US2026415A - Electrical relay - Google Patents

Description

311, 1935. F: J. CHAMPLIN ELECTRICAL RELAY Filed July 17, 1951 Inventor: -Fvanklin J. Champlin,

His Attorney.

Patented Dec. 31, 1935 UNITE STATS ELECTFJICAL RELAY Franklin J. Champlin, Dalton, Mass, assignor to General Electric Company, a corporation of New York Application July 17, 1931, Serial No. 551,536

1 Claim.

My invention relates to electrical relays and more particularly to improvements in electromagnetically controlled relays of the contact-making voltmeter type.

Heretofore, most contact making voltmeter type relays have included a pivotally mounted contact arm. one end of which is connected to an operating solenoid and the other end of which is connected to a resilient balancing element which is usualy referred to as compensating spring. In practice these elements are usually so arranged that the pull of the spring partially balances the weight of the solenoid core. That is to say, the spring balances the otherwise unbalanced weight of the core which is not supported by the pull of the magnet. Among the reasons for making it desirable to have a compensating spring, rather than making the magnet so strong that it normally supports the entire weight of the core, is that by balancing a part of the core weight the magnet will have less unbalanced weight to move and consequently it will be more sensitive to variations in voltage. Another reason for the spring is that it permits of a smaller magnet coil, that is to say, a magnet coil having a lower ratio of reactance to resistance with the result that the energization of the magnet is more independent of changes in frequency of an alternating current energizing circuit. This is, of course, desirable in a. voltage regulating system, where it is not desired to make the arrangement responsive to frequency changes. When such an arrangement is energized from an alternating current source, or from a source of pulsating direct current, I have found that the vibrations of the core of the solenoid which are produced by such energization of its magnet cause a vibratory action of the meter contacts with the result that they become pitted and burned and their life is materially shortened.

It is, of course, possible to damp out these vibrations by making the parts very heavy, or by providing an oil dashpot, or the equivalent, but all of these arrangements result in a sluggish action of the meter, which when the meter is used for controlling a voltage regulator, is not desirable.

In accordance with the illustrated embodiment of my invention, I provide an operating magnet assembly, which is itself balanced by suitable balancing means, connected to a circuit controlling contact arm through a resilient connection whereby any frequency vibrations in the magnet assembly will be absorbed by this connection and not transmitted to the contact arm. This contact arm should preferably be balanced although I have found that the slight unbalance of individual arms which is due to manufacturing variations has no appreciable harmful efiect on the operation.

(Cl. 20i)91) An object of my invention is to provide a new and improved electromagnetically operated relay. Another object of my invention is to provide a substantially vibrationless contact arm alternating current operated contact-making voltmeter.

My 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 claim.

In the drawing Fig. l is a diagrammatic illustration of a specific embodiment of my invention, while Fig. 2 is an illustration of a modification of the arrangement shown in Fig. 1.

In Fig. l or" the accompanying drawing, I have illustrated diagrammatically an embodiment of invention which is connected to be responsive to the voltage of and which controls the operation of an induction feeder voltage regulator 2, connected to this ciran alternating current circuit 1 cuit, through control of the direction of operation of a servo operating motor 3, in the usual manner. The operating assembly of the relay comprises an electro-responsive device, such as a solenoid magnet 4, which is connected across circuit 5, preferably through a potential transformer 5, a core 6 for the magnet, and a compensating, or balancing, means which is preferably in the form of a resilient spring 7. Adjusting means 8 provided for varying the tension of the balancing means i. This arrangement is preferably so adjusted that with normal voltage on circuit i, spring l supports a part of the weight of core 6 and magnet lsupports the rest. If new the voltage of circuit l increases, core 8 will move upwardly, while if the voltage of circuit I .decreases core 6 will move downwardly. However, it will be obvious to those skilled in the art, as the description of my invention proceeds, that this assembly might also be so adjusted that coil 4 normally pulls down instead of up, without departing from my invention in its broader aspects. The circuit controlling assembly of my relay may comprise any kind of a movable circuit controlling arrangement and in the illustrated embodiment consists of a pivotally mounted contact L carrying beam 9, carrying contacts for cooperating with raise and lower contacts and II, respectively. This beam 9 is also arranged to cooperate with the usual holding coils l2 and 13.

Any suitable source of current supply for energizing the holding coils and motor 3 may be provided, and as shown, this means consists of a battery Id.

The control circuits are so arranged that when raise contacts iii are closed motor 3 is operated in a direction to cause regulator 2 to incr ase the Voltage of circuit l and at the same time holding coil l2, which is connected in parallel with the motor, is energized. Similarly, when lower contacts I I are closed motor 3 is operated in a.

reverse direction to cause regulator 2 to lower the voltage of circuit I, at the same time holding coil I3 is energized.

Regulator 2 is a device which is well understood by those skilled in the art, and consists primarily of a transformer for producing. variable amounts of voltage boost or buck, in the circuit to be regulated, through variations in the inductive relation of its windings by mechanical displacement of their axes.

In order to facilitate the balancing of beam 9 I preferably a provide suitable balance means, such as anarm l5 with an adjustable weight in the form of a nut 16. By turning this nut it will be moved along the arm so as to attain a balance of the beam. This, however, is a refinement which is not necessary so long as the contact beam is substantially balanced and is not associated with any biasing means tending to positively unbalance it.

The operating connection between core 5 and beam 9 consists of a resilient element which need not be made of any particular material nor need have any particular shape. In the illustrated embodiment it consists of a flat metallic spring ll. In order to keep the advantages of a compact structure while at the same time having a sufficiently flexible connection between the core and the beam, I have constructed the operating connection ll longer than necessary and join it to core 6 by the relatively rigid connection it.

In operation the small rapid frequency vibrations of core 6 will be absorbed in the resilient connection I? and contact beam 9 will remain substantially free from such vibrations. However, the relatively slow vibrations which are caused by the continual small voltage fluctuations on most load circuits will not be damped out by the resilient connection ll. Therefore, in order to prevent the practically continual operation of the regulator which is controlled by the contact making voltmeter, the contacts l6 and H are preferably so adjusted that it requires a voltage change of approximately two volts for the contact beam to go from one contact to the other. Inthis way the small voltage fluctuations, which usually are less than two volts, will merely cause a free motion, or vibration, of the contact beam between the contacts Hi and H, without touching them. This prevents undue wear and operation of the regulator and meter contacts without detracting appreciably from the speed of operation of the arrangement upon voltage changes in excess of the usual small fluctuations.

I have found that with the above described arrangement relatively large and sudden voltage changes on the regulated circuit cause such quick action of the contact making voltmeter that a rebound of the contacts takes place thereby causing injurious arcing of the contacts. I therefore provide a relatively loose type of damping means which I have illustrated as an air dashpot I9. This dashpot has a relatively light, loosefitting piston 26, the rest of the dashpot being filled with air or any other suitable low density fluid. This arrangement .acts to damp or retard relatively large, sudden movements of the contact making meter, but it has no appreciable effect on slow movements of the meter or on relatively rapid small movements of the meter. I find that this arrangement effectually prevents rebounding of the contacts.

The resilient connection I! produces a further advantageous result in that it causes a snap action of the contacts whereby the circuits are rapidly made and broken. This of course reduces arcing at the contacts and prolongs their 5 life. The operation of the system as a whole should now be clear to those skilled in the art. Thus, if the voltage of regulated circuit I decreases the energization of magnet 4 is weakened and the raise contacts I 0 of the contact-making voltmeter .close, thereby completing energizing circuits for motor 3 and holding coil l2. The circuit for motor 3 is such as to cause this motor to operate regulator 2 in a manner to insert a voltage boost in circuit I. This action continues until a voltage of circuit I is slightly above the voltage at which contacts H3 would normallytendto separate, when the increased pull of coil 4 overcomes the pull of holding coil l2 and beam 9 will be 20 returned to its mid position. Similarly, whenithe voltage of circuit l rises, lower contacts Hare closed thereby energizing holding coil l3 .and motor 3, in such a manner as to cause regulator 2 to insert a voltage buck in circuit I. This will 25 continue until the voltage falls slightly below the value at which contacts ll tend to open, due to the pull of coil l3. When this pullis overcome the contacts will separate and the arm will return to its mid position.

In the modified arrangement shown in Fig. 2 the compensating spring -l is connected directly'to the stem of the core 6 instead of being ofi-set as in Fig. I. This allows core 5 to hang with its axis vertical, which in some cases may result in an improved operation of the control magnet. Alsoa special bracket 2| is employed for connecting spring I1 to arm 9, and the other end of spring H is connected directly to the core stem. This is merely an alternative way of obtaining a relatively long spring while keeping the meter structure compact.

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secureby Letters Patent of the United States is:-.-

An alternating current contact making voltmeter comprising, in combination, a pivotally mounted contact arm which is substantiallybalanced with respect to its mounting, an operating magnet therefor, a vertically movable core for said magnet, a. spring for supporting a portion of the weight of said core, a flat spring for providing (2- an operating connection between said. core and said arm which will not transmit to said arm any frequency vibrations of said core, said spring being longer. than the distance between said core and said arm, connections between the ends of said spring and said core and arm respectively, one of said connections being a bracket whose length equals the difference between the length of said spring and the distance between said arm and core, and a loosely damped dashpot connected to said core. V

' FRANKLIN J. CHAMPHN. I

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