US3794945A

US3794945A - Automatic tripping electro-magnetic contactor

Info

Publication number: US3794945A
Application number: US00296619A
Authority: US
Inventors: C Terracol
Original assignee: Merlin Gerin SA
Current assignee: Merlin Gerin SA
Priority date: 1971-10-25
Filing date: 1972-10-11
Publication date: 1974-02-26
Anticipated expiration: 1991-02-26
Also published as: GB1409809A; IT975340B; CH563659A5; DE2252004A1; FR2161751A1; FR2161751B1; BE790323A

Abstract

Automatic tripping electromagnetic contactor having a trip-free mechanism such as a collapsible spring leaf to open the contacts automatically under predetermined conditions. A lost motion connection between the armature of the electromagnet operating the contacts and the movable contact by-passes and overrides the trip-free mechanism to permit the electromagnet to open the contacts strikingly.

Description

United States Patent- 1191 Terracol Feb. 26, 1974 AUTOMATIC TRIPPING 2,895,028 7/1959 Ellenberger 335/24 ELECTR MAGNET]C CONTACTOR 3,402,374 9/1968 Gaines et al 335/188 [75] lnventori Claude Terracol, Grenoble, France Primary Examiner-Harold Broome [73] Ass1gnee. Merlin Germ, Grenoble, France Attorney Agent, or firme q Davis-Mme; & [22] Filed: Oct. 11, 1972 Mosher [2!] Appl. No.1 296,619

v [57] ABSTRACT [30] Foreign Application Priority Data 1 Oct. 25, 1971 France 71.38342 Automatic tripping electromagnetic Contact having a trip-free mechanism such as a collapsible spring leaf 52] us. 01. 335/188, 335/24 to Open the contacts automatically under predeter- [511 1111. C1. H01h /00 mined conditions- A st motion connection between 5 n w f Search, 35 7 7 167, 168, 183,, the armature of the electromagnet operating the 33 5 24 1 2 1 5 contacts and the movable contact by-passes and overrides the trip-free mechanism to permit the electro- 5 References Cited magnet to open the contacts strikingly.

UNITED STATES PATENTS 7 Claims, 4 Drawing Figures 2,658,972 ll/l953 Brown 335/188 7 3 h 34 10 -32 12 E an g 1 AUTOMATIC TRIPPING.ELECTRO-MAGNETIC CONTACTOR This invention relates to an automatic tripping electromagnetic contactor and more particularly to a con- .tactor comprising an electromagnet having an armature which is reciprocable to operate a movable contact of the contactor, a trip-free motion transmitting device connecting the varmature to the .movable contact.

In prior art contactors of this kind, the trip-free motion transmitting device comprises generally a toggle lever mechanism which collapses under the action of a tripping device responsive'to a fault condition, such as a'fault current, thereby causing an opening spring to open the movable contact. The normal opening and closing of the contacts is effected by deenergizing and energizing the electromagnet, whereby a closing spring incorporated in the motion transmitting device ensures the contact pressure between the closed contacts. This motion transmitting device in the non-tripped condition is operative to transmit the normal opening movement of the armature to the movable contact (herein normal relates to the operation of the contactor with the transmitting device in the non-tripped condition due to the absence of faults); Thus the normal opening movement of the movable contact starts slowly and accelerates progressively thereby producing prolonged prejudicial'arcing between the contacts. It is apparent that contactors of this kind are not very suited to serve for instance to switch large motors or other inductive charges, I

It is an object of the invention to provide an automatic tripping electromagnetic. contactor of simple construction inwhich the trip-free motion transmitting mechanism is bypassed during at least the beginning of the normal contact opening movement by a drive connection permitting an abrupt separation of the contacts with a substantial strike energyimparted to the movable contact.

It is another object of the invention to provide an automatic tripping electromagnetic contactor in which the trip-free motion transmitting mechanism is bypassed by a lost motion device permittingthe movable contact to move in unisonwith the armature of the contact operating electromagnet at the end of an initial part of the opening movement of the armature when other the output contact. The bridging contact 10 traverses a slide 16 which is integral with magnetic armature l8 constituted by a plunger guided to slide up and down within a stationary coil 20. Coil 20 and armature l8 constitute an electromagnet controlling the movement'of movable contact 10, the energization of which produces a downward movement of the bridging contact 10 whereas the de-energization of coil 20 causes an upward or opening movement of the bridging contact 10. Slide 16 is hollow and accomodates in its inner cavity 22 a support member 24 which can slide up and down in the cavity, that is, in the direction of reciprocation of armature l8 and slide 16. A spring leaf 26 is .also lodged in cavity 22 and constitutes a collapsible trip-free member of the kind described in French Pat. No. 2,057,181 or British Pat. No. 587.782. The

ends

28 and 30 of spring 26 bear on the upper wall of cavity 22 and of support member 24, respectively, and the spring leaf is prestressed or has a curved crosssection or is adapted in any other suitable manner to withstand a considerable compression pressure in its normal extended position shown in FIG. 1 and 2 in which the backside of its central portion bears against a bearing plate 40. The longitudinal rigidity of spring leaf 26 can be annihilated by exerting a slight transverse tripping force on the central dorsal part of spring the latter has acquired a substantial. kinetic energy causing an abrupt separation of the contacts.

These and other objects and advantages will become apparent from the following description of some embodiments of the invention shown in the accompanying drawings, in which 7 FIG. I is a schematic elevation in section of a contactor embodying the invention in a closed-circuit posi' tion;

FIG. 2 shows the switch in a normal open-circuit p0: sition; Y Y e FIG. 3 showsthe switch in a tripped condition pursuant to a fault in the circuit in which the contactor is inserted;

FIG. 4 is an elevational view in section of another embodiment of the invention, the contactor being shown in a closed-circuit position.

Referring-now. to FIG. 1, 2 and 3, there is shown a bridging contact l0 cooperating with a .pair of stationary contacts 12, 1 4, oneiof which is theinput and the leaf 26 as schematically shown by arrow 42. The trip ping force may be exerted by a finger or any other appropriate device such as the armature of a (not shown) tripping relay responsive to the fault current flowing in the circuit in which the contacts -12, 14 are inserted or in a circuit in which a circuit breaker controlled by the shown contactor is inserted. The tripping force separates the spring leaf 26 from its backing plate 40 and causes the spring to bend as shown in FIG. 3 thereby looseningits longitudinal stiffness.

Bridging contact 10 traverses apertures or slots 32 in the sidewalls or legs of slide 16 and also an aperture 34 provided in support member 24. A .compression spring 36 is inserted between the upper wall of aperture 34 and of bridging contact 10 and ensures the contact pressure between bridging contact 10 and

stationary contacts

12 and 14 in the closed-circuit position thereof. A second compression spring 38 urges support member 24 upwards in the contact opening direction.

It is to be noted that in the closed position of the contacts shown in FIG. 1, the clearance between the bridging contact 10 and the bottom 44 of slots 32 is smaller than the clearance between contact 10 and the bottom 46 of aperture 34.

The operation of this switch as a contactor will now be described.

In the normal closed-circuit position of the contacts shown in FIG. 1 the coil 20 of the electromagnet is energized and the armature 18 with slide 16 urgeddownwardly whereby the trip-free mechanism constituted by collapsible spring leaf 26 transmits in its rigid condition along the slide 16 and the armature 18 with it through the rigid spring leaf 26. The assembly moves as a single unit until the bottom 44 of the slots 32 has come into contact with the bridging contact which is then carried along to its open-circuit position shown in FIG. 2. Thus the lost motion provided by the initial clearance between the bottom 44 of the slots 32 and the under side of the bridging contact 10 permits the armature 18 and the slide 16 during the initial part of the opening movement to acquire a certainamount of kinetic energy under the action of the spring 38. During this initial part the clearance is taken up and the 'bias spring 36 expandsleaving the bridging contact 10 applied on the

fixed contacts

12, 14 until the bottom 44 strikes the bridge 10 which is then propelled upward by the inertia of the moving masses of the armature 18 and of the slide 16 acting directly on it. a

The normal closing is operated by energizing the coil 20 which pulls the armature l8 downward whereby the movement of the armature is transmitted by the spring leaf 26 in its rigid condition to the support member 24 and through the bias spring 36 to the bridging contact 10. After closing of the

contacts

10, 12, 14, a limited continued movement of the armature l8 and of the slide 16 causes the compression of the bias spring 36 which produces the contact pressure and permits the bottom'44 of the slots 32 to disengagefrom the bridging contact 10.

The operation of the switch functioning as an automatic circuit interrupter (circuit-breaker)will now be described Assuming that the switch is in its normal closedcircuit position shown in FIG. 1, it is assumed that the switch is to be instantaneously opened when a predetermined conditionis reached, such as the appearance of an abnormal fault current; A striking pin or finger (not shown) which may be integral with the armature of an electromagnetic or thermal fault relay, passing through the side wall of the slide 16 and through the backing plate 40, exerts a slight transverse tripping force in the direction of the shown arrow on the central dorsal part of the spring leaf 26 causing it to collapse and to bend as shown in FIG. 3 under the action of the spring 38 which urges the support member 24 upward. After a dead stroke the bottom 46 of the support member 24 strikes the bridging contact 10 and carries the latter instantaneously along towards the open-circuit position. During this movement, the slide 16 and the armature 18 remain stationary so that almost the entire energy of the spring 38 is transmitted to the support' member 24 and to the movable contact 10 which opens rapidly, the slots or apertures 32 permitting this movement.

To reset the switch, the coil 20 is de-energized so that the unit is brought back to its normal open-circuit position shown in FIG. 2. Of course, the spring leaf 26 is preformed or prestressed to recover its extended position as soon as the force exerted by the spring 38, has sufficiently yielded as a result of its expansion caused by the upward movement of slide16 and support member 24. It is of course possible to replace spring leaf 26 by another collapsible device such as a toggle joint. The

trip-free mechanism may be common to several poles.

ment shown in FIG. 4 in which identical reference numbers designate like elements with respect to the embodiment of FIGS. 1 to 3.

The trip-free motion transmitting means connecting the armature 18 to the bridging contact 20 comprises a pair of drive rods 51 which are secured to the armature 18 and which include abutment ends 52 spaced apart from the bridging contact 10 in the closed-circuit position of the latter and which are similar to the bottom surface 44. of FIGS. 1 to 3. Again, the distance separating the abutment surfaces 52 from the contact bridge 10 is smaller than the distance between the bottom 46 of support member 24 and the contact bridge. The support member 24 is connected to the armature 18 through a latch 48 which is pivotally mounted on the armature and which engages normally the support member 24 whereby the

linkage

24, 48 is now tensionstres sed (or stretched) by the compression springs 38 acting upon a pair of lateral projections of support member 24. It is apparent that the abutment ends 52 open the switch normally after de-energizing coil 20 and under the action of springs 38 as soon as the dead stroke is taken up. On the other hand, the abutment The switch shown in FIGS. 1 to 3 comprises a comsurface 46 strikes the bridging contact 10 upon tripping of the

connection

24, 48, that is, after pivoting of latch 48 under the action of a tripping mechanism diagrammatically shown as an arrow 42. Of course, appropriate slots in rods 50 pennit support member 24 tomove freely upon tripping of the

latching connection

24, 48.

What is claimed is: 1. A trip-free electromagnetic contactor comprising:

separable contact means including a movable contact,

an electromagnet having an armature reciprocable.

between a first and a second position to operate said movable contact through a first lost-motion mechanical connection means,

second mechanical connection means connecting said armature to said movable contact and comprising a movable tripping link selectively movable between a non-tripping motion transmitting and a tripping movable contact releasing position, and

energy storage means cooperating with said second mechanical connection means to bias said contact means to the open-circuit position thereof,

said second mechanical connection means comprising resilient bias means toproduce a contact pressurewhen said contact means are in closed-circuit position,

said lost-motion mechanical connection means being adapted to take up the lost motion thereof during the initial part of the movement of said armature from said first to said second position to actuate said movable contact at the end of said initial part with a striking energy derived from the kinetic energy acquired by said armature during said initial part thereby to move said movable contact from the closed circuit to the open-circuit position thereof when said tripping link is in said nontripping position.

. 2. A contactor according to claim 1, said tripping link comprising an elongated, substantially longitudinally compressed collapsible member.

3. A contactor according to claim 2, said member comprising a leaf spring.

4. A contactor according to claim 2, said member comprising a toggle lever.

5 A contactor according to claim 1, said second mechanical connection means comprising a slidable member, a releasable latch connecting said slidable member releasably to said armature, said resilient bias means comprising spring means connecting said slidable member to said movable contact.

6. A contactor according to claim 1, said second mechanical connection means comprising a support member for said movable contact, said support member being slidably guided with respect to said armature in the direction of reciprocation thereof, said energy storage means urging said support member in the direction of opening of said contact means, said support member comprising a first abutment surface cooperating with said movable contact, said resilient bias means urging said movable contact in the direction of said first abutment surface, said lost-motion mechanical connection means comprising a second abutment surface cooperating with said movable contact, said first and second abutment surfaces being adapted so that said first abutment surface engages said movable contact in the contact opening direction upon tripping of said tripfree motion mechanical connection means and said second abutment surface engages saidmovable contact in the contact opening direction upon movement of said armature from said first to said second position.

7. A contactor according to claim 6, the clearance between said first abutment surface and said movable contact being greater than the clearance between said second abutment surface and said movable contact in the closed-circuit position of said movable contact.

Claims

1. A trip-free electromagnetic contactor comprising: separable contact means including a movable contact, an electromagnet having an armature reciprocable between a first and a second position to operate said movable contact through a first lost-motion mechanical connection means, second mechanical connection means connecting said armature to said movable contact and comprising a movable tripping link selectively movable between a non-tripping motion transmitting and a tripping movable contact releasing position, and energy storage means cooperating with said second mechanical connection means to bias said contact means to the open-circuit position thereof, said second mechanical connection means comprising resilient bias means to produce a contact pressure when said contact means are in closed-circuit position, said lost-motion mechanical connection means being adapted to take up the lost motion thereof during the initial part of the movement of said armature from said first to said second position to actuate said movable contact at the end of said initial part with a striking energy derived from the kinetic energy acquired by said armature during said initial part thereby to move said movable contact from the closed circuit to the open-circuit position thereof when said tripping link is in said non-tripping position.

2. A contactor according to claim 1, said tripping link comprising an elongated, substantially longitudinally compressed collapsible member.

3. A contactor according to claim 2, said member comprising a leaf spring.

4. A contactor according to claim 2, said member comprising a toggle lever.

5. A contactor according to claim 1, said second mechanical connection means comprising a slidable member, a releasable latch connecting said slidable member releasably to said armature, said resilient bias means comprising spring means connecting said slidable member to said movable contact.

6. A contactor according to claim 1, said second mechanical connection means comprising a support member for said movable contact, said support member being slidably guided with respect to said armature in the direction of reciprocation thereof, said energy storage means urging said support member in the direction of opening of said contact means, said support member comprising a first abutment surface cooperating with said movable contact, said resilient bias means urging said movable contact in the direction of said first abutment surface, said lost-motion mechanical connection means comprising a second abutment surface cooperating with said movable contact, said first and second abutment surfaces being adapted so that said first abutment surface engages said movable contact in the contact opening direction upon tripping of said trip-free motion mechanical connection means and said second abutment surface engages said movable contact in the contact opening direction upon movement of said armature from said first to said second position.