US3264428A

US3264428A - Relay in combination with a circuit breaker for auxiliary tripping of the latter

Info

Publication number: US3264428A
Application number: US276575A
Authority: US
Inventors: Joseph S Hollyday
Original assignee: Heinemann Electric Co
Current assignee: Heinemann Electric Co
Priority date: 1963-04-29
Filing date: 1963-04-29
Publication date: 1966-08-02
Anticipated expiration: 1983-08-02
Also published as: DE1463282B2; GB1058485A; DE1463282A1

Description

Aug. 2, 1966 J. s. HOLLYDAY 3, 64, 8

RELAY IN COMBINATION WITH A CIRCUIT BREAKER FOR AUXILIARY TRIPPING OF THE LATTER 5 Sheets-Sheet 1 Filed April 29, 1953 w fiW WI 7? 7 0 I I /ee H0 157 [35 5 INVENTOR. ij'yj JOSA'PH s, #011704) Aug. 2, 1966 J- S- HOLLYDAY RELAY IN COMBINATION WITH A CIRCUIT BREAKER FOR AUXILIARY TRIPPING OF THE LATTER Filed April 29. 1983 5 Sheets-Sheet 2 Eg s.

INVENTOR. JOJfPl/ S. HOALYDA) I 1 I I l l i Ill-L Q I I I 2 Aug. 2, 1966 J. s. HOLLYDAY 3,264,428

RELAY IN COMBINATION WITH A CIRCUIT BREAKER FOR AUXILIARY TRIPPING OF THE LATTER 5 Sheets-Sheet 5 Filed April 29. 1963 IN VEN TOR f U 4 A. MW Z T w w I 5 MM H m m United States Patent RELAY IN COMBINATION WITH A CIRCUIT BREAKER FOR AUXILIARY TRIPPING OF THE LATTER Joseph S. Hollyday, Pennington, N.J., assignor to Heinemann Electric Company, Trenton, N .J., a corporation of New Jersey Filed Apr. 29, 1963, Ser. No. 276,575 3 Claims. (Cl. 200-106) This invention relates to improved relays and particularly relays sensitive to low or undervoltage for tripping of circuit breakers upon the occurrence of such low or undervoltage so that the circuit breaker contacts are opened automatically to prevent damage to the equipment in the circuit being protected by the circuit breaker where such equipment is of the kind that it might be damaged if allowed to continue to operate on such low or undervoltage. While this improved relay is described herein mostly in terms of undervoltage protection it will be seen that it could also be used for the remote control of the circuit breaker and the circuits protected by the circuit breaker by intentionally terminating, or reducing below a first, approximate predetermined level or tripout voltage, the energization of the relay by suitable means located remotely from the relay and circuit breaker but in the circuit of the relay.

Also, this invention relates to a circuit breaker having an automatically resettable linkage and an automatically resetable electromagnetic control means therefor in combination with an automatically resettable relay for actuating the electromagnetic control means of the circuit breaker.

Various undervoltage relays are known in the prior art but they are not adapted to be readily added to existing circuit breakers. The known undervoltage relays have in the past been incorporated within the molded insulation casings of the circuit breakers. It is another object of my invention to provide an improved relay that can be attached to and disposed mostly outside the circuit breaker case for controlling the contacts of the circuit breaker.

It is a further object of this invention to provide an improved relay that will automatically reset itself to the position before the occurrence of the undervoltage when a second, approximate predetermined voltage level or pickup voltage returns to the relay coil in combination with a circuit breaker having a circuit breaker armature for controlling the circuit breaker linkage mechanism in which both (i.e., the circuit breaker armature and the circuit breaker linkage) automatically reset themselves. to positions wherein the circuit breaker contacts can be manually, directly moved to the closed position without an intermediate reset position.

It is a still further object of this invention to provide a trip rod in combination with the aforesaid circuit breaker, the trip rod extending from outside the circuit breaker case to the interior thereof and engageable with the circuit breaker electromagnetic means for latching and unlatching the circuit breaker linkage, the trip rod being arranged and constructed so that a mechanical motion originating outside the circuit breaker case is transferred into the inside of the circuit breaker case in an arrangement wherein the circuit breaker linkage is automatically "ice resettable and trip free and wherein the trip rod is also automatically resettable.

In one embodiment of this invention the undervoltage relay is attached to the case of the circuit breaker unit, the relay comprising an electromagnetic coil mounted upon one leg of a U-shaped core formed by a plurality of stacked laminations. The other leg of the core indirectly supports the relay armature which includes a trip rod or finger, the latter extending through a hole in the circuit breaker case. A portion of the finger that extends into the circuit breaker case is engageable with one of the pivotal armatures of the circuit breaker unit to (upon undervoltage) turn this circuit breaker armature in the direction to trip the circuit breaker linkage associated with this circuit breaker armature.

The relay is providedwith a spring which is under tension at all times, the spring always tending to bias the relay armature in the direction which will cause engagement of the relay finger with this circuit breaker armature. At rated voltage, the electromagnetic flux is sufficient to produce a force on the relay armature opposite in direction, and greater than, the spring force, maintaining the relay armature attracted toward the core leg extremity portions. Upon the tripout undervoltage this spring moves the relay armature and finger, but when the pickup voltage returns to the coil, the relay armature and finger automatically reset because the electromagnetic flux at such time again becomes greater than the spring force on the relay armature and is in the opposite direction to the spring force. When the relay armature and finger reset, the disengagement which results between the relay finger and the circuit breaker armature allows the circuit breaker armature to reset, which in turn allows the circuit breaker linkage to automatically reset.

The foregoing and other objects of the invention, the principles of the invention, and the best mode in which I have contemplated applying such principles will more fully appear from the following description and accompanying drawings in illustration thereof.

In the drawings:

FIG. 1 is a perspective view of a three pole circuit breaker unit with which the relay is associated;

FIG. 2 is a sectional view through the circuit breaker unit illustrated in FIG. 1 adjacent the internal parts of one end pole, taken along the line 2--2 in FIG. 1 and illustrating the parts mostly in side elevation;

FIG. 3 is a sectional view taken along the line 3-3 in FIG. 2 but illustrating only the end pole illustrated in FIG. 2;

FIG. 4 is a view looking at the underside of the relay (generally taken along the line 4-4 in FIG. 2) in which the relay cover has been broken away to show the internal relay structure and illustrating the position of the relay armature including its trip finger at rated voltage or above in solid lines and their position after the occurrence of a tripout undervoltage in dot-dash lines;

FIG. 5 is a side view taken along the line 55 in FIG. 4, omitting the relay cover, and showing the position of the relay finger at rated voltage or higher and the associated circuit breaker armature;

FIG. 6 is a view similar to FIG. 5 but illustrating the position of the relay finger and circuit breaker armature after the occurrence of a tripout undervoltage condition;

' FIG. 7 is a side view of the relay but of the side opposite to that shown in FIGS. 5 and 6 and taken generally along the line 77 in FIG. 4, and (unlike FIGS. 5 and 6) showing in FIG. 7 the relay cover;

FIG. 8 is a view of the relay taken generally along the line 88 in FIG. 4 but omitting the relay cover;

FIG. 9 is a sectional view taken along the line 99 in FIG. 8;

FIG. 10 is a view of the relay taken along the line 10-10 in FIG. 2 but omitting the relay cover;

FIG. 11 is a sectional view taken along the line 11-11 in FIG. 10; and

FIG. 12 is a perspective view of the armature including its trip finger.

Referring to the drawings in detail, FIG. 1 illustrates a relay 10 attached to a case 12 of a three pole circuit breaker unit 15, the relay 10 being provided with a cover 11 of molded insulation material similar to the case 12.

As illustrated in FIGS. 4 to 8, the relay 10 comprises an armature (or clapper) 22 including a trip rod or finger 35 which at predetermined electrical conditions engages and pivots a circuit breaker armature 40 to open the

contacts

26 and 27 of the circuit breaker at such time and for this purpose the finger 35, as illustrated in FIG. 2, extends upwardly through a hole 42 in the circuit breaker case 12 and into association with the circuit breaker armature 40.

The three pole circuit breaker unit 15 will be described somewhat hereinafter but this invention does not reside in the details thereof, this circuit breaker unit being described in greater detail in copending US. Patent application 109,914 filed by the applicant herein. Further, the circuit breaker unit in combination with which it is intended that this invention be used is a circuit breaker unit of the automatically resettable type such as is illustrated by US. Patent No. 2,360,922.

In FIG. 4, which is a view looking at the underside of the relay 10, the relay cover 11 has been broken away (in the drawing) to show an electromagnet comprising a coil 14 wound about an insulator bobbin and disposed around a leg 16 of an inverted U-shaped core 18, the latter being formed from magnetizable stacked laminations, preferably high silicon steel.

Attached to the other leg 19 of the core 18 is a support bracket 20 for the pivotal relay armature (or clapper) 22, the support bracket 20 being preferably of nonmagnetic material such as brass. The relay armature comprises two spaced L-

shaped plates

24 and 25, also preferably of nonmagnetic material such as brass, and placed between the lower ends (FIG. 9) of the

plates

24 and 25 are rectangular, stacked clapper laminations 28 of magnetizable material, preferably of high silicon steel, the stack of clapper laminations being thicker than that of the core (FIG. 8) but coextensive therewith (FIG. 9).

The

core legs

16 and 19 have

extremity portions

30 and 31, respectively, which will be further described hereinafter and against which portions of the clapper laminations 28 abut uponpredetermined energization of the coil 14.

Attached to the upper ends (FIG. 9) of the

relay armature plates

24 and 25 is the relatively fiat finger or trip rod formed by an insulator plate, preferably of paperphenolic composition and roughly of V-shape, the upper end (in FIGS. 5 and 6) of which is spaced (FIG. 5) from but associated and engageable (FIG. 6) with the circuit breaker armature 40, a portion of the finger 35 for this purpose extending through the elongated hole 42 in the circuit breaker case 12. End tab portions of the

relay armature plates

24 and 25 extend through holes in the finger 35 and are split and bent over, as illustrated in FIG. 12, to retain the finger 35.

The trip finger 35 is biased at all times toward engagement with the circuit breaker armature by a tension spring 45, one end of the spring 45 being attached to the finger 35 by extending into a hole 46 between the

plates

24 and 25 and the other end being attached to a spring support bracket 48 by extending through a hole in an upstanding, bendable (to vary the spring tension somewhat), arm 50 of the bracket 48, the latter having a second arm 51 riveted (by suitable rivets preferably of nonmagnetic material such as brass) to the lower side of the core at the base of the U-shape thereof. Further, the bracket 48 has a third arm 52 which jointly with a portion of the support bracket 20 to be hereinafter further described are used to attach the relay 10 to the circuit breaker case 12 by suitable screws.

Referring to the support bracket 20 for the relay armature 22, the bracket 20 comprises a thin flat plate 55 (FIGS. 4, 7 and 8) and another thin fiat body or plate 56 disposed intermediate the L-

shaped armature plates

24 and 25, the

plates

55 and 56 having aligned holes through which extends a pin 58, the pin 58 also extending through other aligned holes provided in the L-

shaped armature plates

24 and 25 near the heels of these last mentioned plates. The

plates

55 and 56 and the pin 58 are also preferably of nonmagnetic material such as brass and the pin 58 has an enlarged head at one end and a flared over at the other end to prevent its dropping out. Also, suitable rivets (preferably of nonmagnetic material such as brass) extend through the core leg 19 and the

plates

55 and 56 and secure these plates to the core 19.

The plate (or body) 56 (FIG. 7) is integral with an arm 60 and a foot 61 which jointly define a U-shape, as illustrated in FIGS. 7 and 11. A portion of the armature plate 25 abuts against the vertical arm 60 as shown in FIG. 4 (wherein this position of the armature plate 25 is shown in dot-dash lines) to limit counterclockwise movement of the relay armature 22 under the bias of the spring 45.

The

lower extremity portions

30 and 31, referring to FIG. 9, of the

legs

16 and 19 are constructed so that the inner halves, 16a and 19a, of the

legs

16 and 19 extend farther than the outer halves, 16b and 19b thus forming

air gaps

70 and 71 between the leg halves 16b and 19b and the clapper laminations 28 which are not closed even when the clapper laminations 28 abut the end surfaces of the

longer leg halves

16a and 19a.

Further, in each of the shorter leg halves 16b and 19b slots 89 are provided (FIG. 9) to snugly receive parts of shading coils or short circuiting slugs 90, preferably formed of copper. In the embodiment illustrated, three shading coils 90 are used in abutting side-by-side relation, the longer leg end vportions extending through suitable holes, but in close fitting relationship therewith, so as to be frictionally retained thereon. As illustrated in FIG. 9, the slots 89 are long enough so that the lowest surface of the lowest shading coil 90 is above the end surfaces of the leg halves 16b and 19b as well as the end surfaces of the

longer leg halves

16a and 19a.

As illustrated in FIG. 2, the relay 10 is attached to the circuit breaker case 12 next to a vertical wall 88 thereof and thus the relay cover 11 need only comprise three sides which are provided with integral feet 93 through which suitable screws extend for securing the relay cover 11 to the circuit breaker case 12.

FIG. 2 illustrates the internal arrangement ofone of the circuit breaker poles, the farthest end pole in FIG. 1, it being understood that the other poles are similarly constructed and interconnected for virtually simultaneous tripping of the three poles upon the occurrence of an overload in any one pole, as described in the aforementioned US. Patent application Serial No. 109,914, by an interconnecting trip rod having depending therefrom trip fingers 101 and 102, but it being understood that similarfingers are provided for the other poles although not illustrated.

The internal mechanism of each circuit breaker pole can be briefly described as comprising a movable arm 105 carrying the movable contact 27, the latter being engageable with the stationary contact 26 which is connected by g. suitable terminal structure 106 to a connector 107. The movable arm 105 is connected by a flexib e conductor 128 to a coil 122 of an electromagnet 123, the coil 122 having its other end connected to a terminal structure 125 and to another connector 126.

The movable contact arm 105 is biased by a spring 128 toward the open position of the contacts. The opening spring 128 biases the movable arm 105 toward the stationary shaft 130 which has its ends secured to similar parallel, and spaced frame plates 132 and 133 (FIG. 3), intermediate which is disposed the mechanism for operating the circuit breaker. The movable arm 105 is connected to (and manually operable by) a handle 140 common to all three circuit breaker poles through a linkage mechanism 142, the linkage mechanism 142 being electrically controlled by the electromagnet 123 and

armature devices

144 and 145, upon predetermined electric currents.

The main armature device 144 is a two piece mechanism comprising the balanced, pivotal magnetizable armature 40 (previously mentioned), having side legs 135, for pivoting a balanced latch 147, the latter comprising side plates and top and bottom interconnecting bars 148 and 149, respectively, preferably of non-magnetizable material. The lower bar 148 (FIG. 2) restrainably engages the spaced, lock lips 163 of a cradle 160, the lower latch bar 148 being rotated counterclockwise out of engagement with the lock lips 163 upon predetermined overload currents in the coil 122 by suitable engagement of the lower side legs 135 of the armature 40 with the lower bar 148, the cradle 160 being pivotal about pintle 162 whose ends are carried by

plates

132 and 133.

Referring to FIG. 2, which illustrates the closed position of the

contacts

26 and 27, the handle is illustrated in its leftwardmost or contacts closed position having pivoted the associated handle link 150 to its most counterclockwise position about its pintle 151, the latter having its ends carried in suitable openings in the

frames

132 and 133. The handle link 150 is connected to the handle 140 by a pintle 153 carried by the upper end of the link 150. The mechanism is restrained by a catch link 155, pivotally connected to the pintle 151 at one end and provided with a straight nose portion 157 at the other end for engaging a lock pin 158 carried in slots 159 of the cradle 160. The lock pin 158 is biased to the top of the slots 159 by a spring (not illustrated) for restrainably engaging the nose portion 157.

To connect the catch link 155 to the movable arm 105, -a toggle is utilized, comprising upper and lower links 164 and 170. The upper link 164 comprises two side-by-side spaced members having their ends connected between the ends of the member forming the catch link 155 by a pintle 174, FIG. 2. The lower link 170 also comprises two side-by-side spaced members connected at their ends to the opposite sides of the movable arm 105 by another pintle 173. The knee of the toggle is formed by a pintle 171 and its overset (to the right) is limited by a pin 172 having its ends secured to the

plates

132 and 133. The four bar linkage is completed by pivotally connecting the bottom portion of the handle link 150 to the upper link 164 by a cross link 175 and providing a pintle 176 for connecting the ends of the handle link 150 and the cross link 175 and, also, providing a pintle for connecting the other end of the cross link 175 to the upper link 164, intermediate the ends of the latter.

Thus, the handle link 150, the catch link 155, the upper toggle link 164 and the cross link 175 form a four bar linkage in which each of the links are pivotally connected to the other and one of the links, the upper toggle link 164, is connected to a fifth link, the lower toggle link 170. Rotation of the handle 140 rotates the handle link 150 which, through the linkage just described, moves the contact 27 to the closed position, illustrated in FIG. 2, at which time the knee of the toggle is over center to the right and the handle is at its leftwardmost position.

Referring to FIG. 2, between the two spaced members forming the link 170 and the movable arm are disposed the legs of a generally U-shaped automatic reset spring 183 having the base of the U biased against the upper side of the arm 105 (the reset spring 183 having portions of its legs coiled about the pintle 173 on opposite sides of the arm 105. Also, the reset spring 183 has its ends 184 hooked over the two members forming the link 170.

The cradle 160 is approximately of channel shape in cross section and the pintle 162 about which it pivots is disposed intermediate the ends of the slots 159 but adjacent the lower end thereof. The right hand end of the cradle 160 freely interfits with (and the sides thereof are spaced from) the sides of the armature 40.

A cradle spring (not illustrated) biases the cradle 160 in the counterclockwise direction and into engagement with the lower bar 148 of the latch 147. The spaced side plates of the cradle 160 form the lips 163 are provided with straight surfaces 166 (shown in a dotted line in FIG. 2) for pivoting the bar 148 and allowing the lips 163 to slip behind the bar 148 during automatic resetting, if the bar 148 has returned to the reset position before the cradle 160.

The electromagnet 123, further comprises a tube 193, about the lower portion of which the coil 122 is wound, and a main frame 194 of magnetizable material. Within the tube 193 is a movable core (not shown) of magnetizable material biased toward the top of the tube 193 by a spring (not shown). The tube 193 is preferably of nonmagnetizable material, such as brass, electrically spaced from the coil 122 and the frame 194 by suitable insulators and soldered to the horizontal frame legs to provide a mechanical connection thereto.

Associated with the frame 194 is a shunting frame 201 for the armature device 145, as illustrated in FIG. 2.

From the foregoing it is seen that on predetermined overload current conditions in the coil 122 the armature 40 is pivoted counterclockwise until the side plates thereof engage the bar 148 moving it out of latching engagement with the cradle lips 163 which releases the cradle 160 permitting it to pivot clockwise under the pressure of the opening spring 128 until the catch link nose 157 is released by the lock pin 158. Release of the catch link nose 157 permits the linkage to collapse, the

contacts

26 and 27 to open, the handle to move to the contacts open position and the spring 183 to reset the nose 157 under the lock pin 158, so that the handle 140 can be immediately turned to the contacts closed position to close the contacts (if the current in the coil is now below said predetermined overload current), the spring 188 resetting the cradle 160 to the initial position, as also the armature devices 144 and are reset by their springs, the latter not being illustrated in detail in the drawings.

To trip the adjacent circuit breaker poles upon an overload in one of the poles only, during collapse of the linkage the nose 157 of the overloaded pole engages the trip finger 102 of the interconnecting trip rod 100 which has other fingers 101 associated with the upper bars 149 of the armature device 144 to turn the latter in the direction to release the associated cradles of the nonoverloaded poles.

Referring to FIGS. 2 and 3, it is seen that the trip finger 35 is disposed opposed to and spaced from one of the two side plates 135 forming part of the circuit breaker armature 40 so that at the predetermined tripout undervoltage, when the clapper laminations move sufiiciently away from

legs

16 and 19, the relay trip finger 35 en- .gages the circuit breaker armature 40 and moves it in the direction to release the circuit breaker cradle 160. Thus, it is seen that by providing a relay 10 having one relay trip finger 35 associated with one circuit breaker armature 40 of one of the poles of the multipole circuit breaker unit, all of the circuit breaker poles can be made to trip virtually simultaneously because of the interconnection of the circuit breaker poles by the trip rod 100.

The relay coil 14 is connected electrically directly across two phases of a three phase system, the normal phaseto-phase voltage being the rated voltage of the relay coil '14. The circuit breaker coil 122. is connected, in series, with the return line to the opposite phase through the load. Thus, normally the relay coil 14 is energized at phase-to-phase voltage and the circuit breaker coil 122 is energized at phase-to-phase voltage minus the voltage drop of the load. At rated voltage the electromagnetic flux produced by the relay coil is sufficient to overcome the force of the spring 45 in the opposite direction, the relay armature being in the solid line position of FIG. 4 and in the position of FIG. at such time. (The relay coil could be constructed so as to have a rated voltage at a predetermined percentage of the phase-to-p-hase voltage rating but the various parts of the relay would have to be proportioned and/ or adjusted for this condition.) When the phase-to-phase volt-age decreases below the normal voltage to a first predetermined or tripout level, the electromagnetic flux produced by the relay coil is insufiicient to overcome the force of the spring 45 in opposite direction and the relay armature is moved by this spring force to the dot-dash line position of FIG. 4 and that position illustrated in FIG. 6, this being the tripped position of the relay.

Upon an increase in the phase-to-phase voltage, toward the normal voltage, the coil flux will increase to a second predetermined or pickup level at which the force produced by the electromagnetic flux on the armature exceeds the force of the spring 45 sufficiently to pivot the armature so that the clapper lamination-s abut the

legs

16 and 19. However, it should be noted that the pickup voltage is a higher voltage than the tripout voltage but, of course, below the rated voltage. The reason that the pickup voltage is at a higher level than the tripout voltage is seen by reference to the dot-dash lines of FIG. 4 which show that in the tripout position movement of the clapper lamin-ations 28 away from the legs 16 and '19 creates therebetween a very large air gap (compared with the normal armature position in which the clapper laminations 28 abut the end surfaces of the

leg portions

16a and 19a to form the small air gaps 70 and 71). Hence, after tripout, the electromagnetic flux produced by the relay coil has to produce a force across the large air gap then formed to overcome the force of the spring 45 in the opposite direction.

A further feature of this invention, it will be seen from the foregoing, is that so long as a voltage below the pickup level persists, in the relay coil, the

circuit breaker contacts

26 and 27 cannot be reclosed. The reason for this is that after the occurrence of the tripout voltage and movement of the trip finger 3'5 and circuit breaker armature 40 to the positions illustrated in FIG. 6 have taken place, trip finger 35 maintains the circuit breaker armature 40 in the unlatching position until the piclcup voltage (or higher) energizes the relay coil 14, so that even if the handle 140 is manually moved to the contacts closed position while a voltage level below the pickup level persists in the relay coil, the collapse of the linkage 14-2 due to the pressure of the spring 128, since the lips 163 are unlatched from the bar 148 at such time, prevents the

contacts

26 and 27 from being reclosed. Of course, after the pickup (or higher) voltage energizes the relay coil and the trip finger returns to the position illustrated in FIG. 5, the bar 148 latches the lips 163, if no overload above a predetermined value energizes the circuit breaker coil 122, and the

contacts

26 and 27 may then be reclosed by pivotal movement of the handle 140.

This relay is intended for use primarily with alternating current and, hence, the laminated core and the laminated clapper are both made from material having a high electrical resistance to minimize heating of the parts due to hysteresis and eddy current losses.

Also, as relatively well known, alternating current relays sometime chatter or hum at a frequency which is double that of the electrical supply. The previously described shading coils in combination with the air gaps 7d and 71 result in a steady state pull or force attracting the clapper lamin-ations 28 tothe

legs

16 and 19 superimposed on an alternating pull or force whose frequency is double the frequency of the electrical supply to the relay coil. By proportioning the various parts so that the steady state pull or force minus the negative portion of the alternating pull is greater than the force of the spring 45 on the relay armature, no chatter or hum of the relay armature will result.

Because of mechanical inertia and friction, it should be noted that the tripout voltage level is lower than the level where the force of the spring 45 just exceeds the steady state pull or forceminus the negative portion of the alternating pull or force aforementioned. Hence, just before reaching the tripout level, the relay may chatter or hum slightly, at twice the frequency of the electrical supply, but this slight chatter is insignificant because usually when a substantial voltage drop occurs it takes place quickly and sharply to below the tripout level.

Having described this invention, I claim:

1. In combination, a circuit breaker comprising an automatically resettable linkage connected to and controlling a pair of separable contacts, said circuit breaker further comprising an electromagnetic coil and an automatically resettable armature therefor, an electromagnetic relay associated with said circuit breaker, said electromagnetic relay including a relay coil and a relay armature, said relay further including a trip finger biased toward engagement with the circuit breaker armature, said coil when energized at substantially rated voltage maintaining said trip finger out of engagement with said armature against said bias but upon energization of said relay coil below rated voltage to a predetermined level said trip finger engages said circuit breaker armature to open the circuit breaker contacts and prevent the circuit breaker armature from resetting itself at such time, energization of said relay coil at a second predetermined level automatically above said first predetermined level automatically returning said trip finger to its initial position permitting said circuit breaker armature to auto matically reset itself.

2. In combination, a circuit breaker having a case enclosing a pair of separable contacts, an automatically resettable linkage connected to and controlling tone of said contacts, a latch forming part of said linkage, an electromagnetic coil and a pivotal armature movable into engagement with said latch to trip said linkage on predetermined overload currents, and a trip finger means extending through said case and engaging said armature to move the latter into engagement with said latch to trip said linkage, said trip finger means being automatically resettable to its initial position subsequent to the tripping ot the linkage to permit said linkage to automatically relatch.

3. In combination, a circuit breaker comprising a pair of separable contacts and a handle, a movable arm carrying one of the contacts, a linkage means connecting said movable arm to said handle, a first electromagnetic means automatically opening said contacts on predetermind overload and relatching said linkage means after the contacts open automatically; a case enclosing said contacts, said linkage means and said first electromagnetic means; a second electromagnetic means actuatable independently of said first electromagnetic means, said second electromagnetic means being movable from a first position out of engagement with said first electromagnetic rneans into a second position engaging and actuating said first electromagnetic means -to open said contacts, said second electromagnetic means when in said second position preventing relatching of said first electromagnetic means, and said second electromagnetic means being automatically movable back to said first position to permit said first electromagnetic means to relateh.

UNITED 2,697,148 12/ 1954 Slebodnik 200-106 2,759,063 8/ 1956 Rypinski 200-89 2,912,544 11/ 1959 Piteo, et a1 200-106 References Cited by the Examiner 2,916,533 12/1959 Noyes STATES PATENTS 5 2,924,685 2/ 1960 Burch 200-104 Wittingham 317-187 X Tnombetta 317 l84 BERNARD A. GILHEANY, Przmary Exammer.

Morgenstern 313-184 ROBERT K. SCHAEFER, Examiner.

8 253 111, g 10 T. D. MACBLAIN, Assistant Examiner.

Claims

2. IN COMBINATION, A CIRCUIT BREAKER HAVING A CASE ENCLOSING A PAIR OF SEPARABLE CONTACTS, AN AUTOMATICALLY RESETTABLE LINKAGE CONNECTED TO AND CONTROLLING ONE OF SAID CONTACTS, A LATCH FORMING PART OF SAID LINKAGE, AN ELECTROMAGNETIC COIL AND A PIVOTAL ARMATURE MOVABLE INTO ENGAGEMENT WITH SAID LATCH TO TRIP SAID LINKAGE ON PREDETERMINED OVERLOAD CURRENTS, AND A TRIP FINGER MEANS EXTENDING THROUGH SAID CASE AND ENGAGING SAID ARMATURE TO MOVE THE LATTER INTO ENGAGEMENT WITH SAID LATCH TO TRIP SAID LINKAGE, SAID TRIP FINGER MEANS BEING AUTOMATICALLY RESETTABLE TO ITS INITIAL POSITION SUBSEQUENT TO THE TRIPPING OF THE LINKAGE TO PERMIT SAID LINKAGE TO AUTOMATICALLY RELATCH.