cornell Test Station, representative sections of the high-pressure pipe-type cable supplied for the test by the authors' company were subjected to laboratory evaluation. No indications of instability or significant deterioration resulting from the field test were found. The returned cable withstood the standard high-voltage-time test for new cable and had slightly lower power factor at all temperatures than it had before being tested, as well as essentially unchanged radial power-factor distribution. Mechanical properties and dielectric strength of the paper were not significantly affected. No electrical disturbance of any kind was found in the cable proper or in the joints; however, there was slight carbonization in the vicinity of electrode interruptions provided for power-factor measurement and also at the base of the paper buildup in one of the terminals. Both the-saturating oil and the pipe oil were in essentially the original condition. Apparently, however, some of the pipe oil had migrated into the cable from the potheads because of expansion and contraction incident to load cycling.

Thermal stability of insulation for extra high voltage direct current service

Abstract: The theory of thermal instability was first analyzed in detail by Wagner1 He assumed that thermal instability occurred locally due to a concentration of current in highly conductive filaments His results indicate that the breakdown voltage is proportional to the thickness of the insulation Wagner's theory was later supplemented by Rogowski,2 who introduced a term involving the voltage gradient in order to bring the theoretical results in line with the experimental evidence available at that time The effects of field strength were disregarded by other authors until recent times Further work was done on the equations for thermal equilibrium in solid insulation by Dreyfus3 The first broad treatment of electrothermal breakdown was carried out by Fock,4 who considered both thin and thick specimens He indicates that for thin specimens the breakdown voltage is proportional to the square root of the thickness, while for thick specimens the breakdown voltage is independent of the thickness Fock's calculations were later simplified by Moon5