US2678410A - Lightning relief gap for relays - Google Patents

Description

y 11, 1954 H J. E. WiLLiNG ET AL 78,410

LIGHTNING RELIEF GAP FOR RELAYS Filed Ma'roh 29;"1952 2 Sheets-Sheet 1 1 11 5- INVENTORS 12 24 22 lE w'nlinq and R.d.Li+1'le.

BY lNSULATION m THEIR ATTORNEY.

y 1954 J. E. WILLING ETAL LIGHTNING RELIEF GAP FOR RELAYS 2 Sheets-Sheet 2 Filed March 2\9, 1952 TRACK RAlLs MM m,

INSULATION THEIR ATTORNEY.

Patented May 11, 1954 UNITED r r s PATENT OFFICE 2,678,410 .mammo ra engr ssin Joseph E. Willing and Robert J. Little, Rochester,

" Company, Rochester, NrY'.

arch 29, i952, Serial No 279,324 8 Claims. (01.317-9) HPP JFE P employed to'control line circuits for the'as sociated f ,Lsignals. In an arrangement of this kind, it is evi- "fdent' that the linewires will collect s'taticicharges under certain atmospheric conditions, which charges may be dissipated to ground through the J usual lightning arrester protective means. However, there are cases when direct or semi-direct lightning discharges strike th line wires and seek notonly the ground butalso' the track rails to which the wires of the track relay are connected. 'In some cases, the discharge breaks across air gaps in sucha way as to pass from the contact'fingers cfonnectedto the line wires-to th relay-arrnature and thence through the pole pieces of the relay Railway. Signal vious from the accompanying drawings, and in part po'inted'out as the description of the invenionprogress'esf In"describing the invention in detail, reference"will"be made to the accompanying drawings, in which like" reference characters designate corresponding parts'throughout theseveral -views,

and: in which:

Figil is 'a bottom view of a relay to which the 10 present invention has been applied, such bottom iewhavingcerta'in parts'removed in order to ore clearly illustrate the present invention;

Fig. '2 'isaside' sectional View illustrating the present'invention applied to the relay of Fig. 1; 5 f Fig. 3 is fan "isometricwiew showing certain artsof therelay of Figs. land 2 to more clearly 1 strate the present'invention;

-Figl lis a topview 'of'the adjustable extensions of the contact fingers which form the relief W means-more particularly showing one end of dc supporting means to give additional details omit from the' isoinetric'view of Fig. 3;

picked up position. This is obviously unsafe,

""'Fig;6is" asectionn view of a typical insulat- -in'-gsupporter" stud member-for connecting the contact fingers on the relay armature;

' Fig/j is a bottom View of another relay to which the present invention has been applied, 6such'bottom"viewhaving certain parts removed fi'n order t'o'more clearly illustrate the present in- Fig. 8 is a side sectional view taken on line 8-3 (bfl igfl'looking in'the' direction of the arrows; 5 Fig. 9"is' an isometric view of the parts of the relay of Figsi'l and 8 to more clearly illustrate this form of the present invention;

Fig. 10 is a back view of one end of the arma ure supporting means to illustrate the trunama bearingfo'r"the'armature indicated in Figs.

"7 andB but omitted from Fig; 9; and

ince the presence of the next train on the associatedtrack circuit would not cause the armature ,"'to release and open the line circuits as is re- 'j' quired for proper operation. 'It is awell known fact that railway signalling systems must be organized in such a way that [any failure will be on the side of safety. ;Ob- 'fviously, if a reIaybecomes frozen or" wel ded in :its "energized position, a condition is established which is wholly unsafe, and it is the'purpose of the present invention to add auxiliary structure to track relays in such a way that this can-- In accordance with the present invention, it is proposed to provide track relays with relief air v Fig. 1 1 is"'a"'circuit" diagram tov illustrate the y cohditiofis'under'whichthe relays embodying the present inyenti'on a're employed in practice.

gaps so that static charges on the line wiresmay ,pass directly from the connecting contacts to the cooperatingpole pieces without passing through the cooperating armature.

, Another purpose of the invention is to provide ,relietgaps of this type in such away that they will not interfere with the regular operation of the relay and may be readily removed d'ur'ing'the repairand adjustment of the relays;

v: Qther objects, purposes and characteristic fea- ..w e o .ihasis fie f r it Wi he TWP trackirails ofa'railroad. For this reason, it has become desirable tdprovide the usual "spark gap V arresters between the line Wires and ground, and.

5 :5 ddition otherarrestersfbetween' the line wires 3 and the rails. But in spite or this protection, either because it becomes faulty or because it is inadequate to handle the entire amplitude of the discharge, or for some other reason, it sometimes happens that the lightning discharge seeks a path to the rails via the armature and the associated pole pieces because the windings on the pole pieces are connected directly to the track rails.

If a discharge of substantial amplitude takes place between the armature and its associated pole pieces, it may happen that the residual pins which maintain the minimum air gap between the armature and the pole pieces will become welded to the armature and prevent its release p the shunting of the associated track circuit by a train. This of course is unsafe and the present invention proposes to protect against it.

It should be pointed out that this may occur under peculiar circumstances. If the armature is firmly held against the residual pin the discharge may pass through it without causing any welding effect; but if the armature is only lightly held in an energized position, or some dust or the like interferes with its making a good contact with the residual pins, resistance is built up to the discharge current and heat develops to effect the welding operation between the armature and pole pieces. Also, the use of insulated residual, pins causes the discharge to seek some other path from the armature to the pole pieces; and in some instances the welding of the armature will occur with this arrangement. It is thus evident that the protection of the relay against a welding or freezing condition of its armature in an energized position cannot be accomplished by merely providing additional residual pins or the insulation of the usual pins.

The present invention proposes that the armature be protected by providing a relief gap between the contacts attached to the armature and the pole pieces themselves so that any discharge which may from one cause or another seek a path to the pole pieces from the line wires may do so directly through the relief gap without passing through the armature.

In both forms of the present invention, the relief gap is proposed to be adjacent the ends of the movable contacts which are nearest to the pivoted side of the armature, so that their movement during the operation of the armature will always be within substantially the same distance of the metal parts forming the relief gap and connected to the pole pieces. In accordance with the present invention, it is proposed that this gap be of such a size as to dissipate any lightning discharge which collects on the line wires and seeks to pass through the pole pieces before such charge becomes of a value that it seeks unwanted air gaps formed in the relay by the fingers and armature and its other parts.

It is also proposed that the connecting link between the relief gap and the pole pieces will be of sufficient size as to carry the discharge without material limiting effects.

In other words, it is proposed that the relief gap be sufliciently short as to readily allow any dangerous static charges to be shunted from the contact fingers to the pole pieces with the shunting path being made of suitable conducting material of such substantial size and length as to have little, if any, inductance to hinder the ready passage of the discharge.

Various other characteristics of the present invention will be better understood by reference to 4' the following detailed description or the structure.

Referring to Fig. 1, a bottom view of a relay of the same general type as disclosed in the prior Patent Nos. 1,749,331 and 1,824,129 has been shown as having the present invention embodied therein. This relay is shown as having six contact fingers 5 connected to the armature 6. This is accomplished, as shown in Fig. 2, by the use of insulating supports or studs 1 which may be constructed as shown in detail in Fig. 6. The armature 6 has been shown in Fig. 2 as being in an attracted position bearing against the residual pins is inserted in the faces of the two pole pieces 9. The residual pins 8 are of non-magnetic ma terial and also of such a character as to be good electrical conductors. In brief, a relay of this type has a U-shaped core structure, as shown in the above mentioned prior patents with the free ends of the core having pole pieces 9. The windings on the core structure are located above the base plate It of insulating material while the pole pieces 9 extend beneath the base plate 10. Only one pole piece 9 connected to a portion of its leg of the core 4 is shown in Fig. 2, it being understood that this portion of the structure may be of any conventional type, such as shown in the above mentioned prior patents.

At the back of relay a bracket member II is supported on the base 10 by being suitably mounted on two stud bolts [2. The ends of the bracket ii are up-turned, as indicated in Fig. 5 for one end, and are provided with holes l3 for receiving trunnion bearings l5. The armature 6 has fastened to it two support arms It extending to the rear of the relay. Each arm 14 has a bifurcated portion at the end for receiving its respective trunnion bearing 15, which is held in position by the tightening of bolt 16. In this way, the ar- Lmature 6 is pivotally supported at the back of the relay.

The armature B is shown in its attracted position in Figs. 2, 3 and 5 but, when it is released, it is limited in its downward movement by the back contacts (not shown) cooperating with the contact fingers 5 and by a limit bolt 11 which is mounted on a T-shaped bracket l8 with up-turned ends that are also supported by the stud bolts I! at opposite sides of the relay. More specifically. with reference to Fig. 5, it can be seen that this bracket 18 is held between lock nuts l9 and 20; and in addition to the ends of this bracket l8 are the shunt connectors 2|, one at each end of the bracket, which are clamped between the lock nut l9 and the end of the bracket l8. These shunt connectors 2| are up-turned and bear with intimate firm contact against their respective pole pieces 9, as best seen in Fig. 2, although this is also indicated in Figs. 1, 3 and 5.

Although the supports 1 for the contact fingers 5 may be of any suitable type, one typical form has been shown in detail in Fig. 6. The support or stud l is shown as having a metal insert 25 separated from another metal insert :25 by suitable moulded material of an insulating character. The extending ends of these inserts 25 and 26 are of course threaded. Thus, one end of the stud I can be screwed into the armature '6 and the other end can receive the contact fingers 5, their extensions 22, connecting leads (not shown), and securing nuts. These insulating studs 1 are usually made of suitable insulating material with the proper spacing of the inserts 25 and 26 to withstand relatively high voltages, suchas inthe order of seven to eightthoun olts.

R rring to Fig. 2, it will be noted that the studs V I are screwed into' the. armature land have extending threaded portions at the ottom for mounting thefingers by tightening suitable nuts, A suitable flexible lead extends from each contact finger 5 to a suitable binding post on the base plate Ii all as indicated in the above rnentioned prior patents, but not shown herein. The base end of the fingers 5 have attached thereto pointed extensions 22 as shown in Figs. 1, 2 and 3. Referring to Fig. 3, it can be seen that these extensions 22. have their sides pp-turned so as to remain in definite alignment ith the contact fingers 5 when the securing nut Thus, when the .arefully tightened, such extension 22 may be moved within limits to adjust the distance between. its points 24 and the support bracket H. Inother words,,the, air space between the points 24 of the extensions 22 and thebracket ll form .the relief gaps, In this connection, it is desirable that these relief gaps be made of such a size as tolbreak down or allow a discharge upon the application of betweenfifty and sixty percent of the voltage required to break down any unwanted paths between the. contact fingers and the core pieces via the armature. Also, although the holes 23 in the extensions 22 permit the necessary adjustments, they are not long enough to permit the extensions 22 to actually contact the bracket l l in the event the securing nuts become loose.

In brief, the points 24 of the contact extensions 22..are directed toward the metal supporting bracket H for the armature 6 supported from the base ID at two points along the back of the relay, i. e. that side of the relay farthest away from where the movable contacts coact with front and back contacts mounted on the insulated base of the relay, as shown for example in the above mentioned prior patents. Since thepoints l 24 of the contact extension pieces 22 are immediately adjacent this. metal support, it may be used as a part of a discharge path to the pole pieceswhich is completed by the clips or shunt "connectors 2|, there being one between each of the two stud bolts i2 and the adjacent pole piece 9 as indicated in Fig. 1. Thus, the armature support bracket is made use of as a part of a shunt path between the contact. fingers and the pole pieces, which'shunt path is wholly independent of the armature and its trunnion bearings.

Since the relief gap including the extensions [22 and the support member H is at the back of the relay closely adjacent the pivot point of the ,.armature, it is noted that the length of such relief gap is not substantially changed by the release of the relay armature from its normal picked up position. For this reason, the protection provided by the present invention is always v eftective regardless of whether the relay is picked up orreleased.

, The invention is shown embodied in another form of relay in Figs. '7, 8, 9 and wherein the 9212911 9 s r c e r: the arma net the formabove described.

Referring tof ig; 7, it 111 be noted that four tbntaet fingers 55 aremounted on the relay arrnature 56 by suitable insulating studs 51. These insulating supports or studs 51 may be 01' any suitable type, such for example as disclosed in Fig. 6 and fully described above. Thearmature 56 has beenshown in its attracted position in Fig. 8as pressing against the residual pins 58 inserted in the faces of the pole pieces 59. The resi dual pins 58 are of non-magnetic material andare also of such a. character as to be good in electrical conductors.

Inbrief, a relay of this type, such as shown in H general in'the prior Patent Nos. 1,749,331 and v 1,.82, l2,9, includes a U-shaped core structure with its free ends terminating in pole pieces 59. The

, windings on the core structure are located above a base plate 51) of suitable insulating material,

while the ,pole pieces 59 extend beneath the base plate 65. and are connected thereto.

, At the back of the relay abracket fit is attached to the base plate 59 by bolts 52 ateach end asshown inFig. 7. This bracket is of course electrically isolated from the pole pieces 59 by ...r,eascn of its attachment to the insulating base plate 60. The bracket 5! is held away from the baseflplate by reason of the bolt 52 so as to be opposite the armature as shown in Figs. 8 and 10;

' and is provided with down-pressed portions 53 f for supporting the trunnion bearing for the armature. There are two supporting arms 54 connected beneath the armature and extending to the back of the relay with bifurcated portions to hold the trunnion bearing 55 in place. In this way, the armature 56 is pivotally supported at two points at the back of the relay. It is limited in its upward movement by the residual pins 58 and in its downward movement by the back contacts (not shown) cooperating with the ends of the contact fingers 55.

. Since the base ends of the contact fingers do nothave the bracket member 6! directly adjacent as in the previously described form of relay this form of the invention employs a shunt connector or clip 55 which is a fiat strip of metal bent in a fashion to be snapped over the bracket 61 which has a central ribbed portion 51. This can best be seen in Fig. 9. This main body of the jeep 56 has two fingers 53 and 69 reaching resp'ectively to the two pole pieces 59. Another j'fi'nger 10 extends from the body of the shunt pieces 59. terial and also to hold the shunt connector or connector 66 outwardly and between the two pole This serves as added conductive mafrom its main body are four fingers I i l2, l3 and 14 which have their ends bent downwardly and also onthe horizontal so that their points or corners are adjacent the corners of the contact fingers as seen in Figs. '7 and 8. In this way a relief gap is created directly between the base ends of the contact fingers 55 andthe shunt connector or clip 65. These fingers H, i2, 13

and 14 are held in position opposite the base ends of contact fingers 55 by reason of the finger 10 between the pole pieces 59 preventing endwise movement.

' Since the shunt connector 66 has its fingers 68 and 69 contacting both the pole pieces 59, it

i is evident thatit should be made of suitable nonmagnetic spring material such as Phosphor bronze, German silver, or the like, so as to avoid the shunting of any magnetism away from the armature and directly between the two pole pieces 59.

Referring to Fig. 8 it will be seen that the connector 66 is ribbed at I along the full length of its body, as can be seen in Fig. 9. Also, the connector 66 has a raised portion at 16 along the full length of its body. The ribbed portion and the raised portion T6 cooperate and having such relative positions that the tension on the fingers 68 and 69 against the pole pieces 59 causes the back portion of the body of the con.- nector 66 to lay flat along the bracket Bl. This can be seen in both Figs. 8 and 9. However, should the tension on fingers 68 and 69 weaken because of metal fatigue, the ribbed portion 75 and the raised portion 76 are so located with respect to each other that the fingers H, 12, 13 and 14 cannot inadvertently move to contact the fingers 55. If anything, the tendency under such circumstances, is for the connector 66 to move the fingers ll, 12, I3 and 14 away from the contact fingers 55 in the event of vibration or the like, and thus preserve the integrity of the contact fingers 55 as circuit controlling elements.

Thus, the present invention has been shown as embodied in two forms of relays where the core structure and armature are electrically isolated from each other by reason of their common support on a base plate of insulating material. The invention provides that a relief gap shall be established between the contact fingers which are also insulated from each other and their armature, and a shunt path to the repective pole pieces of the core structure which is wholly exclusive of the armature and its trunnion bearing. This provides that any high voltage static charge applied to the fingers will have an opportunity to discharge directly to the core structure without passing through the armature and causing an undesired welding effect.

A diagrammatic or symbolic view of a relay constructed in accordance with the present invention has been shown included in the circuit diagram of Fig. 11. The windings 80 of the relay are connected across the two track rails. The armature 8| is pivoted at 82 as above described in connection with Figs. 7, 8, 9 and 10. The support bracket 83 for the armature trunnion bearings provides a mounting for the shunt 'connector or clip 8 A relief gap is provided as at 85 so that any static voltage which may appear on the line wires and reach the contact finger 86 can find a discharge path through the shunt connector 8 3 to the pole piece 81 and via the winding leads to the track rails assuming that such voltage is sufiicient to break down the winding insulation.

It should be understood that it is assumed that normal static charges on the line wires are dissipated to ground or to the track rails by the arresters or spark gaps 98. But in some instances where extreme high voltage charges reach the line wires, or in the event of failure of the arresters 90, the charge on the contacts may reach such a high value as to break down the usual winding insulation. In such a case, as has been explained, the discharge through the armature might cause a welding operation, and for this reason the present invention in providing a relief gap between the contacts and the pole pieces establishes a safety factor so that the relay will not erroneously be held in a picked up position even though a very severe discharge has broken down its winding insulation.

It should also be noted that the winding acts as an inductance between the two connections to the track rails so that a breakdown with respect to one track rail does not necessarily provide a breakdown with respect to the other track rail. For this reason, it is desirable that arresters 90 be employed on both sides of the relay winding and on both sides of the relay contacts in addition to which the present invention pro vides a safety relief gap under the conditions described in detail above.

It should be noted that in Fig. 11 the diagrammatic representation of a relay constructed in accordance with the present invention has been drawn to illustrate the structure more particularly shown in Figs. 7, 8, 9 and 10; but it should be understood that the same circuit diagram is representative of the structure shown in Figs. 1 through 6. In other words, the symbolic representation of the relay in Fig. 11 might just as well be drawn to represent the structure of the first form of the invention.

Having thus described a relief gap device for the protection of electromagnetic relays from lightning discharges in two different forms embodying the present invention, it is desired to be understood that these forms are selected to facilitate in the disclosure of the invention rather than to limit the number of forms which it may assume; and, it is to be further understood that various modifications, adaptations, and alterations may be applied to the specific forms shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention.

What we claim is:

1. In an electromagnetic relay structure having a base plate of insulating material, an electromagnet having pole pieces mounted on the base plate, an armature support bracket mounted on the base plate, an armature pivotally supported by said bracket in cooperative relation to said pole pieces, contact fingers mounted on said armature by insulating supports and having extending points closely adjacent said bracket to provide a relief gap for static discharges, and a shunt connector of conducting material extending between said bracket and said pole pieces, whereby a relief gap for static discharges is provided between said contact fingers andsaid bracket in a conducting path extending to said pole pieces and exclusive of said armature;

2. In an electromagnetic relay structure.having a base plate of insulating material, an electroinagnet having pole pieces mounted on the base plate, an armature support bracket mounted on the base plate, an armature pivotally supported by said bracket in cooperative relation to said pole pieces, contact fingers mounted on said armature by insulated supports, and a shunt connector member of conducting material adapted to snap over said bracket and extend from said pole pieces to points closely adjacent the ends of said contact fingers, whereby a relief gap for static discharges is provided between said contact fingers and said pole pieces eXclusive'of said armature.

3. In an electromagnetic relay structure having a base plate of insulating material, a U- shaped electromagnet having windings and extending pole pieces, said electromagnet being mounted on said base plate with its windings on one side and its pole pieces on the other, an armature pivotally supported in a cooperating position with respect to said pole" pieces by bracket means attached to said base plate and electrically isolated from said pole pieces, contact fingers mounted on said armature by insulating support members and having extending points adjacent the pivoted side of said armature, and a shunt connector providing a conducting path between said pole pieces and extending to a point closely adjacent the extending ends of said contact fingers, whereby a relief gap for static discharges is provided between said contact fingers and said shunt connector, which relief gap is substantially of the same size regardless of the picked up or dropped away position of said armature since such relief gap is adjacent the pivoted side of the armature.

i. In an electromagnetic relay structure having a base plate of insulating material, an electromagnet having a U-shaped core structure with windings mounted thereon and pole pieces at the open ends of the core, said electromagnet being mounted to said base plate with the pole pieces extending through the base plate and connected thereto, an armature for cooperating with said pole pieces, bracket means connected to said base plate and electrically isolated from said pole pieces for pivotally supporting said armature on one side, contact fingers mounted on said armature and extending to one side for cooperating with fixed contacts mounted to said base plate, said contact fingers also extending to the other side of said armature to a point near its pivot on said bracket, and a shunt connector adapted to fit around said armature support bracket and extending between said pole pieces to a point closely adjacent the extensions of said contact fingers near said armature pivot point, whereby a conducting path for static discharges is provided between said contact fingers and said pole pieces if such static discharges are of sufficient magnitude to break down the relief gap between said fingers and said shunt connector, and whereby such conducting path for static discharges excludes said armature and its pivoted mounting.

5. In an electromagnetic relay, a core structure having extending pole pieces, windings mounted on said core structure, a cooperating armature pivotally supported with respect to said pole pieces, contact fingers mounted on said armature with separating insulating material to electrically isolate such contact fingers from said armature, said contact fingers extending away from said armature to cooperate with fixed contacts but having their opposite ends terminate near said armature pivot point, and a shunt connector extending from intimate contact with said pole pieces to points adjacent said opposite ends of said contact fingers to thereby provide a relief gap for static discharges from said contact fingers and over a conducting path to said core structure wholly independent of said armature.

6. In an electromagnetic relay structure, a U- shaped electromagnetic core structure having windings mounted on each leg of the core and having extending pole pieces at the ends of said core members, an armature pivotally mounted with respect to said pole pieces and normally biased away from said pole pieces, residual pins of conductive material but having non-magnetic characteristics mounted on the face of said pole pieces to limit the extent to which said armature may approach said pole pieces when said windings are effectively energized, a plurality of contact fingers, means including insulating material for mounting said contact fingers on said armature to electrically isolate such fingers from said armature, and means providing an electrical conducting path from a point near the free ends of said contact fingers to said pole pieces independently and exclusively of said armature and said residual pins.

'7. In a railway signaling system, a track section, a track relay having a core structure with pole pieces and with windings mounted thereon, said windings being connected across the track rails of said track section, and said relay having an armature for operating contact fingers included in associated line circuits, said contact fingers being electrically isolated from said armature, and means for providing a relief gap adjacent the ends of said contact fingers and connected to the pole pieces of said relay structure, whereby static discharges that may seek the track rails via the pole pieces and windings of said relay may do so without passing through said armature.

8. In an electromagnetic structure having a base plate of insulating material, an electromagnet having a U-shaped core terminating in two pole pieces mounted on the base plate, an armature support bracket mounted on the base plate, an armature pivotally supported at both ends by said bracket and in cooperative relation to said pole pieces, contact fingers mounted on said armature by insulating support members, contact extensions for each of said contact fingers, each of said extensions having alignment flanges and an oblong mounting hole, and each of said contact extensions being adjustably mounted on its respective contact finger to have its end closely adjacent said bracket to provide a relief gap for static discharges, said oblong mounting holes allowing only a limited adjusting movement to positively prevent said extensions from making actual contact with said bracket, and shunt connectors of conducting material extending between said bracket and said pole pieces, whereby relief gaps between said contact fingers and said bracket provide conducting paths for static discharges to said pole pieces from said fingers exclusive of said armature and its pivoted mounting.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,766,665 Merkel June 24, 1930

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