US2624818A - Voltage regulating relay - Google Patents

Description

Jan- 6, 1953 l. E. MCCABE VOLTAGE REGULATING RELAY Filed May l0, 1950 INVENTOR.

/RA MC'C'E Muss. Mig) w 2\ .4l

Patented Jan. 6, 1953 UNITED STATES PATENT OFFICE VOLTAGE REGULATING RELAY Ira E. McCabe, Chicago, lll.

Application May 10, 1950, Serial No. 161,045

6 Claims. 1

The invention relates to electrical regulating devices of the relay type and has reference more particularly to an improved voltage regulating relay which will be sensitive to small changes in operating voltage to open and close the relay contacts of said device. Apparatus of this character is employed in control equipment for regulating electric power supplies and similar apparatus is employed in the control of conveyor systems.

In -connection with providing satisfactory electrical service to consumers of electricity, the maintenance of a substantially constant voltage on the service line becomes a critical and important factor in maintaining customer satisfaction and economy of operation for the power company. For control of the supply through the feed circuits various types of automatic feedervoltage booster regulators are employed. Forming part of the control mechanism of certain vregulators are relay devices which are sensitive to slight variations in the load circuit whereby the devices respond to eiect operation of the regulator to step up or down the voltage of the outgoing feeder to compensate for the variable line drop or variable bus voltage and thus maintain a constant voltage at the center of distribution of the particular feeder. Generally rheostats are employed to set the operating voltage of the relay and as such they represent an item oering need of improvement in the development of relay control to which this invention is directed.

Further need for simplicity of adjustment and more satisfactory performance of voltage control devices is evidenced in their application to control of belt conveyorsystems. In one such system the relay is energized from a tachometergenerator which may be driven through speed change mechanism operated by a conveyor belt. In the system, the relay contacts are connected to the control circuit of a feeding conveyor so as to stop its movement should the main `conveyor speed drop below a preselected speed. Operation of the relay results from a voltage drop which occurs as the tachometer-generator speed is reduced by the slowing down of the main conveyor upon which it depends for operation.

Accordingly an object of this invention is to produce a relay device for the above and other related and similar uses which will possess a. Sensitivity of operation, simplicity of adjustment, and an elimination of the eilect of vibration upon the contact controlling elements such as will improve the function and performance of the apparatus with which it is used.

A further object is to provide a voltage regulating relay of the repulsion type, employing separate and independent coils of wire mounted on an iron core and which are relatively adjustable to vary the gap between them whereby the relay device -can be set for different operating voltages between maximum and minimum values as determined by said adjustability,

Another object of the invention is to provide a voltage regulating relay incorporating adjustable means for adjusting the position of one of the relay contacts whereby to increase or decrease the spread as regards the uctuations in the operating voltage required to cause opening of one relay contact and closing ofthe other.

In connection with the adjustability of one 0f the relay contacts another object of the invention is to provide eccentric abutments adjustable by rotation of the same to increase or decrease the amplitude of movement of the magnet carrier arm between the abutments, whereby as regards the mercury switches providing the relay contacts it is possible to secure that relationship of the magnets therewith for the most eicient and sensitive operation.

A further object is to provide a voltage regulating relay as described which will additionally embody novel and improved temperature compensating means for compensating for ambient temperature changes or for temperature changes caused by the operation of the device itselfi A still further object is to provide a relay device for the voltage regulation of feeder lines which will be highly sensitive in operation by reason of the improved pivot mounting of the movable coil, which will embody temperature compensating means carried by the movable coil in a manner for modifying the action of the same, and which will be positive in operation since the relay contacts in the form of mercury switches are actuated by magnets carried by an arm depending from the movable coil.

With these and various other objects in view, the invention may consist of certain novel features of construction and operation, as will be more fully described and particularly pointed out in the specification, drawings and claims appended hereto.

In the drawings which illustrate an embodiment of the device and wherein like reference characters are used to designate like parts- Figure l is a front elevational View of a voltage regulating relay embodying the improved structural features of the present invention;

Figure 2 is a side elevational view of the apparatus shown in Figure l;

Figure 3 is an enlarged fragmentary view with parts in section to better illustrate the construction of the switch contacts and the manner in which they are actuated by the magnet carrier arm;

Figure 4 is a detail plan view illustrating the structure for pivotally supporting the movable coil of the relay means; and

Figure 5 is a fragmentary view .with parts in section to illustrate the construction of the compensating means for modifying the action of the movable coil in accordance with temperature changes.

Referring to the drawings, the illustrated embodiment of the invention is housed lwithin container or box providing a base .pate lli hai-ting securing means such as the threaded screws ll for releasably fastening a cover to the base plate. A metal supporting plate-.l 2 is xedly secured in spaced"ielation to the base plate 'lil by-.means of the 'fastening screws i3 which carry sleeves orfspacing 'elements i4 forfmaintaining the supporting plate vin proper spaced `relation. The upper central portion iof plate-"l2 is cut away to provide spaced supporting arms i 5 and .15, 4.which arms `have iixedly secured thereto :the .iron lcore i3 of any preferred forno either asa Ybar or-asa continuous rectangular core, :as vbest -shown in Figure -l. Theironcorefis formed of 4laminations which are riveted together except at the.corners where Vbolts is and `t Iare employed for -purposes of assembly. In the present instance the bolts 2B `:serve Vto .secure the iron 'core to the arms i5 and I6. A'berterminalplatej'! is .secured by theY rivets 2l to the bottom edge of the plate i2 anda plurality of posts 22, 23, Eiland .25 are secured to the terminal plate, .eachxbeing suitably insulated from the other .bythe insulating character. .of the plate itself.

VSeparate .and .independent vcoil-s. are mounted formovement on the lower horizontal barof the iron corell The said coilscomprise a repulsion type rela-y which-operates .to open andclosecertain relay switch contacts in accordance with fluctuations in Van operating voltage. A multiturn coil .25 of -wire is mounted on .the bottom horizontal bar of the. iron core I8 in ,a manner to permitright and left vhand movement V.of the same for adjusting the `repulsion type .relayfor different-.operating voltages. '.lliecoil 26 is .provided with terminals 2 .Which..a1te .electrically connected to the posts .23 andt, saidposts eX- tending .through the ber terminal .plate tothe underside .of .the same, the .threaded .extremity o1 each .post receiving a .nut 23 .for releasably securingv the terminals Ysuch as 27 .to their .respective posts.

.Numeralll .indicates the y.movable coil .of the relay and which vmay comprise a.n1ulti-turn.coil of `,wire such .as 26 or thesaidmovable rooilmay constitute a single turn .coilof .aluminum or oopper in accordance with .the .disclosure of Figure l. The movable coil is pivotally supported for oscillating movement by improved means which renders the movable coil extremely sensitive to fluctuations inthe voltage of the current traversing coil 2t. The bracket 3i, suitably secured to leg l5, provides a at horizontally'disposed supporting portion r32, Figure 4, which in turn supports the movable coil Si? through 'the instrumentality of thin nexible blades 33. Two `such blades areshown in Figure 4 although more may be'employed. Said'blades, which may consist ci' exible material such as a .603 beryllium copper, are secured at one end to the support 32 by' means of the screws 34 and at their 'othersen'dtothe bot- 4 tom surface of the movable coil 3Q by the screws 35 which provide the flanged head 36 in spaced relation with respect to the bottom surface of the movable coil. The relationship of the movable coil and the support therefor when joined by the nexible blades is such as to cause the adjacent edges of the support and coil to slightly overlap, as is evident from Figure a, to provide a iulcrum vedge for operation. Vertiealniovement of the coil Se is'limited by the iianged heads it on the screws 35, each flanged head being or" such diameter as to extend under the support 32 a disvtancesuiicientto limit upward movement of the coil 3Q. When the normal gap exists between `flanged heads 35 and the support 32 there is no interference with the oscillating movement or the coil.

The primary or adjustable coil 2% provides a depending bracket 3l which is U-shaped at its lower. end, the vsame having threadedv engagement with-arotatable screw The screw 3&3 is Vsuitably fmounted for rotation in the .-.upstanding ange .Sit struck from the lsupporting plate .i2 and coil .-25 caribe adjustably positioned -with respect to-movable coil 35 by rotation or" said screw .38. The U-shaped end of bracket .3l applies .sufficienttension `upon `the screw threads to maintain the movable coilin its adjusted position.

The carrier arm e? is suitably secured to movable coil 3i) .in .depending `relation therewith whereby ,the carrier arm oscillates in accordance with similar movement of the-coil. 'Ihe magnets 43 .and @Il are suitably secured by the screw 55 to the terminal .end .of -saidcarrier arm .e2 and the structure ior -Xedly securing the magnets to the arm, see Figure 3, additionally provides resilient contactelements @it and Il?. Saidresilient contact elements are adapted to .engage eccentric abutment members :if and Epcsitionedon respective sides ,of ,the .carrier .arm in the vicinity of magnets .and fifi. 'Theabutments 't8 and 5) consist of eccentricmembers rotatably mounted inthe plate t2 .and by rotation of said members it ispossible to control the amplitude of movement of the carrier arm. When arm ft2 swings to the leftcontact ,element 4t .will engage .the abutment et and movement of .the arm in vthis left hand direction can be adjusted within limits by rotation cf said abutment 8. In a similar inanner when carrier arm 42 .swings in a direction toward the right contact element Il? willengage the abutment '5S and movement of the arm .in this direction can be adjusted .within limits .by rotation of the abutment.

.Apair of mercury switches provide therelay contacts ofthe present device, each .mercury switch'providing a normally open switch .Contact which is adapted to be actuated .into a closed position by its respective magnet carried by arm 42. The electric switches .are adapted to control t'he operation of a tap changer motor for varying the turn ratio on the regulating transformer, thus maintaining a substantially constant voltage in the `load circuit. In other applications ofthe device, however, only one mercury switch may be employed, such nas inthe aforementioned system of conveyor belt control. The mercury switch 52 is suitably supported by the member' 53 which is secured by screw 5t to bracket 55 bent from the metal of plate l2. The 'position of --switch 52 is fixed, the same being located to the left of the carrier arm, and the switch Contact provided thereby-being .actuated by magnet 43. A similar mercury switch 55 is located to the -right ofthe carrier varm and the switch contact provided by 'this switch is actuated Vby magnet 44. The member 51 supports the switch 56 in a manner providing for adjustment of the switch toward and from 52. For said adjustment a carriage 58 is provided, the same extending through a slot in bracket 59 and having the nut 60 threaded to the end thereof for securing member 51 to the bracket in a manner permitting adjustment of said member and thus the s-witch. The carriage 58 is adjustably supported by the threaded screw 6l which is suitably mounted for rotation, being suported by bracket. By rotation of screw 6l the carriage 58 can be moved in either a right or left hand direction and similar movement is imparted to switch 56.

The mercury switches 52 and 56 are of the capillary tube type such as disclosed and claimed in my Patent 2,325,785 granted August 3, 1943, :and entitled Enclosed Mercury Switch. The xed electrode 62 of mercury switch 52 is provided at its lower end with a capillary tube 63, which tube dips into the mercury pool at the bottom of the glass container 64. Said tube provides a meniscus of mercury as at 65 for contact by the movable electrode '86. Said movable electrode 66 includes the armature 6l vand the tension spring 68, one f end of which is fixed to the armature 61 for supporting the armature and the movable electrode 66, whereas the other end of the spring 6B is fixed to support 10. When armature 61 is attracted by magnet 43 the movable contact 66 is caused to move toward capillary tube 63 and eventually contact will be made between the same and the meniscus of mercury 65 provided by said capillary tube. This action of the movable contact will close an electric circuit connecting with terminals 1| and 'I2 of the mercury switch 52.

The construction of switch 56 is similar, the same including a iixed electrode I3 supporting at its lower end the capillary tube 'I4 which dips into the mercury pool at the base of the glass container 15 and provides a meniscus of mercury at 16. 'I'he movable electrode H additionally includes the armature 'I8 and the tension spring 80 having one end secured to the armature and its other end secured to support 8|. The switch 56 is provided with terminals 82 and 83 and when armature 18 is attracted by magnet 44 the movable electrode Tl closes the electric circuit by contact with the meniscus of mercury in the capillary tube 14.

It will be observed that the switch contacts are located on the respective sides of the magnet carrier arm and that said switch contacts are normally open, this being the normal position of the movable contact of the switch owing to the ten-sion imparted thereto by resilient parts 8S and 80. The switch contacts are closed by movement of the same toward each other and which is effected by the magnets carried by arm B2. However, the magnets will -actuate only one switch contact at a time so that when 66 is closed contact 11 is open and when the arm moves to the right to close contact TI it will be understood that -contact 66 will automatically open. The terminals of the respective switches are connected to the post-s in a manner as shown in Figure l, with the terminals H and 12 of switch 52 being connected to posts 22 and 23 and terminals B2 and 83 of switch 56 being connected to posts 23 and 25. When switch 52 is actuated to close, the circuit -connecting with the terminals H and 'I2 is energized and the same results in an increase in the voltage of the load circuit of the regulating transformer as is well known in the Cil cuit connecting with the terminals 82 and 83` is energized and -a decrease in the voltage of the load circuit results.

In this embodiment of the invention it is possible to adjust the primary coil 26 for an operating voltage ran-ging from forty to sixty-five volts. As described, the coil is moved toward or from movable coil 38 by turning the screw 38, the adjustment varying the gap between the coils. A particular voltage in the current traversing the primary coil 26 requires va particular position of the coil to insure operation of the relay switches. The total voltage change for effecting an opening of one switch and closing the other, may be adjusted in the present relay device to a minimum of three volts. Switches 52 and 56, as determined by the position of the abutment members 48 and 49 adjacent thereto, may each operate on a one volt change in the primary voltage. Switch 56 is supported by the adjustable carriage structure so that this switch may be adjusted for predetermined voltage conditions. When screw 6i is rotated to increase the distance between the switches the eiiect is to increase the spread as regards the fluctuations in the primary voltage such as will result in the opening of switch 52 and closing of switch 56. In making an adjustment of the carriage 58 it should be accompanied by an adjustment of the abutment 50 so as to increase the amplitude of movement of carrier arm 42 to maintain the proper relationship of the magnets with the switches for their most eiiicient and satisfactory operation.

Y Energization of the relay as a result of current flow in the primary coil 26 and flow of induced current in the movable coil 30, results in an increase in the temperature of the unit. This temperature increase together with the effect of ambient temperatures may result in a change in the resistance of the primary coil. With the device calibrated for a particular operation in response to a variation in voltage in the primary coil under normal operating conditions it is apf parent that with the change of a few volts effecting switch operation, a change in temperature from that prevailing at the time of calibration could produce operation of the device when not desired.

The invention provides means compensating for those temperature changes which tend to affect operation of the device at voltage values other than those for which it has been set. In other words, if under normal operating conditions the device is calibrated to operate the switch contacts over a predetermined voltage range, a change in voltage as a result of temperature changes will not produce an operation of said contacts owing to said compensating means. An extreme condition may be best exemplified by considering the diilerence in temperature between that representing normal operating temperatures and that prevailing when the device is energized cold after a period of inactivity. When cold the repelling force of coil 26, due to its low resistance, is greater than its repelling force when the coil attains its normal operating temperature. This is due to the fact that the temperature rise increases the voltage drop in the coil and so decreases the magnetic effect of the current flowing through the same. The result is that the force operating on movable coil 30 is correspondingly decreased. The compensating means of the invention compensates for temperature changes by Ameans foffa weight-suspended from i the mov- `vable coil by means of a ibi-.metallic element.

lbest `shown ink Figures .2 :and `5, the bimetallic strip 84 is suitably secured .to movable coil-30 so as to depend therefrom, vthe strip being located and having movement with the coil in thespace between plates I and I2. The threaded stud -85 is .xed to the lower depending end lof the vbi-metallicstripk and projects horizontally in a directiontoward the left as viewed in Figure 5. Th'eweight-SB is supportedby'the rotatablemember 181 which is threaded on 35 and .accordingly the weight can be positioned for securing the desired Voperation-of the compensating means by rotation of 8? which adjusts its position on 85. Said weight 86 is vprovided with'the fiber insert 88fand'the 'samelis retained on member 81 by the snapwasher 90. The bi-metallic element 84 isso constructed and the weight 86 -so balances themovable coil 30, that with-.a predetermined voltage'impressed on the primary coil. 26 and with normal operating temperatures prevailing, the carrier arm 42 is positioned bythe movable coil in .its repelled vstate withthe magnets t3! and Ml centered between the .switches with both switch contacts inopen position. When the voltage of the current -traversing lcoil`2i drops to a predetermined level, vswitch 52 is actuated to close since this voltage ldrop will reduce the repelling force on coil "30 and the carrier arm Willmove to 'the left. 'Upon Van increase in the primary voltage to a predetermined level the repelling force is increased Yto an Iextent causing movement of carrier arm "42 to the right whereby Aswitch -156 .is caused to close. 'Should a temperaturefcondition exist diiTering from that at the time of calibration;the'bimetallic element 84 will ilexUdue to the change in temperature to thereby shiftthe weight 86 so that'its action with respect to' movable rcoil 53B lwill compensate for such temperature change. For'example, should the temperature ofthe relay increase, the compensator 'will ex in .a direction toward the left to compensate 'fora reduction in therepelling force actingzon movable coil 30 and in asimilar manner, should the temperature Vof .the relay `drop, the bifmetallic element v.811 will .flex in a direction toward the right tocompensate. for Yan increase in the repelling force. The temperature'compensating .meansmay be adjusted over a vwide range andin accordance with the .invention the weight isloosely -supported by memberlto provide a dampening elect on the oscillating movementsr of .the movable coil. Y

llncompensatingfor the effect of temperature changes-upon theoperation of the relay,.due to energization of the relay and ambient temperatures, whereby to maintain a constant voltageat the center of distribution of a particular feeder, such compensation may be varied throughout a predetermined range of temperature, including atmospheric temperatures, so as to over compensate at various stages of temperature change tothe extent that under certain conditions transformer capacity may be increased within its design 'limitations Asis well known, transformer capacities are limited by their abiilty to dissipate heat generated under load demands and 'as affected'by weather conditions. Thus their capacityis `governed in part by the effect of therange of atmospheric temperatures through which the transformer will be subjected in use. Since the rate of transformer capacity is thus based with consideration to the highest temperatures to which-it may besubjected, it follows that at very low atmospheric temperatures, "when .increased dissipation of .heatilow'ers the transformer temperature, thetrans'former will be op'eratingbelow its-design capacity.

`In the use of electrical energyiffor heating'purposes and particularly withrespect to the :increasing use of the improved forms ofielectrical radiant heating units now makingtheir appearance on the market for houselheating, kit is `apparent that the load-demands of .such heating systems are greatest at a'time Whencold itemperatures prevail and which .have an effect upon the capacity Vof power transformers, constituting the source ofelectrical energy, to vpermit anincrease in their capacityiwithout Yexceeding Ytheir design limitations. Thus, there is availableffrom such transformers la ypotential power output .in cold weather in excess of its rated capacity, which increase under such `conditions could Vbe zused to meet electric heating demands.

In these situations where excessive demands upon transformer installations .are potentially existent and Vdirectly related to temperature ythe present invention 'may'incorporate the .compensating structure, so designe'das to be responsive to temperature changes, that control of lthe outgoing voltage ofthe transformer may befa'ccomplished to raise .or lower Vthe voltage las l-a direct result'of atmospheric temperature changes and in proportion tothe effect of said temperatures upon the capacity of the transformer within its designed limitations. l

'From the drawings and description preceding itis apparent that the bi-neta'llic compensator may be made so responsiveto temperatureconditions that as a result of `.changes .therein the weight may be shifted to require the voltage impressed upon the primary coil to begreater or less in order to cause such repulsion :of rth'e movable coil as 'will actuate 'the switch `contacts controlling the apparatus regulatingthe voltage output of thetransformer. lSince iloadfdeniand represents an ever increasing 'problem to lthe power company, the `present `improved voltage regulating relay oiers a means of satisfying ce1'- tain load demands without an expensive outlay of additional equipment.

Whether for the limited Ypurpose .of 7compensating suiiicientlyl within arange of temperature change 'tol'nullify the effect of such changes upon the operating values of the relay or 1in :the broader form such as to compensate tothe extent that the relay operating values 'are varied with changing temperatures, the present invention may provide for the accomplishment of 'either objective through proper design and selection of materials comprising the bi-metallic compensator. In either case, however, the sensitivity of the relay to variations in the operating voltage which effects the operation o`f either switch and one with respect to the other, remains the same, and as made adjustable by the abutment members e3 and 553 for the arm l2 and the adjustable carriage for switch 5.

The invention is not be limited to or by details of construction ofthe particular embodiment thereof illustrated by the drawings as "various other forms of the device will cf course be apparent to ythose skilled in the art withoutdeparting from the spirit of the invention or the scope of the claims.

What is claimed is:

l. In a relay forcontrolling an electric circuit, a pair of coils mounted upon a-core and-adapted forv energization `from a source of electrical en- 9 ergy, one'of said coils having a stationary position on the core with respect to the second coil, and said second coil being mounted for oscillating movement as a result of variations in the voltage of the current traversing the stationary coil, supporting means for the movable second coil comprising thin flexible spring members having connection to a support providing an edge fulcrum for flexing the spring members, a pair of electric switches disposed in spaced relation andl each switch providing a normally open switch contact, a carrier arm fixed to the movable coil and extending between the electric switches, magnetic means xed to the carrier arm on respective sides of the same, whereby the switch contacts of the electric switches are actuated by the magnetic means one at a time to cause them to close as the carrier arm is oscillated by movement of the movable coil, a resilient stop element also fixed to the carrier arm in associated relation with each of said magnetic means, and adjustable abutment posts located on respective sides of the carrier arm fcr engagement with the resilient stop elements to limit oscillating movement of the carrier arm in both directions.

2. In a voltage regulating device for controlling the voltage of an electric circuit, a repulsion type relay including an adjustable coil and a movable coil, said movable coil having movement as a result of voltage variations in the current traversing said adjustable coil, an adjustable member for varying the position of the adjustable coil with respect to the movable coil whereby to vary the spread as regards the variations in the voltage of the current traversing said adjustable coil required to eiiect actuation of said movable coil, supporting means for the movable coil comprising thin flexible spring members having connection to a support providing an edge fulcrum for flexing the spring members, a pair of electric switches disposed in spaced relation and each switch providing a normally open switch contact, a carrier arm xed to the movable coil and extending between the electric switches, magnetic means xed to the carrier arm on respective sides of the same whereby the switch contacts of the electric switches are actuated by the magnetic means one at a time to cause them to close as the carrier arm is oscillated by movement of the movable coil, and adjustable means including a carriage supporting one of said electric switches for movement toward or away from the other electric switch, whereby the amplitude of movement of the carrier arm for effecting actuation of the switch contacts thereof is varied.

3. In a relay for controlling an electric circuit, a pair of coils mounted upon a core and adapted for energization from a source of electrical energy, one of said coils having a stationary position on the core with respect to the second coil, and said second coil being mounted for oscillating movement as a result of variations in the voltage of the current traversing the stationary coil, supporting means for the movable second coil comprising thin flexible spring members having connection to a support providing an edge fulcrum for nexing the spring members, a pair of electric switches disposed in spaced relation and each switch providing a normally open switch contact, a carrier arm xed to the movable coil and extending between the electric switches, magnetic means fixed to the carrier on the respective sides of the same, whereby the switch contacts of the electric switches are actuated bythe magnetic means one at a time to cause them to close as the carrier arm is oscillated by movement of the movable coil, temperature compensating means for modifying the action of the movable coil to compensate for temperature changes, said compensating means including a biasing weight and a bi-metallic element securing the weight in depending relation to the movable coil, and adjustable means for adjusting the position of the weight with respect to the coil to thereby vary the modifying action of lthe weight on the coil.

4. In a voltage regulating device for controlling the voltage of an electric circuit, a repulsion type relay including an adjustable coil and a movable coil, said movable coil having movement as a result of voltage variations in the current traversing said adjustable coil, an adjustable member for varying the position of the adjustable coil with respect to the movable coil whereby to vary the spread as regards the variations in the voltage of the current traversing said adjustable coil required to effect actuation of said movable coil, supporting means for the movable coil comprising thin flexible spring members having connection to a support providing an edge fulcrum for flexingthe spring members, a pair of electric switches disposed in spaced relation and each switch providing a normally open switch contact, a carrier arm fixed to the movable coil and extending between the electric switches, magnetic means fixed to the carrier arm on respective sides of the same whereby the switch contacts of the electric switches are actuated by the magnetic means one at a time to cause them to close as the carrier arm is oscillated by movement of the movable coil, adjustable means including a carriage supporting one of said electric switches for movement toward or away from the other electric switch, whereby the amplitude of movement of the carrier arm for effecting actuation of the switch contacts thereof is varied, temperature compensating means for modifying the action of the movable coil to compensate for temperature changes, said compensating means including a biasing weight and a bi-metallic element securing the weight in depending relation to the movable coil, and adjustable means for adjusting the position of the weight with respect to the coil to thereby vary the modifying action of the weight on the coil.

5. in a voltage regulating relay for controlling the voltage of an electric current, the combination with an elongated metal core, of a primary coil in encircling relation with said metal core, a movable coil also in encircling relation with the metal core and positioned in associated relation with respect to the primary coil, means supporting the movable coil for limited oscillating movement as a result of voltage variations in the current traversing the primary coil, means for adjusting the position or the primary coil toward and away from the movable coil, a carrier arm fixed to and depending from said movable coil, magnetic means secured to the free end of said arm, an electric switch disposed on ea-ch side of the carrier arm and each switch providing a switch contact positioned for actuation by the magnetic means, an adjustable carriage supporting one of said electric switches whereby adjustment of the carriage varies the spaced relation between the electric switches, resilient stop elements fixed to the carrier arm, adjustable abutment posts located on respective sides of the carrier arm and adapted for contact by the resilient stop elements to limit the oscillating movement o f: thearrer arm. in; both. direct-ima. and come nensatinameans includngxa biasing. weight. and.

a iii-metallic, element securing; theY weight in; dependingrrelation to themovable coil, said compensatingr means modifyingv the action of the movable coil to compensate for temperature changes'zsuch as elect avchange in voltage ofthe current traversing the primary coil,

6. Ina voltageregulating relay for controlling thevoltageoan electric current, the combinationwith anelongated metal.;core;,of a primaryv coilin encirclingy relation with saidmetal core, 'al-,movable coil'. also in encirclingxrelation with the metall. core. and. positioned in associated relation. with respect. to theprimary coil, meanssupporte ingz-,the` movable-.coil.for-limited oscillating moveament,y asga result: ofvoltagevariations in the cur,-Y

rent'., traversing the, primaryV coil, means for adjust-ing` the position ofthe primary -coil toward and away. from the movablecoil, a carrier arm xedf to and: dependingqfrom saidl movable coil, magnetic means securedtothefree end of said arm, anzelectric switch disposed` on each side of the carrier arm.- and` each switch providing a switchconta-ct.. positioned for actuation by the magnetic means; anadjustablecarriage supporting onev ofv said. electric switches whereby. adjust4` ment-.of` the, carriage varies) the spaced. relation between the electric; switches, reilients toplel` ,Q ments; xed to the;v carrierv arm;A andpadjustablef; abutment postslocated on respectivesidesiof. the.

carrier-arm and adapted for contact by-the,resi1e= ient stop` elements to limit:theoscillatingfmovef ment oftheicarrier arm; in both directions.

IRAE. MCCABE:

REFERENCES; CITED.`

The following references are-'of'record in the le of thispatent:

UNITED STATES,V PATENTS."

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