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Publication Date: 2017-Jun-07
Document File: 3 page(s) / 97K

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The Prior Art Database


A reduced capacitance cable.

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[0001]          In industries such as at the oilfield, the need for utilizing electrical cables of extensive lengths often arises such as where cables are extended several thousand feet into a well or along a seabed to supply power to remotely positioned tools and equipment.  For example, it would not be uncommon to see cables exceeding 20 kilometers used in this way.  The charging current is a major challenge in long cable applications using high voltage level and alternating current.  The charging current is proportional to the capacitance and the frequency and amplitude of the voltage.  Increased voltage is favorable to reduce cable losses, but when the charging current becomes large the benefit is reduced, and in some cases will make the system less able to transmit power.  For example, where a conventional cable of such length is called for to supply 400 kW of power to an electrical tool, it is very likely that that this level of power will not actually reach the tool.

[0002]          Efforts to address the issue have been undertaken.  For example, one known method is to reduce the frequency.  However, this requires complicated frequency converting apparatus, often in both ends of the cable. Since lowering the voltage will increase receiving end current, a better overall solution may be to reduce the cable capacitance.

[0003]          To reduce cable capacitance, one method is well known, namely increase insulation thickness. This can be done by selecting a cable with higher voltage rating than is needed for the system. The drawback with this solution is that the overall diameter of the three phase cable is also increased.  Thus, weight, materia...