GB1603960A

GB1603960A - Electrical apparatus utilizing polypropylene felt filter

Info

Publication number: GB1603960A
Application number: GB2584078A
Authority: GB
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1978-05-22
Filing date: 1978-05-31
Publication date: 1981-12-02
Also published as: CA1117209A; JPS54153294A; JPS583726U; AU4635979A; JPS6013221Y2

Description

(54) ELECTRICAL APPARATUS UTILIZING POLYPROPYLENE FELT FILTER (71) We, WESTINGHOUSE ELECTRIC COR PORATION of Westinghouse Building, Gateway Center, Pittsburgh, Pennsylvania, United States of America, a corporation organised and existing under the laws of the State of Pennsylvania, United States of America, do hereby.declare the invention, for which we pray that a patent may be granted t6 us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to electrical apparatus, and in particular to gas-insulated electrical transmission lines.

Gas-insulated electrical equipment is being used on an ever-increasing scale for the transmission and distribution of electrical energy, particularly at higher voltages. This equipment offers advantages in the reduced land area required, the increased safety because of the typically grounded outer enclosure of the equipment, the non-toxicity of the insulating gas even in the presence of decomposition products, and the quieter operation of the equipment. Also, for gasinsulated transmission lines, there is no disturbance of the surrounding environment by the intrusion of electromagnetic fields from the high current-carrying conductor, because of the grounded outer sheath.

In this gas-insulated equipment, there are numerous locations where it is desirable to provide a flexible filter material within the outer enclosure of the equipment. The pur pose of this flexible filter is to prevent the passage of particulate matter, which can cause deleterious effects and a lessening of the dielectric strength of the insulating gas, but which filter should allow the passage of the insulating gas, which typically is sulfur hexafluoride. For all of these apparatus, it is required that the filter material be compatible with the dielectric-type materials present within the apparatus, and with the insulating gas. A critical requirement is that in the unlikely event of an arc in sulfur hexafluoride, for example due to a failure, the filter material should not be attacked by the arc products in the sulfur hexafluoride.

This latter requirement eliminates virtually all of the open cell foam materials such as polyurethane and polystyrene, which are attacked by sulfur hexafluoride products and can disintegrate. Materials that are not attacked by sulfur hexafluoride products, such as polypropylene and tetrafluoroethylene cannot be made in an open cell foam structure to allow the passage of sulfur hexafluoride gas. Thus, what is needed is a filter material for use in gas-insulated electrical apparatus which will prevent the passage of particulate matter but which will allow the passage of the insulating gas.

According to the present invention, an electrical apparatus includes an enclosure containing sulfur hexafluoride gas, a conducting member disposed within said enclosure, a barrier insulator member insulatably supporting said conducting member within said enclosure, and a filter disposed adjacent to the insulator member, said filter being made of polypropylene felt.

The invention also includes a gas-insulated transmission line comprising a cylindrical outer sheath, an inner conductor disposed within said outer sheath, an insulating gas disposed within said outer sheath and electrically insulating said inner conductor within said outer sheath, and support means for insulatably supporting said inner conductor within said outer sheath and in which a polypropylene felt filter is disposed at selected locations within said outer sheath.

The invention will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a sectional view of a gasinsulated transmission line, typical of the electrical apparatus; Figure 2 is a cross-sectional view of the transmission line taken along line Il-Il of Figure 1; Figure 3 is a detailed view of the filter utilized in conjunction with a spacer ring in the transmission line of Fig. 1.

Figure 4 is a detailed view of the filter utilized in conjunction with an insulating support of a transmission line; Figure 5 is a view of the filter utilized with a plug-in conductor joint; and Figure 6 is a view illustrating the filter used in an insulating support spacer of a transmission line.

Figure 1 illustrates a transmission line 10 comprising an elongated, cylindrical outer sheath 12 which is typically at low or ground potential, an inner conductor 14 disposed within the outer sheath 12, and an insulating gas 16 which is generally sulfur hexafluoride disposed within the outer sheath 12 and which gas 16 electrically insulates the inner conductor 14 from the grounded outer sheath 12. The inner conductor 14 is typically at a high electrical potential, for example 1451200 KV, and both the outer sheath 12 and the inner conducting member 14 will be of a good electrically conducting material such as aluminium.

Means 18 are utilized for insulatably sup porting the inner conductor 14 within the outer sheath 12. The support means 18 illustrated in Figures 1 and 2 are insulating supports 20 which comprise a central portion 22 and a plurality of legs 24 which extend from the central portion 22 outwardly to the outer sheath 12. The support 20 is typically comprised of an epoxy resin material.

Secured to the insulating support 20 is a particle trapping ring 26 which has a plurality of openings 28 therein. The ring 26 is electrically connected to the outer sheath 12, as by the contact 30, so as to form a low field region 32 between the ring 26 and the outer sheath 12. Electrically conducting or semiconducting particles which may be contaminating the interior of the outer sheath 12 can then pass through the openings 28 in the ring 26 and be entrapped within the low field region 32 therebetween so as not to cause electrical flashover or breakdown within the transmission line 10. One location where it may be desirable to provide a filter is in the low field region 32 between the particle trapping ring 26 and the outer sheath 12.

As shown in Figure 3, in some locations, the transmission line 10 of Figure 1 may be disposed at an angle to the horizontal, so that any particles which may have been trapped within the low field region 32 would have a tendency, due to gravity, to migrate out of the low field region 32. Because of this possible migration, it is desirable to include a barrier 34 at the longitudinal end 36 of the particle trapping ring 26 to prevent this migration of particles from within the low field region 32. The barrier 34 should be in contact with both the outer sheath 12 and the trap ping ring 26. Thus, in this location, it may be desirable to provide a filter which will prevent the passage of particulate matter, and where it may be desirable to allow the passage of the insulating, sulfur hexafluoride gas.

The barrier 34, which would also be the filter, is made of a polypropylene felt material.

This filter 34 would not be attacked by sulfur hexafluoride, and can operate satisfactorily even in the event of a sulfur hexafluoride arc.

The filter, of polypropylene felt, can be made to the required porosity and filter size by weaving polypropylene fibers of suitable diameter and suitable mesh. If necessary or desirable, the filter material can be glazed and singed so as to bind the fibers into the filter, and prevent the fibers from working loose.

Figure 4 illustrates another location where it is desirable to provide a filter which will prevent the passage of contaminating particles but will allow the passage of sulfur hexa flloride gas, which filter must be impervious to the effects of sulfur hexafluoride or the arc products resulting therefrom. In this figure, the supporting means 18 comprises a barrier insulator 40, illustrated as being of conical cross section, which is secured to the inner conductor 14 and extends to a support ring 42 which is disposed adjacent to, and secured to, the outer sheath 12. The purpose of this barrier insulator 40, is to substantially compartmentalize the sections of the transmission line 10 on opposing longitudinal sections 44, 46 of the barrier insulator 40. By such compartmentalizing, any fault which occurs in one section, for example 44, will not transmit its contamination particles across the support insulator 40 into the other transmission line section 46. However, to facilitate the filling of the transmission line 10 with sulfur hexafluoride gas, it is desirable to provide a means for allowing the passsge of the gas past the barrier insulator 40. This can be provided by the filter 48. As with the preceding embodiment, this filter should allow the passage of the sulfur hexafluoride gas without permitting the passage of the contamination particles. The filter 48 may be disposed within an opening 50 within the support ring 42, and the filter 48 should contact both the ring 42 and the outer sheath 12. The filter 48 is of the polypropylene felt material previously described with respect to Figure 3.

Another location where it may be desired to utilize the polypropylene felt filter of this invention is illustrated in Figure 5. This figure illustrates a plug-in joint connection between electrically conducting members 56, 58, which, for example, may be two sections of the inner conductor 14. The electrically conducting member 56 has a plug member 60 at one end thereof, and the electrically conducting member 58 has a socket 62 at one end thereof. The plug member 60 would be disposed within the socket 62 to provide electrical connection between the conduct nag members 56 and 58.

A plurality of contacts 64 may be utilized to provide electrical contact between the plug member 60 and the conducting member 58. To minimize corona and arcing at this connection, a shield 66 may be disposed about and encircle this joint connection.

The shield 66 would extend longitudinally outwardly to both the conducting members 56 and 58. A mounting rod 68, or a plurality of similar rods, would be utilized for securing the shield 66 to the conducting member 58.

A wiper 70 would be disposed between the sheild 66 and the conducting member 56 to prevent the escape of any conducting particles from the area 72 between the shield 66, the conducting members 56 and 58, and the plug member 60. However, it is desirable to allow this insulating gas 16 to enter into this joint region 72. This can be accomplished, without allowing the passage of the contamination particles, which may be generated by the sliding action of the plug member 60 in the socket 62, by utilizing a polypropylene felt filter 74. This filter 74, of the polypropylene felt construction previously described, would be disposed within an opening 76 in the shield 66, and would contact both the shield 66 and the conducting member 58. By being so disposed, the filter 74 would allow the passage of the insulating gas 16 into the region 72 of the joint, but would prevent the passage of conducting particles from within the joint area 72 outwardly into the insulating gas 16 where it maycauseflashover and breakdown. Although described with respect to the transmission line 10 of Figure 1, the plug-in joint of Figure 5 may, for example, be within a disconnect switch, a gas-insulated substation, or any other gas-insulated electrical apparatus.

Another location wherein the polypropylene felt filter may be utilized is illustrated in Figure 6. In this Figure, the insulating spacer 80 completely fills in the cross-sectional area between the inner conductor 14 and the outer sheath 12. The spacer 80 has a central opening 82 therein through which the inner conductor 14 extends, and one or more openings 84 which extend longitudinally through the spacer 80. In this opening 84 is disposed the polypropylene felt filter 86, which can be utilized to stop the migration of decomposition particles, dust, or dirt, but which permits the flow of the insulating gas therethrough throughout the length of the transmission line 10. As before, the polypropylene felt filter 86 can be made to the desired size by weaving polypropylene fibers of suitable diameter and suitable mesh, and may be glazed and singed so as to bind the fibers into the filter and prevent the fibers from working loose.

Thus, it can be seen that the filter prevents the passage of contamination dust but which allows the passage of the insulating gas in gas insulated electrical apparatus. The polypropylene felt filter can be utilized in those numerous locations in gas-insulated electrical apparatus where it is desired to provide such filtering, and provides such filtering without being attacked by a sulfur hexafluoride arc or the decomposition products resulting from such arc.

WHAT WE CLAIM IS:- 1. Electrical apparatus including an enclosure containing sulfur hexafluoride gas, a conducting member disposed within said enclosure, a barrier insulator member insulatably supporting said conducting member within said enclosure, and a filter disposed adjacent to the insulator member, said filter being made of polypropylene felt.

2. An apparatus as claimed in claim 1 wherein an insulating spacer insulatably supports said conducting member within said enclosure, said spacer having an opening therethrough, said filter being disposed within said spacer opening.

3. An apparatus as claimed in claim 1 wherein a spacer ring is secured to said spacer spaced-apart from said enclosure, and said filter is disposed between, and in physical contact with, said spacer ring and said enclosure.

4. An apparatus as claimed in any one of claims 1 to 3 wherein a pair of cylindrical conducting members are insulatably supported within said enclosure, one of said conducting members having a plug member secured at one end thereof and the other of said conducting members having a socket at one end thereof, said plug member being disposed within said socket, a shield is disposed within said enclosure encircling said conducting members adjacent said plug member and said socket, and said filter is disposed intermediate, and in contact with, one of said conducting members and said shield.

5. A gas-insulated transmission line including a cylindrical outer sheath, an inner conductor disposed within said outer sheath, an insulating gas disposed within said outer sheath and electrically insulating said inner conductor within said outer sheath, and support means for insulatably supporting said inner conductor within said outer sheath and in which a polypropylene felt filter is disposed at selected locations within said outer sheath.

6. A transmission line as claimed in claim 5 wherein a ring is disposed within, and spaced-apart from, said outer sheath, and said filter is disposed between, and in physical contact with, said ring and said outer sheath.

7. A transmission line as claimed in claim 6 wherein said support means comprises a support insulator, said support insulator being secured to said ring.

8. A transmission line as claimed in claim 7 wherein said support insulator substantially fills in the cross-sectional area

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. connection, a shield 66 may be disposed about and encircle this joint connection. The shield 66 would extend longitudinally outwardly to both the conducting members 56 and 58. A mounting rod 68, or a plurality of similar rods, would be utilized for securing the shield 66 to the conducting member 58. A wiper 70 would be disposed between the sheild 66 and the conducting member 56 to prevent the escape of any conducting particles from the area 72 between the shield 66, the conducting members 56 and 58, and the plug member 60. However, it is desirable to allow this insulating gas 16 to enter into this joint region 72. This can be accomplished, without allowing the passage of the contamination particles, which may be generated by the sliding action of the plug member 60 in the socket 62, by utilizing a polypropylene felt filter 74. This filter 74, of the polypropylene felt construction previously described, would be disposed within an opening 76 in the shield 66, and would contact both the shield 66 and the conducting member 58. By being so disposed, the filter 74 would allow the passage of the insulating gas 16 into the region 72 of the joint, but would prevent the passage of conducting particles from within the joint area 72 outwardly into the insulating gas 16 where it maycauseflashover and breakdown. Although described with respect to the transmission line 10 of Figure 1, the plug-in joint of Figure 5 may, for example, be within a disconnect switch, a gas-insulated substation, or any other gas-insulated electrical apparatus. Another location wherein the polypropylene felt filter may be utilized is illustrated in Figure 6. In this Figure, the insulating spacer 80 completely fills in the cross-sectional area between the inner conductor 14 and the outer sheath 12. The spacer 80 has a central opening 82 therein through which the inner conductor 14 extends, and one or more openings 84 which extend longitudinally through the spacer 80. In this opening 84 is disposed the polypropylene felt filter 86, which can be utilized to stop the migration of decomposition particles, dust, or dirt, but which permits the flow of the insulating gas therethrough throughout the length of the transmission line 10. As before, the polypropylene felt filter 86 can be made to the desired size by weaving polypropylene fibers of suitable diameter and suitable mesh, and may be glazed and singed so as to bind the fibers into the filter and prevent the fibers from working loose. Thus, it can be seen that the filter prevents the passage of contamination dust but which allows the passage of the insulating gas in gas insulated electrical apparatus. The polypropylene felt filter can be utilized in those numerous locations in gas-insulated electrical apparatus where it is desired to provide such filtering, and provides such filtering without being attacked by a sulfur hexafluoride arc or the decomposition products resulting from such arc. WHAT WE CLAIM IS:-

1. Electrical apparatus including an enclosure containing sulfur hexafluoride gas, a conducting member disposed within said enclosure, a barrier insulator member insulatably supporting said conducting member within said enclosure, and a filter disposed adjacent to the insulator member, said filter being made of polypropylene felt.

between said inner conductor and said ring.

9. A transmission line as claimed in claim 6 wherein said ring has a plurality of apertures therein, and said ring is electricllly connected to said outer sheath.

10. A transmission line as claimed in claim 5 wherein said support means comprises a support insulator having an opening therethrough, and said filter is disposed within said support insulator opening.

11. A transmission line as claimed in claim 5 wherein said inner conductor comprises two cylindrical conductor sections, one of said conductor sections having a plug member at one end thereof and the other of said conductor sections having a socket at one end thereof, said plug member being disposed in said socket, a shield encircles said conductor sections adjacent said plug member and said socket, and said filter is disposed intermediate, and in contact with, said shield and one of said conductor sections.

12. A transmission line as claimed in any one of claims 5 to 11 wherein said polypropylene felt filter comprises a plurality of polypropylene fibres weaved into a mesh structure.

13. A transmission line as claimed in claim 12 wherein said polypropylene fibres are glazed and singed so as to bind said fibres into said filter.

14. Electrical apparatus as claimed in any one of claims 1 to 4, wherein said polypropylene felt filter comprises a plurality of polypropylene fibres weaved into a mesh structure.

15. Electrical apparatus as claimed in claim 14, wherein said fibres are glazed and singed so as to bind said fibres into said filter.

16. Electrical apparatus as claimed in any one of claims 1 to 4, 14 and 15, constructed substantially as hereinbefore described and illustrated with reference to the accompanying drawings.

17. A gas-insulated transmission, constructed substantially as hereinbefore described and illustrated with reference to the accompanying drawings.