US1110021A - Electrically-controlled switch. - Google Patents

Description

H. E. WHITE.

ELEGTRIGALLY CONTROLLED SWITCH.

APPLICATION FILED JULY 15, 1912,

1,1 10,021, Patented Sept. 8, 1914 Fig. 2.

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UNITED s ATEs HAROLD E. WHITE, 01 GLEN RIDGE, NEW JERSEY, ASSIGNOR T GENERAL ELECTRIC PATENT OFFICE.

COMPANY, A CORPORATION OF NEW YORK.

ELECTRICALLY-CONTROLLED SWITCH.

Specification of Letters Patent.

Patented Sept. 8, 1914.

Application filed July 15, 1912. Serial No. 709,498.

sey, have invented certain new and useful Improvements in Electrically-Controlled Switches, of which the followingis a specification.

This invention provision of a device of this character which will operate under relatively high current and at the same time be simple in construction and efficient in operation.

,"My invention relates more specifically to electromagnetic relays and more particularly to the type knownas series relays employed in motor starting apparatus, These relays carry the motor current and are frequently used to regulate the starting of electric motors, In some cases the current handled is very large, as for instance, 2000 amperes or more and with such a current it is often I difficult to obtain a small enough excitation for the particular use to which the relay is put.. In many cases a'small fraction of a turn of a-conductor is a greatdeal more than is necessary; i

One of the objeets'of my invention isto provide a relay of this character in which eral application, I have found it particu-' llarly useful in connection with motor starting apparatus 1n which a serles of switches are arranged to operate progressively to cut out sections of resistance to bring themotor up to speed. These switches or contactors .havebeen constructed in a great many ways and have been arranged in various systems which include a series relay to retard the progression of the switches.

One arrangement which has been used very successfully is described and claimed in my Patent No. 969,738, September 6, 1910, and

/ also in patent issued to myself and E. R.

Oarichofli', No. 969,585, September 6, 1910.

In the arrangement described in these patents .a series relay is associated w1th each I contactor, the arrangement being such that the relay is mechanically supported mopen position whenthe contactor is open. When the contactor closes the mechanlcal support relates to electrically con-i trolled switches and has for its object the is removed so. as to permit the relay to close when the current falls to a predetermined value. My present invention is particularly 'appllcable to a relayused in this manner, although it is in no sense limited to this application.

Other objects. of my invention will appear in the course of the following specification 'in which I have shown my invention embodied in illustration. In the accompanying drawings illustratmg my mvention, Figure 1 is a side view of a contactor shown in connection with my improved relay; Fig. 2 is a front view of 1 the same; Fig. 3 shows a detail of the energizing element; and Fig. 4 is adiagram'of a iysiterg in which my invention may be em- 0 1e Refering first to Fig. 4:, in which Ihave shown the relay in one of its many uses, it

will be seen that in this system there are two contactors 10 and. 11 having associated with them the overload relays 12 and 13.

The core of each relay is supported in its open positionby aprojection .or tail on the contactor arm. The core of the relay 12 00- operates with an energizing element which ordinarily would be a winding of heavy copper. Where the current is very heavy, as in the present instance, this winding would make the excitation so high that the core would not'drop out at the proper current value. In order to overcome this difliculty I employ instead of a winding, a strip of metal, preferably copper, as shown in Fig.

3. This strip is provided with a perforation 14 through which the comet the relay 12 moves and at opposite ends is provided with terminals 15 and 16, respectively. Opposite the'fperforation 14 is a projection 17 having a circuit terminal 18. i

It will be seen froman inspection of Fig.

3 that when current passes between terminals 15 and 16 it divides around the perforation 14: as shown in broken lines and when a circuit connection is made at 18 instead of at 16 the path of the current will be changed as shown in dotted lines. This arrangement may be employed in various ways to bring about the variation in the pull upon the core when the circuit connections are changed.

If, for example, the core operates in a magnetic frame, such, for instance, as the frame .12 (Fig. 1) then when the current passes concrete form for purposes of between the terminals 15 and 16 the pull upon the core will be determined almost exactly by the current in the branch conductor threading the magnetic circuit formed by the magnetic frame and the core, 2'. e. by the current passing through the branch which is to the rear or on the opposite side of the perforation 11 from the terminal 18. If now the current passes between terminals 15 and 18 instead of between 15 and 16, then the percentage of current passing through the rear branch will be decreased and the pull on the core greatly reduced. On the other hand, in the absence of the magnetic frame, as for instance where the frame 12 is made of non-magnetic material, the excitation due to each branch circuit will be equal and opposite to that of the other branch so that the core will be unaffected. If, however, under these conditions the current passes between terminals 15 and 18 one of the branch circuits will be considerably longer than the other so as to have a greater magnetizing effect and the excitation which affects the core will be the differential of the effects produced in the two paths.

In the present case I employ an arrangement in which the magnetic frame is used. In Figs. 1 and 2 is shown a contactor employing such a relay. The particular construction of this contactor forms no part of my invention and for purposes of illustration I have shown the contactor of the type shown in my Patent No. 969,738, above referred to. Energizing the coil 10 actuates the switch arm 19 pivoted at 20, the contacts 21 being located in the arc chute 22. The switch arm is provided with a projection 23 which engages with the stem 21 of the core of the relay 12 to hold it in raised position when the switch is moved to open posit-ion. The iron frame 12 is secured to the contactor frame and the conducting strip through which the core 12 passes is secured to the iron frame by a bolt 18. It will be seen from an inspection of Fig. 4 that intermediate terminal 18 of Fig. 3 is connected with the contact arm 19 through conductor 25.

The operation of my device will be clearly understood from a description of the operation of the system shown in Fig. 4:. Referring to this figure, A represents the armature and S the series field of an electric motor. 26 and 27 are line contactors both of which have windings in a control circuit. R, R and R represent sections of resistance and C the master controller. hen the controller is moved to the first position the contactor 26 will be closed so that current passes from the positive side of the line through the contactor 26, armature A, wire 28, through the conducting strips of the cores of relays 13 and 12, through the resistances R, It and R series field S and back to the negative side of the line. It will be noted that the current passes between the terminals 15 and 16 of the energizing elements of the relays and that therefore the magnetic pull upon the cores is a maximum. If now the controller C is moved to the second position, the winding of the contactor 10 is energized so as to bring the contact arm 19 to closed position. This removes the mechanical support from the core of relay 12, but since the pull upon the core is a maximum, the holding up of the core until the increase of current due to short circuiting the resistance R has taken place is assured. hen, however, the contactor is closed and the resistance section R cut out, the holding effect upon the core decreases, since by the short circuiting of the resistance R the current now passes from the terminal 15 to the terminal 18. The core is now magnetically supported, since there is a rush of current due to the cutting out of resistance section When the current falls to a predetermined value due to the speeding up of the motor, the core will drop so as to energize the next contactor. This contactor will close so as to short circuit a section of resistance R and change the connections of the relay in the same manner as that described in connection with 0011- tactor 10. hen the current drops to a predetermined value the core of the relay 13 of contactor 11 will drop so as to energize the contactor 27 which will short circuit the resistance R to connect the motor across the line. From this it will be seen that although the current which is taken by the motor may be exceedingly high the actual excitation of the relay at the time when it is responsive to motor current conditions may be exceedingly small.

While I have described my invention as embodied in concrete form for purposes of illustration, and as operating in a particular manner, in accordance with the patent statutes, it should be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

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

1. An electromagnetic relay comprising a core, an energizing element therefor consisting of a conducting strip having a perforation through which the core moves, circuit connections to said strip whereby two branch circuits are formed around the perforation, and means for changing the path for the branch circuits so as to change the effect thereof upon the core.

2. An electromagnetic relay comprising a core, an energizing element therefor consisting of a conducting strip having a pair of circuit terminals and a perforation for 'said core between the terminals and in alinement therewith, a third terminal out of alinement, and means for changing connections from one of said terminals to said third terminal.

3. An electromagnetic relay comprising a core, an energizing element therefor consisting of an elongated conducting strip having a circuit terminal at each end and a perforation for the core intermediate the terminals and in alinement therewith, a projection'on said strip opposite the perforation provided with a third circuit terminal, and means for changing the connections from one of said terminals to said third terminal.

4:. An electromagnetic relay comprising an electro-magnet having a core and an energizing element therefor, said element consisting of a conducting strip having a perforation through which the core moves, circuit connections to said strip whereby two branch circuits are formed around the perforation one of which is effective u on the core and the other substantially ine ective, and means for changing the path for the branch circuits so as to vary the effect upon the core.

5. An electromagnetic relay comprising an electromagnet having a core and an energizing element therefor, said element consisting of a conducting strip having a perforation through which the core moves, circuit connections to said strip whereby two branch circuits are formed around the perforation one of which is effective on the core and the other substantially ineffective, and means for changing the path for the branch circuits so as to decrease the effect of the effective branch circuit.

6. An electromagnetic relay comprising an electromagnet having a core provided with a contact member, an energizing element for said core consisting of a conducting strip having a perforation therethrough, circuit terminals at opposite sides of said perforation symmetrically arranged so that the current in flowing between the terminals divides into two branches around the per foration one of which is effective while the other is substantially ineffective upon the core, a third terminal located out of line with said terminals and perforation, and means for changing connections from one of said terminals to said third terminal.

In witness whereof, I have hereunto set my hand this twelfth day of July, 1912.

HAROLD E. WHITE.

Witnesses:

E. H. WARING, E. C. JoNEs.

copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C.

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