US3265840A - Vacuum type circuit interrupter device - Google Patents

Description

Aug. 9, 1966 VACUUM TYPE CIRCUIT INTERRUPTER DEVICE E. L. LUEHRING Filed Dec. 12, 1963 FIGZ INVENTOR ELMER LUEHRING ATTORNEY United States Patent "ice 3,265,840 VACUUM TYPE CIRCUIT [NTERRUPTER DEVICE Elmer L. Luehring, Cleveland Heights, Ohio, assignor t0 Joslyn Mfg. and Supply Co., Chicago, 111., a corporation of Illinois Filed Dec. 12, 1963, Ser. No. 330,125 5 Claims. (Cl. 200-124) This invention relates to circuit interrupters and has particular significance in connection with contact operating structure in a vacuum, or other enclosed against ambient, switch.

In high voltage power line switching and disconnect apparatus, interrupter contacts which, for opening sequence (see, for example H 12, US. Pat. 2,955,181, Luehring, assigned to the assignee of the present invention) break a circuit in a vacuum, or in an inert gas such as SP have become well known and widely accepted. The enclosed against ambient interrupter is expensive and a large economic loss results when surrounding parts, oil, etc., are affected by catastrophic failure if the enclosed contacts attempt to, but are in fact unable to, open a r circuit, e.g., because abnormal high current or other conditions prevail.

It is an object of the present invention to provide simple means for overcoming the above mentioned difficulty.

Other objects and advantages will become apparent and the present invention may be better understood from consideration of the following description taken inconnection with the accompanying drawing, in which:

FIG. 1 is a sectional view of a vacuum switch incorporating stationary and movable contact structure according to the invention; and

FIG. 2 is an enlarged view showing a modification for the movable contact support structure.

Referring first to FIG. 1, an evacuated envelope 10 of an insulating material such as glass is provided with suitable conventional seals to render the envelope vacuum tight. As illustrated, the envelope encloses an upper fixed contact 11 and a lower movable contact 12. Contact 11 is connected by a rod 13 to a terminal 15 which is also fixedly stationary.

The movable contact 12 has a depending portion 16 (e.g., of copper) which is initially loosely mounted in a tubing 18 of conductive material such as copper. Tubing 18 is electrically associated with a terminal conductor 20 and mechanically associated, as through a pin 22 and an end fitting 24, with an insulating material control rod 26 which, due to operation of conventional apparatus (not shown), normally pushes upon the movable contact to close and pulls upon it to open the contacts. A conventional flexible metallic bellows 28 seals parts associated with envelope with respect to parts associated with movable contact, and a compression spring 30 biases movable contact portion 16 upwardly for a purpose later to be explained.

The contact 12 and the contact portion 16 are bonded together in a high temperature resisting joint, or are integrally fashioned as one piece, while the contact portion 16 and the portion of the rod 18 thereabout are normally held together by a braze or relatively low temperature joint, e.g., with -a eutectic alloy solder 32 or by a silver solder, in any even having a melting point lower than that of the contact 12, the portion 16 and the tube 18.

In the modification shown in FIG. 2 the contact 12 depending portion is divided into a top (soldered) piece 16a which may be of copper and a bottom thermal insulator piece 16b which may conveniently be of alumina (A1 0 16a and 16b are held in mutual engagement by the spring 30 and in FIG. 2 a pin 34 is shown serving as a restrainer for the opposite end of the spring.

Patented August 9, 1966 In designing apparatus according to the invention the solder length dimension L (see FIG. 2) is preferably made greater than the full open position contact space S (see FIG. 1).

During operation, if (1) the contacts, upon opening, fail to interrupt a current flowing through them, (2) the heat from arcing causes the solder 32 to melt whereupon (3) the spring 30 serves to reclose the contacts. With the are thus eliminated the heating of the parts is reduced and (4) the solder will resolidify, it being understood, of course, that for purposes of clarity some of the dimensions in FIGS. 1 and 2 (not to scale) are exaggerated and normally the solder layer will be thin enough so that the liquid solder of step 3, though it serves as a lubricant, will be held in place by capillary action.

Steps 1, 2, 3 and 4 all occurred during the contact opening sequence (of rod 26 operation), but after step 4 (contacts closed) the switch will resist any subsequent efforts of closure and thereby warn a human operator of a failure which is, however, relatively inexpensive to cure.

Normally the switch failure (failure to interrupt) will be due to loss of vacuum or ambient gas, oil or whatever. To protect against a switch failure due to any other cause the .solder 32 can be placed off-center (that is thicker at one side of tube 18 than at another) so that with loss of vacuum or insulating fluid, and consequent melting of solder, only the solder at the thicker solder side will be displaced by any pressure differential, while at the sides where the solder layer is thinner some molten solder will remain in place, by capillary action, so that the latter can resolidify (with cooling) and hold in closed position the switch which has failed.

There is thus provided arrangements of the class described capable of meeting the objects above referred to and of protecting a vacuum, or gas ambient, or even an air switch of proper design, against catastrophic failure, contact burn out, explosions, and the like, by causing the contacts to close automatically (and stay closed) if overheated because unable to interrupt a circuit current.

While I have illustrated and described particular embodiments, various modifications may obviously be made without departing from the true spirit and scope of the invention which I intend to have defined only by the accompanying claims taken with all reasonable equivalents.

Iclaim: 1. A vacuum type enclosed electric circuit interrupter having:

a housing, first and second terminals, I a stationary contact electrically connected to said first terminal and mounted within, and stationary with respect to, said housing, a movable contact mounted within said housing and electrically connected to said second terminal, means including a control rod portion and operating temperature responsive solder connecting said control rod portion to said movable contact for normally alternately moving said movable contact into engagement with and away from said stationary contact, and means including a spring having one end connected to said control rod portion and an opposite end connected with said movable contact for biasing said movable contact away from said control rod portion thus biasing the contacts together during an abnormal condition such that said temperature responsive solder is ineffective to operate said movable contact. 2. In an enclosed high voltage interrupter switch, the combination comprising:

a housing having a pair of terminals,

a stationary contact supported by and within said housing and connected in circuit with one of said terminals,

a contact normally movable within said housing and adapted to cooperate with said stationary contact and connected in circuit with the other of said terminals,

a conductive material extension of said movable contact,

a control rod means normally connected to said conductive material extension and for normally operating the movable contact to open and closed positions, with respect to the stationary contact, where the open position represents a contact spacing of S, said control rod means having a portion connected by relatively low melting point solder to said conductive material extension over a length L when said solder is in its first in situ solid state, and

a spring means having one end connected to said control rod means and its other end connected to operate said conductive material extension of said movable contact and for biasing said conductive material extension away from said control rod means, whereby said movable contact is held in engagement extension and for preventing heat drain from said extension to said spring means.

5. A high voltage electric circuit interrupter having first and second normally engageabl'e and disengageable contacts,

first retaining means connected to retain said first contact,

second retaining means connected to normally retain said second contact,

said second retaining means comprising an operating temperature responsive solder joint,

a spring having one end connected to said second contact and its other end connected to a portion of said second retaining means whereby said spring, during operation, whenever, and after, the solder has melted biases said contacts substantially permanently together, and

control rod means connected through one of said re-' taining means to the associate one of said contacts and for, before the solder has melted, normally selectively disengaging and engaging said contacts. 9

References Cited by the Examiner UNITED STATES PATENTS by the length L being greater than the spacing S.

' by, a member of thermal insulating material interposed with said stationary contact, at any time when, and 2,472,625 6/1949 Smith 200-144 after, the solder subsequently reaches a liquid state, 2,934,628 4/ 1950 Massar et a1 200-418 despite sequence of control rod operation, 3,179,770 4/1965 Demaret 200-1 18 3. The combination of claim 2 further characterized 3,18 5/ 1965 Lee et 4. The combination of claim 2 further characterized BERNARD GILHEANY, Examiner- H. B. GILSON, Assistant Examiner. between said spring means and said conductive material

Claims (1)

1. 5. A HIGH VOLTAGE ELECTRIC CIRCUIT INTERRUPTER HAVING FIRST AND SECOND NORMALLY ENGAGEABLE AND DISENGAGEABLE CONTACTS, FIRST RETAINING MEANS CONNECTED TO RETAIN SAID FIRST CONTACT, SECOND RETAINING MEANS CONNECTED TO NORMALLY RETAIN SAID SECOND CONTACT, SAID SECOND RETAINING MEANS COMPRISING AN OPERATING TEMPERATURE RESPONSIVE SOLDER JOINT, A SPRING HAVING ONE END CONNECTED TO SAID SECOND CONTACT AND ITS OTHER END CONNECTED TO A PORTION OF SAID SECOND RETAINING MEANS WHEREBY SAID SPRING, DURING OPERATION, WHENEVER, AND AFTER, THE SOLDER HAS MELTED BIASES SAID CONTACTS SUBSTANTIALLY PERMANENTLY TOGETHER, AND CONTROL ROD MEANS CONNECTED THROUGH ONE OF SAID RETAINING MEANS TO THE ASSOCIATE ONE OF SAID CONTACTS AND FOR, BEFORE THE SOLDER HAS MELTED, NORMALLY SELECTIVELY DISENGAGING AND ENGAGING SAID CONTACTS.

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