US1677336A - Induction relay - Google Patents

Description

July 17, 1928.

S. L. GOLDSBOROUGH INDUCTION RELAY F iled May 25, 1925 WITNESSES ATTORNEY Patented July 17, 1928 UNITED STATES PATENT oFFicE.

SHIRLEY L. eoLns oRoU Gn, or PITTSBURGH, PENNSYLVANIA,VASSIGNORVTO wEsT- menousn ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION or PENN- SYLVANIA.

INDUCTION RELAY.

Application filed May 25, 1925. Serial No. 32,544.

My invention relates torelays and particularly to relays of the induction type.

One object oi my invention is to provide a reverse-energy relay thatshall have means 1 core member with projecting pole pieces on which windings aredisposed, the electrical and magnetic circuits are necessarily unsymmetrical. to some extent. The efiect upon the characteristics of the relayis too slight to cause trouble in most types of relays, but it cannot be ignored in the case of a reverseenergy relay which must operate over a wide range of currents.

It is often desirable to use a reverse-energy, relay for the protection of a distribution system in which the short-circuit current may be ten or twenty times the normal full-load current. The relay is provided with a voltage winding and is designed to operate only whenthe flow of power is in a predetermined direction. If the current winding of the relay or the portion of the core member energized thereby is slightly unbalanced, it is evident that the effect of such unbalance becomes greater nnder short-circuitconditions,

particularly as a short-circuit is usually accompanied by 'a considerable reduction in system voltage. The result is that the relay operates or does not operate, as the case may be, in a certain directiouwhen the current reaches four or five times the normal value irrespective of the phase relation of the voltage, unless the relay is relatively insensitive.

It has been found that the undesired characteristics of the relay resultfrom a number of causes, such as an unequal number of ampere-turns upon the series pole pieces, an uneven air gap between the upper and lower po'le pieces, an armature that is not properly alined with respect to the pole pieces, and I equality in the resistances ofth'e electrical paths in the laminated core member. As it' is impracticable to attempt tocorrect each of these causes, I obtain the desired compensation by modifying theflux traversing the armature from the series poles. In accordance'with my invention, an adjustable magnetizable shunt member around the armature is disposed adjacent to the series poles. By adjusting this member, the flux traversing the armature may be so anodified that no torque is exerted on the same by the current winding alone even when the current is excesslve.

' Fora more complete understanding of my invention, reference should be had to the accompanying drawing, in which V Figure 1 is a diagrammatic view of a relay of the induction, type embodying my invention; and, f

Figs. 2, 3 and 4: are detail views of the magnetizable shuntmember shown in Fig. 1. Referring to Fig. 1, the relaycomprises a' magnetizable core member 1 having windings 2 and '3 thereon and a movable armature member 4 controlling the co-operating contact members 5'.

The relay shown is adapted to be used as a watt or reverse-energy relay, the winding 2-being connected in series and the winding 3 in .shunt with an alternating-current cir cuit. TheIcore member 1 comprises upper pole pieces 6 andu'? and lower pole pieces-8,.

9 and 10. The series winding 2 is disposed upon the upper pole pieces and the shunt winding 3 on thelower pole piece '9.

l The armature member 4% is a pivoted'conducting disc disposed'in the air gap between the upper and the lower pole pieces and operated by the magnetic fluxes traversing this air gap and produced by the windings 2 and 3. The armature member 4 should only be actuated when both windings '2 and 3 are energized and the direction and torque of the armature member should depend upon the value and the phase relation of the currents in said windings".

subjected to 100 volts.

It is found in practice, however, that the magnetic circuits of the windings 2 and 3 are usually slightly unbalanced or the ampere turns upon the upper pole pieces 6 and 7 are unequal so that a torque is exerted upon the armature member 4- when the winding 2 alone is energized Other conditions may aggravate this effect, such as unequal air gaps between the upper pole pieces 6 and 7 and the lower pole pieces, a faulty alinement ofthe armature member 4 in the air gap or transverse electric circuits across'the laminatedfacesof the upper pole pieces 6 and 7 that are of unequal resistance;

Since it is impossible to eliminate this unbalancing of the magnetic and electrical circuits ofthe relay, I provide magnetizable shunt membersll and 12 mounted on the 'core member -1 adjacent to the upper pole pieces 6 and 7 to compensate for the torque otherwise exerted on the armature, The shunt members 11 and 12 are pivoted, as shown iii Figs. 2 and 3, upon a bolt 13 and may be secured in adjusted position by means of a locking screw 1 1. As shown in Figs; 3 and 4, the shunt member 12 comprises an L-shaped sheet-metal portion 15 riveted at 16 to a perforated sheet metal portion 17 that receives the bolt 13. The portion 1770f the shunt member is perforated at 18 to receive the head 19 of the bolt 13,

the perforation 18 being large enough to permit slight relative movement of the shunt member about the bolt 13. Washers 20 and 21 are clamped between the portion 17 of the magnetizable shuntmember 15 and the core member 1, the Washer 20 being threaded to receive the locking screw 14.

To adjust the relay, the series winding 2 is connected to a source of current and the voltage winding 3 is open-circuited. A current of 25 or amperes, which is five orten times the-normal value, is passed through the winding 2. The magnetizable shunt members 11 and 12 are then adjusted until l balance and no ber 41 by the encrgization of the current winding-alone. If the voltage Winding is then energized,'the direction of the torque exerted upon the armature member 4; will depend solely upon the phaserelation of the currents in the windings 2 and 3 and the relay will operate properly, even when an excessive current traverses the winding 2 and only a small voltage is applied to the voltagewinding 3. I

Under normal conditions, the ,current winding 2 may be traversed by three amp'eres and the voltage winding 3 may be Under these conditions, the torqueexerted on the armature member 4 is in such a direction as to maintain the contact members 5 open. When the flow of energy in the circuit reverses, however, the phase relation of the voltage with respect to the current changes and a torque is exerted upon the armature member 4 which tends toclose the contact members 5. Since a short-circuit is usually accompanied by a drop in voltage, the relay may be adjusted to operate even when the voltage appied to the winding 3 is reduced to 1 or 2 volts. Furthermore, although the short-circuit may cause the current winding 2 of the relay to be traversed by 50 or 100 amperes, the relay will still operate in accordance with the direction of the flow of energy, since the effectof the current winding alone is accurately compensated by the magnetizable shunt members ll and 12.,

I do not consider that my invention is limited to the precise form shown and described, as it may be applied to relays of other. types and thedetails of construction of the shunt member may be varied without departing from the invention. I do not 'WlSh to be limited in scope, therefore, ex-

cept as limitations may be indicated in the appended claims.

I claim as my invention:

1. Aninduction relay comprising a magnetizable core member having upper and lower pole pieces, a movable armature disposed betweensaid pole pieces and a magnetizable shunt for said armature extending between an upper and a lowerone of said pole pieces. 7 i v 2. .An induction relay comprisinga magnetizable core member having upper and lower pole pieces, a movable armature disposed between said pole pieces and an adjustable. magnetizable shunt for said armature extending between upper and lower pole pieces and movable with respect to one of said pole pieces.

3, An induction relay comprising a ,magnetizable core member, current and voltage windings thereon, a movable armatureac- ,t-uated thereby in accordance with the phase relations of the currents traversing said windings and an adjustable magnetizable shunt about said armature and pivotally mounted upon the core member.

, 4. An induction relay comprising a mag-- netizable core member having projecting pole pieces, an armature member adjacent said pole pieces, an L-shaped magnetizab'le shunt member pivotally mounted on said core member and controlling the flux traversing said armature member and means for securing said shunt member in desired position. F

5. An induction relay comprising a onepiece magnetizable core member having upper and lower projecting pole pieces, an armature member disposed between said pole'pieces, and an Lshaped magnetizable shunt member pivotally mounted on said core member on each side of said upper pole pieces and extending adjacent thereto.

6. An induction relay comprising a onepiece magnetizable core member having two upper and a lower projecting pole pieces, an armature member disposed between said sets of pole pieces and means for so shunting the magnetic flux between the sets of pole pieces from the armature member that the armature is precluded from operating except by the cooperation of the magnetic flux produced by both sets of pole pieces.

In testimony whereof I have hereunto subscribed my name this 14th day of May, 1925.

SHIRLEY L. GOLDSBOROUGH..

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