US2513952A - Electric switch contact mounting detail - Google Patents

Description

July 4, 1950 s. MINNECI ELECTRIC SWITCH CONTACT MOUNTING DETAIL Filed May 1, 1946 0 e :n. rm 0 M 6 0 t. a a 5 His Attbrney.

Patented July 4, 1950 ELECTRIC SWITCH CONTACT MOUNTING I DETAIL Salvatore Minneci, Pittsfield, Mass., assignor to General Electric Company, a corporation of New York Application May 1, 1946, Serial No. 666,293

2 Claims.

This invention relates to electric switches and more particularly to improvements in high voltage switches for changing transformer connections. Certain features of the complete rotary type switch shown in Fig. 1 form the subject matter of my divisional application, Serial No. 780,026, filed October 15, 1947.

It is often desirable to be able easily to change the connections between the windings of a transformer. For example, one of the windings of a polyphase transformer may have a plurality of coils per phase and by connecting these coils either in series or in parallel the voltage and current rating of the transformer may be materially varied. Also, it is frequently desirable to be able to reverse the phase of one of the windings of a polyphase transformer; that is to say, to reverse the direction of the individual phase windings. Switches for accomplishing these purposes are known but they usually include a number of metal parts in addition to the actual contact elements themselves, and as the voltage rating of the circuits to which they are connected increases, the size of the switches also increases in order to obtain sufliciently great creepage paths and arcover distances and the presence of extra metal in the switches requires that they be extra large. However, in large high voltage transformers it is often desirable to mount the switches in the transformer tank and under the surface of its cooling and insulating liquid. It is therefore highly desirable that such switches be as small as possible so as to reduce the volume of liquid which they displace to as low a value as possible and so as to prevent increasing the size of the transformer tank any more than is absolutely necessary.

In accordance with this invention there is provided a novel and simple switch construction in which all of the parts except the actual current carrying parts are made of insulation and the invention'is characterized by a novel construction of the insulating parts so as to give them the necessary mechanical strength.

An object of the invention is to provide a new and improved electric switch.

' Another object of the invention is to provide a compact polyphase electric switch construction which employs the maximum amount of insulating material and the minimum amount of metallic conducting material. I

The invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the drawing Fig. 1 is a perspective view of an embodiment of the invention, Fig. 2 is a detailed exploded view of a part of one of the stationary contact carrying assemblies of the switch shown in Fig. 1, Fig. 3 is a detailed exploded view of a part of the movable contact carrying assembly shown in Fig. 1, Fig. 4 is a circuit diagram illustrating the connections of the switch shown in Fig. 1 for making series-parallel connections between windings, and Fig. 5 is a connection diagram of a modified switch construction for obtaining phase reversal.

Referring now to the drawing and more particularly to Fig. 1. the switch is illustrated as comprising a pair of end plates or supports l and 2 between which extend four stationary contact carrying assemblies 3, 4, 5 and B and one movable contact carrying assembly 1. These parts are made entirely of insulating material which may be fabric which has been impregnated with a thermosetting synthetic resin so as to form a very hard and mechanically strong material. The switch shown in Fig. 1 is a three-phase switch in which the contacts for each phase are in the same plane and the contacts for the different phases are placed in different planes, the planes being all perpendicular to the axis of the movable contact carrying assembly. Thus, each stationary contact carrying assembly is shown as having three stationary contacts which are equally spaced from each other. These contacts are identified as 8, 9 and ill in connection-with the stationarycontact carrying assembly 3 audit will be understood that the other stationary contact carrying assemblies have corresponding contacts. Likewise, the movable contact carrying assembly has three movable contacts indicated as arcuate metal strips II, II and I3 which are attached to segmental insulating members l4, l5 and I6 respectively.

As shown most clearly in Fig. 2, each stationary contact carrying assembly comprises a main insulating tube H which has a separate hole l8 drilled through it for each of its stationary contacts. Each stationary contact is carried by a tube of similar insulating material which is inserted through the hole ill in the main tube H. The tube I9 is provided with notches 20 in opposite sides and these are engaged by a pair of, notches 2| in a sleeve member 22 of insulating material which is slid over the tube l1 and may be held in place by means of suitable insulating varnish and tape. The stationary contact in each case is attached to a conductor which passes through the tube l9 and, as shown in Fig. 1, each stationary contact 8, 9 and I0 is a double or split contact which grips the top and bottom surfaces of its cooperating arcuate movable contact l3, I2 and II, respectively.

The details of the movable contact carrying assembly I are shown in Fig. 3. This consists of a number of tubular members 23, the ends of which are provided with projections 24 and indentations 25, the ends of the pieces 23 being similar in shape. The segmental movable contact carrying members are all the same and in Fig. 3 a portion of the member I5 is illustrated. This is provided with an opening having a number of keyway-like grooves or slots 26 into which the projections 24 are fitted, the two members 23 being turned 180 degrees relative to each other when their projections are fitted into opposite slots 26 in the opening in the member l5. The projections 24 of each member 23 extend out beyond the opposite side of the member l5 and into the indentations 25 on the other member 23. In this way all three parts shown in Fig. 3 are securely locked together as the sliding fit between the various parts can be made as tight as necessary.

The bottom of the shaft on which the movable contact carrying assembly rotates is preferably seated in a, sleeve bearing member 21 which is preferably made of the same insulating material.

In Fig. 4 the switch is shown diagrammatically with its contacts in the same relative positions that the are shown in Fig. 1 and these contacts are connected to windings 28 and 28, 30, 3!, 32 and 33 and to the conductors 34, 35 and 36 of a three-phase circuit. Each pair of axially aligned coils or windings belong to a diiferent phase of the three-phase system and in the position of the switch shown in Fig. 4 these pairs of coils are connected in parallel, coils 30 and 3i being connected in parallel between line conductors 34 and 35, coils 32 and 33 being connected in parallel between line conductors 35 and 36, and coils 28 and 29 being connected between line conductors 36 and '34 so that the three-phase connection is delta connection. When the movable contact carrying assembly is rotated to its opposite position in which each movable contact bridges only another stationary-contact carrying assembly,

corresponding in all respects to those which are shown, in the space between the assemblies 3 and 4. In this figure the switch serves to interconnect a three-phase circuit comprising conductors 31, 38 and 33 and three windings 40, 4i and 42 in such a way that winding 42 is connected between conductors 31 and 38, winding 4i is connected between conductors 38 and 39 and winding 40 is connected between conductors 31 and 36. The connection is therefore a delta connection of these windings with respect to the three-phase circuit. When the switch is moved to its other extreme position in which each arcuate movable contact bridges its three uppermost cooperating contacts, as viewed in Fig. 5, instead of its three lowermost, as shown, then the terminal connections of the three windings are reversed while they are still connected between the same pairs of line conductors.

While there have been shown and described particular embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the invention and, therefore, it is aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A fixed contact assembly for a switch comprising, in combination, a. support of insulating .material, a transverse hole in said support, a tube in said transverse hole, notches in said second tube parallel with the axis of said first tube and adjacent the outer periphery thereof, a third tube fitted over said first tube, the end of the third tube having a notch whose sides fit into the side notches of the second tube so as to lock said second tube in position.

SALVATORE MINNECI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Leighton Jan. 18, 1938

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