US1856125A

US1856125A - Heater for insulators

Info

Publication number: US1856125A
Application number: US414349A
Authority: US
Inventors: Arthur O Austin
Original assignee: Ohio Brass Co
Current assignee: Ohio Brass Co
Priority date: 1929-12-16
Filing date: 1929-12-16
Publication date: 1932-05-03
Anticipated expiration: 1949-05-03

Description

y 3, 1932- A. o. AUSTIN 1,856,125

HEATER- FOR INSULATORS Filed Dec. 16, 1929 2 Sheets-Sheet 1 IN VENTOR Ar/hur 0/11/5277;

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""f M r U A TTORNEY May 3, 1932. A. o. AUSTIN HEATER FOR iNSULATORS Filed Dec. 16, 1929 2 Sheets-Sheet INVENTOR Arfhur 0. flush/7. B Y

A TTORNEY 1 Patented May 3, 1932 UNITED STATES PATENT f OFFICE ARTHUR O. AUSTIN, OF NEAR BARIBEBTON, OHIO, ASSIG-NOR, BY MESNE ASSIGNMENTS, TO THE OHIO BRASS COMPANY, OF MANSFIELD, OHIO, A CORPORATION OF NEW JERSEY HEATER non msuLA'roas Application filed December 16, 1929. Serial No. 414,349.

This invention relates to heating means for insulators, and has for one of its objects the provision of a heating device which will prevent the accumulation ofmoisture or other conducting substance on the surface of thein the accompanying drawings and describedin the following specification, and it is more particularly pointed out in the appended claims.

- In the drawings:

Fig. 1 is a somewhat diagrammatic elevation with parts in section showing one embodiment of the present invention.

Fig. 2 is a view similar to Fig. 1 showing a -slightly different arrangement of the inven Fig. 3 is an elevation with parts in section showing another form of the invention.

Fig. 4 is an elevation showing stillanother modification.

In transmission lines operating at high voltage, considerable difliculty is caused by heavy leakage currents to ground or by in- 85 sulators arcing over where the insulators are subjected to fog or to chemical or dust deposits. Lines'operating along the sea coast or along lakes where salt or other chemical deposits become heavy, are likely to arc over,

particularly when the insulators are subjected to fog or rain. In the vicinity of railroads, cement plants, coke ovens or other locations where there are discharges into the air, conditions are likely to be very severe. Along railroad lines, insulators coated with a deposit are likely to be subjected to heavy discharges of steam from the locomotive which greatly increases the leakage, and sometimes causes an arc to ground interrupting the service. On many lines, the discharges on the insulator, frequently cause radio disturbances.

The above considerations apply not only to transmission insulators of either the suspension, strain or pin type, but'also to bushings, bus insulators and other insulating supports; both on the line and at stations. Due to the presence of spray ponds, very severe conditions frequently exist at the electrical station. In many cases, the outer ends of bushings projecting from station walls or roofs have to be increased in size in order to prevent arcing under the more severe conditions existing in fog or rains.

It is well recognized that if the surface of the insulator can be maintained in a dry condition the danger of arcing is greatly reduced or eliminated. 'Where the surface of the insulator can be maintained in a dry condition, heavy deposits do not cause trouble to the same extent as where they are damp or wet. Where the surface is maintained in a dry condition, the deposits apparently do not adhere so strongly to the surface, consequently, wind or wind and rain tend to keep the surfaces cleaner than where the surfaces are wet for a great portion of the time. This is probably due, in part at least, to the fact that the leakage current or charging current flowing over the surface of the insulator is greatly reduced where the surface is kept dry. This leakage or charging current flowing over the surface undoubtedly forms new compounds with the deposit in many cases, producing deposits which are highly conducting when damp or wet.

While it is recognized that maintaining the temperature of the insulator above the dew point will greatly improve the effective insulation of the insulator and reduce the dantype. a with ger of arcing to ground for a given electrical stress, it has been found diflicult and expensive to warm the insulator, particularly where the line voltage is hi h, without lowering its effective insulation Tor lightning or other severe conditions.

In the present invention, an arrangement is employed which makes it possible to provide an insulator of high length efficiency or arcing voltage for abnormal conditions so that hi 'h electrical integrity may be maintained for. these conditions, and, at the same time, permits of heating of the insulator to raise at least an appreciable portion above the condensation point.

In the scheme used, it is possible to apply the improvement to a part or all of the menlator as desired. In many cases, a part of the insulator only need be equipped with heating means. This reduces the cost and makes it ossible to use ordinary insulating elements or the remainder of the insulator. Keeping the insulator surface dry, even though it may be covered by a deposit, makes it possible to provide high effective flashover voltage for very severe conditions, such as lightning, where the surface deposits do not necessarily affect the performance of the insulator to the same degree as fog or damp surface under the normal operating voltage. This ap lies to suspension or dead end strings, bus ing insulators, tandem insulators or other types of insulation.

The difliculties of providing satisfactory means for raising the temperature of the working surfaces of insulators has heretofore prevented the use of such means for high voltage transmission lines. The present invention, however, makes it possible to provide insulators with heating means which may be readily constructed and applied to any transmission line, particularly those where it is desirable to maintain a high standard of insulation even under the most severe conditions. A part or all of the insulator string may be heated as desired. In general. a part of the insulator string only need be heated. When fo s occur Whichare most likely to cause flasliover. the transients or abnormal voltage disturbances usually have a comparatively small magnitude compared to those during electrical storms If, therefore. a portion of the insulator is given a high effective resistance for fog conditions or when rain first starts to fall, it is possible that a portion of the insulator string only need be provided withheating means.

Fig. 1 shows an insulator composed of two parts, the u per part having a heated shell 10, and the ower part composed of suspen- -sion insulator elements 11 of any suitable The insulating shell 10 is provided flanges 12 and a safety or supplemental core 13. The space between the shell and the core 13 is filled with an oil or insulating medium 14. The shell 10 is provided with an attachment 15 for attachin to the tower. A tubular member 16 is place inside of the shell or provided in the core 13. The lower end of this member is open at 17 and the upper end 18 is attached to a flexible tubular member 19. The cap 20 is provided with an outlet 21 which is attached to a flexible tube 22, communicating with an expansion chamber or reservoir 23. The chamber 23 is connected by pipe 24 to the lower end of a heated tubular member 25. The tubular member 25 is heated by a resistance element 26 which maybe" laced either inside or outside of the mem er 25. In operation, the

terminals

27 and 28 of the heating element 26 are connected to a suitable source of energy. This in general will consist of an auxiliary line 31, Fig. 2, running along the transmission line but operating at a relatively low voltage. This line may be energized from any suitable means such as an electrostatic coupling 32 with a step-down transformer 33 as shown in Fig. 2, or by any suitable step-down transformer. In operation, the insulating fluid 14 which may be oil or even air in some cases is heated. Where the column 25 is of suflicient length, the fluid in the column will be lighter than in the column 2 1 and cause the fluid to flow into the tube 16 and out the lower end at 17. Suitable 'venting means is provided between the circulating tubes so that where oil or a fluid of this type is used, air may escape into the expansion chamber through a small vent by a small tube Ortrap 29.- This prevents the system from becoming airbound.

It is evident that with this arrangement, the fluid is caused'to heat a large portion of the insulating shell. It of course is possible to reverse the circulation as shown in Fig. 2, allowing the heated fluid from the tube 30 to enter at the to of the insulator and removing the colder fluid from the interior of the insulator at the bottom until the whole is warmed sufliciently. It is also evident that with a system of this kind, electrical heating is not essential, but that the heating means may be provided by gas, oil, or any suitable means. Since the heating is applied from a separate circuit, it may be controlled by a remote control system by manual operation or by automatic appliances, if desired. The heating need be ap- Jlied only during conditions when flashover is likely, to take place unless the insulator is warm.

In radio tower installations or in some stations, it is possible to supply the heated fluid or air by a forced circulating system. For this a pump or blower 35 is placed in the system. TlllS may be driven by any suitable means and any number of insulators supplied from the heating fluid. In general, the tubes leading to and from the insulators should be of poor heating conductivity or insulated to prevent radiation. Where air is used for heating the insulators, it is usually not necessary to provide a return tube or conduit. In order to provide necessary movement in the insulator, the ducts or tubes connected to the insulator should be of flexible construction. Any suitable type of hose, either metal fabric or rubber, may be used, depending upon the condition 'If desired, ball and socket fittings or those of a corrugated or diaphragm type may be provided. Where the motion of the insulator is restricted'by the use of trunnions or hinge connection, the inlet and outlet members may be incorporated with these members. the insulators are rigid as in bus and switch construction, the matter of connection is very simple. The expansion chamber 23 provides a reservoir so that slight leakage will not interfere with the operation. of the insulator. Since the temperature of the circulating or heating fluid will be an aproximate indication of the condition of the insulator, the temperature of this fluid may be made to control an automatic thermostat for regulating the heating means.

It may sometimes be found desirable to provide a heating duct or conduit in the material of the insulator itself. Such an arrangement is shown in Fig. 3 in which a helical duct 36 is formed in the porcelain of the dielectric member 10 and communicates at one end w th a pipe or tube 37;"by which a heating medium may be supplied to the duct 36. After circulating through the duct 36, the heating medium may discharge through an opening 37 into the interior of the tubular member 10, and if the medium be air, it may be permitted to escape through a vent 38 at the top of the insulator. If the medium be liquid, it may be returned through a return tube communicating with the top of the insulator. It of course is not essential where air isused that it be returned through the center of the insulator but it may be permitted to escape at the lower end through a suitable vent. However, ifv it is returned through the center of the insulator, it will have additional opportunity for heating the shell. The

heating medium may besupplied by a suitable pump or blower situated at any convenient position, and the same source of supply fnay be used for any number of insulators distributed along the line.

In some cases it may not be desirable to have a mechanical connection of any kind with the insulator or to provide a special form of insulator through which the heat medium may be circulated. One means for I heating the insulators under such conditions is shown. in Fig. 4, in which a radiator 39 is provided with a suitable reflector to direct the heat against the insulator string 40. The radiator 39 may be supplied with an electrical Where heat element or any other suitable means for radiating heat, and the reflectoris so constructed and shaped as to concentrate the heat upon the dielectric members. The current for the radiator 39 maybe supplied from any suitable source, such as that described in connection with Fig. 2, or from a separate conductor or conductors for supplying current to the radiator. It is, of course, apparent that any number of radiators may be supplied from the same source and that the supply may be controlled from a station at a distance from the towers so that it will not be necessary to heat the insulators except when the'weather conditions require. This same thing is true. of course, in connect on with Fig. 3 in which the heat medium maybe shut off when it is not re-'.

with a portion of said insulator, and means for heating sa d medium.

2. The combination with an insulator, of

a circulating medium for heating said insulator, and means disposed at a distance from said insulator for heat ng said medium.

3. The combination'with an insulator having'a chamber therein. a conduit connected with said chamber, and means for supplying a heating medium through said conduit to said chamber.

4. The combination with an nsulator having a chamber therein. a conduit connected with said chamber, a circulating medium disposed in said chamber and conduit, and means connected with said conduit away from said insulator for heat ng said medium.

5. The combination with an insulator having a chamber therein, of a circulating medium disposed in said chamber, and means for heating a restricted portion of said medium to cause heat to be carried to sa d insulator by the circulation of said medium.

6. The combination with an insulator having a chamber therein, of a flexible conduit disposed outside of said insulator and connected with said chamber. and means for supplying a heated medium through said conduit to said chamber.

7. The combination with an insulator having a chamber therein, of a conduit having opposite ends thereof communicating with said chamber, and means for heating a circulating medium in said chamber and conduit and for causing said medium to circulate throu h said chamber.

8. The combination with an insulator having a chamber therein, of a conduit having one end thereof connected with said chamber. an electrical heating element associated with said conduit for heating a circulating medium in said conduit to cause said medium to carry heat to said insulator by the circulation of said medium, and means for energizing said heating element.

a 9. The combination with an insulator having a chamber for circulating a medium, of a pump for circulatii'ig a medium throu h said chamber, and means for heating said medium.

10. The combination with an insulator having a chamber therein, of a circulating fluid disposed iii said chamber, an expansion chamber or reservoir communicating with said chamber, and means for heating the fluid in said chamber and for producing circulation thereof.

11. The combination with a transmission line, of an insulator for supporting said line, said insulator having a chamber therein, a heating medium disposed in said chamber, and means ener ized by said transmission line for heating t 1e medium in said chamber.

12. The combination with a transmission line, of an insulator for supporting said line, said insulator having a chamber therein for receiving a heating medium, and a flexible conduit connected with the upper portion of said insulator for supplying a heating medium to said chamber.

13. The combination with a transmission line, of an insulator for supporting said line having a chamber therein for a heating medium, and a pair of flexible conduits connected with the upper portion of saidinsuiator for supplying a heating medium to said chamber and for circulating said medium.

14.-The combination with a transmission line, of an insulator for supporting said line having a chamber therein, a pair of flexible conduits connected with the upper portion of said insulator, a tube connected with one of said conduits within said chamber and extending to the bottom portion of said chamber, and means for heating the conduit connected with the tube in the chamber and for causing an inflow of a medium through said conduit and tube.

15. The combination with a transmission line, of an insulator for supporting said line having a chamber therein, a conduit having one end thereof connected with the upper portion of'said chamber and the other end connected with the lower portion of said chamber, a heating medium filling said chamber and conduit, and means energize from said transmission line for heating the medium in said conduit.

16. The combination with an insulator for supporting a conductor, of means for supplying heat to said insulator from adistant source to raise the temperature of the surl ace of said insulator above that of the surrounding atmosphere.

17. The combination with an insulator, of means spaced from said insulator for generating heat, and means for directing the heat so generated to said insulator to raise the temperature of the surface of said in- SIiIIatOI' above that of the surrounding atmosp ere.

18. The combination with an insulator having a circulation duct therein, of means for circulatin a heating medium through said duct to raise the temperature of the surface of said insulator above that of the surrounding atmosphere.

In testimony whereof I have signed my name to this specification this-11th day of December, A. D. 1929.

ARTHUR O. AUSTIN.