US1869222A - Electric protective relay - Google Patents

Description

y 1932-v H. LEBEN 1,839,222

ELECTRIC PROTECTIVE RELAY Filed No'v. 21. 1929 "-2 .2 V I w Z Patented July 26, 1932 UNlTED STATES PATENT prince HENRY IiEBEN, 0F HARROW, ENGLAND, ASSIGNOR TO A. BEYROLLE & COMPANY LIMITED, OF HEBB'URN-ON-TYNE, ENGLAND, A COMPANY OF GREAT BRITAIN ELECTRIC PROTECTIVE RELAY Application filed November 21, 1929, Serial No. 408,884, and in Great Britain December 27, 1928.

This invention relates to electric protective relays of the kind in which the relay contacts are operated after a time interval dependent on the ratio of two operating currents. number of such relays may be employed, for instance, at the ends of sections of the protect-- ed circuit, in what are known as impedance or like protective systems, the two operating currents applied to each relay being sochosen that the operational ratio of the relay is dependent upon the position of the fault on the protected circuit, whereby the relays nearest the fault will operate first, thus preventing the operation of the more remote relays.

Various constructional forms of impedance or like relay have been employed, amongst which may be mentioned those employing a measuring instrument energized from the two operating currents and a separate time-delay mechanism which drives a member at a definite speed through a distance determined by the measuring instrument. In such an arrangement the time-delay mechanism (generally in the form of clockwork) consumes a certain amount of power which is supplied from an external source, and consequently has to be wound up at more or less frequent intervals depending on the number of faults occurring in the vicinity of the relay, automatic winding equipment being as a rule too complicated and costly. Another difficulty experienced with such relays is their unreliability owing to the fact that the measuring instruments are not dead heat in action and are delicate, this being due to the limitations imposed by considerations of size ofthe relaysthemselves and of the current and potential transformers used for energizing them.

The present invention has for its object to provide a relay of the kind described employing separate time-delay mechanism wherein large external forces are available to ensure reliability and the necessity for periodical rewinding of the mechanism is obviated.

To this end the relay according to this invention comprises an electromagnetic system supplied with energy derived from the two operating currents, a regulating member therefor which is driven from an external source of power and whose movement to an operative position corresponding to the operational ratio of the relay determines the amount of energy stored in a time-delay A mechanism, and means whereby the electro magnetic system releases such stored energy when the regulating member reaches its operative position, the time-delay mechanism acting after a time interval dependent on the amount of energy stored therein to operate the contacs of the relay. Conveniently the energy stored in the time-delay mechanism is imparted thereto from the external source of power during the movement of the regulating member to its operative position, the elec tromagnetic system acting when such position is reached to disconnect the regulating member from the source of power whereby the energy is released to drive the time-delay mechanism.

The constructional form of the electromagnetic system and the manner in which it is controlled by the regulating member may vary, but the arrangement is preferably such that the resultant force exerted on the movable element of the electromagnetic system normally acts to restrain the element against operation but is so varied by the movement of the regulating member as to cause operation of the element when the regulating member reaches its operative position. Thus for instance, the movable element of the electromagnetic system may be subjected to restraining and operating forces derived from the two operating currents, the regulating memher acting to vary the relative action of the two forces on the element or the relationship between one or each of the forces and the current from which it is derived. Alternatively the movable element may be subjected to a torque due to the interaction of two or more magnetic fluxes derived from the two operating currents, the regulating mem her acting to vary the relationship between one or each of the fluxes and the operating currents. With either of these arrangements a preferred form of control is for the regulating member to vary the amount of resis tance in circuit with one or more of the windings of the electromagnetic system.

When installed 011 the circuit to be protected, the relay is preferably normally out of circuit and only brought into circuit when required by an instantaneously acting initiating contactor responsive to fault conditions in the protected circuit, this contactor acting to establish an operative driving connection between the external source of power and the regulating member. The windings of the electromagnetic system may be normally connected in circuit or alternatively may also also be brought into circuit when the initiating contactor operates. The operative driving connection may conveniently comprise an electricmotor or like device energized from the source of power and driving against the action of a spring an arm abutting against the regulating member, the energy thus imparted to the spring, which forms part of the time-delay mechanism, being utilized (when the motor is deenergized by the operation of the electromagnetic system) to drive the arm back again at a predetermined rate to its" initial position leaving the regulating member in its operative position, the operative contacts of the relay being actuated when the arm reaches its initial position. The resetting of the various parts of the relay may be brought about by the deenergization of the initiating contactor when the fault has been cleared either by the relay itself or by another protective relay on the protected circuit.

It will be appreciated that the arrangement according to the invention, in addition to rendering periodic rewinding of the time-delay mechanism unnecessary, enables large forces to be employed to control the movements, whereby the re ulating member can be moved to its operative position with a negligible time-delay, the movement yet being dead beat so that great accuracy in time discrimination is ensured. In order to obtain substantially instantaneous operation for faults near the relay with time discrimination for the more remote faults, the regulating member may be initially set in such a position that when the operational ratio has a value below that corresponding to such initial setting the relay will operate immediately after the initiating contactor has operated.

Theinvention may be carried into practice in various Ways, but two preferred arrangements of relay according thereto are illustrated diagrammatically in the accompanying drawing, in which Figures 1 and 2 show one arrangement, and.

Figure 3 shows an alternative form of electromagnetic system for use in the ar rangement of Figure 1.

These arrangements will be described with reference to a protective relay forming one of a number of similar relays disposed respectively at the ends of sections of an electrio power line to be protected, each relay being operative after a time interval dependent on the ratio of two operating currents, this ratio in turn being dependent on the distance of the fault from the relay. The operational ratio may be the impedance ratio V/I or preferably the reactance ratio V sin /I where V is the voltage, I the current and the phase angle, but other ratios may be employed, ifdesired. rents are derived from suitably arranged cur rent and potential transformers, indicated at A and A in Figure 1.

Each relay comprises an electromagnetic system for measuring the operational ratio, a regulating member therefor, a driving mechanism for the regulating member supplied with power from a D. C. battery B or other source, and a time-delay mechanism. The relay is normally disconnected and is only brought into circuit when a fault occurs, byv

means ofan instantaneously actinginitiating contactor C operative in any of the well known manners on the occurrence of a fault and acting to control the supply of power from the battery B to the driving mechanism.

In the arrangement of Figures 1 and 2 the electron agnetic system comprises a pivoted contactoperating lever D on which two coils E E exert opposed forces. For convenience of description these coils E E will be termed the voltage coil and'the current coil respectively, although if an operational ratio other than the impedance ratio is employed the two coils will be energized in accordance with other functions of the voltage and the current. Shunted across the current coil 13 is a variable resistance F, Whose magnitude is controlled by a regulator arm G. Normally the voltage coil 13 exerts a greater force on the lever D than the current coil E but movement of the regulator arm G across the resistance F increases the energization of the current coil E until its force overcomes that of the voltage coil E, whereupon the lever D moves to open a set of normally closed contacts D and to close a set of normally open contacts D The normally closed contacts D of the lever D are connected in series with, contacts C on the initiating contactor C, which are closed when thecontactor operates, to control the supply circuit. from the battery B to the operating coil "of a solenoid H whose core acts to rock a driving arm J mounted on a rotatable spindle K. Alternatively the sole: noid H may be replaced by a small electric motor whose rotor is mounted on the spindle K carrying the driving arm J. The driving arm J is provided with a roller J abutting against the regulator arm G. Thus when the initiating contactor C closes its contacts C the solenoid H is energized and drives the arm J against the action of a spring L until the regulator arm G has moved The two operating curto its operative position, at which it causes the lever D to open its contacts D and deenergize the solenoid H. The energy meanwhile stored in the spring L then tends to return the arm J to its initial position, but

is prevented from doing so instantaneously by means of suitable delaying mechanism con nected to the spindle K.

This delaying mechanism may be arranged in various ways, but in the example illustrated the spindle K carries a ratchet wheel K with which engages a pawl K carried by a gear wheel K loosely mounted on the spindle K. This gear wheel K meshes with a pinion l\ whose spindle M is connected to a time-lag device M, which may take the form for example of an escapement mechanism or of a governor driving against a friction disc. Tl us the arrangement is such that the driving arm J returns to its initial position at a definite timed rate, and when that position is reached it closes contacts J which together with the normally open contacts D of the lever D control (either directly or as shown through an auxiliary relay N) the tripping circuit for a circuit-breaker in the protected circuit.

During the return movement of the driving arm J, the regulator arm G remains in its operative position, but suitable mechanism is provided for resetting the arm G when the fault is cleared. In the example illustrated this resetting mechanism comprises a small electromagnet operating a pawl 0 engaging with a ratchet wheel 0 carried by the arm G, the arm G being biasedtowards its zero position by a spring G The circuit to the electromagnet O is controlled by normally closed contacts C on the initiating contactor C and by contacts G which are closed in all positions of the regulator arm G other than the initial rest position.

Thus the regulator arm G is normally held against a zero stop G by the spring G and holds open the contacts G VJhen the initiating contactor C operates the driving arm J drives the regulator arm G in the manner above described to its operative position in which it is held by the pawl O and ratchet wheel 0 while the driving arm J is returning to its initial position. Whenthe fault is cleared (whether by the relay itself or by some other relay on the protected circuit) ,the initiating contactor C is deenergized and closes its contacts C This energizes the electromagnet O which releases the pawl O- and allows the regulator arm G to return to its initial position, when the opening of the contacts G deenergizes the electromagnet The driving force of the solenoid H and the opposing force of the spring L are made large in relation to the inertia of the moving parts, so that the forward movement of the regulator arm G to its operative position is performed in so short a space of time as to be negligible in comparison with the time delay of the relay. Moreover (since the torque exerted on the spindle K changes suddenly from a large forward torque equal to the difierence between the solenoid torque and the sprin torque into a large backward torque due to the spring L alone) the movement is dead-beat in action and the duration of the time delay, which depends upon the extent of forward travel of the driving arm J and regulator arm G, is determined with great accuracy.

The accurate determination of the time delay is of importance in order to ensure proper discrimination between the various relays on the protected circuit, i. e. to ensure that the relay nearest to the fault will operate before the more remote relays, theclearing of the fault due to the operation of one relay at once deenergizing the initiating contactors of the other relays and causingsuch relays to reset themselves. Since however it is desirable to reduce the time delay of the relay as much as possible consistent with adequate discrimination, it is preferable to arrange that each relay will operate instantaneously for faults on the major portion of the protected secv tion, the time function being operative only for more remote faults. This can be readily obtained with the relay above described by initially setting the regulator arm G at a position corresponding to its operative position for a fault, say, three-quarters of the length of the section from the relay. The zero position of the driving arm J is correspondingly adjusted and the speed of the return movement of the arm J allowed by the delaying mechanismis made slower, in order to provide adequate time discrimination for a fault just beyond the remote end of the section. This arrangement will operate in the manner above described with the exception that for faults within the instantaneous Zone the tripping circuit will be completed by the operation of the contacts C and D of the initiating contactor C and the lever D before the arm J has started from its zero position, whilst for faults beyond that zone the time delay will be dependent on the distance of the fault from the remote end of the Zone.

The desired instantaneous operation can alternatively be obtaii d over practically the whole section by setting the regulator arm G to a position corresponding to its operative position for a fault at the remote end of the section, and leaving the zero of the driving arm J at its original position. In this case for faults within the section the relay will operate instantaneously as above described, but for faults beyond the end of the section the arm J will be driven against the spring L for the appropriate distance before it comes into driving engagement with the regulator arm (1''.

The arrangement of the electromagnetic system and the manner in which it is controlled by the regulating member G may be modified in various ways. Thus the regulating member may act in other ways to vary the magnitude of the current supplied to the current coil E or may vary the magnitude of the current supplied to the voltage coil E, that supplied to the current coil E then bearing constant relationship to the operating current from which it is derived.

It will be appreciated that in all these arrangements the pivoted contact-making lever 1) may be replaced by any other mechanical contact-maning system to which two opposed forces can be applied in such a manner that the regulating member G acts to vary the resultant force so it changes from a restraining force into an operating force.

In the arrangement shown in igure 3 the movable element of the electromagnetic system is subjected to a single torque due to the interaction of two or more magnetic fluxes derived from the operating currents, one or more of such fluxes being varied by the regulating member relatively to the current or currents from which it is derived. Thus two magnetic core members i Q may be employed one carrying two windings (a voltage winding P and a current winding P and the other a single winding current winding Q the movable element, which may consist of a disc R or like element passing between the poles of the two fixed core members P Q5, being operated by the interaction of the resultant flux in the first core member P with the flux in the second core member Suitable means are inserted in the circuits of the windings to ensure the proper phase relationships between the currents supplied to the three windings. In the example illustrated a large swamping resistance S is connected in series with the voltage winding P to ensure that the current in that winding is in phase with the applied voltage and that the flux due to the winding P does not change in phase on alteration oi"- the variable resistance F (which in the case illustrated is shown in the circuit of the voltage winding), and another resistance S is connected across the current winding Q for phase-shitting purposes. In this way the relay characteristic is made to depend on the reactance ratio V sin /l, but other ratios may readily be obtained with other phase-shifting devices. The arrangement of the variable resistance F in the circuit of the voltage winding P is given by way of example, and this resistance may be in the circuit ofthe current windings in a manner analogous to th shown in igure 1.

With this arrangement, it should be made clear that the torque on the disc B is produced by the interaction ot the fluxes in the core members P and Q and that these core members do not exert separate torques on the disc. Thus if either member were removed, there would be no torque exerted on the disc at all.

The flux in the core member P is proportional to the vectorial sum (or difi'erence) of the currents flowing in the windings P and P Since these are respectively energized by the current I and the voltage V and since the desired phase relationship between these two quantities is ensured in the manner above referred to, the flux in the core member P is proportional to 701 V sin The flux in the core member Q is propor tional to the current I. The torque T on the disc R is proportional to the product of the two fluxes and is expressed by the equation T=c(/cZ-V sin qb). I where 0 and 7c are constants, i. e. T==c7cZ cVl sin 5. The expression for the torque thus consists of two terms of opposite sign, and the relay operates its contacts when the first term exceeds the second term, the movable element being held against a stop so long as the second term exceeds the first. The movement of the regulating member G gradually reduces the second term, and the relay finally operates as soon as the torque changes sign, i. e. as soon as the torque changes from a restraining torque to an operating torque, this taking place at the moment when the two terms in the expression are equal, so that the relay characteristic depends on the reactance ratio V sin qS/I, as above mentioned.

In each of the modifications above mentioned, the regulating member G is preferably initially set to an appropriate position in order to give substantially instantaneous relay operation for faults occurring in the major portion of the protected section and the desired time discrimination for more remote faults.

It will be appreciated that a. relay arranged according to the present invention has the further advantage that it can readily be adapted to give an indication of the position. of the fault by fitting a loose pointer on the regulating member G, this pointer being arranged to remain in the operative position of the regulator member after the other parts of the relay have been reset. Such an arrangement is indicated in Figure 1, wherein the loose pointer is driven over a suitably calibrated scale l/V by a projection X on an arm X driven through a parallel linkage by the regulating member G. The pointer W carries a ratchet wheel W with which a spring-pressed pawl engages, whereby the pointer can only move in one direction, the pawl being withdrawable from the ratchet wheel for resetting purposes by means of a handle W Thus every relay in the vicinity of the fault, except that (if any) which has operated instantaneously, can be made to give an indication of the exact position of the fault, since its regulating member will in any case already have reached the operative position before the fault is cleared.

The foregoing arrangements have been described by way of example only, and it will be understood that the invention can be carried into practice in other ways.

What I claim as my invention and desire to secure by Letters Patent is 1. An electric relay arrangement for the protection of an electric circuit including in combination cont-acts contro ling the protected circuit, an electromagnetic system comprising windings supplied with currents derived from the protected circuit and a movable member electro nagnetically controlled thereby, a regulating member controlling the electro-magnetic system, means for driving the regulating member from an initial position to an operative position, an energy storing device, a time-delay mechanism associated with such device, means whereby the movement of the regulating member causes energy to be stored in the device, means whereby the movable member of the electro-magnetic sys tem acts when the regulating member reaches the operative position to release the energy stored in the device, and means whereby such released energy under the control of the time-delay mechanism acts to operate the relay contacts after a time interval dependent on. the amount of energy stored in the device.

2. An electric relay arrangement for the protection of an electric circuit including in combination contacts controlling the protected circuit, an electro-magnetic system com prising windings supplied with currents derived from the protected circuit and a movable member electro-magnetically controlled thereby, a regulating member controlling the electro-magnetic system, a source of power, means whereby the regulating memher is driven by such source from an initial position to an operative position, an energystoring device, a time-delay mechanism associated with such device, means whereby energy derived from the source of power is stored in the device, means whereby the amount of such stored energy is rendered dependent on the extent ot the movement of the regulating member, means whereby the movable member of the electro-magnetic system acts when the regulating member reaches the operative position to disconnect the regulating member from the source of power thereby determining the extent of the movement of the regulating member, and means whereby the energy stored in the device is released when the regulating member is disconnected and acts under the control of the time-delay mechanism to operate the relay contacts after a time interval dependent on the amount of energy stored therein.

3. An electric relay arrangement for the protection of an electric circuit including in combination contacts controlling the protected circuit, an electro-magnetic system comprising a movable member and windings so supplied with currents derived from the protected circuit as to exert on the movable member a resultant force normally tending to restrain the member against operation, a regulating member, a source of power, means whereby the regulating member is driven by such source from an initial position, means whereby the regulating member so controls the electro-magnetic system that the resultant restraining force on the movable member progressively decreases as the regulating member moves away from its initial position, means whereby when the restraining force passes the zero value and changes to an operating force'the movable member acts to disconnect the regulating member from the source of power, an energy-storing device, a time-delay mechanism associated with such device, means whereby energy derived from the source of power is stored in the device in accordance with the extent of the movement of the regulating member, and means whereby when the regulating member is disconnected from the source such stored energy is released and acts under the control of the time-delay mechanism to operate the relay contacts after a time interval dependent on the amount of energy stored in the device.

4. An electric relay arrangement for the protection of an electric circuit including in combination contacts controlling the protected circuit, an electro-magnetic system comprising windings supplied with currents derived from the protected circuit and a movable member electro-magnetically controlled thereby, a regulating member controlling the electro-magnetic system, a source of power, a spring, a time-delay mechanism associated with the spring, an arm abutting against the regulating member, a driving connection through which. the source of power drives the arm against the action of the spring thereby also driving the regulating member, means whereby the movable member of the electromagnetic system acts when the regulating member reaches an operative position to break the drivin connection and thus allows the spring to drive the arm back again to its initial position at a predetermined rate controlled by the time-delay mechanism, and means whereby the relay contacts are actuated when the arm again reaches its initial position.

5. An electric relay arrangement for the protection of an electric circuit including in combination contacts controlling the protected circuit, an electro-magnetic system comprising a movable member and windings so supplied with currents derived from the protected circuit as to exert on the movable member a resultant force normally tending to restrain the member against operation, a regulating member, a source of power, a spring,a time-delay mechanism associated with the spring, an arm abutting against the regulating member, a driving. connection through which the source of power drives the arm against the action of the spring thereby also driving the regulating member, means whereby the regulating member so controls the electro-magnetic system that the resultant restraining force on the movable member progressively decreases as the regulating member moves away from its initial position, means whereby when the restraining force passes the zero value and changes to an operating force the movable member acts to break the driving connection and thus allows the spring to drive the arm back again to its initial position at a predetermined rate controlled by the time-delay mechanism, and means whereby the relay contacts areactuated when the arm again reaches its initial position.

6. An electric relay arrangement for the protection of an-electric circuit including in combination contacts controlling the protects ed circuit, an electro-magnetic system comprising windings supplied withcurrents derived from the protected circuit and a movable member electro-magnetically controlled thereby, a variable-resistance in the energizing circuit of one of'the'windings of the electro-magnetic system, a regulating member controlling such resistance, a source of power, means whereby the regulating member is driven over the resistance by the source of power from an initial position toan operati ve position, an energy-storing device, a timedelay mechanism associated with such device, means whereby anamount of energy derived from the source of power and dependent on the extent of themovement of the regulating member is stored inthe device, means where by the movable member of the electro-magnetic system acts when the regulating member reaches the operative position to release the energy stored in the device, and means whereby such released energy under the-con trol of the ti1nedelay mechanism acts to'operatethe relay contacts after a time interval dependent on the'amount of energy stored in the device.

7. An electric relay arrangement for the protection of an electric circuit including in combination contactscontrolling the protected circuit, an electro-magnetic system comprising a movable member and windings so supplied with currentsderived from the protected'circuit as to exert on the movable mem ber a resultant force normally tending to restrain the member against operation, aregulating member, a source of power, a variable resistance in the energizing circuit of one of the windings of the electro-magnetic system controlled by the regulating member, means whereby the regulating member is.

driven over the resistance from an initial position by the source of power, means whereby when the restraining force onthe movable member changes to an operating force as the result of the variation in the resistance due to the movement of the regulating member the movable member acts to disconnect the regulating member from the source of power, an energy-storing device, a time-delay mechanism associated with such device, means whereby energy derived from the sourceof power is stored. in the device in accordance with the extent of the movement of the regulating member, and means whereby when the regulating member is disconnected from the source such stored energy is released and acts under the control of the time-delay mechanism to operate the relay contacts after a time interval dependent on the amount of energystored in the device.

8; An electric relay arrangement for the protection of anelectric circuit including in combination contacts controlling the protected circuit, an electro-magnetic system. comprising a pivoted lever and two windings respectively supplied with currents derived from the protected circuit and exerting opposed electro-magnetic forces on the lever so as normally to restrain the lever against op eration, a regulating member, a source of power, means whereby the regulating member is driven from an initial position-by. such source, means whereby the regulating member so controls the electro-magnetic system that the resultant restraining force on the lever progressively decreases as the regulating member moves away from its initial position, means whereby when therestraining force passes the zero value and changes to an operating force the lever rocks about its pivot and thereby disconnects the regulating member from the source of power, an energystorin g device, a time-delay mechanism associated with such device, means whereby energy derived from the source of power is stored in the device in accordance with the.

extent of the movement of the regulating member, and means whereby when the regulating member is disconnected from the source such stored energy is released and acts under the control of the time-delay mechanism to operate the relay contacts after atime interval dependent on the amount of energy stored in the device.

9. An electric relay arrangement for the protection of an electric circuit, including in combination contacts controlling the pro tected circuit, an electro-magnetic system comprising a pivoted lever and two windings respectively supplied with currents derived from the protected. circuit and. exerting opposed electro-magnetic forces on the lever so as normally to restrain the lever against operation, a variable resistance in the energizing circuit of one of the windings, a regulating member controlling such resistance, a source of power, means whereby the regulating member is driven from an initial position over the resistance by such source of power thereby decreasing the resultant restraining force on the lever, an energy-storing device, a time-delay mechanism associated with such device, means whereby an amount of energy derived from the source of power and dependent on the extent of the movement of the regulating member is stored in the device, means whereby when the resultant restraining force on the lever passes the Zero value and changes to an operating force the lever rocks about its pivot and thereby releases the energy stored in the device, and means whereby such released energy acts under the control ofthe time-delay mechanism to operate the relay contacts after a time interval dependent on the amount of energy stored in the device.

10. An electric relay arrangement for the protection of an electric circuit, including in combination contacts controlling the protected circuit, an electro-magnetic system comprising windings supplied with currents derived from the protected circuit and serving to produce magnetic fluxes and a movable member subjected to a torque due to the interaction or" such fluxes, a. regulating member controlling the relationship between the fluxes and the currents derived from the protected circuit, means for driving the regu lating member from an initial position to an operative position, an energy-storing device, a time-delay mechanism associated with such device, means whereby the movement of the regulating member causes energy to be stored in the device, means whereby the movable member oi the electro-magnetic system acts when the regulating member reaches the operative position to release the energy stored in the device, and means whereby such released energy under the control of the timedelay mechanism acts to operate the relay contacts after a time interval dependent on the amount of energy stored in the device.

11. An electric relay arrangement for the protection of an electric circuit, including in combination contacts controlling the protected circuit, an electro-magnetic system comprising windings supplied with currents derived from the protected circuit and serving to produce magnetic fluxes and a movable member subjected to a torque due to the interaction of such fluxes such torque normally tending to restrain the member against operation, a variable resistance in the energizing circuit of at least one of the windings of the electro-magnetic system, a regulating member controlling such resistance, a source of power, means whereby the regulating member is driven over the resistance from an initial position by the source of power, means whereby when the restraining torque on the movable member changes to an operating torque as the result of the variation in the resistance due to the movement of the regulating member the movable member acts to disconnect the regulating member from the source of power, an energy-storing device, a time-delay mechanism associated with such device, means whereby energy derived from the source oi power is stored in the device in accordance with the extent of the movement of the regulating member, and means whereby when the regulating member is disconnected from the source such stored energy is released and acts under the control of the time-d lay mechanism to operate the relay contacts after a time i terval dependent on the amount of energy stored in the device.

12. An electric relay arrangement for the protection of an electric circuit, including in combination contacts controlling the protected circuit, an electromagnetic system comprising windings and movable member electromagnetically controlled thereby, means whereby two operating currents derived from the protected circuit are supplied to such windings, a regulating member controlling the electromagnetic system, means for driving the regulating member from an in itial position to an operative position, an energy-storing device, time-delay mechanism associated with such device, means whereby the movement of the regulating member causes energy to be stored in the device, means whereby the movable member of the electromagnetic system acts when the regulating member reaches the operative position to release the energy stored in the device, and means whereby such released energy under the control of the timedelay mechanism acts to operate the relay contacts after a time interval dependent on the amount of energy stored in the device, the arrangement of the electromagnetic system and the control exercised thereon by the regulating member being such that the extent of the movement of the regulating member and therefore also the time-delay of the relay is lependent on the ratio of the two operating currents.

18. An electric relay arrangement for the protection of an electric circuit, including in combination contacts controlling the protect ed circuit, an electromagnetic system comprising windings and a movable member means whereby two operating curents de rived from the protected circuit are so supplied to the windings as to cause them to exert on the movable member a resultant force normally tending to restrain the member against operation, a regulating member, a source oi power,'means whereby the regulating member is driven by such source from an initial position, means whereby the regulating member so controls the electromagnetic system that the resultant restraining force on the movable member progressively decreases as the regulating member moves away from its initial position, means whereby when the res'tr 'ning force passes the Zero value and changes to an operating forcev the movable member acts to disconnect the regulating member from the source of power, an energystoring device, a time-delay mechanism associated with such device, means whereby energy derived from the source of power is stored in the device in accordance with the extent of the movement of the regulating member, and means whereby when the regu lating member is disconnected from the source such stored energy is released and acts under the control of the time-delay mechanism to operate the relay contacts after a time interval dependent on the amount of energy stored in the device, the arrangement of the electromagnetic system and the control exercised thereon by the regulating member being such that the extent of the movement of the regulating member and therefore also the time-delay of the relay is dependent on the ratio of the two operating currents.

14. An electric relay arrangement for the protection of an electric circuit, including in combination contacts controlling the protected circuit, an electromagnetic system comprising windings and a movable member electromagne ically controlled thereby, means whereby two operating currents derived from the protected circuit are supplied to such windings, a regulating member con trolling the electromagnetic system, a source of power, means whereby the regulating member is driven by such source from an initial position to an operative position, an energy-storing device, a time-delay mechanism associated with such device, means whereby energy derived from the source of power is stored in the device, means whereby the amount of such stored energy is rendered dependent on the extent of the movement of the regulating member, means whereby the movable member of the electromagnetic system acts when the regulating member reaches the operative posit-ion to disconnect the regulating member from the source of power thereby determining the extent of the movement of the regulating member, means whereby the energy stored in the device is released when the regulating member is disconnected and acts under the control of the time-delay mechanism to operate the relay contacts after a time interval dependent on the amount of energy stored therein, an in stantaneously acting initiating contactor responsive to fault conditions in the protected circuit, and means whereby such contactor establishes the operative driving connection between the source of power and the regulat ing member which is broken by the movable member of the electromagnetic system when the regulating member reaches its operative position, the arrangement of the electromag netic system and the control exercised thereon by the regulating member being such that the extent of the movement of the regu lating member and therefore also the timedelay of the relay is dependent on the ratio of the two operating currents.

15. An electric relay arrangement for the protection of an electric circuit, including in combination contacts controlling the protected circuit, an electromagnetic system comprising windings and a movable member,

means whereby two operating currents derived from the protected circuit are so supplied to the windings as to cause them to exert on the movable member a resultant force normally tending to restrain the member against operation, a regulating member, a source of power, a variable resistance in the energizing circuit of one of the windings of the electromagnetic system controlled by the regulating member, means whereby the regulating member is driven over the resistance from an initial position by the source of power, means whereby when the restraining force on the movable member changes to an operating force as the result of the variation in the resistance due to the movement of the regulating member the movable member acts to disconnect the regulating member from the source of power, an energy-storing device, a time-delay mechanism associated with such device, means whereby energy derived from the source of power is stored in the device in accordance with the extent of the movement of the regulating member, means whereby when the regulating member is disconnected from the source such stored energy is released and acts under the control of the time delay mechanism to operate the relay contacts after a time interval dependent on the amount of energy stored in the device, an instantaneously acting initiating contactor responsive to fault conditions in the protected circuit, and means whereby such contactor establishes the operative driving connection between the source of power and the regulating member which is broken by the movable member of the electromagnetic system when the regulating member reaches its operative position, the arrangement of the electro-magnetic system and the control exercised thereon by the regulating member being such that the extent of the movement of the regulating member and therefore also the time-delay of the relay is dependent on the ratio of the two operating currents.

16. An electric relay arrangement for the protection of an electric circuit, including in combination contacts controlling the protected circuit, an electromagnetic system comprising windings and a movable member electromagnetically controlled thereby, means whereby two operating currents derived from the protected circuit are supplied to such windings, a regulating member conmember is driven by such source from an 1n1t1al posltionto an operative pos1t1on, an

energy-storing device, a time-delay mechanism associated with such device, means whereby energy derived from the source of power is stored in the device, means whereby the amount of such stored energy is rendered dependent on the extent of the movement of the regulating member, means whereby the movable member of the electromagnetic system acts when the regulating member reaches the operative position to disconnect the reg ulating member from the source of power thereby determining the extent of the movement of the regulating member, means whereby the energy stored in the device is released when the regulating member is disconnected and acts under the control of the time-delay mechanism to operate the relay contacts after a time interval dependent on the amount of energy stored therein, an instantaneously acting initiating contactor responsive to fault conditions in the protected circuit, means whereby such contactor establishes the operative driving connection between the source of power and the regulating member which is broken by the movable member of the electromagnetic system when the regulating member reaches its operative position, and means whereby the deenergization of the initiating contactor when the fault has been cleared, either by the relay itself or by another protective relay on the protected circuit, causes the parts of the relay to be reset to their initial positions, the arrangement of the electromagnetic system and the control exercised thereon by the regulating member being such that the extent of the movement of the regulating member and therefore also the time-delay of the relay is dependent on the ratio of the two operating currents.

17 An electric relay arrangement for the protection of an electric circuit, including in combination contacts controlling the protected circuit, an electromagnetic system comprising windings and a movable member, means whereby two operating currents derived from the protected circuit are so supplied to the windings as to cause them to exert on the movable member a resultant force normally tending to restrain the member against operation, a regulating member, a source of power, a spring, a time-delay mechanism associated with the spring, an arm abutting against the regulating member, a driving connection through which the source of power drives the arm against the action of the spring thereby also driving the regulating member, means whereby the regulating member so controls the electromagnetic system that the resultant restraining force on the movable member progressively decreases as the regulating member moves away from its initial position, means whereby when the restraining force passes the 'zero value and changes to an operating force the movable member acts to break the driving connection and thus allows the spring to.

drive the arm back again to its initial position at a predetermined rate controlled by the time-delay mechanism, means whereby the relay contacts are actuated when the arm again reaches its initial position, an illstantaneouslyacting initiating contactor responsive to fault conditions in the protected circuit, means whereby such contactor establishes the operative driving connection between the source of power and the regulating member which is broken by the movable member of the electromagnetic system when the regulating member reaches its operative position, and means whereby the deenergization of the initiating contactor when the fault has been cleared, either by the relay itself or by another protective relay on the protected circuit, causes the parts of the relay to be reset to their initial positions, the arrangement of the electromagnetic system and the control exercised thereon by the regulating member being such that the extent of the movement of the regulating member and therefore, also, the time-delay of the relay is dependent on the ratio of the two operating currents.

18. An electric relay arrangement for the protection of an electric circuit, including in combination contacts controlling the protected circuit, an electromagnetic system com-.

prising windings and a movable member electromagnetically controlled thereby, means w iereby two operating currents derived from the protected circuit are supplied to such windings, a regulating member controlling the electromagnetic system, a source of power, means whereby the regulating member is driven by such source from an initial position to an operative position, an energystoring device, a time-delay mechanism associated with such device, means whereby energy derived from the source of power is stored in the device, means whereby the amount of such stored energy is rendered dependent on the extent of the movement of the regulating member, means whereby the movable member of the electromagnetic system acts when the regulating member reaches the operative position to disconnect the regulating member from the source of power thereby determining the extent of the movement of the regulating member, means whereby the energy stored in the device is released when the regulating member is disconnected and acts under the control of the time-delay mechanism to operate the relay contacts after a time interval dependent on the amount of energy stored therein, an instantaneously acting initiating contactor responsive to fault conditions in the protected circuit, and

source of power and the regulating member which is broken by the movable member of the electromagnetic system when the regulating member reaches its operative position, the arrangement of the electromagnetic system and the control exercised thereon by the regulating member being such that the extent of the movement of the regulating mem ber and therefore also the time-delay of the relay is dependent on the ratio of the two operating currents, the regulating member being initially set in such a position that when the ratio of the two operating currents has a value below that corresponding to such initial setting the relay will operate its contacts substantially instantaneously when the initiating contactor operates.

19. An electric relay arrangement for the protection of an electric circuit, including in combination contacts controlling the protected circuit, an electromagnetic system comprising windings and a movable member, means whereby two operating currents derived from the protected circuit are so supplied to the windings as to cause them to exert on the movable member a resultant force normally tending to restrain the mem ber against operation, a regulation member, a source o1 power, a variable resistance in the energizing circuit of one of the windings of the electromagnetic system controlled by the regulating member, means whereby the regulating member is driven over the resistance from an initial position by the source of power, means whereby when the restraining force on the movable member changes to an operating force as the result of the variation in the resistance due to the movement of the regulating member the movable member acts to disconnect the regulating member from the source of power, an energy-storing device, a time-delay mechanism associated with such device, means whereby energy derived from the source of power is stored in the device in accordance with the extent of the movement of the regulating member, means whereby when the regulating member is disconnected from the source such stored energy is released and acts under the control of the time-delay mechanism to oper ate the relay contacts after a time-interval dependent on the amount of energy stored in the device, an instantaneously acting initiating contactor responsive to fault conditions in the protected circuit, and means whereby such contactor establishes the operative driving connection between the source of power and the regulating member which is broken by the movable member of the electromagnetic system when the regulating member reaches its operative position, the arrangement of the electromagnetic system and the control exercised thereon by the regulating member being such that the extent of the movement of the regulating member and therefore also the time-delay of the relay is dependent on the ratio of the two operating.

setting the relay will operate its contacts subr stantially instantaneously when the initiating contactor operates.

In testimony whereof I have signed my name to this specification.

HENRY LEBEN.

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