US2094986A - Electric current responsive device - Google Patents

Description

Oct. 5, 1937.

D. JOURNEAUX 2,094,986

ELECTRIC CURRENT RESPONSIVE DEVICE Fi1ed Aug. 27, 1930 2 Sheets-Sheet l Invenzor Didier Joumeaux Attorney Oct. 5, 1937. D. JOURNEAUX 2,094,936

ELECTRIC CURRENT RESPONSIVE DEVICE Filed Aug. 27, 1930 2 Sheets-Sheet 2 Fig.4.

D/di Joumeaux By Patented Oct. 5, 1937 UNITED STATES PATENT OFFICE Didier Journaux, West Collingswood, N. J., assixnor, by mesne assignments, to Allis-Chalmers Manui'actuflnz Company,

Milwaukee,

Wis., a corporation or Delaware Application August 27,

17 Claims.

This invention relates to improvemnts in electro-magnetically operated, current responsive devices et the induction type and particulafly to relays actuated upon the occurrence of a variable current condition.

The usual electrical installation is provided with relays operating to disconnect the various portions of the installation upon the occurrence of overioads which may not only disturb operatien but actuaily destroy portions of the installation. When several units of machines are available, the eflect of such overloads may be minimized or avoided oy providing relays to connect the units in parallel to divide the overload among so manv units that the total overioad is so distributed as to constitute less than the permissible maximum ioad on each unit. As soon as the overioad has disappeared, the same relays should disconnect the superfluous units to maintain the units at the maximum efliciency. It is, however, necessary to use relays having a characteristic approximately following the permissible load capacity of a machine for the purpose of protecting the machine aainst overloads of long duration and of values lower than the setting of the overload relays used for disconnecting the machine on short-circuits. Such relays should, however, have a long-time characteristic and their operatien should vary not only in function of the degree of overioad but also as a function of the load carried by the machine previously to the overload. Thus, for example, if a machine is rated at 1000 kw. with an overioad guarantee of 50% for hour following continuous operation at the rated load, the relay used for protecting the machine must have a characteristic such that if the machine has carried 1000 kw. continuously and the load is then increased to 1500 kw., th e relay should disconnect aiter hour operation of such increased load.

However, if the machine has been carrying only 500 kw. continuously and the load is then increased to 1500 kw. the machine should be permitted to carry such increased load for more than the above pre-decermined time limit following continuons capacity loading, Thermal overload relays have been used heretoiore to provide the above protection against overloads of long duration and to open or close a switch element at certain temperatures and thereby operate to connect or disconnect the machine. Thermal relays are also used in automatic substations for the purpose of starting up additional machines when the total load exceeds the capacity of the ma- 1930, Serial No. 478,035

chines in operation and to shut down the additiona1 machines when the load is again reduced.

The thermal relay, however, has a number of disadvantages which result in inaccurate operation. One of such disadvantages is that the operation of the relay is dependent largely upon the ambient temperature, Thus if the relay is adjusted to close its contacts at a certain load and after a certain time-delay for a low ambient temperature, the relay will disconnect the machine at a lower current or after too short a time-delay if the ambient temperature is higher. Conversely, if the relay is adjusted for a higher ambient temperature, it will not function soon enough and the machine will be overloaded for a long time which may result in serions damage thereto. Another disadvantage of the thermal relay is the difllculty of adjustment for the required service conditions due to the fact that it is difficult to duplicate the bi-metaliic or other thermostatic element used on account of variations in the properties of the material and the workmanship of each element so that each relay must be adjusted and calibrated individuaily which process requires considerable time. Changes, during operation, in the properties 015 the material used in the thermostatic element likewise cause the relay to lose its adjustment aiter having been in operation for a certain length of time.

It is, therefore, among the objects of the present invention to provide a current responsive electro-magnetic device in which the time required for a movable element to take a predetermined position, in response to a change in the current impressed on the device, depends on the current value preceding the change in current.

Another object of the invention is to provide a current responsive electro-magnetic device responsive to values of current impressed thereon, for relatively long periods of time.

Another object 01 the invention is to provide a time element electro-responsive device, the action of which is not dependent upon the ambient temperature.

Another object of the invention is to provide a time element electro-responsive device in which an extensive range of movement of the moving element thereof insures a positive and accurate action of the device.

Another object of the invention is to provide a time element electro-responsive device which may be so proportioned as to have an inverse time characteristic or to have any other desired characteristic.

Another objeet of the invention is. to provide an electroresponsive device which may be used for indicating and for reeording continuously, a load demand and/or the maximum of a load demand.

Another objetzt of the invention is to provide an electro-responsive device for operating eontrol circuits in relation to an eleetrical load demand.

Anotlier objeet of the invention is to provide an electro-responsive device for disconnecting eleetric eurrent rectifiers of the vapor type from a load when the gas or vapor pressure in the rectifler becomes excessive.

Objects and advantages, other than those above set forth, will be apparent from the following description when read in connection with the aceompanying drawings in Which Figure 1 is a diagrammatic illustration of one embodiment 0;. the present invention partially showing the mechanieal construction of the device schematicafly and the electrical connections thereof, in diagram, partieularly,

Fig. 2 is a top eross-sectional view taken on the line AA cf Fig. 3 With a portion of the dise broken away to show the meehanieal structure of the device in greater detail,

Fig. 3 is a front elevation showing eonstructional details of the device,

Fig. 4 is a dagrammatie illustration similar to that shown in Fig. 1, but showing a modification thereoi,

Fig. 5 is a partial top view showing a modified contact-making arrangement,

Fig. 6 is a partial front elevation of the device showing the modified contacting arrangement,

Fig. 7 is a top crcss-sectional view taken on the line BB cf Fig. 8 and illustrating one means whereby the operating eharacteristics of the device may be ehanged, and

Fig. 8 is a partial front elevation further illus trating the means for varying the characteristics of the device shown in Fig. 7.

Reierring more particularly to the drawings by charaeters of reference, the reference numeral Il designates the core of an electro-magnet, the

coil 52 of which is connected with a source of constant alternating voltage designated at l3. The ocre il of the electro-magnet is formed with the pole pieces M and l6, each of which is provided with a shading ring H and [8 respectively et suitable shape as will be set forth hereinafter. Pale piece M is movably mounted on a spindle l9 suitably supported and extending through a portion of the core II. The spindle I9 carries a contact-making arrangement for suitably controlling circuits which arrangement inciudes a drum 21 having eonductive portions or inserts 22 connected With the common line 23 of the circuits to be controlled (only partially shown), the other lines of which are shown at 24 and 26 as resilient arms ca'rrying rollers moving in contact with the surface of the drum.

The mechanical details may be seen in Figs. 2 and 3 whieh-show that the movable pole piece [4 is rotated by a gear 21 mounted on the spindle l9 and in mesh With gears 28 transmitting the rotation of a driving pinion 29. The driving pinion is mounted on a suitably supported shaft 3l carrying a disc 32 rotating between pole pieces [4 and [6 and which is also under the influence of a second electromagnet ineluding a ocre 33 having pole pieces 34 and 36 with shading rings 31 and 38 and a coil 39 connected with 3. circuit of the apparatus to be controlled as at 4|. A pair of permanent magnets 42 and 43 are 59 a'rranged that the dise 32 passes between the pales thereof and the magnets therefor act, as is Wellknown, to obtain the proper speed characteristics of an induction type relay.

A leaf spring 44 is so'mounted on the core Il as to permit shading ring Il te engage therewith when the pole piece M has been rotated sufliciently thereby again causing engagement et gear 21 with the gears 28, whieh are disengaged during operation as will be expiained hereinafter, when the disc 32 again rotates in conter-clockwise direction. Pale piece 34 is rotatable by hand and is so adjusted as to be able to retain the characteflstics of the relay for difierent values of rated eurrent in conductors 4l by maintainlng the torque cf magnet 33 at its normal value for diierent eurrent ratings.

Assuming that the several portions of the entire relay structure are in the position shown in Fig. 3 and that coil l2 is excited, the shading rings H and 18 are then se loeated relative to each other that no torque is produced on the dise 32. Oeil 39 being excited in proportion to the eurrent in conductors M, causes disc 32 to rotate in a clockwise direction. But pole piece M 15 moved in counter-elockwise direction through the action of the gears 21, 28 and 29 thereby producing an increasing torque on the dise tending to rotate the same in a eountercloekwise direction due to the changing relative positions of the shading rings H and [8 which torque causes the dise to slow down until the pole piece M reaches a position at which the torque exerted by the action of coil 39 is exaetly counter-balanced by that of coil i 2. Any increase of eurrent in coil 39 repeats the above action until the equilibrium position is again reached and any decrease of eurrent will cause the reverse operation of that above to take place until equilibrium is again reached. The pole piece M thus has a definite equilibrium position for each value of current in the coil 39. The time required for pole piece I4 to rotate from one position to another in response to changes in eurrent in the source 4l depends not only on the magnitude of the current but also on the position of pole piece I4 prior to the current change and, therefore, on the preceding load eurrent passing through the current coil 39. The time required, therefore, for pole piece M to reach a certain position will be shorter if the preceding eurrent was high and longer if the preceding eurrent was low. The final position of pole piece M may be placed in any desired relation to the value of the current in conductors 4l merely by varying the shapes of pole pieces M, S and the shading rings I1, I8. Thus, the displacement cf pole piece M may be made proportional to the current in conductors 4! or to the square of the current, or to a more complicated function dependent on the purpose in view. In the first instance, a pointer l 5 afiixed to the drum 2l carried by pole piece M will be made to move over a uniformly sub-divided scale 20 calibrated to values proportional to the short time eurrent demand in the conductors M and means, such as a second pointer 25 rotatably supported on a braeket 30 and arranged to be actuated by a pusher 35, forming a part of pointer I5 to register the largest displacement of the pointer [5 to indicate the maximum demand. As is usual in so-called demand meters, the response of the moving element is not instantaneous and the rate at which changes in ourrent are followed may be adjusted, usually by var ying the position of the drag magnets 42, 43.

As the moving element approaches the position of equilibrium the speed thereo1 decreases according to a law determined by the physical dimensions of the pole pieces I4, I6 and the shading rings I1, [8. The displacement of the moving element is therefore completed only if the current is maintained in conductors 4l for a predetermined length of time. The time necessary for the contacts to close may be inversely proportional to such currents as is usual in an inverse time delay relay, or may follow an arbitrary law also depending on the shapes 015 the pole pieces I4, [S and of the shading rings I1, I8. If it is desired to control the operation of an electric current rectifier, by means of the relay heretofore described, the position of the polepiece [4 may be made to foilow the pressure in the rectifier tank which pressure should not exceed a pre-determined value in operation of the rectifler. It will be apparent that, if excessive current is maintained for a protracted length of time in conductors 41, or if coil I2 accidentally becomes de-energized, disc 32 will tend to rotate pole piece l4 continuaily without regard to the normal operating range thereof. Provision has thereiore been made to prevent overtravel in that, it will be observed that, a few of the teeth of gear 21 are removed and that the gear rim ls slit along a portion of its periphery adjacent the removed teeth and that the free portion is bent downwardly in such a manner that the gear 21 will disengage from the transmitting gear train 28. Gears 28 then rotate without engaging gear 21 and any wear on the gear 21 will occur on the beht portion of such gear and wear of the pinion will coeur on a portion not normally in engagement with gear 21. Such rotation is however limited by the removal of portion of the piece of gear 21 as above explained and pinion 28 then slips on the tooth of gear 21 with which it was last meshed. When normal conditions are restored, disc 32 will first rotate in a counterclockwise direction to return pole piece i4 to a corresponding position and gears 21 and 28 will re-engage under the action of the spring 44.

In the modified form of the system shown in Fig. 4, a current coil 39', connected in series with the coil 38, is arranged on the core Il adjacent the voltage coil l2 and in opposition therewith to reduce the action 01 coil 12 as the current increases in conductors 4l thereby accelerating the response of the disc to high current values in the conductors 4l and changing the characteristics of the relay.

A switching arrangement diifering from that previously illustrated and above descrlbed is shown in top view and in aide elevation in Figures 5 and 6 respectively. The drum 2| above described as attached to spindle 18 of the pole piece I4 is here replaced by a rotatable armature 46. The core il et the electro-magnet is provided with a member 41 shunting a portion oi! the flux therethrough. A suitable tilting armature 48 on which a mercury switch tube 49 is mounted, is pivoted on the shunt armature 41 in such position that the armature 46 may complete the circuit from armature 48 to core Il. When armature 48 has been sufliciently rotated to be directly under armature 48, the magnetic flux is forced to shlft in such manner as to flow through rotatable armature 46 so that armature 48 tilts thereby opening or closing the control circuits dependent on the arrangement of the contacts in the switch 49. Suitable stops are provided to limit the movement of tilting armature 48 thereby preventing interierence with the free movement ci rotating armature 48.

It is, of course, not essential that the movable pole piece be made as 8. portion of the core il and pivoted thereon as above described, but such pole piece may be made as shown in Fig. 7 which illustrates a movable pole piece comprising a rectangular frame 5l iilled with iron laminations 52. The trame o! pole piece 5l, 52 is however attached to the spindle l8 suitably mounted on the core Il and carrying the drum 2! or other contacting arrangements as immediately above described. There are also many other ways of varying the operating characteristics ot the electro-magnet il, l2 which will readily occur to one skilled in electro-magnet construction and operation and which need not, therefore, be here described in detail; .it being suflicient to mention means such as displacing the magnet relative to the disc, progressively shunting the air gap or the entire magnat, etc.

- It is evident from the above description that a structure according to the present invention may be provided with as long a. time delay as may be required by proper dimensioning 01 the electro-magnets and of the gears. It will also be seen that the operating time depends not only on the load current but also on the position 01 movable pole piece l4 which depends on the previous load current carried by the relay. It will 'be seen irom the above that the present relay has all of the elements necessary to give it the characteristics of a thermal relay without having the disadvantages inherent in such thermal relays. A relay of the character herein described and to be hereinaiter claimed is not affected by changing ambient temperatures because the operation thereof is independent of temperature. The operation of the relay being based on mechanical and electro-magnetic principles similar to those employed in watt-hour-meters and induction type relays, which are well-known to the art, the relay has a greater accuracy than a thermal relay. The characteristics of the relay can be determined accurately before construction thereof thus facllitating correct setting for any required condition and such characteristics or setting will not change with age as is the case in thermal relays. The relay will therefore retain its adjustments and its accuracy et operation.

Although but a few embodiments of the present invention have been illustrited and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

The invention claimed is:

1. In a deviceof the character described, the combination of an electro-magnet responsive to momentary load conditions of an electric circuit, a disc mounted to be rotated by said electro-magnet, a second electro-magnet having an element adjustablc to position in dependence upon the instant load conditions of said circuit in time in dependence upon prior load conditions thereof, and means for controlling an electric circuit, said disc and element cooperating to actuate said circuit controlling means.

2. In a device of the character described, the combination of an electro-magnet responsive to the load conditions of an electric circuit, a disc mounted to be rotated by said electro-magnet, a second electro-magnet having a movable pole acustable to position in dependence upon the instant load conditions of said circuit in time in dependence upon the prior load conditions thereof, and a gear train eonneeting said dise and the said movable pole, said gear train being formed to prevent over-travel of said dise and te disengage once per revolution of the movable pole of said electro-magnet to prevent over-travel of said dise, and means for causing reengagement of said gear train.

3. In a device of. the eharaeter described, the

combination of an electro-magnet responsive to the load current conditions of an electric circuit, 3. dise mounted to be rotated by said eleetromagnet, a second electro-magnet eooperating with the flrst said eleetromagnet to control the rate and extent of rotation of said dise in dependence upon prior and instant load conditions of said circuit, and means magnetieally operated by joint action of said dise and said second eIeetro-magnet to actuate a switch element.

4. In a device of the character described, the eombination of an electro-magnet responsive to the load current conditions of an electric circuit, a dise mounted to be rotated by said eieetro-magnet, a second eiectro-magnet, means ar;ranged on the said second electro-magnet for va'rying the rate of rotation of said dise by the flrst said eleetromagnet in dependence upon previous load conditions of said circuit, and means magnetically operated by joint action of said dise and the said second electro-magnet to efieet aetuation cf switch elements.

5. An eleetromagnetie responsive device comprising means exclusively responsive to the momentary ioad conditions of an eleetric circuit, au element adjusted to a position in dependence upon previoSioad conditions of the eleetric circuit, constant gvoltage responsive means cooperating with the flrst said means to adjust said element to a diierent position in dependenee upon the instant lad conditions of said circuit in time in de pendenee upon the previous and instant load conditions of the electric circuit, and switching means controlling the electric circuit, a portion of the second said means being movable by said element and eooperating therewith to operate said switching means.

6. An electro-magneticaliy responsive device comprising an electro-magnet exclusively responsive to the load conditions of an electric circuit, a dise inductively adjusted t0 position in dependence upon previous load conditions of the'eiectric circuit, a constant voltage responsive eleetro-magnet cooperating with the flrst said magnet to adjust said dise to a diierent position dependent upon the instant load conditions of said circuit in time in dependence upon the previous and instant load conditions thereof, and switching means for controlling the electric circuit, a portion of the second said eleetro-magnet being movable by said dise and cooperating therewith to operate said switching means,

7. In an electromagneticaliy operated device, the eombination of electro-magnetic means responsive to the load conditions of an electric circuit, a dise inductively adjusted to positions in dependence upon load conditions of the electric circuit prior to the load conditions thereof at any given moment, constant voltage responsive electro-magnetic means cooperating with the flrst said means to adjust said dise from said position to a difierent position in dependence upon the instant load conditions of said circuit in time in dependence upon the previous and instant load conditions of the electric circuit, the last said electro-magnetic means having a movable pole, and switching means for controiling the electric circuit. the movable pole of the second said electro-magnetie means being movable by said dise and cooperating therewith to operate said switching means.

8. In an eleetro-magnetieafly operated device, an electro-magnet responsive to the current conditions in an electric circuit, 9. dise mounted to be rotated by said eleCtro-magnet, a second electro-magnet having an element adjustable to 8. position in dependence upon current conditions in said circuit prior to the current conditions thereof at any given moment, the said element being operable t0 vary the rate of rotation of said dise by the flrst said eleetromagnet, and means eonneeting said dise with the said element, the said means preventing over-travel of said element.

9. In an eleetro-magnetically operated device, an eleetro-maenet responsive to the load conditions in aneleetric circuit, 8, dise mounted to be rotated by said eleetro-magnet, a second eleetromagnet having a movabl pole positioned by said dise responsive to load conditions in the eleetric circuit prior to the load conditions therein at any given moment, a gear train eonneeting said dise and said movable pole, said gear train being formed to prevent ovr-travel of said movable pole, and means operable by said movable pole to indicate operation of the device.

10. In a device of the eharacter described, an element rotatable in clockwise and eounterclockwise directions, an eleetro-magnet for imparting a torque to said element to cause movement thereof inone of said directions responsive to and in dependence upon a condition of an eleetrie circuit, a second eleetro-magnet for imparting a torque to said element to cause movement thereof in the other of said directions, and means aetuated responsive to movement of said element for varying the torque imparted thercto by the said second eleetro-magnet.

11. In a device of the charaeter described, a dise rotatable in two directions, an electro-magnet for imparting a torque to said dise to cause rotation thereof in one of said directions responsive to and in dependence upon a condition of an electric circuit, a second electro-magnet for imparting a torque to said dise te cause rotation thereof in the other of said direction, and means aetuated responsive to rotation of said dise for varying the torque imparted thereto by the said second eleetro-magnet.

12. In a device of the eharacter described, a. dise rotatable in two directions, an eIcetro-magnet operable to impart a torque to said dise to cause rotation thereof in one of said directions, a second eleetro-magnet operable to impart a torque to said dise to cause rotation thereof in the other said directions, and means aetuated by said dise for varying the torque imparted thereto by the said second electro-magnet.

13. In a device of the eharacter described, a dise rotatable in two directions, an eleetro-magnet operable to impart a torque to said dise t0 cause rotation thereof in one of said directions, a second eleetro-magnet operable to impart a torque to said dise te cause rotation thereof in the other said directions, and means aetuated by said dise operable to vary the rate of rotation thereof responsive to the torque imparted thereto by the flrst said electro-magnet.

14. In a device of the character described, an

element rotatabIe in clockwise and counterwise directions, electromagnetic means variably energized responsive to and in dependence on variations in conditions of an electric circuit for causing movement of said element in one of the said directions, electro-magnetically actuated means for causing movement of said element in the other of said directions, and means actuated responsive to movement of said element for varying the action of the second said means thereon.

15. In a device of the character described, an clament rotatable in clockwise and counterclock wise directions, electromagnetic means variably energized responsive to and in dependence on variations in the conditions of an electric circuit for imparting to said element 2. torque proportional to the energization of said means, electromagnetic means energized independently of said circuit for imparting a torque to said element tending to cause movement thereof in the other of said directions, and means actuated responsive to movement of said element in either of said directions for varying the torque imparted threto by the second said means.

16. A demand indicator comprising in combination, a pair of torque-producing mechanisms acting in opposition, one of said mechanisms having a torque proportional to the momentary value of the quantity the demahd for which is to be indicated and the other of said mechanisms having an adjustable torque, a member acted upon jointly by said torque-producing mechanisms and movable in response to unbalance in their actions, and movable means for adjusting the torque of said latter torque-producing mechanism, so connected to said movable member as to be moved thereby in a direction required to balance the action of said torque-producing mechanisms.

17. A demand indicator comprising in combination a pair of torque-producing mechanisms acting in conjunction, one of said mechanisms having an output proportional to the momentary value of a quantity, the demand for which is to be indicated, and the other of such mechanisms having an adjustable output, an adjustable device acted upon jointly by said torque-producing mechanisms arranged to have its adjustment varied when said mechanisms act thereon unequally, said device being 50 connected to said adjustable torque-producing mechanisms as to vary the output thereof in the direction required to equalize the action of said torque-producing mechanisms.

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