US1758752A - Means for protecting contacts of electric switches - Google Patents

Description

May 13, 1930. Y c. w. KUHN 1,758,752

MEANS FOR PROTECTING CONTACTS OF ELECTRIC SWITCHES Filed Feb. 7, 192' INVEN TOR.

gla/vMMW.W1 rv ATTORNEY Patented May 13, 1930 UNITED STATES PATENT OFQFICE,

CLARENCE W. KUHN, OF MILWAUKEE, WISCONSIN, ASSIGNOR, BY MESN-E ASSIGN- MENTS, TO CUTLER-HAMMER, INC.

, A CORPORATION OF DELAWARE J MEANS non .rno'rnorme containers on nnnc'r'nro swrronns Application fl led February 7, 1927. Serial No. 166,487.

This invention relates to imprqvements in means for protecting contacts of electric switches, and the invention moreparticular ly relates to the provision of improved means. for protecting relatively movable contacts of a switch from the destructive infiuence of arcs drawn therebetween.

It is customaryto provide one or both of the relatively movable contacts of a switch 10 with an arcing horn of shoe to receive and provide for disruption of the are developed by'opening of said contacts, an electromagnetic blow-out device being usually employed 9 to effect or expedite passage of the are from the contacts to the arcing horns. Moreover,

such arcing horns have usually been formed of steel or brass, whereas 'in practice it is found that the contacts in conjunction with which such arcing horns are employed are subjected to severe destructive influences of the are, so that the contactsrapidly become destroyed and rnust be frequently renewed;

I have discovered that by providing for shifting of the are from one or both of the contacts to an arcing element or elements of relatively high melting point the vapor. of which does not readily conduct the current the life and usefulness of such contacts will be M very greatly increased, thereby minimizing the amount of time, labor and material required to keep the switch in proper ,working condition. I V i I Z/ An object of the invention is to provide arcing elements of such character and construction as to greatly increase the'life of switch contacts associated therewith.

Another object is to provide for utilization of aknown commercial alloy in constructing 1 said improved arcing elements.

Another'object is to provide an improved 1 structure of the aforementioned character ,vgh'ich may be readily and economically manufactured. i

(Other objects and advantages of the inven tion will hereinafter appear.

The accompanying drawing illustrates cer tain embodiments of my invention which willfnow be described, it being understood thatvarious changes in details may belnade without departing from the spirit and scope h of the invention as defined by the claims.

In the drawing, Figure 1 illustrates the contacts ofa conventional form of switch, said contacts having my improved arcing horns or elements associated therewith.

Fig. 2 is asimilar view of a modification in which but one of my improved arcing elements is employed, and

Fig. 8 is a similar view of another modification embodying. my invention.

Referring first to the device illustrated in .Fig. 1, the numerals 5 and 6 designate the usual contacts of an electric switch, contact 5 being carried by a stationary support 7 and contact 6 being supportedbymember 8 for movement into and out of engagement with said contact 5. Member 8 is preferably so operated as to provide for final separation of contacts 5 and 6 at the tips 5 and 6 whereby the normal contacting surfaces thereof are protected to a certain extent from influence of the are developed upon separation of the contacts. Electrically and mechanically united with each of said contacts is an arcing horn or element 9 of any usual or preferredform. Assuming provislon of an elect-romagnetic blow-out device for the switch, the same, is adapted upon separation of the contacts to transfer or shift the resulting arc fromrsaid contapts td the arcing-elements 9,

with-consequent attenuation and extinguishment of the arc'after a given time interval.

As aforeindicated, however, if the arcing elements 9 are formed in the usual manner from steel. brass or similar material it is" found that Y the contactsare severely attacked by the arcs resulting from separation thereof, so that after service for acomparatively short time the same are rendered unfit for further use and must therefore bereplaced by new contacts.

On the other hand if the arcing elements are formed of amaterial of the character dis closed herein it has been found that the life of such contacts is increased from fifty to bne hundred per cent or more; thus achieving a desirable economy in the upkeep andrepair of the switches. More sipecifia'ally,the mate- ,rial of which the arcing elements areformed 1 spending parts are given like characters ofpreferably comprises an alloy composed prin-' cipally of nickel and chromium, in the pro-- portions of about eighty per cent nickel and reference; whereas it will be noted that only the stationary contact 5 is provided with a "so-called arcing element,thus requiring attenuation and extinguishment of the are between the tip 6 of. contact 6 and the element 9. However, it is found that by forming element 9 of the aforedescribed alloy of nickel and chromium the life of both contacts of the switch is materially increased or extended, as compared with that of contacts having the ordinary arcing element or elements associated therewith. The use of such alloy in this case likewise renders possible the more nected to ,said contacts, said elements being composed of a nickel chromium alloye- 3. The combinationwith relatively movable switch contacts, of arcing elements therefor composed of the nickel chromium alloy nichron e.

4. The combination with relatively moyable switch contacts, at least one ofsaid contacts having an arcing element mechanically and electrically connected thereto, said element comprising an alloy of about twent per cent chromium and eighty per cent nicke 5. The combination with relatively movable switch contact members, of arcing elements integrally united therewith mechanically and electrically, said elements consistng of the nickel chormium alloy nichrome. I

6. The combination with a pair of relatively movable switch contacts formed of con.- ducting material of relatively low resistance, of arcing tips integrally united with said contacts b welding, said arcing tips consisting of an a loy of nickel-and chromium.

In witness whereof, Lhave hereunto subscribed my name.

CLARENCE w. KUH'N'.

rapid extinguishment of the arc,-due probably to the resulting higher resistance value of the arc vapor.

Fig. 3' illustrates a modification wherein the supports 7 and -8 carry contacts 10 and 11,

respectively, of slightly diflerent construction. Thus said contacts'may each comprise a body portion formed in the usual manner from copper or a copper alloy of relatively low resistance, whereas each; of said contacts is provided with a tip 9 of the aforementioned alloy. Thus upon opening of the contacts 10 and.-11 the resulting arc will be initially drawn between the alloy tips or elements 9, so that the contacting surfaces of the contacts are unusually well @protected from destructive influence of the arc. The tips 9 are preferably integrally united with the body portions of the contacts 10 and 11 in any suitable or well known manner, as by welding or brazing. By employment of a device like that shown in Fig. 3 thenecessity for the provision of separate arcing'elements is obviated, whereas the over-all dimensions of the switch structure may consequently be somewhat reduced.

' \Vhat I claim as new and desire to secure by Letters Patent is:

1. The combination with prising analloy. of 'nickel and chromium.

'2; The combination with a pair of relatively movable switch contacts, of' arcing ele- '-ments-associated w1th and electrically conrelatively movable swltch contacts, of an arcing-element as- 'sociated with said contacts, said element com-

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