US2144414A

US2144414A - Oil switch

Info

Publication number: US2144414A
Application number: US81613A
Authority: US
Inventors: Milliken Humphreys
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-05-25
Filing date: 1936-05-25
Publication date: 1939-01-17
Anticipated expiration: 1956-01-17

Description

Jan. 17, 1939. H; MILLIKEN 2,144,414

OIL SWITCH Filed May 25, 1936 3 Sheets-Sheet 2 35 FIG. 3

INVENTOR I HUMPHREYS MILLI KEN ATTO RN'E Y H. MILLIKEN Jan. '17, 1939.

OIL SWITCH Filed May 25, 1936 3 Sheets-Sheet 5 PEI-GL3 INVENTOR HUMPHREYS MH-LIKEN @.@%mu

ATTORNEY Patented Jan. 17, 1939 UNITED STATES PATENT OFFICE omswrrcn v nmphmmmmm. mzs m uunasuu' sou-t (ciao-10$ This invention relates to improvements in oil switches of the class used in underground vaults for opening and closing power circuits.

The vaults in which pndergrolmd oil switches 5 are used are always-damp and are sometimes flooded with water. It is therefore highly important that the insulation be eilectivelyprotected from the eilects of moisture. In switches heretofore used for such service the l brought into the switch through insulating bushings in the space above the oil. Due to unavoidable breathing caused by'changes in temperature, moisture is drawn in by-the air and deposited on the surfaces of the insulation. This lowers the dielectric strengthand is responsible for a large number of the switch failures experienced in practice. The present invention p'roposes to overcome this difllculty by the provision of a switch in which all insulating surfaces are submerged in oil to maintain their dielectric strength.

Underground oil switches are usually patterned after conventional types of oil circuit breakers in which the contacting bars are moved up and down 5 by toggles, levers, cranks, etc. connected toan operating shaft rotating about a horizontal axis. According to the present invention the assembly and operation of the moving parts of the switch are simplified by mounting the contacting bars 99 on a common insulating shaft rotatable through an angle of 90 to open or close the switch. A further advantage of the present invention is that all moving parts are assembled to permit removal thereof as a unit without removing the i 35 oil and without breaking the circuit connected to the switch. The improved assembly also makes it possible to disconnect the cables without making them dead and to then remove the moving parts as a unit Iorinspection, repair or replace- 40 ment.

I It is well known that failure of underground switches, while being opened or closedQhas frequently resulted in serious injury to operators "Standing in the vault, This has led to the practice oi opening or closing the switch by means of u' by reason of the fact that the contactbars are carried by a vertical rotary shaft having a pulley at its imer end from which the rope may lead 01! in any direction to the entrance without the necessity oi? providing snatch blocks or other at-' tachments heretofore employed. Another advan- 5 tage of the switch provided in accordance with this invention is that it occupies considerably less space than the conventional switch of the same voltage and current rating. This is an important advantage because of the limited space available 10 for the installation of switches of this type.

Fig. 1 is a sectional view of my improved switch, showing certain parts in vertical section and others in side elevation.

Fig. 2 is a transverse sectional. view taken substantially along the line 2-2 01 Fig. 1.

Fig. 3 is a top plan view, partly in section, of the switch appearing in Figs. 1 and 2.

In these drawings the switch is shown in closed position completing a three phase circuit 'represented by three pairs of single-conductor leadcovered insulated cables 2. The cables of each pair are passed into the switch through suitable openings formed in opposite sides of a cylindrical container I which is preferably made of cast iron and is filled with oil to the level indicated at-X. The inner ends of the cables are soldered to suitable terminals 3 which make high pressure sliding contact with stationary contacts 4 which. in turn, make sliding contact with the mov able switch contacts 5, the latter being pressed against the contacts I by the springs S. As here shown the movable contacts 5 of each pair are connected by flexible conductors l and are slid-' ably mounted on the protruding ends of a steel rod I which is fixed to a vertical insulating shalt -'1he springs i are housedwithin the pin receiving bores of the contacts .5 and in the closed position of the switch, are subjected to considerable comprwion between the outer ends of the 4 bores and the opposing ends of the pins. To open the switch the shaft 9 is'rotated 90" from the position shown in Pig. 1 so as to carry the movable contacts 8 of engagement with the stationary contacts I. r

'l he three poles or phases of the switch are completely separated by the horizontal and vertlcal insulating barriers indicated at it and H. Thehorizontal barriers I I are apertured for the passage or the shaft 8 and are maintained in vertiealiy spaced relation by insulating sleeves l2. Shaft 5 his closely in sleeves l2 and barriers id but is free to turn relative thereto. when the switch is opened the gas bubbles generated by the arcsdrawn between the stationary and movable I6 contacts of the several poles pass out through small holes and crevices in the vertical barriers of the cap I! and pin I8. The cover I3 is provided with a packing gland I9 to make a watertight bearing for the shaft IS. A cast iron pulley is keyed to the upper portion of shaft I6 as 3 indicated at Ma, the hub of the pulley being limited to 90 by the provision of a quadrant 2I formed integral with the cover I3 and a coacting stop 22 formed integral with the pulley. The

, quadrant 2| is provided with sockets 23 and 23a in which a bolt 24 is adapted to be selectively engaged to hold the switch in either the open or closed position. Bolt 24 is slidably mounted in suitable bearing openings'formed in the pulley 20 and is urged toward the quadrant 2| by a compression spring 25. Retraction of the bolt 24 against the resistance of the spring 25 is efiected through the agency of a. U-shaped lever 21. The fiat bight portion 21a of this lever is fitted in a recess 20b of the pulley 2D and is held against the bottom wall of the recess by means of a nut 24a at the outer end of bolt 24. In order to open the switch a rope 26 is fastened to the lever ann 21b by means of the hook 26a and a pull then exerted on the rope to swing the lever in a clockwise direction about the shoulder 28 which serves as a fulcrum. This movement of the lever causes it to act against the nut 24a in a direction to withdraw the bolt 24 from the socket 23. When the inner end of the bolt is drawn clear of the socket 23 the spring 25 .is fully compressed so that continued pull on the rope serves to rotate the pulley 20 and the shaft 9 to a switch opening position. When it is desired to close the switch this isdiccomplished by attaching the rope 26 and the hook 26a to the lever arms 21c, as indicated by dotted lines in Fig. 3.

As shown in Fig. 2, the lead sheath 2!! is cut away from the inner portion of each cable 2 and replaced by insulating tape 30 wrapped around the factory insulation to build up this portion of the cable so that it fits tightly within the outer portion of an insulating sleeve 3|.- screwed onto the cable terminal 3 as indicated at 3Ia. The outer portion of the sleeve 3| is' a press-fit, in a metal wiping sleeve 32 which is detachably fastened to the cylinder I by means of bolts 35, the joint thus formed being made tight by gasket 35a. A wiped joint 33 is made at the outer end of sleeve 32 after the latter has been assembled with the cable by threading the sleeve 3| onto the terminal 3.

' Each stationary contact 4 is threaded into the inner end of the insulating bushing :4 which is a press-fit in one of the cable receiving openings 34a. The inner end'of each sleeve 3| projects inwardly beyond the terminal 3 and is received in a groove 34' formed in the stationary contact 4. This projection of the sleeve 3| beyond the terminal 3 prevents accidental contact when the cable is withdrawn (after opening of the switch) in order to withdraw the movable Sleeve 3| is parts of the switch for repair, cleaning or replacement.

When the shaft 9 is turned to a switch opening position andthe cover bolts l3a are removed,

the cover I3, together with the shaft 9 and all movable parts carried by the shaft, may be lifted up and removed fromthe cylinder I. It will thus be seen that the withdrawal of the removable parts for inspection, cleaning or other purposes may be conveniently accomplished without disturbing the remainder of the switch and without disconnecting the cables or making them dead. It is also pointed out that such withdrawal of themovable parts is accomplished without the necessity of first removing the oil. In theclosed position of the switch the contacts 5 project into openings I I a, in the vertical barriers I I and thus prevent removal of the shaft 9 and its associated parts. When shaft 9 is turned from the position shown in Fig. 2 the contacts 5 are carried clear of the openings .I la. so that the shaft may then be lifted out of the container as previously described. 7

It will be noted that the axis of the path of current through each pole of the switch is a straight line and that the electromagnetic forces of the current path has no tendency to open or close the switch.- Another important feature is that the contact assembly is such that a large variation in the alignment of the stationary and movable contacts in the closed position of the switch produces a relatively small variation in the amount of pressure on the contact surfaces.

Having thus described my invention, what I claim is:-

1. An oil switch comprising an oil container, a removable cover closing the upper end of said container, a vertical shaft rotatably mounted in said container and secured to said cover so as to be removable therewith, vertically spaced horizontal barriers mounted'on said shaft, movable contactsfixed to said shaft between each pair of horizontal barriers, vertical barriers arranged in said container in contact with all sides of said-horizontal barriers, stationary contacts mounted in openings formed in said vertical barriers at points intermediate said horizontal barriers, the. movable contacts carried by the shaft being adapted to extend into said openings to 2.'An oil switch comprising an oil container having stationary contacts arranged therein, a

vertical shaft rotatably mounted in. said container and carrying movable contacts adapted to cooperate with'said stationary contacts, a cover closing the upper .end of said container, a pulley positioned above the cover and secured to the upper end of said shaft, a quadrant secured to the cover within said pulley, a spring pressed bolt carried by the pulley and adapted to be sclectively engaged in sockets formed in the quadrant in order to hold the pulley in either an opencircuit or closed-circuit position and means for withdrawing said bolt from said sockets, said means also cooperating with said bolt to effect turning movement of the pulley in either a switch opening or switch closing direction.

3. An oil'switch comprising an oil container, 9. vertical shaft rotatably mounted therein, a plurality of vertically spaced poles in said container each including movable pole contacts secured to said .shaft and stationary contacts mounted adiacent the shaft to cooperate with said movable contacts, horizontal barriers mounted on the shaft above and below the contacts of each pole and vertical barriers arranged in said container in contact with said horizontal barriers to isolate arc gases of adjacent poles, said vertical barriers being spaced from the surrounding wall of the container to provide intervening oil passages, said vertical barriers also affording gas passages placing said 011 passages in communication with the spaces reserved between the horizontal barriers.

4. An oil switch as set forth in claim 3 in which the stationary contacts are fitted in openings in the vertical barriers and are carried by the inner ends of suitable insulating bushings having their outer ends secured in openings formed in the container wall in line with the aforesaid openings in the vertical barriers and cable terminals removably inserted in the outer portions of said bushings in sliding engagement with the bushing contacts.

5. An oil switch as setforth in claim 3 in which the stationary contacts are fitted in openings in'the vertical barriers and are carried by the inner ends of suitable insulating bushings having their outer ends secured in openings formed in the container wall in line with the aforesaid openings in the vertical barriers and cable terminals removably inserted in the outer portions of said bushings in sliding engagement with the bushing contacts,- said cable terminals being protected by insulating sleeves projecting beyond opposite ends thereof and said bushing contacts being provided with grooves in which end portions of the sleeves are received to permit engagement of the terminals with said contacts when the terminals are inserted in the bushinss.

6. An oil switch comprising an oil.container having stationary contacts arranged therein, a vertical shaft rotatably mounted in said container and carrying movable contacts adapted to cooperate with said stationary contacts, a cover closing the upper end of said container, a pulley positioned above the cover and secured to the upper end of said shaft, a quadrant secured to the cover within said pulley, a spring pressed bolt carried by the pulley and adapted to be selectively. engaged in sockets formed in the quadrant in order to hold the pulley in either an open circuit or closed circuit position and means for HUMPHREYS MILLIKEN.