High voltage switch with condensation preventing bearing assembly and method therefor

Abstract

A high voltage electric disconnect switch having a rotatable switch blade in operative arrangement with a rotatable high voltage electrical insulator. A rotating bearing assembly in operative supporting arrangement with a rotatable shaft. The bearing assembly containing corrodible ball bearing assemblies including associated corrodible ball bearing races. The rotatable insulator is operatively mounted to the rotatable shaft. The rotatable shaft has a lower rotatable shaft portion contacting the corrodible ball bearing assemblies housed within a sealed housing of the bearing assembly. An air permeable hydrophobic membrane mounted in a membrane assembly is mounted in an aperture of the housing to eliminate condensing humidity within the housing, thereby preventing corrosion of the corrodible ball bearings and races, freezing water, and lubrication degradation by keeping the surfaces dry to prevent switch failure.

Claims

1. A high voltage electric disconnect switch comprising: at least one rotating electric insulator, the rotating electric insulator including a rotating bearing assembly comprising a rotating bearing shaft and a sealed bearing housing having an interior that contains ball bearings or rollers and bearing races for operatively opening and closing the electric switch, the sealed bearing housing having an opening therethrough, an air permeable condensation preventing vent mounted in the opening in operative arrangement with the sealed bearing housing, the air permeable condensation preventing vent configured to allow ambient air to flow into and out of the sealed bearing housing only through the air permeable condensation preventing vent while preventing the flow of water into the sealed bearing housing, but allowing air to enter and exit the sealed bearing housing through the air permeable condensation preventing vent while preventing moist air from condensing to keep the interior of the sealed bearing housing dry and free of water, the air permeable condensation preventing vent includes an air permeable hydrophobic membrane configured to keep the interior of the sealed bearing housing dry and free of water, and, the air permeable condensation preventing membrane vent further includes a membrane vent housing in operative engagement with the opening in the sealed bearing housing and mounted thereto, the membrane vent housing operatively configured for carrying the air permeable hydrophobic membrane.

2. The switch of claim 1, wherein the sealed bearing housing further comprises a plurality of seals configured to seal the sealed bearing housing, the air permeable hydrophobic membrane is configured to maintain the air pressure within the interior of the sealed bearing housing equal to the ambient air pressure outside of the sealed bearing housing, wherein the seals of the sealed bearing housing are maintained free of pressure differential that may cause leakage of the bearing seals.

3. The switch of claim 1, wherein the ball bearings or rollers and/or bearing races are comprised of corrodible and/or non-corrodible material, the air permeable hydrophobic membrane is configured to prevent freezing of water within the interior of the sealed bearing housing to prevent impairment of operation of the ball bearings or rollers and/or bearing races and the opening and closing of the high voltage electric disconnect switch.

4. The switch of claim 3, wherein the ball bearings or rollers and/or bearing races are comprised of corrodible metal.

5. The switch of claim 4, wherein the air permeable hydrophobic membrane is configured to keep the corrodible metal ball bearings or corrodible metal rollers and/or corrodible metal bearing races dry and free of water by preventing condensation within the interior of the sealed bearing housing to prevent corrosion of the corrodible metal ball bearings or corrodible metal rollers and/or corrodible metal bearing races.

6. The switch of claim 1, wherein the air permeable condensation preventing vent further includes a membrane vent housing cap in operative arrangement with the air permeable hydrophobic membrane and configured to protect the air permeable hydrophobic membrane from freezing rain and snow and dirt that can clog the air permeable hydrophobic membrane.

7. The switch of claim 1, wherein the membrane vent housing has a membrane vent housing channel passing therethrough in fluid communication with the interior or the sealed bearing housing, the air permeable hydrophobic membrane in operative arrangement with the membrane vent housing channel and the interior of the sealed bearing housing.

8. The switch of claim 4, wherein the corrodible metal ball bearings or corrodible metal rollers and/or corrodible metal bearing races are configured to be lubricant coated for friction reduction.

9. The switch of claim 5, wherein the corrodible metal ball bearings or metal rollers and/or metal bearing races are stainless steel, iron or alloy or corrodible steel or any metal.

10. The switch of claim 3, wherein the ball bearings or rollers and/or bearing races are comprised of non-corrodible ceramic or beryllium copper.

11. The switch of claim 1, wherein the high voltage electric disconnect switch is a vertical break, side break, center break or double break type of air break high voltage disconnect switch.

12. A method of preventing condensation within the rotating insulator bearing assembly of a high voltage disconnect switch comprising the following steps: a. installing during the assembly of the sealed bearing housing as claimed in claim 1, an air permeable hydrophobic membrane that prevents corrosion of the corrodible metal ball bearings or corrodible metal rollers and/or the corrodible metal bearing races by keeping the corrodible steel ball bearings or corrodible metal rollers and the corrodible metal bearing races dry and free of water; and, b. lubricating during the assembly of the sealed bearing housing only the corrodible metal ball bearings or corrodible metal rollers and/or corrodible metal bearing races for reduction of friction.

13. A high voltage electric disconnect switch comprising: at least one rotating electric insulator, the rotating electric insulator including a rotating bearing assembly comprising a rotating bearing shaft and a sealed bearing housing having an interior that contains ball bearings or rollers and bearing races for operatively opening and closing the electric switch, the sealed bearing housing having an opening therethrough, an air permeable condensation preventing vent mounted in the opening in operative arrangement with the sealed bearing housing, the air permeable condensation preventing vent configured to allow ambient air to flow into and out of the sealed bearing housing only through the air permeable condensation preventing vent while preventing the flow of water into the sealed bearing housing, but allowing air to enter and exit the sealed bearing housing through the air permeable condensation preventing vent while preventing moist air from condensing to keep the interior of the sealed bearing housing dry and free of water, the air permeable condensation preventing vent includes an air permeable hydrophobic membrane configured to keep the interior of the sealed bearing housing dry and free of water, the ball bearings or rollers and/or bearing races are comprised of corrodible and/or non-corrodible material, the air permeable hydrophobic membrane is configured to prevent freezing of water within the interior of the sealed bearing housing to prevent impairment of operation of the ball bearings or rollers and/or bearing races and the opening and closing of the high voltage electric disconnect switch, the ball bearings or rollers and/or bearing races are comprised of corrodible metal, the corrodible metal ball bearings or corrodible metal rollers and/or corrodible metal bearing races are configured to be lubricant coated for friction reduction, and, the air permeable hydrophobic membrane is configured to prevent deterioration of the lubricant coating by inhibiting water infiltration.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details of the invention will become clear from the following drawings and descriptions of the illustrative embodiments represented schematically in the drawings, in which:

(2) FIG. 1 is a perspective view of a high voltage vertical break disconnect switch of the present invention showing the switch blade in the electrically closed operating position and dashed lines showing the switch blade in the electrically open operating position;

(3) FIG. 2 is a perspective view, partially broken away, taken along the line ‘2’-‘2’ of FIG. 1 with an enlarged “pull-out” view of the membrane vent mounting;

(4) FIG. 3 is an elevational view taken along the line ‘3’-‘3’ of FIG. 2;

(5) FIG. 4 is a cross-sectional view taken along the line ‘4’-‘4’ of FIG. 2;

(6) FIG. 5 is a greatly simplified schematic of an elevational view of a side break switch in the closed electrically conductive position;

(7) FIG. 6 is a greatly simplified schematic of an elevational view of a double break switch in the closed electrically conductive position; and,

(8) FIG. 7 is a greatly simplified schematic of an elevational view of a center break switch in the closed electrically conductive position.

DETAILED DESCRIPTION OF THE PARTICULAR EMBODIMENTS

(9) FIG. 1 shows a high voltage disconnect switch 10 which in this embodiment is depicted as a vertical break type switch. Of course, the present invention applies equally to other types of a high voltage disconnect switch, such as, a side break switch, double break switch or a center break switch, for example. These types of disconnect switches are referenced in IEEE Std. C37.30.1-2011 relating to IEEE Standard Requirements for AC High Voltage Air Switches Rated Above 1000 Volts. The vertical high voltage disconnect switch depicted in FIG. 1, includes a base 12 to which is attached two stationary insulators 14a and 14b and a rotatable insulator 14c. The base 12 is comprised of two parallel oppositely disposed flanged beams 15a, 15b with a U-shaped cross-section.

(10) A rotatable switch blade 18 is hinged to a hinge 19 at the proximal end 21 of the switch blade 18. A lever 16 is attached to the bottom 23 of the rotatable insulator 14c by which a force can be exerted either manually or by motor mechanism to rotate the insulator 14c and cause the high voltage disconnect switch to open the switch blade 18. Extending from the top 25 of the rotatable insulator 14c an operating crank 20 is attached to the switch blade 18 as shown in FIG. 1. When lever 16 is caused to rotate the operating crank 20 imparts a motion to the switch blade 18 to cause it to first rotate and then raise vertically as shown by the dashed line to cause blade tip contact 22 at the distal end 17 of the switch blade 18 to be released from contact with the jaw fingers 24. A stationary arc horn 26 is in sliding contact with a moving arc horn contact 28. As the switch 10 is opening the stationary arc horn 26 which had been in contact with moving arc horn 28 attached to the switch blade 18 is caused to slide out of contact with the stationary arc horn 26. Such an arrangement is well known in the art.

(11) FIG. 2 is a perspective view, partially cut away, taken along the line of ‘2’-‘2’ of FIG. 1 showing one end 30 of switch base 12 with a rotating bearing assembly 32 supporting the rotating insulator 14c. The bearing assembly 32 is operatively mounted between the first U-shaped flanged beam 15a and the second U-shaped flanged beam 15b at the one end 30 of the switch base 12.

(12) The bearing assembly 32 includes a sealed bearing housing 34 with a central cylindrical housing portion 36 affixed to a top plate 38 attached to an upper end 40 of the central cylindrical housing portion 36, as shown in FIGS. 2 and 3. Between the upper end 40 of the central cylindrical housing portion 36 and the top plate 38 is an upper housing gasket seal 67. The central cylindrical housing portion 36 is also affixed to a bottom plate 42 attached to a lower end 44 of the central cylindrical housing portion 36. Four plate connecting bolts 46 connect the top plate 38 to the bottom plate 42 by tightened plate connecting nuts 48.

(13) As can be seen in FIG. 2, the top plate 38 is sized larger than the bottom plate 42 so that it sufficiently spans an upper flange 50 of the first U-shaped flanged beam 15a and the upper flange 52 of the second U-shaped flanged beam 15b. The upper flanges 50, 52 are provided with holes, not shown in the drawings, that align with respective holes, not shown in the drawings, in the top plate 38 in the operative position. Top plate bolts 54 pass through the respective top plate holes and upper flange holes. The top plate bolts 54 are locked in position by top plate nuts 56. The bottom plate 42 is sized so that it fits between the first U-shaped flanged beam 15a and the second U-shaped flanged beam 15b as shown in FIG. 2.

(14) The top plate 38 has a top plate aperture 58 passing through it, as shown in FIG. 3. A lower shaft portion 59 of a rotating insulator support shaft 60 exits through the housing 34 through the top plate aperture 58. A flange bracket 62 is attached to the top plate 38 as shown in FIGS. 2 and 3. The flange bracket 62 surrounds the circumference of the rotating insulator support shaft 60 and retains double seals 63. The flange bracket 62 may be made of aluminum, for example. Double seals 63, as shown in FIG. 3, surround the lower shaft portion 59 to seal it with respect to an axial chamber 64 formed by the interior hollow space of the housing 34 which surrounds the lower shaft portion 59 of the rotating insulator support shaft 60. The double seals 63 may be made of a weather resistant material such as silicone, for example. In addition, another seal 65 also tightly surrounds the shaft 60 to seal it with respect to the top plate 38. As the shaft rotates, the seal 65 slides on the flange bracket 62, as shown in FIG. 2. The seal 65 may be made of a weather resistant material such as silicone, for example.

(15) The bottom 66 of the lower shaft portion 59 of the rotating insulator shaft 60 is supported by the bottom plate 42 by way of the lower bearing 72. The gasket seal 68 that is positioned on the bottom plate 42 to seal the lower end 44 of the housing 36. The upper and lower housing gasket seals 67 and 68 respectively, are preferably made of weather resistant material such as cork, for example.

(16) The sealed bearing housing 34 of the rotating bearing assembly 32 includes an upper corrodible steel bearing assembly 70 mounted in operative position at the upper end 40 of the central cylindrical housing portion 36 as shown in FIG. 3. The housing 34 also includes a lower corrodible steel bearing assembly 72 mounted in operative position at the lower end 44 of the central cylindrical housing portion 36. The upper corrodible steel bearing assembly 70 and the lower corrodible steel bearing assembly 72 are operatively arranged around the lower shaft portion 59 of the rotating insulator support shaft 60.

(17) The upper corrodible steel bearing assembly 70 and the lower corrodible steel ball assembly 72 both include a plurality of corrodible steel ball bearings 74 or, in the alternative, corrodible steel rollers, not shown in the drawings. Each of the upper corrodible steel bearing assembly 70 and the lower corrodible steel bearing assembly 72 include an inner corrodible steel bearing race 76 and an outer corrodible steel bearing race 78. The steel ball bearings 74 and the inner corrodible steel bearing races 76 and the outer steel bearing races 78 may be made of 52100 bearing steel, which is corrodible steel, for example.

(18) The rotating bearing assembly 32 of the present invention also includes an air permeable membrane assembly 80 as shown in FIGS. 2, 3 and 4. The air permeable membrane assembly 80 includes a membrane housing 82 that may be made of aluminum or stainless steel, for example. The central cylindrical housing portion 36 is provided with a membrane assembly mounting aperture 83. The membrane housing 82 is mounted in the membrane assembly aperture 83, as shown in as shown in FIGS. 2 and 3. The membrane housing 82 is provided with a membrane housing aperture 86 which vents the axial chamber 64 to the side of the membrane house 82 as shown in FIG. 4. At the entrance or front 87 of the membrane vent housing aperture 86, an air permeable hydrophobic membrane 84 covers the front 87 of the membrane vent housing aperture 86 and acts as a condensing preventing membrane. The air permeable hydrophobic membrane 84 is held in place by a flat washer 88 held in place by a membrane vent housing cap 90 engaging a wave disk spring 92 which cooperates with spiral retaining ring 94 which engages groove 96 in the membrane vent housing 82, as shown in FIG. 4. As can be seen in FIG. 4, the membrane vent housing cap 90 is provided with an opening 98 that permits the axial chamber 64 of the sealed bearing housing 34 to be vented by an ambient air channel 100 between the membrane vent housing cap 90 and the flat washer 88 via opening 98. O-ring 102, made of rubber, such as ethylene-propylene diene monomer, known as “EPDM”, a synthetic rubber, for example, seals the membrane assembly mounting aperture 83 when the air permeable membrane assembly 80 is installed in the central cylindrical housing portion 36. The vent housing cap 90 prevents freezing rain, snow and dirt from clogging the air permeable hydrophobic membrane 84.

(19) The air permeable hydrophobic membrane 84 may be a polymer air permeable hydrophobic membrane such as is marketed as a GORE vent. “GORE” is a U.S. registered trademark of W. L. Gore & Associates, Inc., 555 Paper Mill Road, Newark, Del. 19714. Such a type of membrane vent assembly or plug with a polymer air permeable hydrophobic membrane is also described in U.S. Pat. No. 8,734,573 B2, issued May 27, 2014, to Masashi Ono, et al. and assigned to W. L. Gore & Associates, Co., Ltd., Tokyo, Japan.

(20) The air permeable hydrophobic membrane 84 when installed in the bearing assembly 32 keeps the corrodible steel ball bearings 74 or steel rollers and the inner corrodible steel bearing races 76 and the outer corrodible steel bearing races 78 dry and free of water and therefore prevents any corrosion and contamination of these parts that would require repair or replacement of the high voltage switch 10. Also, as mentioned previously, the air permeable hydrophobic membrane 84 keeps the chamber 64 dry and free of water which protects bearing assemblies having corrodible components and/or non-corrodible components, in that the air permeable hydrophobic membrane 84 prevents freezing of water within the chamber, which may cause the components to fail, resulting in switch malfunction, and the membrane 84 also prevents deterioration of any lubricant coating of the bearings or rollers and associated races by inhibiting water infiltration.

(21) Also, as mentioned previously, the present invention also applies to other types of high voltage disconnect switch types including side break, double break and center break switches shown in FIGS. 5, 6 and 7. With these embodiments like numerals represent like elements of the device. With reference to FIG. 5, a greatly simplified schematic of an elevational view of a side break type high voltage disconnect switch of the present invention is shown. As can be seen from FIG. 5, the side break switch includes a rotating insulator 14c positioned on base 12. The rotating bearing assembly 32 of the present invention is in operative arrangement with the rotating insulator 14c. The rotating switch blade 18 is shown in a closed conductive position with jaw fingers 24, which are operatively attached to the stationary insulator 14a.

(22) With reference to FIG. 6 a greatly simplified schematic of an elevational view of a double break type high voltage disconnect switch of the present invention is shown. As can be seen from FIG. 6 the double break switch includes a rotating insulator 14c positioned on base 12. The rotating bearing assembly 32 of the present invention is in operative arrangement with the rotating insulator 14c. The rotating switch blade 18 is shown in a closed conductive position with jaw fingers 24 operatively attached to the two stationary insulators 14a which contact opposite ends of the switch blade 18.

(23) With reference to FIG. 7 a greatly simplified schematic of an elevational view of a center break type high voltage disconnect switch of the present invention is shown. As can be seen from FIG. 7 the center break switch includes two rotating insulators 14c positioned on base 12. Two rotating bearing assemblies 32 of the present invention are each in operative arrangement with a respective rotating insulator 14c. The switch includes two rotating switch blades 18 each respectively operatively arranged with one of the rotatable insulators 14c as shown in FIG. 7. Both of the rotating switch blades 18 are shown in a closed conductive position with jaw fingers 24. Both rotating switch blades 18 when opening the switch simultaneously rotate away from each other.

(24) A method of preventing condensation within such a high voltage switch bearing assembly 32 is also disclosed. The method comprises the steps of: (a) providing the high voltage switch 10 with the bearing assembly 32 with the membrane assembly 80 as previously described herein; (b) prior to installing the top plate 38 or the bottom plate 42 in the bearing assembly housing 34 lubricating the upper corrodible steel ball bearing assembly 70 and the lower corrodible steel ball bearing assembly 72 with only sufficient lubricant for lubricated rolling of the corrodible steel ball bearings 74 within the respective upper corrodible steel ball bearing assembly 70 and the lower corrodible steel ball bearing assembly 72, while permitting the free space volume of the axial chamber 64 to contain an atmosphere consisting essentially of air that has been prevented from condensing by the air permeable hydrophobic membrane 84. The lubricant for lubricating, for the purpose of lowering the friction, the respective upper corrodible steel ball bearing assembly 70 and the lower corrodible steel ball bearing assembly 72 may be a commercial grease, for example.