US1042183A

US1042183A - Polarized relay.

Info

Publication number: US1042183A
Application number: US55068510A
Authority: US
Inventors: Joseph Lester Woodbridge
Original assignee: Individual
Current assignee: Individual
Priority date: 1910-03-21
Filing date: 1910-03-21
Publication date: 1912-10-22
Anticipated expiration: 1929-10-22

Description

J. L. WO0DBRIDGE.`

POLARIZED RELAY. APPLIUATIONTILBD 11.111. 21. 1910.

1,042,183.. muted 001.122, 1912.

E u {jy-L www wmlfss I 1 n mmf/mw JOSEPH LESTER-WO0DBBIDGE, QF- PHILADELPHIA, PENNSYLVANIA.

PoLanIzun RELAY.

Specification of Letters latentfT Patentedoct. 22,1912.

Application led'arch 21, 1910. Serial No. 550,685.

To all whom it may concern:

Be it known that I, JosErH LESTER Woon- ERIDGE, a citizen of the United States, and residing in the city of Philadelphia, State of Pennsylvania, have invented certain new and useful Improvements in Polarized Relays, of which the following is a specifica tion.

v rIlhis invention comprises certain improvements in the design of polarized relays or similar electromagnetic devices, which are designed to respond to small reversals of current in a given circuit, o r in some cases to smallvariations of current on either side of a predetermined value, and are arranged to discriminate between a fioW of current` in opposite directions in the said circuit, so

as, for example, to close a certain contact* when the current is in one direction and open said contact and close another contact when the current is in the opposite direction. l

One of the principal objects of my invention is to reduce the size of the polarizing coil required when the current strength in the coil to which the device is responsive varies over a wide range.

The nature of my invention Will be more clearly understood by reference to the following description taken in connection with j the accompanying drawing, in whichf A is the armature of an electromagnet, pivoted at X and carrying a conducting tongue T, which is connected at one end to the circuit 3, and may make contact at the other end with either of the contacts l or 2 according lto the position of the armature A. The arzrature is held in one position by the yretractive spring H, adjustable by the screw J and may be drawn into the other position by the attraction of the magnet when properly excited. The design of such a contact device is well known and it may be applied to a variety of purposes well understood. .i

The stationary portion of the electromagnet includes two magnetic paths B and C, arranged in parallel relation with yeach other and with the armature A, these three being thus connected in parallel by the members L L and M M of the magnetic circuit. -The magnetic path B is interrupted by an air gap D, while the magnetic path C is interrupted by an air gap E. The object of these'air gaps will be explained later,

" and it will be, understood that they may be filled by any non-magnetic material, such as brass, in order to facilitate the mechanical construction of the apparatus.

The magnetic path B is excited by the polarizing coil G shown in section, while between the paths B and C is a conductor or electrlc circuit shown in section at F.y This i divide as shown by the arrows, a partpassing through the path C and the air gap E ,and another part passing vthrough the arma. ture A and the air gap I. The adjustment may be such that with the excitation of the coil (l alone and no current in conductor F, the force exerted on the armature A will be just balanced by the spring H and the contact tongue T will remain in a mid position between contact points l and 2. If, now a small flow of current in one direct-ion occurs in conductor F, it will increase the p ull exerted on the armature A, overcoming the tension of the spring H and making contact at point 1. This flowof current will decrease they magnetism in the pat-h vC` and also in the path B, but-will increase the magnetism in the armature A and in the `netic lines through the path B, which will nrembers M M. If, however, a smallgllyv tween the armature and the magnet itself,

ico

very few lines of magnetic force would pass through the armature if the path C were not interrupted by this air gap E. Similarly the air gap D is required in order that the excitation produced by current in conductor F shall cause a change of magnetic lilies through the armature A. Without this air gap D, the path B would act as a magnetic short-circuit and prevent any change in magnetism from taking place in the armature A with changes o current 1n conductor F.

An important feature of the design of this electromagnet lies in the restricted section of the members L L. The object of this restricted section is to permit this portion of the magnetic circuit to become saturated when the current in F reaches a certain value so as to limit the further increase in magnetism due to an increase in'current beyond this value. As stated above, when the currentI in I" is in a certain direction the lines of force produced by this current in the armature A and the members M M will be in the opposite direction to those produced in the same portions of the magnetic circuit by the coil G, thus weakening the pull on the armature A and allowing the spring H to predominate. If the current in conductor F should continue to increase in the same direction the magnetism in the armature A and the members M M would finally be reduced to zero and then reversed, and if a suicient increase of current should occur in F this reversed magnetism might eventually be sufficient again to over-power the spring H and make contact between the tongue T and the point 1, which should 'only occur when the current in F is in the opposite direction. If, however, the section of the members L L is made sutiiciently small these members will become saturated and preventthe above results from taking place, that is, prevent a sufficient amount of reversed magnetism from being produced in the armature A and the members M M to overcome the tension of the spring H. This result may be more clearly indicated by a numerical example. Assume that the section of the path B, the members M M and the armature A to be such that the magnetic reluctance of these portions of the iron circuit may be neglected. Assume that the air' gap I, between the armature A and the stationary portion of the magnet is one-eighth of an inch long and one square inch in section, and assume that it is desired to transmit 15.000 magnetic lines across this air gap. This will call for approximately 585 ampere turns. Assume the air gapD to be one-eighth of an inch in length, and assume that the same magnetic density is produced,

in this air gap. This will call for 585 more ampere turns or a total of 1170 ampere turns in the coil G. A certain 'number of lines portion of the circuit. In order to maintain the above specified density in the air gap D its section must then be 19A; square inches, since the total of 22,500 lines must pass through it. The magneto motive force applied to send lines across the air gap I, that is, 585 ampere turns, will also be available to send lines through the path C and the air gap E, since these two magnetic circuits are in parallel. Assume that the cross section of the members L L is such that the magnetic density is 28,000 lines per square inch. As there are 7500 lines passing through these members their section will be a little over one-quarter of a square inch. It these two members aggregate 24 inches in length it will require about 95 ampere turns to transmit these lines through these two members in series. There will remain 490 ampere turns available to' send 7500 lines across the air gap E, and this air gap may be made 0f suitable length and section to require this excitation.l Ve will then have with an excitation of 1170 ampere turns in the coil G, 22,500 lines through the path B and across t-he air gap D, of which 15,000 lines will pass in one direction through the armature A while 7500 lines will pass in the opposite direction through the a1r gap E. Assume now that we wish to transmit sutlicient current through conductor F to increase the lines in' the armature A by 10%. It will require 10% of 585 ampere turns or 58% ampere turns to produce this excitation. This same excitation will reduce the density in the air gap D in the same prop ortion, and since the air gap D has 50% greater cross section, 50% greater increase in lines will be sent through the path B. That is, the increase of lines in the path B will be 2250. It will be necessary, therefore, to increase the lines across theair gap E and through the members L L by the sum of these two amounts or 3750. This will increase the density in theair gap E by 50% and will call for 50% more ampere turns than were required to produce the 'original density, that is, 50% of 490 or 245. To increase the density in the members L L by 50% will call for about 48 ampere turns. There will be required therefore a total of 351% ampere turns to produce the above results, and as the conductor F is a single conductor it will require 351iV amperes flow of current. Similarly, if it'is required to reduce the magnetic density in the armature by 10% a flow of 351e amperes in the opposite direction through conductor F will produce this result, since the saturation of the iron is at a very low point and the magnetism will therefore be practically proportional to the excitation. Now, let us determine what will call for 15,000 lines through the armature A and air ga I in the reverse direction to that of the original magnetism 1n order to neutralize, and will call for .585 ampere turns to produce this result. This excita-- tion, produced by the current in the conductor F, will cause an increase of 22,500 lines across the air gap D, or a total increase of 37,500 lines across the air gap E and through the members L L. This increase in density in the air ap E will produce a density of six times t e original ensity at this point andcall for an increase 1n magneto-motive force equivalent to five times the original, that is, five times 490 or 2450. This will increase the density in the members L L from 28,000 lines per square inch to six times this amount or 168,000 lines per inch. This would call for about 50,000 am-` pere turns. It will be seen, therefore, that with a device designed in accordanceA with the above proportions, the polarizing ,coil

G designed for 1150 ampere turns will be sufficient toV maintain the olarization and prevent reversal of magnetlsm in the armature A, even with a current strength of 50,000 amperes in conductor F in thedirection to tend to produce such reversal, this result being brought about by the saturation of the members L L.l At the same time the apparatus is sensitive to current reversals in conductor F amounting to but two or three hundredamperes in either direction. It will be seen that 350 amperes in conductor F is sufficient t-o produce a change of 10% in the magnet-ism through the armature A, and much smaller changes than this would be suiiicient to produce contact with either point 1 or point 2.

If it is desired that the apparatus, instead of responding to reversals of current on either side of zero in conductor F shall respond to variations of current in thisconductor on either side of some other value, a coil K may be added embracing that part of the magnetic circuit affected by F and eX- cited to such extent that when the current in F is at the critical value the algebraic sum of the two excitations will be zero. A similar result may be obtained by varying the excitation of the :coil G or the tension of the spring J.

What I claim and desire to secure by'Letters Patent is, v

1. In combination in an electromagnet, three magnetic circuits arranged in parallel relation, whereof the first contains a movable member, the second is providedfwith a polarizing coil and the thirdis provided with a source of varying excitation and includes a restricted section adapted to permit the passage of magnetic flux to increase or diminish the flux produced by the polarizing coil in the movable member, but to become saturated to limit the reversal of said polarizing fiux. v

In combination in an electromagnet, three magnetic circuits arranged in parallel relation, whereof the first contains a movable member, the second is interrupted by a .non-magnetic gap and is provided with a polarizing coil and the third is provided with a source of varying'excitation and includes a'restricted section adapted to permit the passage of magnetic fiux to increase or diminish the fiux produced by the polarizing coil in the movable member, but to become saturated to limit the reversal of said polarizing flux.

3. In combination in an electromagnet, th'ree magnetic circuits arranged in parallel relation, whereof the first contains a movable member, the second is interrupted by a non-magnetic gap and is vprovided with a polarizing coil and the third is interrupted by a non-magnetic gap, is provided with a source of varying excitation and includes a restricted section adapted to permit the passage of magnetic flux to' increase or diminish the fiux produced by the polarizing coil in the movable member, but to become saturated to limit the reversal of said polarizing flux.

4. A polarized electromagnetic device having conductors tending to reverse its magnetic flux, and having a magnetic path of relatively low saturation point which by becoming saturated limits the reversal of the flux.

5. In combination in an electromagnetic relay, a movable contact making member, a retractive spring to hold said member in one position, a polarizing coil adapted to produce a magnetic flux to attract said member against the force of said spring into another position, an electric circuit carrying a variable current and in inductive relation thereto a magnetic pat-h, said circuitand path arranged to cooperate with the polarizing coil Yto increase or diminish the magnetic flux first mentioned with variations of current in said circuit, said magnetic path having a restricted section adapted to become saturated to limit the reversal of said flux to prevent the attraction of the movable En tesmony whereof L have hereunto e magnetism produced in the ,ls

slgned my name.

c path by he Constant excitation. I

".7. En combnaon, en eecrc circuit, and

polarized eeetomagneo device arranged OSEPE LESTER WOODBREDGE.

o to respond to changes of current in saidv cr- I cuit :1nd having a magnetic path adaped to become saturaed to mit the reversa of magneie uz: by the current in Said Circuit.

Witnesses:

JOSEHP Tri. TRACY.