US2732452A

US2732452A - Electric switchgear

Info

Publication number: US2732452A
Authority: US
Priority date: 1950-10-12
Publication date: 1956-01-24
Anticipated expiration: 1973-01-24
Also published as: FR1044960A; GB695296A

Description

Jan. 24, 1956 J. A. JACKSON ET AL 2,732,452

' ELECTRIC SWITCHGEAR Filed NOV. 9, 1951 2 Sheets-Sheet 1 IVELBOt/RNE DEN/MR6? MLQ- HQ Ahorney Jan. 24, 1956 J. A. JACKSON ETAL 2,732,452

ELECTRIC SWITCHGEAR Filed Nov. 9, 1951 2 Sheets-Sheet 2 l mzo 20 Inventors Jam's Aka-x7 J'nrmro/v r154 BOI/RIVE DEwflz/Rsr 8y MM 2. we

Attorney United States Patent O ELECTRIC SWITCHGEAR James A. Jackson, Hounslow, and Melbourne Dewlinrst, Cranford, Hounslow, England, assignors to Dewhnrst and Partner Limited, Hounslow, England, a British company Application November 9, 1951, Serial No. 255,584

4 Claims. (Cl. 200-87) The present invention relates to electric switchgear and more particularly relates to contactor switches.

One object of the invention is the provision of improved constructions of contactor switches.

One trouble which arises with existing constructions is that when the armature closes, the contacts meet at high speed, and, due to the momentum of the moving contact attached to the armature, this contact bounces, which results in arcing. Such arcing, particularly in heavy duty work, seriously reduces the life of the contacts.

Accordingly, another object of the invention is to provide a novel and improved electromagnetic contactor including cushioning or damping means in form of a double pivoting arrangement which counteracts the tendency of the moving contact to bounce away from the fixed contact thereby reducing or even completely eliminating the formation of arcs when the contactor is actuated for closing its contacts. As a result, the useful life of the contacts is appreciably prolonged.

One specific construction of contactor incorporating this feature will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a side elevation of the contactor, one of the arc shields adjacent the contacts being shown removed for clarity, whilst Figure 2 is an end elevation taken along the line Il-Il in Figure l.

In this construction the moving contact 19 is supported by a pair of plates 11 of insulating material which are pivotally mounted near their lower ends on a spindle 12 passing through the contactor armature 13, the plates 11 lying on opposite sides thereof. A second spindle 14 is also fixed to the plates 11 and passes through a hole 13a in the armature 13 near to the top of the latter, the diameter of the hole 13a being somewhat larger than that of the spindle 14. The moving contact 10 is mounted by a bracket 15 on a third spindle 16 fixed to the plates 11 near their upper end, the moving contact 16 being normally maintained at a predetermined inclination by means of the usual compression spring 17 which ensures a rolling and slight rubbing contact action when the moving contact 10 makes with the fixed contact 13. A pair of light springs 19 each fixed between one of the plates 11 and the armature 13 normally maintain the plates 11 relative to the armature 13 in a position such that the second spindle 14 engages that side of the hole 13a in the armature 13 nearest to the contactor coil 29.

When the

contacts

10 and 18 meet, the continued movement of the armature 13 brings the second spindle 14 into engagement with the other side of the hole 13a (as shown in Figure 1), until the armature 13 engages the pole surface. Anytendency of the moving contact 10 to rebound is counteracted by the plates 11 moving forward in relation to the armature 13 under the control of the pair of light springs 19 until the momentum of the moving contact 10 and bracket 15 is absorbed by the spring 17. The design is such that the momentum is 2,732,452 Patented Jan. 24, 1956 absorbed before the spindle 14 engages the side of the hole 13a nearest to the contactor coil 20. Thus, although the moving contact 10 tends to move backwards away from the fixed contact 18, the sideplates 11 move forward towards the contactor coil 20 and the moving contact 10 is kept in engagement with the fixed contact 18. This relative movement between the armature 13 and the plates 11 is possible due to the enlarged hole 13a through which the second spindle 14 passes.

A further feature of the invention is concerned with extinguishing the are drawn between the

contacts

10 and 18 when they are interrupted. According to this feature a magnetic blow-out coil is connected between a conductor from the fixed contact and an auxiliary contact mounted above the fixed contact, whereby a blow-out coil is not energised when the contacts are made but is energised during breaking of the contacts due to jumping of the are from the fixed contact to the auxiliary contact.

in the embodiment of this arrangement which is shown in the drawin s, an auxiliary contact 21 is mounted above the fixed contact 13, and one end of a blow-out coil 22 is connected by a stud 23 to an electrically conductive lead-in bracket 24 which supports this auxiliary contact 21. The other end of the blow-out coil 22 is connected by a stud 25 to the lead-in bracket 26 which supports the fixed contact 18.

With this arrangement drawing of the arc on breaking of the contacts will result in the arc jumping from the fixed contact 13 to the auxiliary contact 21, so that the arc current then flows through, and thus energises, the blow-out coil 22.

As the blow-out coil is only in circuit temporarily it can be of much higher rating than is normal, and the blow-out coil may be designed so that the magnetic value obtained is much greater than usual.

The moving contact 10 may be arranged to drop back onto a second auxiliary contact 27 of greater mass which, in the position when the moving contact 10 has fallen back (as shown in chain-dotted lines) onto the second auxiliary contact 27, is nearer to the first auxiliary contact 21 than the moving contact 10. With this arrangement the arc is then transferred from the moving contact 10 to the second auxiliary contact 27 which, due to the greater mass of the latter, can more readily dissipate the heat generated.

According to another feature of the invention a plurality of discs of ferrous material are mounted in the magnetic field of the blow-out coil, whereby on energisation of the blow-out coil the discs are magnetised to intensify the field acting to draw the arc.

in the embodiment illustrated, the discs 28 are mounted above the

auxiliary contacts

21, 27.

The discs, which may for example be eight or ten in number, will also help to quench the arc owing to their heat conducting properties.

What is claimed is:

1. An electromagnetic contactor, comprising a field member, an armature movably mounted on a fixed part, said armature being attractable to and releasable from said field member, a carrier element pivotally mounted on said armature, a movable contact mounted on said carrier element pivotal about an axis spaced apart from the axis of the carrier element, a relatively stationary fixed contact, first spring means biasing said movable contact relative to said carrier element, to a given limit in the direction towards said fixed contact, and second spring means biasing said carrier element relative to said arma ture to a given limit in the direction to move said movable contact towards said fixed contact, the movement of said armature, when attracted to said field member, being in the direction to move said movable contact to said fixed contact, whereby, upon engagement of said movable 3 contact with said fixed contact in response to the movement of said armataure to the attracted position, said second spring means initially yields before the armature has reached its final position, and subsequently recovers, leaving said first spring means in a condition of yield.

2. An electromagnetic contactor, comprising a field member, an armature movably mounted on a fixed part, said armature being attractable to and releasable from said field member, a carrier element pivotally mounted on said armature, a movable contact mounted on said carrier element pivotal about an axis spaced apart from the axis of the carrier element, a relatively stationary fixed contact, first spring means biasing said movable contact relative to said carrier element, to a given limit in the direction towards said fixed contact, and second spring means biasing said carrier element relative to said armature to a given limit in the direction to move said movable contact towards said fixed contact, said carrier element being movable in opposition to said second spring means to another given limit, the movement of said armature, when attracted to said field member, being in the direction to move said movable contact to said fixed contact, whereby, upon engagement of said movable contact with said fixed contact in response to the movement of said armature to the attracted position, said secondspring means initially yields to the extent of said other given limit of said carrier element before the armature has reached its final position, and subsequently recovers, leaving said first spring means in a condition of yield.

3. An electromagnetic contactor, comprising a field member, an armature movably mounted on a fixed part, said armature being attractable to and releasable from said field member, a carrier element pivotally mounted on said armature, a movable contact mounted on said carrier element pivotal about an axis spaced apart from the axis of said carrier element, a relatively stationary fixed contact, first spring means biasing said movable contact relative to said carrier element, to a given limit in the direction towards said fixed contact, and second spring means biasing said carrier element relative to said armature to a given limit in the direction to move said movable contact towards said fixed contact, said carrier element being movable in opposition to said second spring means to another given limit, the movement of said armature, when attracted to said field member, being in the direction to move said movable contact to said fixed contact, whereby, upon engagement of said movable contact with said fixed contact in response to the movement of said armature to the attracted position,

said second spring means initially yields to the extent of said other given limit of said carrier element, before the armature has reached its final position, and subsequently recovers to the first named given limit of said carrier element, leaving said first spring means in a condition of yield.

4. An electromagnetic contactor, comprising a field member, an armature having a hole, said armature being movably mounted on a fixed part and attractable and releasable from said field member, a carrier element pivotally mounted on said armature, said carrier element comprising two plates mounted one each side of said armature, a bar coupling said plates, parallel to and spaced from the pivot axis of said carrier element, said bar passing through said hole in the armature, said hole being large enough to afford play of said bar therein,

a movable contact pivotally mounted on said carrier element, a relatively stationary fixed contact, first spring means biasing said movable contact relative to said carrier element to a given limit in the direction towards said fixed contact, and second spring means biasing said carrier element relative to said armature, in the direction to move said movable contact towards said fixed contact, to a limit as determined by said bar abutting against one side of said hole, the movement of said armature, when attracted to said field element, being in the direction to move said movable contact to said fixed contact, whereby, upon engagement of said movable contact with said fixed contact, in response to the movement of said armature to the attracted position, said second spring means initially yield to the limit as determined by said bar abutting against the other side of said hole, before the armature has reached its final position, and subsequently recover to the limit determined by the abutting of said bar against the first-named side of said hole, leaving said first spring means in a condition of yield.

References Cited in the file of this patent UNITED STATES PATENTS 1,280,661 Carichofi Oct. 8, 1918 1,309,822 Steen July 15, 1919 1,729,876 James et al. Oct. 1, 1929 1,763,116 White June 10, 1930 1,779,659 Carichofi Oct. 28, 1930 2,071,595 Trofimov Feb. 23, 1937 2,145,327 Van Valkenburg Jan. 31, 1939 2,231,974 Van Valkenburg Feb. 18, 1941 2,255,886 Hudson Sept. 16, 1941 2,424,308 Ellis et a1. July 22, 1947 2,524,287 Ellis Oct. 3, 1950 FOREIGN PATENTS 434,000 Germany Aug 2, 1925