US3214537A

US3214537A - Electrical circuit protector having auxiliary indicating switch contacts

Info

Publication number: US3214537A
Application number: US285176A
Authority: US
Inventors: Alvin W Krieger
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-05-13
Filing date: 1963-05-13
Publication date: 1965-10-26
Anticipated expiration: 1982-10-26

Description

4 Sheets-Sheet 1 A. W. KRIEGER ELECTRICAL CIRCUIT PROTECTOR HAVING AUXILIARY INDICATING SWITCH CONTACTS Oct. 26, 1965 Filed May 13, 1963 w w 3% @m Oct. 26, 1965 A. w. KRIEGER 3 214,537

, ELECTRICAL CIRCUIT PROTECTOR HAVING AUXILIARY INDICATING SWITCH CONTACTS Filed May 13, 1963 4 Sheets-Sheet 2 Oct. 26, 1965 A. w. KRIEGER ELECTRICAL CIRCUIT PROTECTOR HAVING AUXILIAR INDICATING SWITCH CONTACTS 4 Sheets-Sheet 3 Filed May 15, 1963 Oct. 26, 1965 A. w. KRIEQGER 3 214,537

ELECTRICAL CIRCUIT PROTECTOR HAVING AUXILIARY INDIGATING SWITCH CONTACTS Filed May 13, 1965 4 Sheets-Sheet 4 .IIII].

United States Patent i 3,214,537 ELECTRICAL CIRCUIT PROTECTOR HAV- ING AUXILIARY INDICATING SWITCH CONTACTS I Alvin W. Krieger, 315 N. 12th St., P.O. Box 463,

, Milwaukee, Wis.

Filed May 13, 1963, Ser. No. 285,176 12 Claims. (Cl. 200- 106) This is a continuation-impart of my application Serial No. 258,348 filed February 13, 1963, now abandoned.

This invention relates to electrical-circuit protectors. While not limited thereto the circuit'p'rotector of the present invention is particularly suited for protecting circuits in electronic data processing apparatus and the in placeof fuses, and are designed, when connected in a suitable manner, to provide direct and remote indications of their tripping as well as interruption of their immediate circuit, and another, such as a main'power supply circuit or the like.

It is a primary object of the present invention to provide improvedforms of circuit protectors of the aforementioned type.

Another object is to provide circuit protectors of'the aforementioned type in both thermal and magnetic trip versions. I I s A further object is to provide a simplified tripping and reset mechanism for such circuit protectors which comprise relatively few and easily manufactured parts.

A still further object is to 'prov'ide tripping and reset mechanisms which are characterized by requiring only small electrical fault initiated forces to effect tripping while affording normalcurrent positions under the action FIG. 2 and is substantially a right-hand end view of FIG. 3;

FIG. 5 is an elevational view with'portions broken away to show the device in another of its operating conditions; V

FIG. 6 is a fragmentary sectional-view similar to FIG.

4 but in still another operating condition;

FIG. 7 is an isometric view ofcertain parts of the device in their assembled relationship;

FIG. 8 is a front elevational view of a modified form of the device;

FIG. 9 is a partial sectional view taken along line 9-9 FIG. 10 is a fragmentary view similar to FIG. 8 showing another modified form of thedevice;

FIG. 11 is a fragmentarysectional view taken generally along line 1111 in FIG. 10; and

FIG. 12 is an isometric view of the parts which comprise the modification shown in FIGS. 10-12.

3,214,537 Patented Oct. 26, 1965 ice As seen in FIGS. 1-6, the circuit protector has a'molded insulating base 2 to which a mounting plate 4 and a cover plate 6 are mounted by means of a pair of screws 8. Mounting plate 4 has a pair of tapped holes 411 for mounting the protector to a panel or the like, such panel having an opening for the cover plate 6 to extend through, thus exposing the top of cover plate 6, and anyindicia which may be on it, to view.

A large cavity'2a is formed in the lower'part of base 2 which is open tothe bottom and one-of its four sides, such side being called the front. A front cover plate '10 preferably formed of a molded arc-resistant material,

hastongued edges at its top and'bottom which cooperate with grooves molded into base 2 and'an'au'xiliary contact base 12-to hold it in place, thus closingoffthe frontof the cavity2a. Auxiliary'contact base 12 is alsoforme'd of a molded insulating materialand held in place by screws 14'and servesto close the bottom end of cavity 2a.

A support bracket 16 extends through an opening in the sidewall of the base2, and is riveted to the upper surface ofcavity 2a. One of a pair of-main stationary contacts 18 is secured to a terminal plate 17 which, together with a metal connector strap 17a is riveted tothe upper surface of cavity 2a. The other stationary contact member '18 is secured to a second terminal plate 20, which is also riveted to the upper surface of cavity 2a and'extends through the other sidewall of base 2. A third terminal plate 22 is secured-to the side of base 2 by a hollow rivet (not shown) through which a coil lead will later extend and be soldered to the terminal plate. One of the screws 14 also holds terminal plate 22 in place. A hollow cylindrical insulator 24 is held in place between support bracket 16 and terminal plate 22 by apair of screws to give additional support to plate 22. I s

A frame member 26a of 'amagnetic coil assembly 26 is also riveted at spaced apart tabs 26b tothe top surface of cavity 2a, and extends down along the back surface of the cavity. Near the bottom of the cavity, frame member 26a has a horizontal leg portion 260 which extends toward the front of the device. A coil 26d and a core 26c are held to frame 26w by a screw 26 which takes into' a threaded hole in the frame. One lead of the coil 26d is soldered to connector strap 17a and the other lead is brought through the hollow rivet which holds terminal 22 in place and then soldered to the rivet, completing a connection to the terminal 22.

Coil assembly 26 has an armature 26g pivotally mounted at its lower end on leg portion 26c and is biased away from the core 26c by a spring 28'which hooks at one end to armature 26g and at its other end threads over a screw 30 which is free to turn in a retaining member 32 entrapped in auxiliary contact base 12. Proper spring tension upon the armature 26g is obtained by turning screw 30 to thread the spring 28 in one direction or the other upon the screw. Access to the screw 30 is obtained through a hole in auxiliary contact base 12. Once the proper tension is obtained, the hole is filled with a sealant, such as-epoxy resin. At its upper end, armature 26g has a screw 34 threaded into a tapped hole, this screw serving as'an actuator in a manner to be described later. Screw 34 has a screw driver slot cut into its threaded end to prodownward travel of the contact assembly 36.

molded in base 2 by way of the cavity 2a. sion spring 50 is placed within a slot formed in push bar ,end ofthe slot. .the slide tracks along side of push bar 48.

portion 48a of pushbar 48, and the pin 54a.

.ber 54 forv that.member. helical compression spring 44, trapping pin 54a between recess in the upper surface of cavity 2a until plate 38 is held firmly against a pair of ledges formed in cavity 2a.

Spring 42 rests at its upper end against the top of an enlarged recess in base 2 formed concentric with the recess for screw 40, and at its bottom end against the upper surface of the movable contact assembly 36. This biases -movable contact assembly 36 down .and away from main stationary contacts 1818. At its right end as viewed in -FIG. 4, movable contact assembly 36 has a downwardly bent bearing surface 36 to pivot from that point. As can be seen in FIG. 6, plate 38 also serves as a limit to A slot 36b is formed in the center of contact assembly 36 and a latch plate 36c of somewhat harder material is spotwelded to the bottom of contact assembly 36 so that one edge of the latch plate extends slightly beyond the end of the slot 36b.

A reset latching assembly is mounted in base 2 below cover plate 6. A helical compression spring 44 is placed in the main opening and positioned'around a circular boss.

A second helical compression spring 46 is placed in a cir- A push bar 48 is inserted into slide tracks A comprescular recess.

48 and seated at its bottom end against an outwardly and upwardly bent tongue portion 48a formed at the lower A spring retaining strap 52 is placed in An inverted L-shaped latching member 54, having a pin 54a inserted into a hole at the vertex between its arms, is positioned in the base. A cammed latching surface formed at the-lower end of one leg of member 54 is placed through an opening in the base 2 which extends into wcavity 2a. A pin 54a is placed througha hole in -springretaining strap 52 and the upper end of the slot .in push bar 48, trapping spring 50 under the pin 54a. Spring 50 is thus held in place by one side wall of. the

slide tracksin base 2, the spring retaining strap 52, tongue Pin. 54a is slightly less in length than the distance between the side- A reset button 56 is placed over the member 54. But

.ton 56 has at its lower end a circular boss having spaced transverse slots formed therein to accommodate intermediate portions. of the pin 54a, and has acentral clearance slot conforming to the shape of the vertex of mem- The circular boss fits inside of the spring 44 and the top of its slots.

A trip lever 58 having ahorizontally disposed leg 58a is placed into a recess in base 2 in such a manner as to have leg 58a rest on the horizontal leg 540 of member :54 at right angles, A helical compression spring 60,

having its bottom edge 60a extending tangentially, is

placed over an upper cylindrical portion 56a of button 56 so that portion 60a overlies leg 58a of trip lever 58. Spring 60 also rests on the upper surface of an enlarged rectangular portion 56b of button 56.

With these items in place, mounting plate 4 is placed on the top of base 2 and cover 6 placed over the entire 'assembly in a position to allow strip lever 58 and button 56 to extend through their respective clearance openings in cover 6. The cover is pressed down on the mounting plate 4 against the bias of

springs

44, 46 and- 60, and held in place by screws 8. This causes the mechanism to take the tripped position as indicated in FIG. 6, the cam surface 54b of latching member 54 now extending through the slot 36b in movable contact assembly 36.

Screw 34 is adjusted by pushing the armature 26g against the face of the core 26c, and turning screw 34 until it just trips the mechanism. Then the screw 34 is given a safety factor by turning it an additional amount (on the order of one quarter turn) and is locked in place by applying a sealing compound to the threads where they join the armature.

As can most clearly be seen in FIGS. 5 and 7, the auxiliary contact assembly has three substantially U-shaped terminal members seated in corresponding grooves molded in auxiliary contact base 12. Each of these terminals has its own base portion 62 with holes therein for the connection of wires thereto. Extending upwardly along one side of base 12 are stamped

terminal members

64, 66 and 68 which are riveted to the bases 62. Terminal 64 has riveted to the underside of its upper horizontal leg a movable contact assembly 70 which is of 'an overcenter spring arrangement and has at its other end a contact member secured on both its top and bottom surfaces. Terminal 66 has its upper horizontal leg bent at a right angle to its initial direction (FIG. 7) and carries on the upper surface of that leg a contact member 66a. Terminal 68 has a longer vertical leg than do

terminals

64 and 66 and carries a contact member 68a on the underside of its horizontal leg. An actuator cap 48b molded of insulating material is secured to the bottom of the olfset arm of push bar 48 and bears against a center leg of the movable contact assembly 70 as shown in FIG. 7, causing the movable contacts to trip to one auxiliary position or the other.

In the operation of the circuit protector, let it be assumed that it is inserted in the line to a device it is desired to protect. One wire of the device is connected to terminal 22, the other wire connected to terminal 20. The reset button is then pushed down by an operator as shown in FIG. 5. The button bears down on pin 54a and it in turn moves the vertex of member 54 downward against the bias of spring 44. Pin 54a also moves push bar 48 down causing cap 48b to press down on the center leg of movable contact assembly 70, which in turn snaps the movable contact member into engagement with the upper stationary contact member 68a. Auxiliary contact 68a may be connected through relays to a main,

,The amount of travel required to trip the auxiliary con tact assembly is very small in comparison to the total .travel of button 56, and the tripping occurs at the extreme top end of travel of button 56. Spring 50 and the vertical slot in push bar 48 take up the remaining travel of pin 54a through button 56 (FIG. 5).

-As button 56 moves farther down, along with latching member 54 and pin 5401, the cammed latching surface 54b moves below the latch plate 360. The horizontal leg 54c in following the member 54 compresses spring 46 somewhat, causing spring 46 to exert a clockwise moment (as viewed in FIG. 4) upon the member 54, which will move cammed latching surface into When the button 56 is released, the protector will take the position as shown in FIGS. 3 and 4. The spring 44 biases pin 54a and member 54 upward, surface 54b then pulling the movable contact assembly 36 into engagement with main stationary contacts 18-18, this being the limiting factor in upward travel for the latching member 54, pin 54a, button 56 and trip lever 58. A color dividing line 56c on an upper cylindrical portion 56a of the button .will

.lie on the same plane as the top surface of cover plate 6 in this position. The portion above the line 560 is the same color as the cover 6, and the remainder of the button is of a contrasting color to enable a tripped protector to be located more readily. In this position there is now a circuit completed in the protector from terminal 22 through coil 26c, connector strap 17a, terminal 17, contact 18, movable contact assembly 36, the second an overload of current to the device.

contact member 66a.

I device.

contact 18, and terminal 20. Under ordinary conditions this current will have no effect on the coil, and the particular component it is protecting will be connected to its main source of power.

Now let us assume that a fault occurs which creates This overload, when flowing through the coil, will cause the coil to be picked up, attracting armature 26g. Upon movement of armature 26g toward the core 26e, screw 34 will strike the cammed surface 54b of member 54, pivoting it counterclockwise about pin 54a and release the movable contact assembly 36, interrupting the circuit to the protected device. Movable contact assembly 36, with the aid of spring 42 will drop to the position shown in FIG. 6. The remaining elements will also take the position shown in FIG. 6, with the contrasting color below the line 56c on button 56 now being above the surface of the cover 6 and visible to the outside. .Push bar 48 has been pulled up by pin 54a and the actuator cap 48b has released thecenter leg of movable contact member 70, which has snapped back into normal contact with lower auxiliary This would complete a circuit to a warning device, indicating the fault in that particular section. Other protectors in the same area may have the like contact connected in parallel to the same warning The protector will remain in this position as long as the overload in current exists, holding the armature 26g against the core 26e, and screw 34 in place. As can be seen in FIG. 6, while it is possible to move button 56 down to cause the auxiliary contacts to trip, the screw 34 will not permit the cammed surface 54b to engage the latch plate 36c and reclose the main contacts. As mentioned before, should an arc gap occur between "the

terminals

16 and 22, it will be isolated within hollow insulator 24.

While little force is required to trip and reset the device, the latching surface is under relatively heavy pressure (on the order of 16 02.). The force required to be exerted to trip the mechanism is very small (on the order of 2 02.). Trip lever 58 allows the protector to be tripped manually if desired. By pushing down on the exposed'portion of lever 58, a downward force is transmitted to the portion 58a, which exerts a counterclockwise moment upon leg 540 of member 54 about pin 54a.

FIGS. 8 and 9 show another version of the device. The resetting mechanism is the same as the aforedescribed device and for that reason has not been shown in detail, and like numbers have been given to identical parts.

The fundamental differences between the type of circuit protector shown previously and the type shown in FIGS. 8 and 9 is that the latter is of the thermal trip type, whereas the first described protector was of the magnetic trip type.

The base 72 of the protector shown in FIGS. 8 and 9 is quite similar to the base 2, except base 72 has provisions for only two terminals and has a hole 72b in the back wall of cavity 72a for calibrating the device. A lefthand terminal 74 is riveted, together with a frame member 76, to base 72. A somewhat longer connector strap 75a and a terminal plate 75 are also riveted 'to the upper surface of cavity 72a. Connector strap 75a extends down along one side wall and then is bent outwardly to near center of the cavity 721;. Frame member 76 is riveted on its right side to the upper surface of cavity 72a in the same manner as frame 26, and extends down along the rear wall. A horizontal portion 76a extends to the front and is bent vertically at 76b, which is near the outwardly bent portion of strap 75a. A second vertically bent portion 760 containing a guide hole is bent upwardly from horizontal leg 76a between the back wall and portion 76b. In line with the hole 72b in the base 72 is a threaded hole 76d on frame 76. A calibrating screw 78 is threaded into opening 76d and serves as a guide for an actuator of insulating material and a compression spring 82, and bears against portion 76c, forcing it out from the back wall of the frame. A number of bimetal elements 84 are riveted to strap 75a and portion 76b of frame 76 with an insulating strip 86 separating them. The number of bimetal elements and insulating strips may vary as the amount of current to be handled increases. The rear piece of bimetal must always have a bent portion 84a as shown tobear against the actuator 80.

Two permanent magnets 88 are placed in recesses in the base 72 above the main stationary contacts 1818, and are held separate from the terminals by a T-shaped insulator strip 90. The vertical leg of the insulator strip 90 extends down between the contacts 1818. These magnets serve to quench any are that may occur during a tripped period due to faulty wiring or the like.

Upon calibrating the device by turning screw 78 to either force portion 760 outwardly or let it spring inwardly,'the hole 72b would be filled with a sealant, such as epoxy resin, and the device would be connected and set in the same manner as the aforedescribed protector. The main circuit completed in the protector is from terminal 74, through frame 76, connector strap 75a, terminal plate 75 stationary contact 18, movable contact assembly 36, the other stationary contact 18 and terminal 20. Normal current flowing through connector strap 74a and the bimetal elements 84 would not be suflicient to effect appreciable warping of the latter.

Upon an overload current of sufficient duration however, the elements would become heated in the conventional manner of a bimetal element, and beingproperly assembled, would warp to the right as viewed in FIG. 9. Portion 84a would then bear against actuator 80, which in turn would move cammed latch surface 54b away from latch plate 36c, thereby releasing the movable contact assembly to allow it to drop down under the bias of spring 42, thus breaking the main circuit in the device. It will be impossible to reset the device until the bimetal ele ments have cooled sufficiently to return to a position which does not interfere with the cammed surface 54b and latch plate 36c. v

FIGS. 10-12 show a modified latch means for engagement with movable contact assembly 36. This modification will be described in connection with the thermal trip type of device shown in FIGS. 8 and 9, however, it will be apparent that it could also be used in the magnetic trip type of device shown in FIGS l-6.

As can be seen in FIGS. lO-l2 the modification utilizes a roller type of latch, therefore substituting rolling friction for sliding friction. Although the sliding friction latch responds to small forces to trip the device, the roller latch responds to even smaller forces as directed by the thermal trip type of device.

A movable contact assembly 92, similar to movable contact assembly 36, is pivotally mounted on a bearing plate 94, which is mounted within the base by screw 40 similar to plate 38. It can be seen in FIG. 11 that the right-hand end of contactor 92 does not have a downwardly bent bearing portion such as 36a of contactor 36, but is fiat and rests on an inclined surface 94a of bearing plate 94. As a result, the contactor 92 is more nearly horizontal in its latched position. Assembly 92 also has a' hole 92b corresponding to hole 36b of assembly 36. A cage member 920 is secured to the underside of assembly 92 in place of the latch plate 36c. Cage 920 has a pair of U-shaped leg portions92d which extend along the sides of hole 92b. A roller 96 extends transversely between the legs 92d and across the opening 92b. The same latching member 54 is used, however, the angle of its latching portion has been reduced from the slightly obtuse angle used with the latch plate to a slightly acute angle to cradle the roller 96 in the latched position as shown in FIG. 11. Roller 96 is restricted from lateral movement by portions of the base 72, and has rounded thereby rolls to the right along the underside of member 92, and the latching portion of member 54 rolls off the roller, thereby dropping the member 92 out of engagement with the stationary contacts 18-18. The legs 92d maintain the roller in position, While the device is tripped, so that a resetting action will cause the latching member to pick up the movable contact member and pull it into engagement with contacts 18-18.

I claim:

1. A circuit protector comprising a housing, a pair of stationary contacts mounted in said housing, a contactor pivotally mounted in said housing, a spring biasing said contactor away from said stationary contacts, a reset button, a second spring supporting and biasing said button outwardly of said housing, a pivoted latching lever having its pivots entrapped between said button and said second spring and having a portion extending through an opening in said contactor, said portion having a latch surface, a third spring seated in said housing and biasing said latching lever in a direction to afford engagement of its latch surface with said contactor.

2. A circuit protector comprising a housing, a pair of stationary contacts mounted in said housing, a contactor pivotally mounted in said housing, a spring biasing said contactor away from said stationary contacts, a reset button, a second spring supporting and biasing said button outwardly of said housing, a pivoted latching lever having its pivots entrapped between said button and said second spring and having a portion extending through an opening in said contactor, said portion having a latch surface, said surface extending beyond said contactor upon inward travel of said button, a third spring seated in said housing and biasing said latching lever in a direction to afford engagement of its latch surface with said contactor to hold :the latter in engagementwith said stationary contacts against the bias of said first mentioned spring upon release of said button.

3. The combination according to claim 2 wherein said latching lever is L-shaped, its pivots are at a point common to both legs, and has its latching surface at the end of one leg, wherein said button andsaid second spring afford reciprocable movement of said latching lever, wherein said third spring acts on the other leg of said latching lever, and wherein said third and second springs provide the necessary pivotal and contactor engaging forces on said latching lever necessary to hold and latch said contactor in engagement with said stationary contacts.

4. The combination according to claim 3, wherein said contactor is provided with a roller supported for limited rolling movement across a portion of the opening and along one side of said contactor, and wherein the latch surface of said latching lever is formed to engage with said roller upon release of said button as aforestated.

5. The combination accordingto claim 4, together with a member secured to said one side of said contactor and having alined spaced apart channel portions which with said one side define a cage for said roller.

6. The combination according to claim 3, together with a manual trip lever located within said housing and extending outwardly of the same, and wherein upon inward movement of said manual trip lever it acts upon the last mentioned leg of said latching lever in a direction op- 8 posing the bias and resulting forces of the third mentioned spring.

7. The combination according to claim 6, wherein said manual trip lever has an offset leg portion overlying said last mentioned leg of said latching lever, which, upon inward travel of said manual trip lever, pivots said latching lever in the reverse direction to disengage the same from said contactor to afford disengagement of the latter from said stationary contacts under the bias of the first mentioned spring.

8. The combination according to claim 3, together with means within said housing responsive to abnormal current flow through the stationary contacts and contactor closed thereto to pivot said latching lever in the reverse direction to disengage the same from said contactor to aiford disengagement of the latter from said stationary contacts under the bias of the first mentioned spring.

9. The combination according to claim 8 wherein said means responsive to abnormal current flow through the stationary contacts and contactor closed thereto includes a pivoted member which moves to engage and pivot said latching lever in the reverse direction.

10. The combination according to claim 3, together with an auxiliary switch mounted in said housing and an actuator for said switch, said actuator being driven by a pivot of said latching lever to provide one operating condition of said switch when said latching lever latches said contactor in engagement with said stationary contacts and to provide another operating condition for said switch when said latching lever is disengaged from said contactor.

11. The combination according to claim 10, wherein said actuator comprises a reciprocable member having a longitudinal slot within which one of the pivots of said latching lever extends and a spring seated at one end of said slot and bearing against the last mentioned pivot of said latching lever to provide a resilient driving connection between the latter and said actuator.

12. The combination according to claim 3, together with a manual trip lever located within said housing and extending outwardly of said housing, said manual trip lever having an offset leg portion overlying said last mentioned leg portion of said latching lever, which upon inward travel of said normal trip lever pivots said latching lever in the reverse direction to disengage the same from said contactor to afford disenagement of the latter from said stationery contacts under the bias of the first mentioned spring, means within said housing responsive to abnormal current flow through the stationary contacts and contactor closed thereto, including a pivoted member to engage and pivot said latching lever in the reverse direction, an auxiliary switch mounted within said housing and an actuator for said switch, said actuator comprising a reciprocable member having a longitudinal slot within which one of the pivots of said latching lever extends and a spring seated at one end of said slot and bearing against the last mentioned pivot of said latching lever to provide a resilient driving connection between the latter and said switch to provide one operating condition of said switch when said latching lever latches said contactor in engagement with said stationary contacts and to provide another operating condition for said switch when said latching lever is disengaged from said contactor.

No references cited.

BERNARD A, GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,214,537 October 26, 1965 Alvin W. Krieger It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 10, after "surface" insert 36a which rests on plate 38 and allows the contact assembly column 5, line 51, for "differences" read difference Signed and sealed this 20th day of September 1966.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer ioner of Patents

Claims

1. A CIRCUIT PROTECTOR COMPRISING A HOUSING, A PAIR OF STATIONARY CONTACTS MOUNTED IN SAID HOUSING, A CONTACTOR PIVOTALLY MOUNTED IN SAID HOUSING, A SPRING BIASING SAID CONTACTOR AWAY FROM SAID STATIONARY CONTACTS, A RESET BUTTON, A SECOND SPRING SUPPORTING AND BIASING SAID BUTTON OUTWARDLY OF SAID HOUSING, A PIVOTED FACING LEVER HAVING ITS PIVOTS ENTRAPPED BETWEEN SAID BUTTON AND SAID SECOND SPRING AND HAVING A PORTION EXTENDING THROUGH AND OPENING IN SAID CONTACTOR, SAID PORTION HAVING A LATCH SURFACE, A THIRD SPRING SEATED I/N SAID HOUSING AND BIASING AND LATCHING LEVER IN A DIRECTION TO AFFORD ENGAGEMENT OF ITS LATCH SURFACE WITH SAID CONTACTOR.