US2473992A

US2473992A - Electric switch

Info

Publication number: US2473992A
Application number: US695184A
Authority: US
Inventors: Fowler John
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1945-08-01
Filing date: 1946-09-06
Publication date: 1949-06-21
Anticipated expiration: 1966-06-21

Description

June 21, 1949. J. FOWLER 2,473,992

ELECTRIC SWITCH Filed Sept. 6, 1946 ANGULAR MOVEMENT Inventor: John Fowler; by His Attorney.

proached, the switch having the contact arm 4 will close.

During the return movement of the oscillatory member H, the operating cycle of the switch is reversed, the switch having the arm 4 opening first, then the switch having the contact arm closing next followed by the opening of the switch having the arm 5 and finally the closing of the switch having the arm I so that the mechanism is restored to the position shown in the drawing.

Fig. 2 illustrates how the electrical connections of the switching mechanism shown in Fig. 1 may be made. Conductor 3 may be one of the line conductors of a transformer winding 29 which has a plurality of taps 3| 3|, 32, 33, 34, 35, 36, 31 and 38. A tap changing switch 39 is arranged to make selective engagement with the odd numbered taps and a tap changing switch 40 is arranged to make selective engagement with the even numbered taps. For cooperating with the arcing duty switching mechanism for the purpose of preventing a momentary short circuit of portions of the winding 29 between adjacent taps thereof during operation of the switching mechanism, a pair of impedance elements 4| and 42 are connected respectively to the

tap changers

39 and 40. These impedance elements may be either reactors or resistors. In Fig. 2, the four single pole, single throw switches have been designated merely by the reference numerals of their respective movable operating arms in Fig. 1. It will be seen that the arms are directly connected to the conductor 3, as in Fig. 1. The impedance element 4| is permanently connected between the fixed contacts of the switches which have operating

arms

4 and 5 and the impedance element 42 is permanently connected between the fixed contacts of the switches which have operating arms 6 and l. The positions of the switches correspond to those of Fig. 1 in which the switches having arms 6 and l are closed and the other two are open so that all load current of the winding 29 passes through the switch 1 and the impedance 42 is short circuited. In this position on the circuit, tap changer 39 carries no current and consequently it can be moved to tap 33 without in any way affecting the current in the circuit. If now it is desired to transfer the circuit current to tap changer 39 from tap changer 40, the switch mechanism is operated in the manner described above. Thus, the opening of the switch 1 causes the load current to flow through the impedance 42, the closing of the switch 5 connects impedances 4| and 42 in series between adjacent taps in the main winding, the opening of the switch 6 diverts all of the circuit current through the tap changer 39, the impedance 4| and the switch 5. The closing of the switch 4 short circuits the impedance 4| and permits all of the current to fiow through the switch 4.

In practice, the

tap changers

39 and 40 will be mechanically driven from the rotatable member 28 in any suitable manner (not shown).

The switching mechanism shown in Fig. 1 has the advantage over drum type switches, which have been used in circuits similar to Fig. 2, that it is much easier to replace the arcing contacts which ordinarily require more frequent servicing and replacement than do other parts of the system such as, for example, the contacts of the non-arcing

duty tap changers

39 and 40. The crank and connecting rod driving linkages for the switches shown in Fig. 1 also give more direct and positive operation of the switches than could be obtained by the use of separate cams for operating each of the four

switch arms

5, 6, 1 and 8.

While there has been shown and described a particular embodiment of the invention, it will be obvious to those skilled in the art that changes and modifications can be made 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:

An electric switch comprising, in combination, an electrical conducting shaft, four spaced parallel electrical conducting arms pivotally mounted on said shaft, a separate movable contact pivotally mounted on an end of each arm, four insulated fixed contacts for cooperation respec tively with said movable contacts, separate springs for biasing each movable contact toward its coopcrating fixed contact, a crank shaft having four angularly displaced crank arms, said crank shaft being parallel to said conducting shaft, connecting rods respectively interconnecting said crank arms and said electrically conducting arms, a freely rotatable shaft mounted parallel to said crank shaft, a driving member fixed on said freely rotatable shaft and having a given radius, a fifth crank arm attached to said crank shaft and having a longer radius than said driving member, a connecting rod between said driving member and said fifth crank whereby continued rotation of said freely rotatable shaft in either direction will cause oscillatory rotation. of said crank shaft through a predetermined angular range which is substantially less than 360 degrees, the angular displacement of said four crank arms relative to each other and to said fifth crank being such that at one end of said angular range of oscillatory rotation two of said movable contacts engage their cooperating fixed contacts with one of said movable contacts turned about its pivotal mounting against the force of its spring further than the other one and with the other two movable contacts separated from their respective fixed contacts, while at the other end of said range said other two movable contacts engage their respective fixed contacts with one of said other two movable contacts turned about its pivotal mounting against the force of its spring further than the other one and with the first two movable contacts separated from their respective fixed contacts, while at the middle of said range the two movable contacts which are respectively turned furthest about their pivotal mountings at the opposite ends of said range each engage their respective fixed contacts and the remaining two movable contacts are out of engagement with their respective fixed contacts, and an electrical terminal for said switch con nected to said electrical conducting shaft.

. JOHN FOWLER.

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

UNITED STATES PATENTS Number Name Date 1,761,773 Carpenter June 3, 1930 1,971,832 Paxton Aug. 28, 1934