US3166660A

US3166660A - Contact construction with metallic contact members and auxiliary metallic arc suppressant conducting members

Info

Publication number: US3166660A
Application number: US27702A
Authority: US
Inventors: Joseph J Gribble
Original assignee: Square D Co
Current assignee: Schneider Electric USA Inc
Priority date: 1960-05-09
Filing date: 1960-05-09
Publication date: 1965-01-19
Anticipated expiration: 1982-01-19

Description

. J. GRIBBLE 3,166,660

Jan. 19, 1965 J CONTACT CONSTRUCTION WITH METALLIC CONTACT MEMBERS AND AUXILIARY METALLIC ARC SUPPRESSORS CONDUCTING MEMBERS Filed May 9. 1960 IN VEN TOR. JOSEPH J 62/55: 5

United States Patent Ofitice Patented Jan. 19, 1965 This invention relates to an electrical contact device and more particularly to an electrical contact device employing special contacts in a' relation which provides a more effective self-contained, arc-extinguishing means.

One of the most persistent problems encountered in the use of electrical contacts is the excessive and premature pitting and erosion of such contacts by the arcing which occurs between the contacts as a circuit is made or broken. Because of this arcing, the contacts must be replaced frequently, thereby involving considerable expense in timejand materials.

It is an object of the present invention to provide electrical contacts which are much less subject to pitting, burning and erosion by arcing and which have a substantially longer life than that of prior contacts.

A further object'of the invention is' to provide electrical contacts that extinguish the arc and resist welding more efficiently than that of prior constructions.

A further'object of the invention is toprovide an electrical contact construction which is economical to manufacture andthat is eflicient and trouble-free in use, and in which the specific contacts arearranged in a relation to the arc path so that the arc is moved efiieiently to the extinguishing position, I

Briefly, the foregoing objects-are accomplished by the provisionof an, electrical contact construction including a pair of opposed coacting contacts, each of said contacts having a contiguous auxiliary are receiving conductor and each main contact andits auxiliary conductor being mounted, respectively, adjacent the outer free, parallel-spaced end portions of an electrical conducting bar.

The contacts are oppositely spaced in face to face relation and are adapted for movement into and out of conlariy resistant to welding because of its high melting point. The auxiliary conductors are formed of a semi-refractory composition such as silver cadmium oxide, which is an arc-suppressant material of high interrupting capacity. Thus, the magnetic field created by the current flowing through the contacts causes the arc to travel'from the partially spaced weld-resistant contacts to the substantially spaced arc-suppressant, auxiliary conductors where the arc is interrupted. With this construction, an electrical contact device is provided having self-contained arc xtinguishing means, such contact device being of unusually simple construction and having a substantially longer life than that of prior constructions.

Other objects and advantages of the invention will become apparent from the following description taken in conjunction with the drawings,.wherein:

FIG. 1 is a perspective view of an electrical contact device constructed in accordance with the invention, with tact device shown in FIG. 1, the device being shown in closed position.

Referring to the drawings, there, is shown an electrical contact device A of the invention and comprising the contact supporting means in the form of two spaced electrical load current conducting

bars

10 and 12 having parallel outer end portions, the outer end portions having coacting, oppositely disposed, contacts or contact

members

14 and 16, respectively, supported fixedly thereon in face to face relation. The contact 14 has a con tiguous auxiliary conductor 18 and the contact 16 has a contiguous auxiliary conductor 20. Y

The conducting

bars

10 and 12 areadapted'for movement toward and away from eachaother in any well known manner, whereby, the contacts 14 and .16 move into and out of engagement with each other for making and breaking an electric circuit. For. illustration, the bar 12 is shown as stationary and the bar 10 is movable about a I pivot 13 toward and away from thebar 12.

tact with each other for making and breaking an elec- 5 trical circuit. The auxiliary conductors are disposed also in spaced, face to face relation, but do not come into contact with each other when the contacts are in either open or closed position. More specifically, each contact and its contiguous auxiliary conductor present a stepped construction, in side elevational view, with the distance between the contacts being less than the distance between the contiguous'auxiliary conductors.

In operation, with the contacts in engagement with each other, electric load current flows in through one of the conducting bars, through the engaged contacts and creates a magnetic field ,having a resultant force directed outwardly towards the free ends of the conducting bars. Upon opening of the contacts, if an arc is created, it acts 1 Furthermore, contacts 'aref formedoffa renac'toryeom.

thence through the other conductorbarf Thiscurrent I f position'such' as tungstencarbideimpregnated with silver, such'material being haidand othigh strjength andparticu- The

auxiliary conductors

18 and 20 are disposed in spaced, face to face relation a greater distance apart than the

contacts

14 and 16 so that they do not come into contact with each other even when the'contacts 14 and 16 are in closed position. Thus the contacts and conductors present a stepped construction.

1 In operation, with the contact members i-t and 16 in engagement with each other, as shown in FIG. 4, electric current, flows, for example, through the conducting bar 10,

' down through the engaged contacts 14 and. 16, and thence through theiconducting bar 12, as shown by the arrows 17. This current flow creates a magnetic field having a resultant force which is directed outwardly, to the right in FIG. 4, toward the free ends of the

bars

10 and 12, as indicated by the arrow 21; When the

contacts

14 and 16 are parted, as shown in FIG. 1, an arc is formed between the contacts and the magnetic field, causes the arc to travel from the contacts to the auxiliary conductors 13 'j f 'and 2i? wherethe arc is broken, such are progression ber "ingrepresented by the broken lines 22. Thusthe conf' ductors-lfi and '20 are arranged in. parallel spaced relation along the normal path of the are. This path is in a direction to 'the right; in FIG, 4, and is unobstructed fora. 7

distance outwardly beyond the conductors 18 and 2Q sufiij j'cientlto permit interruption' of the arc. a. Thecontacts 14 and {Glare formed of a refractory conrposition, such as a matrix oftungstencarbide impregnated with silver; This composition is hard 1 and of high strength and resistant-to arc erosion and wear, yet'is a j good conductor of electricity. In the preferred form, such composition consists of about 50% tungsten carbide and about 50% silver, both by volume. However, these percentages may be varied somewhat. For example, tugsten carbide may be from about 40% to 60%, and the silvermay provide the balance.

The contiguous auxiliary conductors are formed of a semi-refractory material, such as silver cadmium oxide. This composition is highly arc-suppressant and has a high interrupting capacity. In the preferred form, such composition consists of about 85% silver and about 15% cadmium oxide, both by volume. The percentages may be varied. For example, the silver may range from about 80% to 90% and the cadmium oxide may provide thebalance.

Having thus described my invention, I claim:

1. A contact construction comprising a pairof elongated load current conducting bars extending lengthwise alongside each other in face to face spaced relation from each other transversely of their lengths and movable transversely of their length toward and away from each other so that the load current path therein is endwise of the bars, metallic contact members on the adjacent faces of the bars, respectively, near to, but spaced from, one end of the pair, and supported by the bars in spaced face to face relation, and movable by the bars into contact with each other upon movement of the bars transversely of their length toward each other, whereby, upon establishment of an are between the members when they are moved apart, a magnetic field is established by the load current which forces the arc to travel from between the contact members endwise of the bars towards and beyond said one end of the pair of bars, auxiliary conducting members of highly arc suppressant metallic material mounted on the bars, respectively, outwardly from the contact members toward said one end of the pair and arranged so that they extend directly from the adjacent outer ends of the contact members, respectively, outwardly toward said end of the pair of bars, and are in spaced face to face relation to each other in the direction of separation of the contact members in all positions of the contact members, means supporting the bars so that the direct path of travel of the are from between the contact members under the influence of the magnetic field created by the load current, outwardly endwise of the bars past said one end of the pair, is unobstructed, endwise of the bars, outwardly from the contact members, past said auxiliary members and therebeyond a distance suflicient to permit interruption of the arc while it is substantially unconstrained endwise and laterally of the bars, said metallic contact members being of material of high electrical conductivity and high resistance to welding, wear, and are erosion, and said auxiliary conducting members being of metallic material of high arc interrupting capacity.

2. The structure according to claim 1 wherein said contact portion is formed of tungsten carbide impregnated With silver.

3. The structure according to claim 2 wherein said tungsten carbide is present in an amount of about and silver is present in an amount of about 50%, by volume.

4. The structure according to claim 1 wherein said auxiliary portion is formed of silver cadmium oxide composition.

5. The structure according to claim 4 wherein said silver is present in an amount of about 85% and the cadmium oxide is present in an amount of about 15 by volume.

6. The structure according to claim 1 wherein said contact portion is formed of a material consisting of about 50% tungsten carbide and about 50% silver, and said auxiliary portion is formed of a material consisting of about 85% silver and about 15% cadmium oxide, by volume.

7. The structure according to claim 1 wherein said contact members are formed of a material consisting of about 40% to tungsten carbide and from about 60% to 40% silver, both by volume, and said auxiliary members are formed of a material consisting of about to silver and from about 20% to 10% cadmium oxide, both by volume.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,166,660 January 19, 1965 Joseph J. Gribble 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 4, after line 43, insert the following:

2,289,708 Jackson July 14, 1942 2,307,668 Cox Jan. 5, 194

2,360,522 Shobert 11 et a1. Oct. 17, 1944 2,506,991 Brown May 9, 1950 2,730,594 Page -Jan. 10, 1956 2,890,315 Graves, Jr. -June 9, 1959 Signed and sealed this 24th day of August 1965.

(SEAL) Attest:

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

Claims

1. A CONTACT CONSTRUCTION COMPRISING A PAIR OF ELONGATED LOAD CURRENT CONDUCTING BARS EXTENDING LENGTHWISE ALONGSIDE EACH OTHER IN FACE TO FACE SPACED RELATION FROM EACH OTHER TRANSVERSELY OF THEIR LENGTHS AND MOVABLE TRANSVERSELY OF THEIR LENGTH TOWARD ANS AWAY FROM EACH OTHER SO THAT THE LOAD CURRENT PATH THEREIN IS ENDWISE OF THE BARS, METALLIC CONTACT MEMBERS ON THE ADJACENT FACES OF THE BARS, RESPECTIVELY, NEAR TO, BUT SPACED FROM, ONE END OF THE PAIR, AND SUPPORTED BY THE BARS IN SPACED FACE TO FACE RELATION, AND MOVABLE BY THE BARS INTO CONTACT WITH EACH OTHER UPON MOVEMENT OF THE BARS TRANSVERSELY OF THEIR LENGTH TOWARD EACH OTHER, WHEEREBY, UPON ESTABLISHMENT OF AN ARC BETWEEN THE MEMBERS WHEN THEY ARE MOVED APRAT, A MAGNETIC FIELD IS ESTABLISHED BY THE LOAD CURRENT WHICH FORCES THE ARC TO TRAVEL FROM BETWEEN THE CONTACT MEMBERS ENDWISE OF THE BARS TOWARDS AND BEYOND SAID ONE END OF THE PARI OF BARS, AUXILIARY CONDUCTING MEMBERS OF HIGHLY ARC SUPPRESSANT METALLIC MATERIAL MOUNTED ON THE BARS, RESPECTIVELY, OUTWARDLY FROM THE CONTACT MEMBERS TOWARD SAID ONE END OF THE PAIR AND ARRANGED SO THAT THEY EXTEND DIRECTLY FROM THE ADJACENT OUTER ENDS OF THE CONTACT MEMBERS, RESPECTIVELY, OUTWARDLY TOWARD SAID END OF THE PAIR OF BARS, AND ARE IN SPACED FACE TO FACE RELATION TO EACH OTHER IN THE DIRECTION OF SEPARATION OF THE CONTACT MEMBERS IN ALL POSITIONS OF THE CONTACT MEMBERS, MEANS SUPPORTING THE BARS SO THAT THE DIRECT PATH OF TRAVEL OF THE ARC FROM BETWEEN THE CONTACT MEMBERS UNDER THE INFLUENCE OF THE MAGNETIC FIELD CREATED BY THE LOAD CURRENT, OUTWARDLY ENDWISE OF THE BARS PAST SAID ONE END OF THE PAIR, IS UNOBSTRUCTED, ENDWISE OF THE BARS, OUTWARDLY FROM THE CONTACT MEMBERS, PAST SAID AUXILIARY MEMBERS AND THEREBEYOND A DISTANCE SUFFICIENT TO PERMIT INTERRUPTION OF THE ARC WHILE IT IS SUBSTANTIALLY UNCONSTRAINED ENDWISE AND LATERALLY OF THE BARS, SAID METALLIC CONTACT MEMBERS BEING OF MATERIAL OF HIGH ELECTRICAL CONDUCTIVITY AND HIGH RESISTANCE TO WELDING, WEAR, AND ARC EROSION, AND SAID AUXILIARY CONDUCTING MEMBERS BEING OF METALLIC MATERIAL OF HIGH ARC INTERRUPTING CAPACITY.