DEVICE FOR MEASURING THE CONCENTRATION OF A GAS DISSOLVED IN AN ELECTRICAL INSULATION OIL
A device for measuring the concentration of a gas dissolved in an electrical insulation oil comprises a measuring member ( 2 ), internally defining a measuring chamber ( 3 ) and a conduit ( 4 ) to access the measuring chamber ( 3 ), a membrane ( 6 ) permeable to gases, inserted inside the conduit ( 4 ) for insulating the measuring chamber ( 3 ) against the oil and allowing gas to pass from the oil to the measuring chamber ( 3 ), a sensor ( 20 ) located in the measuring chamber ( 3 ) for measuring the concentration of gas in the measuring chamber ( 3 ), and a reinforcing grid ( 8 ) positioned in the conduit ( 4 ) for preventing deformation of the membrane ( 6 ), where the grid ( 8 ) is located at a position adjacent to the membrane ( 6 ) on the side opposite to the measuring chamber ( 3 ), and has at least one through section ( 9, 10 ) for allowing the oil to exert pressure directly on the membrane ( 6 ).
1 . A device for measuring the concentration of a gas dissolved in an electrical insulation oil, comprising:
a measuring member ( 2 ), with a measuring chamber ( 3 ) and a conduit ( 4 ) communicating with said measuring chamber ( 3 ), said conduit ( 4 ) defining a termination ( 4 a ) which is connectable to a container for the electrical insulation oil of said equipment;
a membrane ( 6 ) permeable to gases, inserted inside the conduit ( 4 ), for separating the measuring chamber ( 3 ) from the oil in said container and for allowing gas to pass from the oil towards the measuring chamber ( 3 );
a sensor ( 20 ) located in the measuring chamber ( 3 ) to measure a value of the gas concentration in the measuring chamber ( 3 ),
wherein said measuring member ( 2 ) comprises a reinforcing element ( 8 ), located in the conduit ( 4 ) at a position adjacent to a surface of the membrane ( 6 ) facing the side opposite to the measuring chamber ( 3 ), and having a plurality of resistant portions ( 11 ) defining between them through apertures ( 9 ), which form a section ( 9 , 10 ) through which the oil passes and comes operatively in contact with said surface of the membrane ( 6 ).
2 . A device according to claim 1 , wherein said reinforcing element ( 8 ) is grid shaped and extends about an axis (X), said through apertures ( 9 ) being angularly spaced on said grid ( 8 ) about said axis (X).
3 . A device according to claim 2 , comprising a plurality of through apertures ( 9 ) which are uniformly spaced and separated by corresponding resistant portions ( 11 ) which are radially arranged.
4 . A device according to claim 1 , wherein said reinforcing element ( 8 ) has a ring shaped resistant portion which is positioned centrally, and defining a middle aperture ( 10 ) of the reinforcing element ( 8 ).
5 . A device according to claim 1 , wherein said reinforcing element ( 8 ) is rigid.
6 . A device according to claim 1 , wherein said resistant portions ( 11 ) have a minimum dimension (D) of at least 2 mm, which is measured in any one direction along a plane in which the membrane ( 6 ) lies.
7 . A device according to claim 1 , wherein said resistant portions ( 11 ) define rounded or radiused side edges in a zone of the reinforcing element ( 8 ) adjacent to said surface of the membrane ( 6 ).
8 . A device according to claim 1 , wherein the reinforcing element ( 8 ) has a plurality of intersecting zones of the resistant portions ( 11 ) and is shaped so that the edges defined by said intersections are radiused, without corners.
9 . A device according to claim 1 , wherein said measuring member ( 2 ) comprises at least a first part ( 2 a ) defining at least one section of said conduit ( 4 ) and wherein the reinforcing element ( 8 ) is made in a single piece with said first part ( 2 a ).
10 . A device according to claim 9 , wherein said measuring member ( 2 ) comprises a second part ( 2 b ) able to be abutted to said first part ( 2 a ) and defining a seat ( 7 ) for housing the membrane ( 6 ) in cooperation with the first part ( 2 a ), said second part ( 2 b ) comprising a full disc, at least partly made of porous material, which is permeable to gases and which is located at a position adjacent to a surface of the membrane ( 6 ) facing towards the measuring chamber ( 3 ), for preventing deformation of the membrane ( 6 ) towards the measuring chamber ( 3 ).
11 . A method for making a device for measuring the concentration of a gas dissolved in an electrical insulation oil of electrical equipment, comprising the following steps:
preparing a measuring member ( 2 ), with a measuring chamber ( 3 ) and a conduit ( 4 ) communicating with said measuring chamber ( 3 ), said conduit ( 4 ) defining a termination ( 4 a ) which is connectable to a container for the electrical insulation oil of said equipment; a membrane ( 6 ) permeable to gases, inserted inside the conduit ( 4 ), for separating the measuring chamber ( 3 ) from the oil in said container and for allowing gas to pass from the oil towards the measuring chamber ( 3 ); a sensor ( 20 ) located in the measuring chamber ( 3 ) for measuring the concentration values of gas in the measuring chamber ( 3 );
positioning a reinforcing element ( 8 ) in the conduit ( 4 ) at a position adjacent to a surface of the membrane ( 6 ) facing the side opposite to the measuring chamber ( 3 ), said reinforcing element ( 8 ) having a plurality of resistant portions ( 11 ) defining between them through apertures ( 9 ) which form a section ( 9 , 10 ) through which the oil passes and comes operatively in contact with said surface of the membrane ( 6 ).
12 . A method according to claim 11 , wherein said reinforcing element ( 8 ) is made in a single piece with at least one portion ( 2 a ) of the measuring member ( 2 ).
13 . A method according to claim 12 , comprising the following steps:
preparing said at least one portion ( 2 a ) of the measuring member ( 2 ) so that it at least partly defines said conduit ( 4 ) and having, inside said conduit ( 4 ), a wall which at least partly obstructs the conduit ( 4 ) made in a single piece with said portion ( 2 a ) of the measuring member ( 2 );
performing, on said wall, mechanical drilling to obtain said resistant portions ( 11 ) and said through apertures ( 9 ).
14 . A method according to claim 13 , comprising mechanical radiusing of said resistant portions ( 11 ), to remove sharp edges from portions of the reinforcing element ( 8 ) facing the membrane and operatively in contact therewith when the membrane is subjected to a suction action by the oil.