US2311035A - Electrical relay - Google Patents

Description

' Feb. 16, 1943.

R. M. GILSON ELECTRICAL RELAY Filed May 17, 1940 I l I I Fig. 2.

227mm Bail/ Fig.4.

l NTOR Robe .Gimn BY nTTORNEY Patented Feb. 16, 1943 UNITED STATES PATENT OFFICE ELECTRICAL RELAY Application May 17, 1940, Serial No. 335,781

9 Claims.

My invention relates to electrical relays, and it has particular reference to the provision of improved forms of relays of the class employed in direct current railway track circuits.

An electrical relay of ordinary construction when employed as a track relay is relatively quick in picking up, is comparatively slow in releasing, and may be subject to undesirable operations due to momentary losses of train shunt in its associated section. These characteristics are in a large measure due to the fact that the energy required to pick up the armature of an ordinary relay is considerably in excess of the energy necessary to hold such armature in its attracted position after it has picked up. Such a relay must, of course, be designed to create its pick-up energy level, at least, in order to insure that the relay armature will be picked up properly, and as a result once this armature has reached its attracted position, the energy level in the relay then exceeds by a considerable degree that necessary to maintain the armature in its picked-up position. In order for a train shunt to be effective to release such relay, the shunt must be sufiiciently low in resistance to shunt away from the relay winding the increment of energy above the drop-away energy level of the relay. Such shunt, however, provides a low resistance or short-circuit path across the relay winding which maintains for an appreciable interval of time the flux in the relay, so that a correspondingly long time interval is required for even a low resistance train shunt to lower the energy level of the relay below its drop-away value. Hence, if the train shunt varies intermittently in effectiveness, the release period of the relay might be materially increased; and after the relay releases due to a shunt, there is a possibility that these variations in shunt might cause the relay to be picked up and released and thus follow the fluctuations in the applied shunt. This tendency of an ordinary relay to follow varying train shunts, and the slow releasing characteristics possessed by such relay when shunted, are undesirable in a track relay since such relays often are incorporated into signaling or control systems not only for controlling signal indications, but also for establishing directional control in accordance with the sequence in which the relays of two or more successive sections are released, hence if a relay is improperly picked up in response to a momentary loss of train shunt, or if the relay of a section vacated by a train picks up prior to the train causing the release of the relay of the section in advance, an improper directional set-up might be established as well as causing flashing signal indications, etc. Furthermore, such relays are often employed for electrically locking signals and switches against operation, and if a track relay is intermittently released and picked up due to a varying train shunt in its section, the effectiveness of such locking is materially decreased.

I am aware that schemes have been proposed heretofore to condition a track relay to create its pick-up energy level when it is released, and to reduce the energy level in the relay after it has picked up, thereby obtaining quick release of the relay. One of the most effective of such schemes is to employ a secondary relay, which ordinarily is slow acting, controlled by the track or primary relay and in turn controlling the release sensitivity of the track relay. Such systems commonly are termed primary-secondary track relay combinations, and although they materially improve the operation of track relays and track circuits, the use of two independent relays increases the initial and maintenance cost of such track circuit arrangements to a considerable extent.

In view of the foregoing and other important considerations, it is in object of my invention to provide a track relay having means for controlling its own release sensitivity in such manner that the relay is conditioned to create its proper pick-up energy level when released, and when picked up the energy leve1 in the relay is reduced to a value only slightly above that required to hold its armature in its attracted po-- sition.

Another object of my invention is to provide a track relay wherein the functions of the two relays oi a primary-secondary relay combination are incorporated into a single relay structure.

A further object of my invention is the provision of relays particularly suitable for use as track relays, and incorporating novel and improved means for delaying the pick-up oi the armatures of such relays.

An additional object of my invention is the provision of safe, reliable, and relatively inexpensive means for obtaining in a single relay the benefits and advantages of a primary-secondary relay combination.

Another object of my invention is the provision of novel and improved forms of electrical relays having slow pick-up, fast release characteristics.

objects and characteristic features of my invention which will become readily apparent from the following description, are attained in accordance with my invention by inductively coupling to the operating winding of a track relay a retaining winding which opposes the action of the operating winding on the contacts operated by the relay armature, and by utilizing a make-before-break contact combination operated by such armature to control the energy level created by the operating winding. This coupling of the operating and retaining windings of the relay is effected in accordance with my invention in such manner that the decay of flux due to current in the operating winding is not affected, but the growth of flux is prolonged to aid in providing the relay with quick release, slow pick-up characteristics. Various means for coupling the windings in the above-described manner are provided; in certain forms of my invention shortly to be described, the retaining winding is coupled to the operating winding over a back contact operated by the relay armature; and in other forms of my invention the retaining winding is coupled to the operating winding through an asymmetrical unit or through a fullwave rectifier.

The present invention is somewhat similar to that disclosed in a copending application, Serial No. 395,925, filed on May 31, 1941, by Arthur E. Dodd, and which said copending application contains claims which cover broadly certain features of the invention described in my present application.

I shall describe four forms of electrical relays embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view showing a preferred form of an electrical relay embodying my invention, and incorporated into a railway track circuit. Figs. 2, 3 and 4 are diagrammatic views each illustrating a modified form of the relay shown in Fig. l, and each also embodying my invention.

In each of the several views of the drawing, similar reference characters have been employed to designate corresponding parts.

Referring first to Fig. 1, the reference character'TR designates, as a whole, a relay embodying my invention. As shown, this relay comprises an electromagnet having two magnetizable cores 5' and 6 connected together at one end by a back strap 1. These cores are provided with an operating or primary winding comprising two coils 8 and 8a disposed one on each core and connected in series in such manner that when energized the coils cooperate in circulating a flux in agreement in the magnetic circuit of the relay. The cores 5 and 6 also carry a secondary winding comprising two coils 9 and 9a, one coil 9 being disposed on core 5 and the' other coil 90. being disposed on core 6. An armature l0, pivoted in the usual manner (see Fig. 4), is disposed in magnetic relationship with the two cores 5 and 6 and is operated from a released position (see Fig. 2) to an attracted or pickedupposition (see Fig. 1) when coils 8 and 8a are energized. Armature It) is connected in the usual manner (not shown) to a plurality of contact members II, l2 and [3, which members engage associated contact fingers to form front or back contacts according as armature It is picked up or released. In addition, another contact member I4' is operatively connected to armature l0 make-before-break contact arrangement. This contact arrangement, as shown, comprises a movable contact element I5 pivoted at [6 and provided with a front contact point I! and a button i3 of insulating material. The operation of the make-before-break contact arrangement will be explained in detail hereinafter, but at this time it should be pointed out that element I5 preferably is restrained by any suitable means, such as by friction washers, to remain in its last operated position until acted upon by contact member I4 attached to armature H].

An auxiliary magnetizable core 29 disposed beneath armature It is engaged by the armature in its released position (see Fig. 2) and this core carries a retaining winding 21 which is effective when energized to create magnetic flux which tends to hold armature H3 in its released position, thus opposing the action on armature ll] of the flux due to current in coils 8 and 8a. Winding 21 is supplied with current at times from the two secondary winding coils 9 and 9a disposedon the two main cores 5 and 6, these coils being connected in series in such manner that when electromotive forces are induced therein due to a change in magnetic conditions in the cores 5 and 6, such forces are additive. In the embodiment of my invention illustrated in Fig. 1, the two coils 9, 9a of the secondary winding are connected to retaining winding 2| over a back contact |l--22 closed in the released position of armature H0; in a second embodiment of my invention illustrated in Fig. 2, the two coils 9, 9a are connected through back contact H-22 of' relay TRI to the input terminals of a full-wave rectifier R (see Fig. 2), and the output terminals of this rectifier are connected to winding 2!; and in another embodiment of my invention illustrated in Fig. 3 an asymmetrical unit 23 (see Fig. 3) is interposed in the connection of coils 9 and 9a. of relay TR2 to winding 2|.

As shown in Fig. 1, relay TR is connected in a track circuit including the two track rails l and la of a section of railway track D-E, which section is formed by insulating the track rail portions of section D-E from the adjacent portions of such rails through the medium of the customary insulated joints 2. The track circuit also includes, as shown, a suitable source of current,

2 such as a track battery TB, connected in series with the usual current limiting resistor 3, across the rails I and la at one end E of the section, and at times only a portion and at other times the entire operating winding of relay TR. connected in series with a current limiting resistor and controls what I shall term a drag or a 4 across the track rails I and la at the other end D of the section.

The operation of the apparatus illustrated in Fig. 1 is asfollows: When section D-E is unoccupied, armature Ii] of relay TR is in its attracted or upper position as shown in Fig. 1, and in this position of armature in front contact l4- ll of relay TR is closed to complete an obvious circuit path which connects coil 8 of relay TR across the rails I and la. The parts of relay TR preferably are designed and proportioned in such manner that with only coil 8 energized, an energy level only sufiiciently above the release value of the relay to assure reliable operation of such relay under the various ballast conditions, is created in the relay due to current supplied to the one coil 8 of the operating winding from the rails l and la.

When a train enters section D-E, the current supplied from battery TB to the track rails I and l a is shunted away from the operating winding of relay TR. Since the relay armature normally is held attracted by an energy level only slightly in excess of its release value, the energy level in the relay is rapidly decreased by the applied shunt and as a result armature it drops to its leased position wherein back contact finger I9 is engaged by contact element l5 (see Fig. 2).

In the released position of armature ID of relay TR, back contact ||-22 is closed to connect coils 9 and 9a of the secondary winding disposed on cores 5 and 6 to retaining winding 2|. Also, both coils 8 and 8a of the operating Winding of relay TR are connected in series over back contact |5|9 across the track rails and la, thereby conditioning the relay to create its pick-up energy level. When the train shunt is removed from relay TR, as for example when the train vacates section D-E or when the shunt is'momentarily lost due to rail film conditions or other poor shunting conditions, current from battery TB is supplied through rails and la to both coils 8 and 8a of relay TR. During the building up'oi the flux in cores 5 and 6 due to such current, electromotive forces are induced in the secondary winding coils 9 and 9a disposed on cores 5 and 6. and are applied through back contact |i-22 to retaining winding 2|. The fiux set up due to current in winding 2| threads armature ID to hold that armature down and thus opposes the action on armature ll! of the flux due to current in coils 8 and Ba. If the energization of the relay operating winding is caused by the train vacating the section, the action of winding 2| in opposing the pick-up effect of the flux due to current in coils 8 and 8a functions to maintain armature H3 released until the flux condition in the cores 5 and 6 reaches substantially a constant state condition so that no electromotive forces are induced in coils 9 and 9a. This steady state flux condition in the cores 5 and 6 substantially corresponds to the pick-up energy level of the relay, and since under the condition of flux equilibrium in cores 5 and 8 no current is induced in the coils 9 and 9a, the tractive eiTect of the flux due to current in coils 8 and Ba on armature I0 is no longer opposed by flux due to current in winding 2|, and as a result armature I0 is operated to its picked-up position wherein contact members I2 and I3 engage their respective front contact points and back contact ||-22 is opened to disconnect retaining winding 2| from coils 9 and 9a. Also, When armature l0 reaches substantially its full attracted position, contact member l4 engages its associated front contact point I! to form circuit controlling contact |4--|'| and to operate contact element l5 about its pivot 55 to a position wherein back contact |5-i9 is opened. The closing of front contact |4-|'| connects coil 8 in circuit with the track rails and Ia; and the opening of back contact |5--| 9 opens the circuit path connecting coil 8a in series with coil across the track rails. The armature of relay TR accordingly is held in its attracted position by All virtue of the energization of coil 8 only of the operating winding of relay TR, consequently the energy level of the relay is reduced to a value only slightly greater than the release value of the relay, as was pointed out heretofore. Relay 'IR accordingly is slow to pick up when the train vacates its associated section, thereby enabling the train to shunt the relay of the section in advance and permitting the advance track relay to be released to establish the proper directional set-up, signal control, looking, or other function wherein it is required for proper operation that the advance relay be released prior to the rear relay picking up,

In the event that armature ID of relay TR is released so that both coils 8 and 8a are connected in circuit with the track rails, and current is supplied from the rails and la to such coils due to a loss of shunt in section D=E, then retaining winding 2| is energized by current supplied from secondary coils 9 and 9a during the building up of flux in cores 5 and 6, and armature Ill is held down by the flux due to current in winding 2|. This hold-down effect of winding 2| prevents relay TR from picking up immediately on a loss of shunt, and provides a delayed pick-up period for relay TR sufiicient under normal conditions to enable the train shunt to be restored and the coils 8 and So again to be shunted prior to armature it being attracted from its released to its picked-up position. It can be seen, therefore, that the delayed response characteristics of a relay of the class illustrated in Fig. 1 prevents false operation of the relay due to a momentary loss of train shunt in its associated section.

It should be noted that the contacts operated by contact member M of relay TR function as make-before-break contacts during the travel of the relay armature from its released to its picked-up position, that is, front contact |4-|'l is closed prior to back contact |5-|9 being opened. In addition, the control of these contacts effected during the travel of armature Hi from its released to its picked-up position is such that front contact M-ll is closed and back contact |5-|9 is opened only after the armature reaches substantially its full attracted position, and since there is but a slight air gap between the cores 5 and 6 and armature Hi When contact |5--|9 opens to remove coil 8a. from the track circuit, the reduced energy level created in the relay after contact |i| closes and con tact |5|9 opens, is efiective to maintain the armature in its picked-up position. On the re verse travel of the armature from its picked-up to its released position, however, front contact i is first opened and then back contact !5|9 is subsequently closed, the closure of the back contact being delayed until the armature reaches substantially its full released position. This delayed closure of contact |5|i| permits the armature to be separated from the relay cores by a relatively large air gap prior to contact iii-l9 closing to connect both windings 3 and 8a of the relay in the relay circuit, thereby insuring that the relay will be conditioned to create its pick-up energy level only after the relay armature reaches substantially its full-released position. This avoids any tendency of the relay armature to be re-attracted to its pickedup position due to interposing both primary coils in the track circuit before the armature separates from the relay cores.

It should, of course, be understood that while the particular construction and arrangement of the drag or make-before-break contact arrangement operated by contact member I4 of relay TR. is to be preferred for the reasons set forth in detail, such contact arrangement may take the form of the usual make-before-break contact arrangement such as is shown in Fig. 4 and presently to be explained in detail.

In addition, it should be noted that the two secondary coils 9 and 9a disposed on relay cores 5 and 6 are open-circulated at all times except when back contact H22 of the relay is closed and it follows that when armature I is picked up, such coils cannot operate to delay the decay of relay flux such as might happen if the secondary coils were connected at all times in circuit with winding 2|.

I have represented in Fig. 2' a modified arrangement of the relay shown in Fig. 1, whereby further increased insurance against false operation by shunts of varying effectiveness is provided by interposing a full-wave rectifier R between the secondary coils 9 and 9a and retaining winding 2! of relay TRI. Referring now to Fig. 2, one input terminal of rectifier R is shown connected to coil 90,, the other input terminal of rectifier R is connected to coil 9 through back contact I |-22 of relay TRI, and the output terminals of the rectifier are connected to retaining winding 2!. It is readily apparent, therefore, that when armature l!) of relay TRI is released so that back contact I l22 is closed, winding 2! is supplied with unidirectional current from rectifier R irrespective of the polarity of the induced current in secondary coils 9 and 911. That is to say, current of one relative polarity is induced in coils 9 and 9a during the interval that the relay flux is building up in cores 5 and 6, and current of the other relative polarity is induced in such coils when the flux in cores 5 and 6 is decaying. When back contact |l-22 is closed to connect rectifier R to coils 9 and So, it is obvious that rectifier R functions to supply current of only one polarity to winding 2| even though the flux in cores 5 and 6 might be increasing and decreasing by turns, and consequently the unidirectional flux threading armature ID in its released position due to this current in winding 2| functions to hold such armature down when the train shunt in the section varies intermittently due to varying conditions of rail surface film, rust, etc, in the section. Accordingly, it can be seen that when the effectiveness of the train shunt varies intermittently, the armature of a relay constructed as illustrated in Fig. 2 is held down in its released position due to the variations in the relay flux, and increased assurance is provided against improper operation of the relay due to train shunts of varying effectiveness in section D E. The relay shown in Fig. 2 of course functions to provide retardation in the pick-up of the relay armature, and to vary the energy level of the relay from its pick-up to its hold-up value, in a manner corresponding to that pointed out in detail in connection with relay TR illustrated in Fig, 1, and further detailed explanation of the operation of relay TRI is believed to be unnecessary.

Relay TEE, illustrated in Fig. 3, incorporates another modification of the relay illustrated in Fig. 1. In relay TR2, back contact I l22 of relay TB is replaced by an asymmetrical unit 23 (see Fig. 3), which unit is interposed between retaining winding 2! and secondary coils 9 and 9a and is poled in such manner that winding 2| is supplied with current from coils 9 and to when and only when the growth of flux in cores 5 and 6 causes current of one relative polarity to be induced in coils 9 and 9a. Winding 2| accordingly is energized and functions to delay the picking up of the armature of relay TR2 when current is supplied to the operating winding of the relay due to a train vacating the section or when the train shunt is of intermittent eifectiveness in the section, but since asymmetrical unit 23 opposes the flow of current of the polarity such as would be induced in coils 9 and 9a due to a decaying of the flux in cores 5 and S, such unit in effect functions as an opened contact to prevent any short-circuiting action of the coils 9 and 9a tending to prolong the decay of flux in the cores 5 and 8. It follows, therefore, that asymmetrical unit 23 functions to control the energization of winding 2| in a manner substantially similar to the control established over the corresponding winding of relay TR by contact H22, in that the unit permits the energization of winding 2! to enable that winding to delay the picking up of armature l5, and also prevents the coils 9 and 9a from prolonging the decay of the relay fiux.

Another modification of the relay illustrated in Fig. 1 is shown diagrammatically in Fig. 4, wherein a relay TRS is shown in a side elevational view to better illustrate the construction and arrangement of its parts. This relay is substantially similar to relay TR shown in Fig. 1, and accordingly comprises two cores each having two coils mounted thereon, although only one core 5 and the two coils 8 and 9 are illustrated in Fig. 4.

Relay TR3 of Fig. 4 is characterized by the provision of two armature members iii and 26, pivoted respectively about points 25 and 2?. One armature I9 is disposed in magnetic relationship with the magnetizable cores of relay TR3, and the other armature 26 is disposed in magnetic relation with retaining winding 2 I. Armature I8 is connected through a spring coupling 28 to armature 25 and the armatures are spaced apart in any suitable manner, such for example as by a nonmagnetic member 29 attached to armature I8 and engaging a face of armature 2G. Attached to the latter armature are a plurality of contact members 3?], 3! and 32, one of which 32 is bifurcated and functions as the common or bridging member of a make-before-break contact arrangement. If desired, armature It] also may be provided in the usual manner with contact members (not shown).

In the normal condition of relay TBS, as shown in Fig. 4, both armatures I9 and 25 are in their respective upper or attracted positions and front contacts 39-34 and 32-35 of armature 25 are closed, the latter contact functioning to connect only a portion of the operating winding of relay TR? in its energizing circuit. This portion is shown in Fig. 4 as comprising the upper portion of winding 8 of relay TR3, which is connected through a resistor 39 and front contact 3532 operated by armature 25, to the indicated control circuit (which may be the track circuit represented in Fig. 1) but it is to be understood, or" course. that this showing is merely illustrative, and the upper portion of winding 8 of relay IE3 might correspond to the entire coil 8 of relay TR shown in Fig. 1, in which case the lower portion of winding 8 of relay TR3, which normally is excluded from the control circuit for the relay, would then correspond to coil Ba of relay TR shown in Fig. 1. The parts of relay 'IRt are so proportioned and designed that when only a selected portion of the operatin winding is included over front contact .32-35 in the control circuit of the relay, the

energy level created in the relay due to current in the included portion of such winding is only slightly in excess of the release value of the relay.

Accordingly, armature I is held in its picked-up position due to the magnetic flux in the relay cores, and armature 26 is held in its picked-up position wherein it bears against stop 29 due to the action of spring 28.

If relay TR3 is connected in circuit with the rails of a track section, for example, then a train shunt in the section reduces the energy level in the relay and its armatures I0 and 26 drop. Back contacts 3236, 3|--3| and 3938 are closed by the operation of armature 26 to its released posicircuit with the track rails, thus conditioning the relay to create its pick-up energy level. When the shunt is removed, current induced in coil 9 due to the growth of flux in core 5 is supplied over back contact 3l--31 to winding 2 l, with the result that armature 26 is held down by the flux due to the current in this winding. Armature Hi, however, is attracted to its upper position due to the flux in core 5, and when the armature closes the flux again increases due to the decreased air gap to prolong the interval during which electrornotive forces are induced in secondary winding 9 and are supplied to winding 21. Armature 26 accordingly is held down due to current in winding 2| until the flux condition in core 5 reaches substantially a steady state condition after armature l0 closes, and when this happens, the retaining action of winding 2| ceases so that armature 26 is operated to its upper position due to the action of its spring coupling 28. This movement of armature 26, of course, opens back contact 3l-3l to disconnect secondary winding 9 from retaining winding 2 l, and also closes front contact 32-35 prior to opening back contact 32-36, so that the upper portion of winding 8 is connected to the control circuit prior to opening the connection of the entire control winding to such circuit.

From the foregoing, it can be seen that the construction of relay TR3 is such that armature I0 is operated to its full attracted position prior to reducing the energization of the relay, and that the armature 26 is delayed from responding to the energization of the relay operating winding during the building up of flux in the relay core due both to the energization of the relay winding and the closing of armature [0. It follows, therefore, that an improved relay is provided having quick release, slow pick-up characteristics and incorporating means for varying the energy level created in the relay after its armature has reached its full attracted position.

Although I have herein shown and described only four forms of electrical relays embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a magnetizable core, an operating winding disposed on said core, an armature disposed in magnetic relation to said core and provided with contacts including a makebefore-break contact combination comprising a front contact and a back contact with a bridging member which causes both said contacts to become closed momentarily during the movement of said armature from its released to its attracted position, a control circuit connected over said front contact to a portion only of said operating winding and connected over said back contact to the entire operating winding, a retaining winding disposed to retain said armature in its released position in opposition to the attractive action of said operating winding on said armature, and a secondary winding disposed on said core and connected to said retaining winding through an asymmetrical unit poled in such manner as to permit only the flow of current caused to be induced in said secondary winding due to a growth of flux in said core.

2. In combination, a magnetizable core, an operating winding disposed on said core, an armature disposed in magnetic relation to said core and provided with contacts including a make-beforebreak contact combination comprising a front contact and a back contact with a bridging member which causes both said contacts to become closed momentarily during the movement of said armature from its released to its attracted position, a control circuit connected over said front contact to a portion only of said operating winding and connected over said back contact to the entire operating winding, a retaining winding disposed to oppose the attractive action on said armature of said operating winding for maintaining said armature in its said released position, a

rectifier, and a secondary winding disposed on said core and connected to said retaining winding through said rectifier.

3. In combination, a magnetizable core, an operating winding disposed on said core, an armature disposed in magnetic relation to said core and provided with contacts including a make-beforebreak contact combination comprising a front contact and a back contact with a bridging memher which causes both said contacts to become closed momentarily during the movement of said armature from its released to its attracted position, a control circuit connected over said front contact to a portion only of said operating winding and connected over said back contact to the entire operating winding, a rectifier, a retaining winding connected to the output terminals of said rectifier and disposed to oppose the attractive action of said operating winding on said armature, and a secondary winding disposed on said core and connected through a back contact of said armature to the input terminals of said rectifier.

4. In a relay, in combination, a magnetizable core and an armature, an operating winding disposed on said core for actuating said armature, another magnetizable core disposed in effective magnetic relation with said armature when the latter is released, a retaining winding on said other core, an asymmetrical unit, and a secondary winding disposed on said first core and connected to said retaining winding through said asymmetrical unit, said unit being poled in such direction as to permit only the flow of current induced in said secondary winding due to a growth of flux in said first core.

5. In a relay, in combination, two magnetizable cores, an operating winding disposed on one of said cores, a contact-carrying armature biased to the other of said cores and actuated against its bias to said one core in response to flux due to current in said operating winding, a retaining winding on said other core, an asymmetrical unit, and a secondary winding disposed on said one core and connected through said asymmetrical unit to said retaining winding, said unit being poled in such direction as to permit only the flow of current induced in said secondary winding due to the growth of flux in said one core.

6. In a relay, in combination, two magnetizable cores, an operating winding disposed on one of said cores, a contact-carrying armature biased to the other of said cores and actuated against its bias to said one core in response to flux due to current in said operating winding, a rectifier, a retaining winding disposed on said other core and connected to the output terminals of said rectifier, and a. secondary winding disposed on said one core and connected through a back contact of said armature to the input terminals of said rectifier.

'7. In combination, a relay comprising a magnetizable core and a first armature, an operating winding disposed on said core for actuating said first armature, a second armature spring coupled to said first armature, contacts operated by said second armature, a retaining winding disposed to be effective when energized to retain said second armature in its released position against the action of said spring coupling, and a secondary winding disposed on said core and connected to 'said retaining winding when and only when said second armature is released.

8. In combination, a relay comprising a magnetizable core and a first armature, an operating winding disposed on said core for actuating said armature, a second armature spring coupled to said first armature, a plurality of contacts operated by said second armature and including a make-before-break contact combination comprising a back contact and a front contact with a bridging member which causes both said front and back contacts to become closed momentarily during a portion of the operating stroke of said second armature, a control circuit connected over said front contact to a portion of said operating winding and connected over said back contact to the entire operating winding, a retaining winding disposed to be efiective when energized to oppose the action of said spring coupling on said second armature, and a secondary winding disposed on said core in inductive relation to said operating winding and connected to said retaining winding when said second armature is released.

9. In a relay, in combination, two magnetizable cores, an armature biased away from one toward the other of said cores, an operating winding on said one core for actuating said armature to said first core, a second armature spring coupled to said first armature and disposed in efiective magnetic relation With said second core, a retaining winding disposed on said second core, and a secondary winding disposed on said one core and connected to said retaining winding over a back contact of said second armature.

ROBERT M. GILSON.

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