US3272934A - Circuit breaker unit for abnormally high inrush currents and/or inrush currents of long duration - Google Patents

Description

Sept 1966 N. J. SCHWARTZ ETAL CIRCUIT BREAKER UNIT FOR A3NORMALLY HIGH INRUSH CU ND/0R INRUSH CURRENTS OF LONG DURATION Filed Dec. 50, 1963 3R a e S 5 k m s M mam P MJMA m m A MM P MM 5 WM 0% My p 13, 1966 N. J. SCHWARTZ ETAL 3,272,934

CIRCUIT BREAKER UNIT FOR ABNORMALLY HIGH INRUSH GURRENTS ND/OR INRUSH CURRENTS OF LONG DURATION Filed Dec. 30, 1965 5 Sheets-Sheet 2 INVENTORS' {J A/O/PM/J/V J, JCHWAPTZ A olP/v/m 5. TAD/10A H41 h. Egg/3 United States Patent CIRCUIT BREAKER UNHT FOR ABNORMALLY HIGH INRUSH CURRENTS AND/OR IN- RUSH CURRENTS 0F LONG DURATHUN Norman J. Schwartz, Yardley, Pa, Norman E. Taylor, West Trenton, and Hal H. Bakes, Browns Mills, N.J., assignors to Heinernann Electric Company, Trenton, N.J., a corporation of New Jersey Filed Dec. 30, 1963, Ser. No. 334,108 9 Claims. (Cl. 200-50) This invention relates to a circuit breaker unit for use with an electrical motor, or other load, having an abnormally high inrush current and/ or an inrush current of relatively long duration upon initial energiz-ation of the load, and it is an object of this invention to provide an improved circuit breaker unit for such a load.

Electromagnetic circuit breakers are known, such as is disclosed in Patent No. 2,360,922 issued to Kurt W. Wilckens, in which an electromagnetic sens-ing element including a solenoid coil, a time delay tube housing a movable magnetic core, and a pivotal armature are used for the purpose of providing a time delay upon the occurrence of an overload which, if below a certain value and if it does not persist for a predetermined time, will not cause the tripping by the armature of the circuit breakers operating linkage mechanism and opening of the circuit breaker contacts, thereby avoiding nuisance tripping.

It is a further object of the present invention to provide two circuit breaker poles constructed and combined so that one of the two controls the load during the initial, starting period and the other controls the load thereafter.

The circuit breaker unit of this invention comprises two circuit breaker poles in parallel with each other and in series with a load, one of the circuit breaker poles having an electromagnetic tripping device controlling said load for a time period subsequent to initial energizati-on, and the other circuit breaker pole having another electromagnetic tripping device controlling said load at the end of said time period, the electromagnetic tripping device first mentioned permitting the flow through the load of high inrush currents and/or inrush currents of long duration before actuating the circuit breaker pole relative to the currents and/ or duration permitted by the second mentioned electromagnetic tripping device.

This invention provides two circuit breaker poles each having a pair of relatively movable contacts. One of the circuit breaker poles normally controls the load except during a predetermined time period upon initial energiza-tion of the load and includes an electromagnetic trip ping device with a solenoid coil. The other circuit breaker pole has its contacts in electrical shunting relation with the coil first mentioned to shunt the initial flow of current to said load during initial energization around the first mentioned coil and also has a voltage coil across which the voltage to the load is impressed. At the end of a predetermined time period, normally suflicient for the load current to attain a current level at which it will not trip the first mentioned circuit breaker, the contacts of the second circuit breaker are opened, taking them out of shunting relation with the load and simultaneously opening the voltage coil circuit, but the first circuit breaker remains closed and controls the load thereafter.

The foregoing and other objects of the invention, the principles of the invention, and the best modes in which we 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, illustrating the circuit breaker unit of the present invention with the handles in the contacts off positions;

FIG. 2 is a side elevation, partly in section, taken adjacent the middle operating mechanism of the circuit breaker unit illustrated in FIG. 1, but illustrating the contacts closed position;

FIG. 3 is a side elevation, partly in section, taken adjacent the last operating mechanism of the circuit breaker unit illustrated in FIG. 1, as viewed from left to right in FIG. 1, but illustrating the contacts closed position;

FIG. 4 is a side elevation, partly in section, taken adjacent the first operating mechanism of the circuit breaker unit illustrated in FIG. 1, as viewed from left to right in FIG. 1, but illustrating the contacts closed position;

FIG. 5 is a partial view taken along the line 55 in FIG. 3 of the left hand portion of the circuit breaker shown therein, showing additional details of the auxiliary switch;

FIG. 6 is a partial view taken along the line 66 in FIG. 2 and extending across all three mechanisms and illustrates the common trip member; and

FIG. 7 is a wiring diagram of the circuit breaker unit of this invention in association with a load.

Referring to the drawings, FIG. 1 is a perspective view of a circuit breaker unit 10 comprising an insulating casing 29 enclosing three switch devices or circuit breaker poles 21, 22 and 23, the components of which are mostly similar to each other and, hence, only the components of the circuit breaker pole 22 will be described in detail, it being understood that the others are similar, except as noted hereinafter. When necessary to clarify the description, the similar components of the circuit breaker poles or devices 23 and 21 will be mentioned with the single prime added for circuit breaker pole 23, and the double prime added for circuit breaker pole 21, to better distinguish the various parts.

Referring to FIG. 2, the circuit breaker pole 22 is provided with terminals 25 and 26 for connecting it to a desired load, the terminal 25 being connected to a stationary contact 27 which cooperates with a movable contact 28, the latter being carried by a movable arm 29. The movable arm 29 pivots about a pintle 31 and is biased by a spring 32 to the open position of the contacts.

The movable arm 29 comprises part of a linkage mechanism which includes a toggle 33 comprising links 35 and 36. The link 35 is pivotally connected to the movable arm 29 at one end and to the link 36 at the other end to form the knee 37 of the toggle, the link 36 being pivotally connected at the other end to the handle link 38 by a pintle 39, the link 38 and handle 40 being jointly movable. The handle link 38 oscillates about a fixed pivot 41 supported by extending through openings in the two parallel, spaced extensions 42 of the frame 43, the latter being positioned by opposed lugs 44 disposed in opposed slots 49 formed in the Walls of the casing part 45. The frame 43 is restrained in its proper position by the cover casing part 51 which has wall structure (not illus trated) engaging the ends of the pin 41 extending beyond the frame extensions 42 for restraining movement to the right of the frame when the contacts are closed. The handle link is biased to the off position of the contacts by a torsion reset spring 52 the ends of which are wound about the pivot 41 and held stationary by the frame extensions 4-2, the yoke of spring 52 engaging the underside of the handle link 38 and biasing it to the off position, the spring 52 also resetting the toggle linkage upon tripping of the mechanism.

For locking the toggle in the overcenter position during automatic resetting, the toggle link 36 is provided with a tooth portion 54 engageable with the half moon 55 of a latch 56 carried by the link 35 the latch 56 being biased in the counterclockwise direction of a spring 57.

The latch 56 is tripped by a pivotal armature 59 having three arms, namely a left hand unlatching member 60, an attracted end 69 and a balance portion 84. The left hand unlatching member 60, as viewed in FIG. 2, engages the latch 56 and turns it against the bias of the spring 57 to present the flat portion of the half moon 55 to the tooth 54, thereby allowing the toggle 33 to collapse upwardly under the bias of the spring 32, when the aramtures right hand end 69 (FIG. 2) is attracted upon sufficient overload, toward the pole piece 61 of an electromagnet comprising a solenoid coil 62 formed about a tube 63, the latter projecting through a leg 64 of the L-shaped frame 43. The tube 63 houses a movable core (not illustrated) of magnetic material spring biased toward the left-hand end of the tube and retarded in movement to the right by a liquid within the tube to provide a time delay below certain overload currents before tripping of the circuit break pole 22. The coil 62 has one end connected to the movable arm 29 by a flexible conductor 67 and the other end connected by a conductor 68 to the terminal 26. Thus, an electromagnetic tripping device or sensing element is formed by the coil 62, tube 63, movable core, and armature 59.

The tripping of the circuit breaker poles 22 and 23 is affected upon the tripping of either one by a unitary insulator elongated bar 72, having formed thereon spaced cams 73 and 173.

The bar 72 has two portions intermediate its ends, FIG. 6 (one portion between earns 73 and 173 and the other between cam 173 and shaft 273), disposed in bearings 74 formed in the two partition insulator walls 91 separating the circuit breakers. A more detailed description of the cams 73 and 173 and their relation to the linkage mechanism appears in Patent No. 3,098,912 issued to John M. Sprague.

' Briefly, however, a spring 80 (FIG. 4) is provided with one spring end against an inner surface 97 of the cover casing part 51 and another spring end against the rear cam face 81', urging the cam surface '76 into abutment with the surface 77 of the movable arm 29, FIG. 4.

The armature 59 (FIG. 2) is biased by a spring 98 so that the unlatching member 60 is urged away from the latch 56, the balance end 84 being biased counterclockwise toward the cam finger 83 and the attracted end 69 being biased counterclockwise against a limiting stop 78 clear the half moon 55. The overcenter toggle 33 im mediately collapses under pressure from the opening spring 32 and the movable arm 29 starts to separate from the stationary contact 27. As the separating movement starts, rotation of the cam bar 72 also starts because of the abutment of the movable arm surface 77 and the cam surface 76. Continued movement of the movable arm 29 and continued pivoting of the cam bar 72 causes the cam finger 183 in the adjacent circuit breaker pole 23 to impinge forcefully on its associated armature balance portion 84' and turn the armature 59 in the direction to unlatch the associated latch 56', whereby the contacts of circuit breaker poles 22 and 23 are opened substantially simultaneously since the toggle 33' then collapses under pressure of the opening spring 32'.

The handles 40, 40 and 40" of the three circuit breakers are connected for joint movement by a shaft 300, and spacer sleeves 301, C-washers 302 being placed in suitable grooves to prevent axial movement of the shaft 300, FIG. 1.

While the linkage mechanisms and the common trip bar 72 are similar to those described in Patent No. 3,098,- 912 issued to John M. Sprague, it will be noted that in the present arrangement the common trip bar 72 is actuatable by only two of the movable arms 29 and 29' and not the movable arm 29", because in the circuit 4 breaker pole 21 the cam corresponding to earns 73 and 173 in poles 23 and 22 has been omitted, as illustrated in FIG. 6.

Referring to the circuit diagram of FIG. 7 and FIGS. 4 and 6, it is seen that the circuit breaker pole 23 acts merely as a switch, the tube 64' having no coil wound about it and the flexible conductor 67 being connected 7 directly from the movable arm 29' to the conductor 68 which in turn is connected to the terminal 26 to provide an electrical path from the terminal 26 through the movable contact 28, the stationary contact 27 and the terminal 25 when the contacts 27 and 28' are closed.

The left hand wall of the case part 45, as viewed in FIG. 3, is mostly cut away for a Width below the operating linkage mechanism of circuit breaker pole 21, FIG. 5, and an auxiliary switch 325 is added, the switch 325 comprising a pivotal blade 326 actuatable by the movable arm 29 by engagement with an insulator 327 carried at the upper part of the blade 326. The blade 326 is pivotally'carried intermediate/ends at a reduced part 328 between upstanding shoulders 329 formed near the end of a stepped terminal 332, as illustrated, which has one portion secured by a hollow rivet 333 to an insulator 334 of laminated plastic, two other such insulators 335 being illustrated to space the insulator 334 from the case part 45 and thereby provide central openings 369 (FIG. 5) receiving most of the components of the auxiliary switch 325. The threaded terminals 25 and 26" extend through the insulators 334 and 335 and suitable nuts secure the insulators to the bottom of the case part 45.

The auxiliary switch 325 comprises another stepped terminal 340, as illustrated, similarly secured to the insulator 334 by a hollow rivet 341 through which passes the insulated end 344 of coil 62 and is soldered to the left end of the terminal 340, the end extending through the insulator 334. The terminal 340 carries a stationary contact 346 disposed above but spaced from another sta tionary contact 348 secured to the insulator 334.

Between the contacts 346 and 348 is a movable arm 350 carrying a movable contact 351 at its upper end, the arm 350 being pivotally seated at its lower end in notches formed on opposite sides of the terminal 332, the latter terminal also carrying the blade 326. A spring 355 connects the movable arm 350 with the blade 326 and normally biases the upper end of the movable arm 350 to the left, into engagement with the contact 348, when the circuit breaker contacts 27" and 28" are open. A flexible nylon insulator 380 secured between the insulator 335 and the case part 45 is interposed between the blade 326 and the arm 29".

When the circuit breaker contacts 27" and 28 are closed, as illustrated in FIG. 3, the movable arm 29 engages the insulator 327 and pivots the blade 326 counter clockwise carrying the lower end of the spring 355 to the right, changing the line of action along which the spring 355 acts on the movable arm 350 and causing the latter to snap to the right, bringing the contact 351 into engagement with the contact 346, the position illustrated in FIG. 3.

As also illustrated in FIG. 3, the flexible conductor 67" connects the movable arm 29 to the conductor 68" to which is also connected the other end 360 of the coil 62".

To complete the circuit breaker unit 10, a conductor 400 is connected between the terminals 26 and 26" and secured to the threaded portions thereof by suitable nuts, and, likewise, another conductor 401 is connected between terminals 25 and 25", spacer insulators 370 being used in connection with terminals 25 and 26, as illustrated. If desired, an insulator spacer 372 maybe used with terminals 25 and 26 also.

Referring to FIG. 7, the terminal 25 is then connected to the higher potential side of an alternating current source and the terminal 25 to the lower grounded electrical neutral of the source, the terminal 332 being connected to the ground, as illustrated. The terminals 26' and 26 are then connected to opposite sides of the load.

Thus, when the handles are moved to the contacts closed positions, the coil 62 will be shunted by the contacts 27" and 28", i.e., through a path defined by terminal 25, conductor 401, terminal 25", contacts 27" and 28", terminal 26", conductor 4%, terminal 26, the load, terminal 26, contacts 27' and 28 and terminal 25 to the neutral side of the source. At this same time, a current path exists from the higher potential side of the source through terminal 25, conductor 401, terminal 25", contacts 27" and 28", terminal 26", coil 62", contacts 346 and 351 (which are now closed) and through terminal 332 to the grounded electrical neutral.

The coil 62" is part of an electromagnetic tripping device or sensing element comprising a movable magnetic core (not illustrated) within the tube 63" and the armature 59" constructed so that they permit the inrush currents of higher value and/or the inrush currents of long duration to flow through the load for a predetermined time period sufficient to permit the current to the load to reduce to the rated value of the load and the circuit breaker pole 22. At the end of the predetermined time period the core (which is spring biased to the left and which moves against the retarding action of a liquid) in the tube 63" moves to the right sufiiciently to increase the electromagnetic flux in the magnetic circuit to a value where the attractable end 69 of the armature 59 moves toward the pole piece 61" sufficiently to bring the unlatching member 60 into tripping engagement with the latch 56", releasing the tooth 54" from the latch shaft 55", and permitting collapse of the toggle 33" under pressure of the contacts opening spring 32 and opening of the contacts 27" and 28".

When the contacts 27 and 28" thus open, the flow of current continues through the load uninterrupted, assuming that the current has decreased sufficiently, but the flow is through the coil 62 and contacts 27 and 28, of circuit breaker pole 22, which controls the load subsequent to the opening of the contacts 27 and 28" of circuit breaker 21.

As illustrated, the coil 62" comprises many turns of wire of a small diameter, commonly referred to as a voltage coil, resulting in a high impedance relative to the impedance of the shunting circuit through the contacts 27" and 28".

It is seen that since the circuit breaker pole 21 has no cam corresponding to the cams 73 and 173 in circuit breaker poles 22 and 23, upon the tripping of the operating linkage mechanism of circuit breaker pole 21 at the end of the initial, starting time period, no rotation of the common trip interconnecting bar 72 takes place, and, hence, the contacts of the circuit breaker poles 22 and 23 remain closed, assuming no suflicient overload or short circuit exists to open the contacts 27 and 28.

A circuit breaker unit incorporating this invention was tested with a circuit breaker pole 22 intended to operate controlling a motor rated for operation, after the initial starting time period following energization, drawing a current of 6 amperes at 110 volts, 60 cycles per second alternating current. During the initial, starting time period, the inrush current to the motor was intended to be about 140 amperes during the first cycle, 100 amperes for the following 2 cycles, 60 amperes for the following 3 cycles and after 120 milliseconds from. initial energization, 6 amperes. T o accommodate the foregoing inrush characteristics, the circuit breaker 21 was constructed to have a time delay range in which it may trip after /2 second from initial energization but it must trip after 1 and /2 seconds of time delay from initial energization of the circuit breaker unit 10.

It is understood that while this invention is described in connection with alternating current, it is applicable to direct current also.

It will be noted that when the circuit breaker handles 40, 40 and 41)" are initially turned to the closed positions of the contacts, the contacts 27" and 28" and the contacts 27 and 28 of circuit breakers 21 and 23, respectively, function merely as switches providing a current path to the load, this current path being substantially independent of the coil 62 and coil 62". Hence, during the time delay period provided by the coil 62" of circuit breaker pole 21, a short circuit could be imposed on the load if it exists at the time the handles 40, 40 and 40 are first turned to the closed positions or during the time delay period of circuit breaker pole 21. If it is not desire-d to subject the load to this contingency, a coil (not illustrated) may be added to circuit breaker pole 23 electrically connected between the terminal 26' and the movable contact 28' and constructed so as to trip the circuit breaker pole 23 with substantially no time delay by sufficiently attracting the armature 59 to raise the unlatching member 60 into tripping engagement with the latch 56' so as to collapse the toggle 33 at current values above the highest value of current contemplated during the initial, starting time delay period after first turning the handles to the contacts closed positions.

If desired, the circuit breaker unit 10 could be wired internally (but is not so illustrated) by a conductor extending from terminal 332 to the grounded electrical neutral 25' which would eliminate adding and external connection to ground at terminal 332.

In summary, it is seen from the foregoing that a circuit breaker unit 10 has been provided in which the circuit breaker 21 is constructed so as to provide a time delay during an initial, starting period before its contacts open and that after its contacts open, the circuit to the load remains closed through circuit breaker pole 22. At the end of the time delay provided by the coil 62", the operating linkage mechanism of circuit breaker 21 collapses and remains in the collapsed position, since the mechanism resetting spring 52" is not strong enough to turn the three handles 40, 40' and 453" to their contacts off positions, until the contacts of poles 22 and 23 are either manually or automatically opened, at which time the collapsed operating mechanism of pole 21 automatically relatches as the three handles move to the off positions. Further, the circuit breaker pole 22 is interconnected by the common trip bar 72 with the circuit breaker pole 23 so that when the circuit breaker 22 trips, the contacts of circuit breaker pole 23 also open, and, where desired, an electromagnet may be provided for circuit breaker 23 to insure that the circuit breaker unit 10 will not remain closed for the initial, starting period against a short circuit during the initial, starting period.

Further, it is seen that relative to the coil 62", the shunting contacts 27 and 28 may be viewed as a second load, or a second load may be placed in the shunt circuit which includes the contacts 27" and 28 if it is desired to energize this second load only during the initial time period, such as a starting motor winding, and the two loads referred to in some of the appended claims refer to this aspect of the invention.

Having described this invention, we claim:

1. In combination, two electrical switch devices each including a mechanism and a pair of relatively movable contacts for controlling an electrical load, the first of said switch devices including a first electromagnetic means for controlling said load except during a predetermined time period upon initial energization of said load, the second of said switch devices controlling said load during said predetermined time period and including a second electromagnetic means energizable simultaneously with said load only during said predetermined time period, the contacts of said second switch device being connected in electrical shunting relation with said first electromagnetic means to permit the flow of current to said load during said predetermined time period, and said second electromagnetic means opening the contacts of said second switch device at the end of said predetermined time period.

2. The structure recited in claim 1 and further including an auxiliary means having switch contacts connecting said second electromagnetic means in parallel with the contacts of said second switch device and in series with said load, the electrical path through the contacts of said second switch device being of low impedance relative to the impedance of said second electromagnetic means, 'the mechanism of said second switch device maintaining said auxiliary switch contacts closed when said second switch device is in itscontacts closed position and open said auxiliary switch contacts when said second switch device moves to its contacts open position.

3. A circuit breaker unit comprising three circuit breaker poles each having a mechanism and a pair of relatively movable contacts the first pole including terminal means for connecting said first pole to one side of a load and to an electrical source, the second and third poles being connected in parallel with one another and including terminal means for connecting said second and third poles in series with the other side of said load and to said electrical source, so that the contacts of said second pole shunt said third pole, and said second pole having an electromagnetic means to open the contacts of said second pole subsequent to a predetermined time period upon initial energization of said load, thereby taking the contacts of said second pole out of shunting relation with said third pole at the end of said predetermined time period and leaving said third pole in the circuit to thereafter control the load.

4. The combination recited in claim 3 and further including a common trip member interconnecting said first and third poles for opening their contacts upon predetermined overloads.

5. The structure recited in claim 3 wherein said first pole includes an electromagnetic tripping device to trip at a current above the highest anticipated current to said load during said predetermined time period, whereby it the poles are closed while a short circuit exists the first pole will protect the load by opening the load circuit with substantially no time delay;

6. The structure recited in claim 1 and further .defined by said electrical switch devices being in parallel with each other and connectable in series with said load, each electromagnetic means comprises an armature and a coil disposed about a time delay tube housing a movable core of magnetizable material, the core of said second switch device being moved by the electromagnetic flux of its coil sufficiently to pivot the associated armature into tripping engagement with the associated mechanism after said time delay period, whereby the contacts of said second switch device are opened and the latter is removed from the circuit and thereafter the first switch device controls the load.

7. A circuit breaker unit comprising first and second circuit breaker means for controlling a load, said first circuit breaker means comprising an electromagnetic tripping device controlling said load for a predetermined time period subsequent to initial energization, said second circuit means comprising another electromagnetic tripping device controlling said load at the end of said time period, both means including handles connected for joint movement to the contacts closed and'open positions, the first means further comprising a collapsible mechanism connected to its handle and actuatable by said first mentioned tripping device, whereby at the end of said predetermined time period the contacts of the first means move to the contacts open position, since its mechanism remains collapsed, but the handle thereof remains in its contacts closed position because of the connection between the handles.

8. A circuit breaker unit comprising three circuit breaker means each having a pair of relatively movable contacts, a collapsible linkage mechanism and a handle movable between contacts closed and open positions, the bandles being connected for joint movement, the first means being connectable to one side of a first load and to an electrical source, the second and third means being connectable to a second load and an electrical source, and said first means having an electromagnetic tripping device energizable simultaneously with said first load, and the electromagnetic tripping device of said first means opening the contacts thereof subsequent to a predetermined time period upon initial energization of said first load by tripping said collapsible linkage which remains collapsed until said second and third means are moved to the contacts open position.

0. In combination, a circut breaker unit comprising first and second circuit breaker devices for controlling first and second loads, each circuit breaker device including a handle, said first circuit breaker device comprising an electromagnetic tripping device electrically connected to said first load for controlling said first load for a predetermined time period subsequent to initial energization, said second circuit breaker device comprising another electromagnetic tripping device electrically connected to said second load for controlling said second load, said handles being connected for joint movement to contacts closed and open positions, said first device further comprising a collapsible linkage means connected to said handle and actuatable by said first mentioned tripping device, and said collapisble linkage'means remaining collapsed at the end of said predetermined time period when the contacts of the first circuit breaker device move to the contacts open position while the handle thereof remains in its contacts closed position.

References Cited by the Examiner UNITED STATES PATENTS 1,727,872 10/1929 Evans 20097 3,069,517 12/1962 Cole 20050 X 3,098,910 7/1963 Schwartz 200-106 ROBERT K. SCHAEFER, Primary Examiner.

KATHLEEN H. CLAFFY, Examiner.

M. GINSBURG, Assistant Examiner.

Claims (1)

1. 7. A CIRCUIT BREAKER UNIT COMPRISING FIRST AND SECOND CIRCUIT BREAKER MEANS FOR CONTROLLING A LOAD, SAID FIRST CIRCUIT BREAKER MEANS COMPRISING AN ELECTROMAGNETIC TRIPPING DEVICE CONTROLLING SAID LOAD FOR A PREDETERMINED TIME PEROID SUBSEQUENT TO INITIAL ENERGIZATION, SAID SECOND CIRCUIT MEANS COMPRISING ANOTHER ELECTROMAGNETIC TRIPPING DEVICE CONTROLLING SAID LOAD AT THE END OF SAID TIME PERIOD, BOTH MEANS INCLUDING HANDLES CONNECTED FOR JOINT MOVEMENT TO THE CONTACTS CLOSED AND OPEN POSITIONS, THE FIRST MEANS FURTHER COMPRISING A COLLAPSIBLE MECHANISM CONNECTED TO ITS HANDLE AND ACTUATABLE BY SAID FIRST MENTIONED TRIPPING DEVICE, WHEREBY AT THE END OF SAID PREDETERMINED TIME PERIOD OF CONTACTS OF THE FIRST MEANS MOVE TO THE CONTACTS OPEN POSITION, SINCE ITS MECHANISM REMAINS COLLAPSED, BUT THE HANDLE THEREOF REMAINS IN ITS CONTACTS CLOSED POSITION BECAUSE OF THE CONNECTION BETWEEN THE HANDLES.

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