Method and apparatus for measurement of charge entrained in fluids
First Claim
1. Apparatus for measuring the net charge entrained in a fluid comprising:
- an electrically conductive container;
an electrically conductive shield surrounding and insulated from the container;
means for introducing fluid into the container and thereafter expelling the fluid from the container; and
a detector for detecting, before any introduced fluid is expelled, an electrical signal developed between the container and the shield when the container is filled with fluid.
1 Assignment
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Accused Products
Abstract
The density of charge entrained in fluids such as oils in transformer systems, capacitors, cables, pumps and fuel transfer systems is measured by introducing the oil into a conductive container which expands in volume to receive the fluid without expelling any fluid. The container is shielded by a grounded conductor which prevents inducement of charge on the container by external sources. By measuring the current between the conducting expandable container and the surrounding shield and accounting for the effects of the charge induced on the outer wall of the container by its own induced voltage, the net charge entrained in the fluid as it is brought into the container is deduced. Extraneous effects of conduction and electrokinetic currents are automatically excluded from the measurement. The oil is then automatically returned to the transformer system by the contraction of the conductive container so that the measurement can be repeated without accumulating an inventory of fluid.
28 Citations
51 Claims
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1. Apparatus for measuring the net charge entrained in a fluid comprising:
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an electrically conductive container; an electrically conductive shield surrounding and insulated from the container; means for introducing fluid into the container and thereafter expelling the fluid from the container; and a detector for detecting, before any introduced fluid is expelled, an electrical signal developed between the container and the shield when the container is filled with fluid. - View Dependent Claims (2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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3. Apparatus as claimed in claim2 wherein the probe is recessed inside the conducting shield by a distance that is on the order of the width of an aperture in the shield through which the fluid is received.
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18. Apparatus for measuring the net charge entrained in a fluid in a sampled volume comprising:
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an electrically conductive container, the volume of which can accommodate the sampled fluid while retaining electrical continuity and while not at the same time expelling the fluid; an electrically conductive shield surrounding and insulated from the conductive container; means for introducing fluid into the container in a time that is short compared to the charge relaxation time in the fluid and without significant entrainment of charge with flow of the fluid from the sampled volume to the container and for thereafter expelling the fluid from the container; and a detector for detecting, befor any introduced fluid is expelled, an electrical signal developed between the container and the shield when fluid is introduced into the container. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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27. A method of measuring the net charge entrained in a fluid comprising:
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introducing the fluid into an electrically conductive and shielded container; and measuring an electrical signal developed between the container and the shield when the fluid is introduced into the container before release of any of the fluid from the container. - View Dependent Claims (28, 29)
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30. A method of measuring the net charge entrained in a fluid in sampled volume comprising:
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introducing the fluid into an electrically conductive and shielded container in a time that is short compared to the charge relaxation time in the fluid and without significant entrainment of charge with flow of the fluid from the sampled volume to the container; and measuring an electrical signal developed between the container and the shield before release of any of the fluid from the container. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37)
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38. A method of measuring the charge entrained in oil in a transformer system comprising:
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introducing the oil into an electrically conductive and shielded container; and measuring an electrical signal developed between the container and the shield before release of any of the oil from the container. - View Dependent Claims (39)
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40. A method of measuring the charge entrained in fuel comprising:
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introducing the fuel into an electrically conductive and shielded container; and measuring an electrical signal developed between the container and the shield before release of any of the fuel from the container. - View Dependent Claims (41)
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42. Apparatus for measuring the net charge entrained in a fluid comprising:
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an electrically conductive container comprising a shielded, conductive probe through which the fluid is received; an electrically conductive shield surrounding and insulated from the container; means for introducing fluid into the container and thereafter expelling the fluid from the container; and a detector for detecting an electrical signal developed between the container and the shield when the container is filled with fluid. - View Dependent Claims (43)
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44. Apparatus for measuring the net charge entrained in a fluid comprising:
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an electrically conductive container; an electrically conductive shield surrounding and insulated from the container; a positive displacement element for introducing fluid into the container and thereafter expelling the fluid from the container; and a detector for detecting an electrical signal developed between the container and the shield when the container is filled with fluid. - View Dependent Claims (45)
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46. Apparatus for measuring the net charge entrained in fluid comprising:
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an electrically conductive container; an electrically conductive shield surrounding and insulated from the container; means comprising one-way valves in separate conduits for introducing fluid into the container and thereafter expelling the fluid from the container; and a detector for detecting and electrical signal developed between the container and the shield when the container is filled with fluid.
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47. Apparatus for measuring the net charge entrained in a fluid comprising:
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an electrically conductive container; an electrically conductive shield surrounding and insulated from the container; means for introducing fluid into the container and thereafter expelling the fluid from the container through a common port; and a detector for detecting an electrical signal developed between the container and the shield when the container is filled with fluid.
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48. Apparatus for measuring the net charge entrained in a fluid comprising:
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an electrically conductive container; an electrically conductive shield surrounding and insulated from the container; means for introducing fluid into the container and thereafter expelling the fluid from the container; a detector for detecting an electrical signal developed between the container and the shield when the container is filled with fluid; and means for minimizing change in capacitance between the container and shield as fluid is introduced into the container. - View Dependent Claims (49, 50)
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51. Apparatus for measuring the net charge entrained in a fluid comprising:
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an electrically conductive container; an electrically conductive shield surrounding and insulated from the container; means for introducing fluid into the container and thereafter expelling the fluid from the container, the means for introducing fluid into the container and expelling the fluid comprising a positive displacement element and a spring for countering a pressure head of the fluid against the positive displacement element; and a detector for detecting an electrical signal developed between the container and the shield when the container is filled with fluid.
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Specification