Abstract: Method and apparatus for applying a layer of insulation around an electrical cable core in which the contaminant size is not greater than about 200 microns. Unplasticized insulation material, such as polyethylene, is supplied to an extruder which forces the material through a filter which prevents the passage of contaminants having a size greater than about 200 microns and in which there is a pressure drop. The filtered material is delivered to a pump which increases the pressure thereon and forces it through a static mixer at the output of which the filtered material is delivered to the cross-head of extrusion apparatus which applies the filtered material to the cable core as it is advanced longitudinally. If the insulating material is to be cross-linked by a cross-linking agent, the agent is injected into the filtered material between the pump and the mixer.

Abstract: A water migration resisting filler for filling the interstices of a stranded conductor, an electrical power transmission cable including such filler and a method of making such cable. The filler includes a polymeric compound having a 100 gram needle penetration value between 50 anad 100 tenths of a millimeter at 25.degree. C. and particles of a water swellable material having a particle size of not greater than 20 microns are in contact with the polymeric compound either by admixing it with the compound or applying it to the surface thereof. In the method, the polymeric compound is flowed around the wires of the conductor as they are stranded together and the water swellable material is either admixed with the compound or applied thereto as the conductor is formed, a semi-conductive layer is extruded around the so-filled conductor and a layer of insulation is extruded around the semi-conductive layer.

Abstract: A high voltage electrical power cable with a longitudinally folded, smooth or corrugated, metal strip around a plurality of layers around the conductor and a water swellable material at least at the adjacent edges of the strip. Preferably, the water swellable material is included with a polymeric material which is flowable at a temperature at least as low as 100.degree. C., the polymeric material has a 100 gram needle penetration value in the range from 50-100 tenths of a millimeter at 25.degree. C. and the water swellable material has a particle size not greater than 200 microns.

Abstract: An optical fiber cable with optical fibers surrounded by a first gas blocking layer which is surrounded by a second gas blocking layer spaced from the first layer so as to provide longitudinal gas flow channels between the first and second layers. The channels are filled with a gas under a pressure above atmospheric pressure so that when the second layer is punctured, there is a gas flow and/or gas pressure drop indicating such puncturing and hence, if caused by tampering, the fact of tampering. Also, devices for indicating the gas flow and/or pressure drop and alarms and/or signal transmission terminating apparatus responsive to such devices.

Abstract: A high voltage, gas filled, pipe type electrical cable and method of manufacture thereof. The cable comprises a plurality of insulated conductors, each conductor having a central gas passageway and being gas permeable. The conductor is wrapped with tapes impregnated with an insulating oil, and the wrapped tapes are encircled by gas permeable layers and skid wires. Three of such insulated conductors are encircled by a gas impermeable pipe, and the pipe and the conductor passageways are filled with an insulating gas under pressure above atmospheric pressure so that both the interior and exterior surfaces of the wrapped tapes are subjected to such gas. Preferably, the gas is a mixture of sulfur hexafluoride and nitrogen at a pressure of at least 200 psig. The tapes are impregnated with the oil and drained before they are wrapped around the conductor so as to provide gaps between the tapes which are substantially filled with the gas.

Abstract: A communication system in which analog signals are multiplexed and then converted into frequency modulated signals which are applied to the laser of an optical transmitter to intensity modulate the laser output. The laser output is supplied to one end of an optical fiber, the other end of which is connected to an optical receiver. The output signals of the optical receiver are applied to a frequency demodulator, and the output signals of the frequency demodulator are demultiplexed to provide the corresponding analog signals. The system may include pilot tone signals for remote monitoring of conditions at an unmanned station, and preferably, some of the multiplexed signals are emphasized relative to the other signals prior to application to the frequency modulator and are correspondingly deemphasized at the frequency demodulator output.

Abstract: A water migration resisting filler for filling the interstices of a stranded conductor, an electrical power transmission cable including such filler and a method of making such cable. The filler includes a polymeric compound having a 100 gram needle penetration value between 50 and 100 tenths of a millimeter at 25.degree. C. and particles of a water swellable material having a particle size of not greater than 200 microns are in contact with the polymeric compound either by admixing it with the compound or applying it to the surface thereof. In the method, the polymeric compound is flowed around the wires of the conductor as they are stranded together and the water swellable material is either admixed with the compound or applied thereto as the conductor is formed, a semi-conductive layer is extruded around the so-filled conductor and a layer of insulation is extruded around the semi-conductive layer.

Abstract: Apparatus for extruding a first layer of a semi-conductive plastic material around the conductor of an electric power cable and for extruding a second layer of plastic insulating material around the first layer as the conductor is advanced in which the extruder for the insulating material includes an extrusion head which comprises a body with a passageway therethrough for the passage of the conductor through the body and having at least one channel therein extending from the exterior thereof to adjacent one end of the passageway for supplying the insulated material around the conductor. An extrusion tip or tubular guide is disposed in the passageway for guiding said conductor and extends across part of the channel for contacting material exiting from the channel. The guide comprises a ceramic tube with a polished inner surface forming the innermost surface of the guide.

Abstract: A measuring tube containing a permanent magnet on a float is connected to a tube, containing steam and water for vulcanizing and cooling the insulation on an electric cable, so that the water-steam interface in the measuring tube corresponds to the water-steam interface in the vulcanizing tube. The magnet position corresponds to the water-steam interface and operates switches external to the measuring tube and connected to a voltage divider so that the output voltage of the divider corresponds to the water-steam interface. The voltage output of the divider is compared with pre-set voltages and differences between the voltages are used to control pumps, valves, etc., so as to maintain the water-steam interface at the desired level and the voltage output of the divider is used to operate lamps, and/or alarms, and valves when the interface is excessively high or low.

Abstract: Insulation for an electric power cable, and a power cable including such insulation, the insulation having an improved dielectric strength and being irradiation cross-linked polymeric material having mixed therewith carbon black having a particle size in the range from about 200 to about 500 millimicrons, the carbon black content being about 10% to about 40% of the weight of the mixture of carbon black and the polymeric material. Also, the cable insulation may be layers of different density polyethylene, at least one of the layers being the described mixture of polyethylene and carbon black.

Abstract: A stop joint for a pair of electric cables having fluid under pressure therein in which the fluid impermeable pipe or shield around the cable, which is spaced at its end from the bared conductor end to expose the cable insulation, is connected to the connector for interconnecting the cable ends by a multi-part stop tube having an intermediate portion of insulating material and a pair of end portions bonded to respective ends of the intermediate portion, the end portions being made of an insulating material rendered conductive by the addition of conductive material or of insulating material having a conductive layer thereon for forming electrodes for electrical stress distribution purposes. The electrodes have substantially the same coefficient of expansion as the material of the intermediate tube portion to prevent separation of the end portions from the intermediate portion with temperature changes.

Abstract: In a pipe type electric cable installation in which portions of the cable cores extend into a joint casing where the conductors of the cores are conductively joined, the portions of the cores within the casing are enclosed by tubes which are longitudinally curved, preferably, S-shaped, to restrict axial movement of the cores with varying load conditions, one end of each tube being anchored, at least with respect to longitudinal movement, to the casing.