US3174010A - Circuit breaker utilizing kinetic energy of trip member to initiate opening of intermediate latch - Google Patents

Description

Malh 16, 1965 s. A. BOTTONARI ETAL 3,174,010

CIRCUIT BREAKER uTIETzING KINETIC ENERGY oF TRI|J MEMEER To INITTATE OPENING 0E INTERMEDIATE LATCH Filed June 27, 1961 WITNESSES: INVENTORS Samuel A. Bottonori ond @www Robert E. Wobrok.

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'g' ATTORNEY United States Patent O CIRCUH BREAKER UTILIZING KINETIC ENERGY F TREE MEMBER T INHIATE OPENING 0F TERMEDIATE LATCH Samuel A. hottonari, Wilkinshurg, and Robert E. Wobralk, North Huntingdon Township, Westmoreland County, Pa., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsyivania Filed `Ilune 27, 1961, Ser. No. 119,851 d Claims. (Cl. G-1116) This invention 'relates to circuit breakers and more particularly to operating mechanisms for circuit breakers.

In the patent to J. D. Findley, Jr., et al., Patent No. 2,515,994, issued July 18, 1950 Vand -assigned to the assignee of the instant application, there is disclosed ya circuit breaker comprising `a latched operating mechanism that is releasable to effect opening of the breaker. The operating mechanism comprises a main latch that is held in latching position by -an intermediate latch that is pivotally mounted intermediate its ends and has a roller on one end thereof that engages the main latch. A trip member engages a roller on the other end of the intermediate latch to hold the intermediate latch in latching position. Spring means are provided to bias the operating mechanism toward the open position. In order to eiiect an opening operation, the trip member is moved either manually or by means of an automatically operated electromagnet to release the intermediate latch whereupon the force of the opening spring means moves the main latch to force the intermediate latch to move to the unlatched position to completely release the main latch whereupon tl e operating mechanism is rapidly moved to open the breaker.

lf the intermediate latch in the above described mechanism becomes jammed in the latching position, the breaker will not automatically trip upon the occurrence ot an overload current and serious damage can occur in the circuit that is to be protected by the breaker.

Accordingly, an object of `this invention is to provide a circuit breaker of the above-mentioned type with improved means for initiating opening movement of the intermediate latch in order to effect a tripping operation.

Another object of the invention is to utilize kinetic energy of the trip member to initiate opening movement of the intermediate latch of the operatingr mechanism of the circuit breaker.

A more general object of this invention is to provide a circuit breaker with improved means for effecting opening movement of the operating mechanism of the breaker.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, yboth as to structure and oper-ation, together with additional objects and advantages thereof, will be best understood from the following detailed description when read in conjunction with the accompanying drawings, in which:

FIGURE l is a side elevational View, partly in section, of a circuit breaker embodying the principles of this invention; and

PEG. 2 is an elevational view, partly in section and enlarged relative to the dimensions shown in FIG. 1, of part of the mechanism of the circuit breaker seen in FIG. 1.

The structure of the circuit breaker shown in FIG. l is specifically described in the above mentioned patent to l. D. Findley, r., et al., for which reason only a brief description of the breaker is given herein.

Referring to the drawings, and particularly to FIG. 1 thereof, a circuit breaker 3 of the roll-out type is mounted on a truck comprising a pair of side plates 11 (only one being shown) which are rigidly joined by cross members hee 13, 15, 17 and 19 to form a rigid frame for supporting the parts of the breaker. The truck is mounted on wheels 20 to facilitate rolling the circuit breaker into and out of a cubicle (not shown) in order to connect and disconnect the breaker in an electrical circuit.

The circuit breaker 3 is of the multi-pole type (only one pole being shown) and it comprises 4a plurality of sets of separable contact means 21, .a common operating mechanism 23, a trip device 25 and solenoid closing means 27.

The contact means 21 comprises stationary contact blocks 29 and 31 mounted on upper and lower terminal members 33 and 35 respectively which terminal members are rigidly supported on a back plate 37. The back plate 37 is supported by `angular brackets 39 (only one being shown) that are rigidly secured to the side plates 11 of the trame. A switch arm 41 pivotally mounted on a stud 43 on the llower terminal member 35, carries a bridging contact member 45 for cooperating with the stationary contacts 29 and 31 to eiect opening and closing of the circuit that is controlled by the breaker. The switch arm l1 carries a movable arcing contact 47 which cooperates with a stationary arcing Contact 49 that is mounted on the upper terminal member 33 for drawing an arc upon opening movement of the switch arm 41.

There lis a switch arm 41 for each pole of the circuit breaker 3 and each of the switch arms 41 is operatively connected by means of an insulating operating rod 51 to the common operating mechanism 23 for simultaneous operation. The upper ends of the operating rods 51 are pivotally connected by means of pivot pins 53 to the corresponding switch arms 41 land the lower ends of the operating rods 51 Iare connected by suitable means to an angular cross bar 59 that is common to all of the poles of the breaker. The cross bar 59 is pivotally connected by means of pivot pins 55 (only one being shown) to an operating lever 61. The operating lever 61 is pivotally supported on a shait o7 that is mounted in the side members of a generally U-shaped frame 69 that is supported on the cross members 13, 15 and 17. The trame 69 is shown partly broken away to more clearly illustrate the operating mechanism 23.

In addition to the operating lever 61, the operating mechanism 2,3 comprises `a closing lever that is also mounted on the shaft 67 which closing lever is connected by means of a link 81 to a movable armature 85 of the solenoid closing means 27. The operating lever 61 and the closing lever 75 are connected by means of an underset thrust transmitting toggle comprising toggle links 87 and 89 that are pivotally connected together by means of a knee pivot pin 91. The toggle link 87 is pivotally connected to the operating lever o1 by means of a pivot pin 92;. The toggle `link 89 is pivotally connected to the closing lever 75 by means of a pivot pin 76. The lever 75 is also connected to the lever 81 by means of the pivot pin 76.

rlhe closing lever 75 is held in the closed position by means `of `a spring biased latch 95 that is pivoted on a pin 97 that is supported in the side members of the frame 6%. The latch 95 is biased, by means of a spring 96, into engagement with a roller 1611 that is mounted on the pivot pin 76 which engagement normally holds the lever 75 in the closed position shown.

The toggle 87, 89, is normally held in `a slightly underset position by means of a main latch 1613 that is rotatably mounted on the shaft 67 and is connected by meanscf a link to the knee 91 or the toggle. The link 105 is connected to the latch 103 by means of a pivot pin 1117.

The main latch 163 is normally releasably restrained in lratching position by means ot the latching and tripping mechanism 25. The latching and tripping mechanism 25 airs-,oto

comprises fan intermediate latch or latch structure 169 that is pivotally supported intermediate its ends on a pin 111 that is supported on a bracket 112 (FIG. 1). A roller 113 (FIG. 2) is rotatably supported on a pin 115 disposed at one end of the intermediate latch 109 which roiler engages the main latch 103. The intermediate latch 109 comprises two twin members 114 connected by a cross member 116. A roller 117 is rotatably supported on a pin 119 `at the other end of the intermediate latch 1119. The roller 117 normally engages a depressed surface 121 of a trip member 123. The trip member 123 is pivotally supported on a pin 12d that is supported on the bracket 112 (FIG. 1). The intermediate latch 109 is biased toward the latching position by means of a torsion spring 125. The trip member 123 is biased toward latching position by means of a torsion spring 126.

The trip member 123 is adapted to be operated either manually or .automatically in a clockwise direction to an unlatching position, to effect release of the intenmediate latch 109 to thereby effect release of the operating mechanism 23 and opening of all of the pole units of the circuit breaker, by means of a tripping electromagnet indicated generally at 137 (FIG. l).

The tripping electromagnet 137 comprises la support member 139 that is secured to a plate 141 that is rigidly mounted on the U-shaped frame 69. In `addition to the support bracket 139, the tripping electromagnet 137 includes an energizing coil 143, a movable armature (not shown) .and a trip rod 145 that is attached to the movable armature.

The closing solenoid 27 (FlG. 1) in Aaddition. to the movable armature 65, comprises a lined core member V147 and an energizing coil 1419. The closing solenoid 27 is supported between the side members of the frame 69 and an end plate 151, which end plate is suitably secured to the frame 69, by means of bolts 153 and spacers 155.

The circuit breaker is shown in F1G. 1 in the closed and latched position. In the closed and latched position, the operating lever 61 is biased in a clockwise or opening direction by means of an opening spring 159 that is disposed in a cylinder 161 that is rigidly mounted on the frame 69. A piston 163 disposed for reciprocal movement in the cylinder 161 is connected by means of a link 165 to an arm portion 166 of the operating lever 61. The cylinder 161 and piston 163 also serve as .a dashpot to absorb the shock of the opening operation of the operating mechanism. The spring 159 acting through the piston 163 `and the link 165 biases the operating lever 61 in a clockwise direction. The biasing `force of the spring 159 is transmitted by means of the underset toggle 87, 39 to the closing lever 75 which is normally restrained in the position shown in FIG. l by the latch 95. The force of the spring 159, therefore, tends to cause the toggle 87, 89 to collapse which movement is prevented by the link 105 and the latching mechanism. A component of the force tending to collapse the toggle 87, 89 is applied through the link 105 to the latch member 1113 tending to rotate this member in a counterclockwise direction about the pivot 67. The -latch member 103 is restrained from this tripping rotation by the slip-oit or roll-olf type engagement with the roller 113 of the intermediate latch 169, which intermediate latch is restrained from counterclockwise tripping movement by engagement of the lroller 117 thereon in the depressed surface 121 of the tripping member 123.

Upon the occurrence of an abnormal current condition, such for example as an excessive overload current in the circuit controlled by the circuit breaker, the tripping electromagnet 137 (FIG. 1) is energized by well known means such, for example, as a fault relay. When the tripping electromagnet 137 is energized, the movable armature (not shown) thrusts the trip rod 145 upward to engage the trip member 123 moving the trip member in a clockwise or tripping direction. Clockwise movement of the trip member 123 disengages the roller 117 (FIG. 2) from the depressed surface 121 in the trip member 123 to unlatch the intermediate latch or latch structure 109. As soon as the intermediate latch 1119 is unlatched, because of the slip-off or roll-oit type engagement of the main latch 163 with the roller 113 on the intermediate `latch 1119, the force tending to collapse the toggle 87, 89, a component of which is applied to the latch member 103, forces the intermediate latch 1119 to move countercl-ockwise or in unlatching direction out of the path of the main latch 103, whereupon the main latch 163 is `free to rotate counterclockwise in a tripping direction and it no longer maintains the toggle 87, S9 in its underset position. Upon release of the latch member 103, the toggle 37, S9, therefore, immediately collapses under the influence of the opening spring 159 the force `of which spring operates immediately to rotate the operating lever 61 in a clockwise direction to move the common cross bar 59 :and `all of the movable contact farms 51 to the open position opening all of the circuit breaker con-tact means 21.

The toggle 87, S9 is reset to its underset position and the main latch member 1113 is reset and relatched during the opening operation. The resetting of the toggle S7, 89 and the relatching of the latch member 163 is effected by means of a pair of springs 169 (only one being Shown) each of which is secured at one end to` a bracket 171 that is secured to the armature S5 and at the other end to a portion of the closing lever 75. During the collapse of the toggle S7, 89, a roller 175 that is mounted on a pin 177 that is secured to the toggle S9, engages a projection 179 on the latch 95 and moves the latch 95 downward to release the closing lever 75. The closing lever is connected at 76 to the link 81 forming a toggle therewith. The springs 169 are tensioned between the lever 75 and the link 51 acting on these members to decrease the obtuse angle between them. This movement can be effected only by movement of the link S1 to the left which latter movement is normally prevented by the latch 95. Upon release of the latch 95, there is no longer any restriction to this movement of the link S1 and the springs 169 act to move the link 81 and armature 85 to the left rotating the lever 75 clockwise until it strikes a stop member (not shown). Clockwise rotation of the lever '75 straightens the toggle 87, 89. Straightening of the toggle 67, 89 thrusts the link 195 to the left thereby rotating the main latch 163 clockwise to its latching position, at which time the intermediate latch 169 is moved by the spring 126 (FIG. 2) to a position in which the roller 113 re-engages with the main latch 103.

After the mechanism is reset and relatched following an automatic opening operation, the contacts are closed by energization of the closing solenoid 27. The solenoid 27 may be energized from any suitable source either automatically or by means of a manually operated switch means. When energized, the solenoid 27 attracts its armature and, through the link 81, rotates the closing lever 75 in a counterclockwise direction about the shaft 67. At this time, the main latch member 163 is restrained in latching position and the toggle 87, 89 is held by the link in thrust transmitting position. The counterclockwise or closing movement of the closing lever 75 is, therefore, transmitted through the toggle 57, 89 to the operating lever 61 to rotate the operating lever 61 counterclockwise to its closed position to thereby move the operating rods 51 and the switch arms 11 for all of the poles of the breaker to the closed position shown in FIG. l. As the operating mechanism arrives at its closed position, the latch 95, biased by the spring 96, re-engages the latch roller 101 to restrain the pin 76 and therefore the operating mechanism 23 and the contact means 21 in the closed position. The final closing movement of the operating mechanism is retarded by means of the opening spring 159 which spring is charged during the closing operation.

The contact means 21 of the circuit breaker are tripfree of the closing means. That is, if, when the circuit breaker is operated to the closed position, the overload current condition has been cleared, the breaker will remain in the closed position. However, should the overload current still persist, the tripping electromagnet 137 will be energized upon closure of the contacts to operate the tripping mechanism 2S in the previously described manner to effect immediate release of the latch member 193 and collapse of the toggle d'7, 89. This movement permits the circuit breaker mechanism including the switch arms d1 for all of the poles of the breaker to go to the open position under the bias of the opening spring 159, even though the closing solenoid 2.7 remains energized and/ or irrespective of the position of the closing lever '75.

The engagement of the roller 113 of the intermediate latch 109 with the main latch 1&3 is a slip-ott or roll-olf type engagement so that upon tripping movement of the trip member 123, the force of the opening spring 159 exerted through the operating mechanism, rotates the member 103 to move the intermediate latch 1d@ in unlatching direction to eil'ect an opening operation. The force exerted by the spring 1d@ is reduced through the operating mechanism 23 so that the intermediate latch 1% is moderately loaded. This meets the general requirements of having a system that releases a mechanism of considerable force which system does not require a high etlort source to effect a tripping operation. Thus, for example, the force exerted by the operating spring S may be a force of 400 pounds when the circuit breaker is in the closed position, which force is reduced in components through the operating mechanism 2? to la force of about 6 pounds or less tending to rotate the intermediate latch 1&9 in unlatching direction. lt can be understood that if a foreign impediment such as a piece of contact that might spawl off of the contact structure becomes lodged between the roller 113 and the main latch 1%, this impediment could restrain tripping movement of the intermediate latch 1G@ to thereby prevent tripping of the circuit breaker even though the forces exerted by the operating spring 159 are considerable. lt the circuit breaker 3 fails to trip upon the occurrence of an excessive overload condition even though the electromagnet 137 is energized to effect tripping movement of the trip member 123, the circuit breaker will remain closed an extensive damage will result in the circuit that is to be protected by the circuit breaker.

improved means are provided by this invention for initiating opening movement of the intermediate latch or latch structure il@ to thereby avoid failure of opening movement of the intermediate latch 169. Referring to HG. 2, a projection 133 is provided on the intermediate latch 109 which projection is disposed in the path of movement of the trip member 123. Thus, the projection 183 receives a iinal impact blow from the back surface of the trip member 123, as shown in dot-dash lines in FiG. 2, upon tripping movement of the trip member 123 to thereby initiate movement of the intermediate latch 169 in a counterclockwise or opening direction. Once this opening movement of the intermediate latch 1%9 is started, the increasing component of force exerted through the main latch 103 will rapidly complete the opening operation in the same manner hereinbefore described.

The projection 183 can be disposed or positioned to receive a blow from the trip member 123 upon each automatic tripping or manual opening operation; or it may be positioned such that it will receive a bleu from the trip member 123 only upon failure of the forces exerted through the main latch 1.@3 to initiate movement of the intermediate latch 169. ln the latter case, during a normal opening or tripping operation, the intermediate latch 109 will start to move immediately upon 'tripping movement of the trip member 123 so that the projection 1?3 on the intermediate latch will move ahead of the trip member 123 during the tripping operation. If the intermediate latch 109 fails to move immediately upon tripping movement of the trip member 123, the member 123 will engage the projection 183 imparting a blow against this projection to initiate opening movement of the intermediate latch 1w.

As was hereinbefore explained, due to the resolution of the opening force components through the system of levers and latches, a force of, for example, 400 pounds exerted by the spring means 159 is reduced to a load of less 'than 6 pounds tending to rotate the intermediate latch 1%9. The mechanism can be so constructed that the force oi the latch member 163 will pass through the center of the pivot 111 of the intermediate latch 109 so that the component of force tending to rotate the latch 169 Will be zero. in such a structure the trip member 123 will engage the projection 183 on each opening or tripping operation. The slightest change in position of the intermediate latch 109, occasioned by the blow imparted by 'the trip member 123, will cause an increasing moment of force exerted by the main latch 103 against the roller 113 moving the intermediate latch clear of the main latch 193. ln this embodiment, the force required to effect opening or tripping movement of the trip member 123 is reduced to a minimum.

From the foregoing description, it is apparent that there is provided an improved circuit breaker comprising improved means for effecting opening or tripping movement of the mechanism to eect opening of the circuit breaker.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details thereof may be made Without departing from some of the essential features of the invention. lt is desired, therefore, that the language of the appended claims be given the broadest reasonable interpretation permissible in the light of the prior art.

We claim as our invention:

l. A circuit breaker comprising, in combination, a stationary contact, a movable contact, a movable contact arm carrying said movable contact and movable to open and close said contacts, an operating mechanism comprising a iirst latch member releasable to effect opening movement of said movable contact arm, a second latch member being releasable and when released normally moving to eiect release of said first latch member, a trip member in a first and latching position engaging said second latch member to latch said second latch member and being movable to a tripping position to release said second latch member, and upon tripping movement of said trip member, means on said trip member operating to strike said second latch member to initiate releasing movement of said second latch member if said second latch member has failed to normally move when it is released.

2. A circuit breaker comprising, in combination, a stationary Contact, a movable contact, a movable contact arm carrying said movable contact and movable to open and close said contacts, an operating mechanism comprising a first latch member releasable to eiect opening movement of said movable contact arm, a second latch member being releasable and when released normally moving to effect release of said iirst latch member, a trip member movable to a tripping position to release said second latch member, means biasing said operating mechanism toward the open position, and upon tripping movement of said trip member means operable to initiate releasing movement of said second latch member by imparting a blow against said second latch member only if said second latch member fails to normally move when it is released.

3. A circuit breaker comprising, in combination, a stationary contact, a movable contact, a movable contact arm carrying said movable contact and movable to open and close said contacts, a toggle collapsible to effect opening movement of said movable contact arm, means biasing said toggle toward the collapsed position, a first latch member releasable to permit collapse of said toggle, a second latch member releasable to normally move to eiect release of said first latch member, a trip member movable to a tripping position to release said second latch member, and means operable upon tripping movement of said trip member to strike said second latch member to initiate releasing movement of said second latch member only if said second latch member does not normally move when it is released.

4. A circuit breaker comprising, in combination, a stationary contact, a movable contact, a movable Contact arm carrying said movable contact and movable to open and close said contacts, a rst latch member releasable to move to an open position to eitect opening movement of said movable contact arrn, means biasing said first latch member toward the open position, a latch structure pivotally mounted intermediate its ends, one end ot said latch structure engaging said rst latch member to prevent release of said rst latch member, said latch structure being releasable to normally move to release said lirst latch member, a trip member, said trip member engaging the other end of said latch structure 'to prevent releasing movement of said latch structure, said trip member being movable to a tripped position to release said latch structure, and upon tripping movement of said trip member means movable with said trip member and. operable only when said latch structure does not normally move when said latch structure is released to strike a part of said latch Structure to initiate releasing movement of said latch structure.

References (Cited by the Examiner UNTED STATES PATENTS 2,125,139 7/38 Schofield 20G- 106 2,515,994 7/50 Findley et al. ZOO-89 2,601,417 6/52 Scott 200-106 2,695,345 11/54 Scott ZOO- 89 2,712,577 7/55 Stene ZOO-106 2,937,258 5/66 Starr 20S- 619 FOREIGN PATENTS 142,860 i0/ 30 Switzerland. 415,393 9/34 Great Britain.

BERNARD A. GLHEANY, Primary Examiner.

MAX L. LEVY, Examinez'.

Claims (1)

1. A CIRCUIT BREAKER COMPRISING, IN COMBINATION, A STATIONARY CONTACT, A MOVABLE CONTACT, A MOVABLE CONTACT ARM CARRYING SAID MOVABLE CONTACT AND MOVABLE TO OPEN AND CLOSE SAID CONTACTS, AN OPERATING MECHANISM COMPRISING A FIRST LATCH MEMBER RELEASABLE TO EFFECT OPENING MOVEMENT OF SAID MOVABLE CONTACT ARM, A SECOND LATCH MEMBER BEING RELEASABLE AND WHEN RELEASED NORMALLY MOVING TO EFFECT RELEASE OF SAID FIRST LATCH MEMBER, A TRIP MEMBER IN A FIRST AND LATCHING POSITION ENGAGING SAID SECOND LATCH MEMBER TO LATCH SAID SECOND LATCH MEMBER AND BEING MOVABLE TO A TRIPPING POSITION TO RELEASE SAID SECOND LATCH MEMBER, AND UPON TRIPPING MOVEMENT OF SAID TRIP MEMBER, MEANS ON SAID TRIP MEMBER OPERATING TO STRIKE SAID SECOND LATCH MEMBER TO INITIATE RELEASING MOVEMENT OF SAID SECOND LATCH MEMBER IF SAID SECOND LATCH MEMBER HAS FAILED TO NORMALLY MOVE WHEN IT IS RELEASED.

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