US2026356A - Electric switch mechanism - Google Patents

Description

Dec. 31, 1935. A. PALME ELECTRIC SWITCH MECI-IAIIISM Filed March 31, 1954 2 Sheets-Sheet l IEvencoT: Art ur a me.

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A. PALME.

ELECTRIC SWITCH MECHANISM Dec. 31, 1935.

Filed March 31, 1934 2 Sheets-Sheet 2 Op P r m e Q T a w m m m B w H 3 7 & m

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Patented Dec. 31, 1935 UNITED STATES ELECTRIC SWITCH MECHANISM Arthur Palme, Pittsfield, Mass, assignor to General Electric Company, a corporation of New York Application March 31, 1934, Serial No. 718,391

1 Claim.

My invention relates to electric switch mechanisms and is particularly applicable in connection with switches for changing transformer tap connections. It is often desirable to maintain con- 5 stant voltage on the secondary circuit of a transformer but changes in the load supplied by the transformer tend to cause this voltage to vary. Transformers are consequently commonly provided with winding taps and means for changing 10. tap connections to vary the voltage ratio and thus maintain the desired voltage in the secondary circuit 'under varying load conditions. It is further desirable in many cases that the tap connections be changed without interrupting the load current 15 supplied by the transformer. The general object of the invention is to provide an improved elec tric switch mechanism particularly adapted for thesepurposes.

The invention will be more fully explained in 20 the following description taken in connection with the accompanying drawings in which Fig. 1 is a side view, partly in section, of a switch mechanism constructed in accordance with the inven-- tion and applied in connection with. a trans- 25 former; Fig. 2 is a front view of the switch mechanism; and Figs. 3 and 4 are'explanatory circuit diagrams.

Like reference characters indicate similar parts in the different figures of the drawings.

30 The transformer l shown in Fig. 1 of the drawings is immersed in an insulating liquid N in a casing I2. A switch casing I3 is secured over an opening in the side of the transformer casing l I, the back of the switch casing forming 35 a partition H which is preferably liquid tight between the transformer and switch compartments provided by the two casings.

A switch l4 shown in Figs. 1 and 2 is immersed in an insulating liquid IS in the switch 40 casing |3. The switch l4 includes two fixed contacts l6 and I! on the ends of two conductive rods I8 and I9 respectively which extend through bushings 20 in the partition I4 into the transformer casing H where they are connected to 45 spaced winding taps of the transformer In. The switch l4 also includes two movable contacts 2| and 22 carried by contact arms 23 and 24 respectively. The contact arm 24 projects from a con-v as but insulated from it by an insulating bushing 30. An impedance 3|, wound on an insulating spool 32, is mounted on the sleeve 29 and connected between the movable contacts 2| and 22 through their contact arms 23 and 24 and sleeves 29 and 25. The impedance 3| may be inductive 5,

or not as desired. To avoid resistance between the contact arm 24 and the conductive rod 28, they are preferably connected by a flexible connection 32. Each of the fixed contacts l6 and H is shown as including two contact blades 33 which have contact surfaces projecting into the paths of the movable contacts 2| and 22 respectively. The sleeves 25 and 29 and the impedance 3| are rigidly connected together so that there can be no relative movement between them and consequent injury to the electrical connections between the impedance and sleeves. The electrical circuits of the arrangement which has been described are shown diagrammatically in Fig. 3 where the fixed contacts l6 and H are connected to taps at one end of the tappet transformer wind ing. If desired, the tappet winding may be formed in two sections as shown diagrammatically in Fig. 4, the fixed contacts [6 and I! being connected to taps in one section of the winding and the other section of the winding being connected between the movable contacts 2| and 22 and the outside terminal of the transformer.

Both of the movable contacts 2! and 22 are normally in contact with one or the other of the fixed contacts l6 and I1 depending on the desired voltage ratio of the transformer l0, both movable contacts being shown on the fixed contact IS in Fig. 1. The movable contacts are operated by two electromagnets 34 and 35 with 35 their plungers 36 and 31 connected by insulating rods or tubes 38 and 39 to spaced ears 40 and 4| projecting from opposite sides of the sleeve 25. The electromagnets 34 and 35 may be energized and controlled in any manner and from 40 a remote point if desired. If the electromagnet 35 is energized, it will pull the ear 4| up and rotate the sleeves 25 and 29 to move the movable contacts 2| and 22 from the fixed contact IE to the fixed contact II. If the other electromagnet 34 is energized, it will similarly pull the V ear 40 up to move the movable contacts 2| and 22 from the fixed contact l'l to the fixed contact IS.

The switch with its impedance 3| is arranged to be operated without interrupting the current flowing through its contacts. In the arrangement shown, the impedance 3| is connected between the two movable contacts 2| and 22. The two contact blades 33 of each fixed contact are arrangedside by side but the two movable contacts 2| and 22 are angularly displaced about their common axis. Thus, one of the movable contacts will leave a fixed contact ahead of the other movable contact and will then reach the other fixed contact first. The fixed contacts I6 and I! are so spaced that the angularly displaced movable contacts may bridge them for a brief instant while they are moving from one fixed contact to the other. Assume that the movable contacts 2| .and 22 are both on the fixed contact l6 as shown most clearly in Fig. 1 and they are to be moved to the fixed contact H. In this initial position of the contacts, practically all the current will flow through the movable contact 22 because the impedance 3| is in series with the other movable contact 2|. The movable contact 22 first leaves the fixed contact i6 breaking the circuit through this movable contact and all the current then flows through the movable contact 2| and the impedance 3| The movable contact then reaches the fixed contact I! and current flows through both movable contacts. The impedance 3| is now connected between the two winding taps of the transformer l0 and the voltage between the two taps causes a circulating current in the impedance which should be of such value as to limit this current to a safe value. fixed contact 16 and all the current flows through the other movable contact 22. The movable contact 2| finally reaches the fixed contact I I The movable contact 2| then leaves the but little current will flow through it because of the impedance 3| in series with it. The movable contacts 2| and 22 may be moved back to the fixed contact I6 in similar manner but the steps will of course be reversed.

The contact arms 23 and 24 with their movable contacts 2| and 22 and the impedance 3| are all rigidly connected together so that there is never any relative motion between these parts. Consequently, no flexibility is necessary in the connections between the impedance and the contacts and these connections may be short and direct and not liable to injury from the movements of the switch parts.

The invention has been explained by describl5 ing and illustrating a particular form of switch and one application thereof but it will be apparent that changes may be made without departing from the spirit of the invention and the scope of the appended claim. i What I claim as new and desire to secure by Letters Patent of the United States, is,

A switch including two fixed contacts, a rotatable contact support, two movable contacts rigidly secured to said support and angularly dis- 25 placed about its axis, an insulating spool surrounding said support, an impedance wound on said spool and electrically connected between said movable contacts, and means for rotating said support to move said movable contacts alternately from one fixed contact to the other.

ARTHUR PALME.

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