GB2042807A - Electric cut-out - Google Patents

Abstract

An electric cut-out has a trip device (21) which is operable by a pivot lever (2) and which is associated with a contact lever (12) disposed parallel to the casing base (13). A magnetic overcurrent trip release mechanism (48) is disposed on one side of the trip device (21) below a connection terminal (3) and has a magnetic core (49), a winding (51), a yoke (50) and, disposed thereon, a pivoted armature (52). The core (49) and yoke (40) are integral with a conductor (20') extending perpendicularly to the casing base (13) and are formed by being bent out of such conductor. The winding (51) is secured in self-supporting manner to the terminal (3) and to the conductor (20'). The armature (52) acts, by way of a thrust arm (54) movingly disposed inside the winding (51), on a trip lever (31, 33) of the trip device (21). The conductor (20') also carries a bimetallic release element (44). A magnetic trip release mechanism requiring only a reduced number of components and taking up little space is therefore provided. <IMAGE>

Description

SPECiFICATION Cut-Out The invention relates to a cut-out of the kind having a manual trip operable by a pivot lever, an at least magnetic overcurrent trip and a trip free feature, the switch comprising in a shell-like casing below the pivot lever a switching lock for a moving contact lever extending substantially parallel to the casing base, the switch having an arc chamber on one side of the switching lock, a magnetic trip mechanism on the other side thereof and one connecting terminal each on either side of the switching lock.

In known cut-outs of this kind such as are disciosed more particularly by Federal German Offenlegungsschrift 2 651158 and Federal German Patent Specifications 1,141,365 and 1,590,759, the magnetic trip facility is disposed laterally in order that the switch may have a reduced overall height.

As a result of the desire for compactness, the switching lock, the contact elements, their electrical supply wiring and the magnetic trip mechanism engage with one another to some extent, with the result not only that the assembly of the cut-out and the arrangement of an additional thermal trip mechanism, such as a bimetallic element, becomes more difficult but also that it is difficult to ensure satisfactory electrical separations between the various components. In particular, the magnetic trip facilities proposed by the known disclosures are of complicated construction, with the result that, because of the large number of components which are relatively difficult to assemble together, costs are high and so the cost of producing the complete cut-out is excessive.

It is the object of this invention to provide a cutout of reduced overall height wherein the magnetic trip mechanism is simple, has a reduced number of components, is physically completely separated from the switching lock and takes up little space, so that an additional thermal trip element, more particularly a bimetallic strip, can, if required, be readily provided without additional outlay.

According to the invention, there is provided a cut-out having a manual trip operable by a pivot lever, an at least magnetic overcurrent trip and a trip free feature, the switch comprising in a shelllike casing below the pivot lever a switching lock for a moving contact lever extending substantially parallel to the casing base, the switch having an arc chamber on one side of the switching lock, a magnetic trip mechanism on the other side thereof and one connecting terminal each on either side of the switching lock, wherein the magnetic trip mechanism is disposed below one of the connecting terminals and has a magnetic core, a winding theraround, a magnet yoke and a pivot armature disposed thereon, the magnetic core and the yoke being unitary with a conductor which extends perpendicularly to the casing base and from which they are bent out, the pivot armature which is carried by the yoke being operatively connected to a trip or release lever of the switching lock.

In the cut-out according to the invention the space available below one of the connecting terminals is occupied logically by the magnetic trip mechanism, and the same does not occupy space in any other part of the cut-out casing. Since there must be conductors between such terminal and the contact lever, the invention is a means of departing from the concept of the magnetic core and the magnet yoke being separate components and from the concept of using separate connecting conductors for the winding of the magnetic trip facility.Also, the cut-out according to the invention enables any bimettalic element provided to be disposed, without problems of space and insulation, between the magnetic trip facility -- i.e. the conductor - and the switching lock with further use of the conductor used for the magnetic trip facility.

An embodiment of the cut-out according to the invention will be described hereinafter with reference to the drawing, the single Figure of which is a partial view of the cut-out in the closed or "on" state and with its cover removed.

The partially shown cut-out comprises a substantially rectangular shell-like insulated casing 1 closable by means of a flat insulated cover (not shown) adapted to be placed on casing 1. Extending from the top of casing 1 is a pivot lever 2 for manual operation of the cut-out or switch. Disposed on a lateral part of the casing is a connection terminal 3 which is in the form of a screwed terminal and which is the output terminal of the switch or cut-out. A corresponding terminal (not shown) is disposed on the opposite lateral casing part as input terminal. The terminal 3 and the input terminal (not shown) are each in the form of a box terminal. A screw 5 is screwed into overlapping ends 4a, 4b of a metal strip 4 bent into the shape of a ring.The space inside the bent metal strip 4 is externally accessible through an aperture 6 in the casing side wali. A strip-like connecting conductor can be clamped between the head of screw 5 and the top end 4a of strip 4, and a connecting conductor in the form of a wire or stranded cable can be connected between the free end of screw 5 and the base 4c of strip 4, the wire or cable being introduced through aperture 6 into the interior of the annulus formed by strip 4.

Casing 1 has in its interior a partly shown contact and arc chamber 8, a switching-lock chamber 9 and a trip chamber 10. Another switch chamber 11 disposed laterally of chamber 9 is of no special concern for this invention and can comprise e.g. elements for a fault current trip, the latter elements acting on the switching lock which is disposed in chamber 9 and which will be described in greater detail hereinafter.

Part of a horn-shaped contact lever 12 is disposed in chamber 8; lever 12 extends substantially horizontally between a base wall 1 3 and an inner rib 14 of casing 1 and is pivotally mounted in a manner to be described hereinafter.

Lever 1 2 acts as a moving contact element 1 5 and experiences the pressure of a contact spring 16 which bears on wall 13. A contact point or the like 1 7 forms the fixed contact of the cut-out according to the invention. The contact point 1 7 is carried by a striplike copper conductor 1 8 connected to the input terminal (not shown).

Disposed on condutor 1 8 near contact point 1 7 is another strip-like but iron conductor 1 9 which extends horizontally to the left as far as the closing side wall of chamber 8 - i.e. of the cut-out - to terminate freely in the interior of the casing. A third strip-like conductor 20, which is also of iron, extends along wall 13, is electrically connected to the output terminal 3 in a manner to be described hereinafter, also extends as far as the closing lefthand side wall of chamber 8 - i.e. of the cut-out - and terminate freely in the casing interior.The distance between the iron conductors 1 9, 20 increases from a minimum at the contacting zone horizontally to the left and outwardly in the drawing in order to drive in this direction the arc arising when the contacts 1 5, 1 7 open. At the end of the widening arc chamber 8, the side wall (not shown) of the casing 1 is formed with an aperture as a known vent for the gases evolved in arcing.

The arc chamber can also have passages formed by casing projections and serving to cool the hot gases.

In the switching-lock chamber 9 which is disposed adjacent the chambers 11, 8 and which extends over the whole height of the cut-out there are disposed the lever 2, the mounted part of contact lever 12 and of contact spring 1 6 and a switching lock 21 which interconnects them and is in the form of a toggle system.

Pivot lever 2 comprises a grip portion 22 and a discoid bearing portion 23 having circular ribs 24 which project on both sides and which are mounted in corresponding grooves in the marjor lateral surfaces of casing 1 and of the cover (not shown). Part 23 also has on both sides short pins or pegs or the like 25. A torsion spring 26 applies an anti-clockwise torque to the lever 2.

One lug-like side member each of a strirrupshaped member 27 is pushed on to the pins or pegs 25 of lever 2. The side members of member 27 are each formed with another aperture through which a first bearing pin 28 engages. The ends of pin 28 are each guided in the major side surfaces of the casing and of the cover in a groove which extends at a slight inclination to the vertical and which is bounded by a bead edge 30 in the major side surfaces.

Also, a two-armed trip or release lever 31 is pivotally mounted on pin 28; one arm 32 of lever 31 extends substantially horizontally while the other arm 33 extends inclinedly downwards. Arm 32 has on its underside a sharp-edged portion 34.

A bent spring 35 applies an anticlockwise torque to lever 31.

A lever 36, hereinafter called a pawl support, is pivotably mounted on pin 28 as a support for a pawl or the like to be described hereinfafter and has at its bottom end a peg or pin or the like 37 on either side. One side member each of a stirrupshaped pawl 38 is pivotally mounted on the pins 37 in slots. The side members are connected at their top end by a yoke 39 whose top end is adapted to engage behind portion 34 of lever 31.

At their bottom end the side members of pawl 38 are formed with a bore, a second bearing pin 40 extending through each such bore. As in the case of the pin 28, each of the ends of pin 40 is guided in the major side surfaces of the casing and of the cover in a groove 41 which is also bounded by a bead edge 42. The end of contact lever 12 is tasso mounted on the second bearing pin 40.

As will be apparent, the pivot lever 2, stirrup 27, pawl support 36 and pawl 38 form a double toggle joint system having two displaceable pivot points -- i.e. the bearing pins 28, 40 -- and two deflecting pivot points -- i.e. the pin 25 of pivot lever 2 and the pin 37 of pawl support 36 - the top pivot point - i.e. the pins 25 of pivot lever 2 moving beyond the dead-centre position of the toggle joint.

The cut-out shown also has a thermal trip which comprises a bimetallic element 44 and is disposed in the release chamber 10. Element 44 is secured to the end of a portion 20' of the strip-like conductor 20 which has a number of bends in it and which is retained in casing 1 by parts thereof.

A calibrating screw 45 screwed into conductor portion 20' serves to adjust the element 44. A piece 46 of stranded cable connects the free moving end of element 44 to the end of contact lever 1 2. Element 44 extends over most of casing height and is disposed near arm 33 of trip lever 31.

Disposed in chamber 10 below terminal 3 is a magnetic trip mechanism 48 comprising a core 49 and a yoke 50. The elements 49, 50 are formed from the strip-like iron conductor 20' by cutting out and bending some of the corresponding regions of the portion 20'. Extending around core 49 is a self-supporting winding 51 having one end rigidly connected, e.g. by welding, to the conductor portion 20' and the other end similarly connected to base 4c of the bent metal strip 4 of terminal 3. A magnetic pivot armature 52 is pivotally mounted on yoke 50 and is retained in the normal position shown in the drawing by a spring 53 engaged with conductor 20. A thrust arm 54 is connected to pivot armature 52 and is mounted in an opposite end region in an aperture in conductor portion 20'. Thrust arm 54 is made of an insulant and is disposed inside winding 51.

When pivot armature 52 is pulled on because of the core 49 being magnetized by a current flowing through winding 51, it thrusts arm 54 to the left so that pressure is applied to arm 33 of trip lever 31.

As will be apparent from the foregoing, the current flow is from the input terminal (not shown) through conductor 18, contacts 17, 1 5, contact lever 12, stranded cable 46, bimetallic element 44, conductor portion 20' and winding 51 to the output terminal 3.

When the cut-out is closed ("on") as shown in the drawing, the toggle joint system, 27,31,36, 38 including the levers 2, 12 forms a rigid system in the absence of external forces acting on it.

Spring 16 presses lever 12 upwardly so that the moving contact element 1 5 of lever 12 is pressed into engagement with the fixed contact 1 7. The contact lever end mounted in the second bearing pin 40 is also pressed upwards. However, the bearing pin 40 cannot shift upwards in groove 41 since it is retained by pawl 38. The same cannot rotate clockwise around pins 37 of pawl support 36 since it is retained by portion 34 of trip lever 31. Nor can pawl 38 move upwards; the upwardly directed force component acts by way of pawl support 36 and stirrup 27 to press pivot lever 2 on to the "on" casing abutment of the grip part 22 of pivot lever 2. The foregoing is of course subject to the consideration that the torque of the torsion spring 26 is less than the torque of the stirrup 27, because of the torque applied by contact spring 16 to pivot lever 2.

'iVhen a heavy excess current occurs, e.g.

because of a short circuit, and the energized winding 51 magnetizes core 49 to attract pivot armature 52, the same acts by way of thrust arm 54 to pivot trip lever 31 clockwise. Similar considerations apply when as a result of heating by the current the bimetallic element 44 deflects to the left and therefore presses on the arm 33 of trip lever 31. The pivoting thereof releases pawi 38. Due to the pressure applied by contact spring 16, the second bearing pin 40 moves upwards in groove 41 so that contact lever 12 abuts rib 14 and pivots around this abutment.The moving contact 15 therefore disengages from the fixed contact 1 7. Also, pawl 38 presses the pins 37 of support 36 to the left so that pawl 38 takes up a substantially horizontal intermediate position and pawl support 36 takes up an intermediate position at an inclination to the vertical, the contact lever 12 finally being disposed in the "off" or open position mentioned. Since during the movement of the second bearing pin 40 in the groove 41 a torque opposed to the torsion spring 26 is still applied to pivot lever 2 by way of the elements 38, 36 and 27, the first bearing pin 28 - i.e. the stirrup 27 - do not initially change their position.

However, when the second bearing pin 40 abuts the top end of groove 41, the torque opposing the torque of torsion spring 26 disappears. Torsion spring 26 therefore rotates the bearing part 23 of pivot lever 2 anti-clockwise, the stirrup 27 pivoting beyond its dead-centre position and being turned upwards in the groove 29 and moving the first bearing pin 28, so that rip lever 31 is pulled upwards and the pawl support 36 and pawl 38 move into an extended position. Spring 35 pivots trip lever 31 on to pawl 38 so that portion 34 of trip lever 31 is again disposed on yoke 39 of pawl 38.

Clearly, an overcurrent release occurs in the event of the pivot lever 2 being locked in its "on" position for any reason, since the intermediate position of the pawl 38 and of the pawl support 36 does not cause any change in the position of the pivot lever 2. While the pivot lever 2 remains blocked, this position remains with the contacts 15, 1 7 completely open, thus providing a trip-free feature.

Clearly too, in the event of a manual opening by actuating of lever 2 the movement patterns described occur but in a different sequence, the pawl release which opens the contacts 1 5, 1 7 occuring because the trip lever 31 is pulled upwards when the lever 22 is moved and therefore when the stirrup 27 pivots around its dead centre position.

Upon closure of the cut-out, pivoting of the stirrup 27 moves the two pins 28, 40 downwards in their respective groove 29, 41. The pins 37 of support 36 cannot be deflected outwardly since pawl 38 is an engagement with portion 34 of trip lever 31. Spring 16 is therefore tensed by the operation of lever 2 and is retained in this position when stirrup 27 has passed beyond its dead centre position.

The cut-out according to this invention has in advantageous manner a very reduced number of components. More particularly, locking and tripping are provided, disregarding the two contact pins 28, 40 and the three springs 16, 26, 35, just by the pivot lever 2, contact lever 12, the switching-lock parts - i.e. the stirrup 27, trip lever 31, paw support 36 and pawl 38 - and the overcurrent parts - i.e. the pivot armature 52, spring 53, thrust arm 54 and bimetallic element 44. No separate components are required for the core 49 and yoke 50 of the magnetic trip mechanism 48 nor is a support member required for winding 51 of mechanism 48. Also, assembly of the components of the cut-out according to the invention is very simple.More particularly, the cutout parts connected to the conductor 20 -- i.e.

the bimetallic element 44 with the calibrating screw 45, the complete magnetic trip mechanism 48 and the terminal 3.-can be introduced independently as a pre-assembled unit into casing 1.

The construction and arrangement according to the invention of the thermal and magnetic trip mechanism are very advantageous since there is mechanical and thermal "decoupling" of the bimetallic element 44 from the terminal 3.

Mechanical forces which are exerted in any case on the terminal 3 by connected conductors and which may tilt or twist the terminal 3 are kept away from the bimetallic element 44 because of the presence of the resilient winding 51 between terminal 3 and conductor portion 20', so that the calibration of the element 44 is not affected.

Thermally, the evolution of heat from the bimetallic element 44 via the conductor portion 20' is less than when the element 44 is connected directly to the terminal 3. Since the energized conductor portion 20' is of iron, the flow of current produces an additional heating. An accumulation of heat therefore arises at the bottom point of the bimetallic element 44 and is advantageous for the proper operation thereof.

Arm 32 of trip lever 31 need not be of the size shown in order to perform the cut-out functions described and a short projection with the portion 34 will be sufficient. The arm 32 is provided in the cut-out shown in order to be able to act on the trip lever 31 by way of a fault current mechanism received in the switch chamber 11 and to be able to provide a release corresponding to release by the element 44 or by magnetic facility 48 without additional components. Clearly, to provide a release the fault current mechanism would have to act substantially downwards on arm 32 of trip lever 31.

Claims (9)

1. A cut-out having a manual trip operable by a pivot lever, an at least magnetic overcurrent trip and a trip free feature, the switch comprising in a shell-like casing below the pivot lever a switching lock for a moving contact lever extending substantially parallel to the casing base, the switch having an arc chamber on one side of the switching lock, a magnetic trip mechanism on the other side thereof and one connecting terminal each on either side of the switching lock, wherein the magnetic trip mechanism is disposed below one of the connecting terminals and has a magnetic core a winding therearound, a magnet yoke and a pivot armature disposed thereon, the magnetic core and the yoke bering unitary with a conductor which extends perpendicularly to the casing base and from which they are bent out, the pivot armature which is carried by the yoke being operatively connected to a trip or release lever of the switching lock.

2. A cut-out according to claim 1, in which the winding has one end secured to the terminal and its other end secured to the conductor.

3. A cut-out according to claim 2, in which the terminal is a box terminal having a metal strip which is bent to a ring shape and whose base is rigidly connected to one end of the winding.

4. A cut-out according to any of claims 1 to 3, in which the conductor, the core bent out therefrom and the yoke also bent out from the conductor are in strip form.

5. A cut-out according to claim 4, in which a thrust arm movable parallel to the core and connected to the pivot armature is disposed in the winding and the free end of the thrust arm is disposed adjacent an arm of the trip or release lever.

6. A cut-out according to any one of claims 1 to 5, in which a return spring is secured to the pivot armature and to the conductor.

7. A cut-out according to any of claims 1 to 6, in which the conductor carries, at its end adjacent the top of the casing, through which top the pivot lever extends, a bimetallic element which extends substantially parallel to the conductor between the same and the switching lock towards the casing base and which has its free end connected by way of a flexible conductor to the contact lever which is disposed near and substantially parallel to the casing base.

8. A cut-out substantially as hereinbefore described with reference to and as shown in the accompanying drawing.

9. Any novel feature or combination of features disclosed herein.