US2141114A - Contact - Google Patents

Description

Patented Dec. 20, 1938 UNITED STATES CONTACT Chester Peterson, Maplewood, N. J., assignor to The H. A. Wilson Company, a corporation of New Jersey No Drawing. Application April 24, 1937,. Serial No. 138,755

4 Claims.

This invention relates to electrical circuit breaker mechanisms, and is concerned more particularly with contacts for use in such apparatus, which are made of a novel composition and give better results for specific purposes than contacts of the materials heretofore available.

Contacts employed in electrical circuit breaker devices are made of various metals, alloys, or metallic compositions selected because of their physical and electrical characteristics. Among the desired characteristics are relatively high current carrying capacity, low contact resistance, and durability and resistance to mechanical wear, but in specific applications, certain characteristics may be so much more important than others as to determine the selection of the particular materials. Thus, in circuit breaker mechanisms operating on direct current, the current and voltage conditions in the circuit being so made and broken are frequently such that various contact materials suitable for other uses can not be employed because they have a tendency to build up and stick together. These changes in the contacts interfere with the proper operation of the mechanism and may require frequent repair or replacement of the contact members.

The tendency of contacts to build up and stick together in direct current apparatus is especially pronounced when both points are made of the same material as it is found that with similar contacts made of materials heretofore ordinarily used, such for example as fine silver, a high sharp local peak is produced on one point and a corresponding deep cavity or crater on the other.

When such a peak and crater are formed in an apparatus in which the points move together and apart with a shearing or rubbing action, as is frequently the case, the peak enters the crater and-the points interlock and stick even though there is no action comparable with welding.

The present invention is accordingly directed to the provision of a novel contact which may be used to great advantage in those forms of circuit breaker mechanism in which the tendency of the contacts to build up and stick together must be minimized, an example of such a contact being an automotive voltage regulator.

In my copending application, Serial Number 138,754 filed April 24, 1937, I have disclosed contact members made of a silver-manganese alloy which may be used advantageously in circuit breaker apparatus of the type referred to, and while those contacts are satisfactory in operation, the present high cost of silver renders their u use somewhat expensive.

I have found, however, that contacts giving equally good, and in some cases better, results may be made by adding a diluent to the silvermanganese alloy of the application mentioned. This diluent may be one or more of the members of the group made up of copper and cadmium, and the results obtained from its use depend on the nature and amount of the diluent present in the contact members. I

In general, a contact of the invention contains 0 silver ranging from about to about 97%, manganese ranging from about 2% to about 20%, and the remainder consisting of one or both members of the group above set forth. A preferred composition contains about silver, 15 about 5% to about 15% manganese, and the diluent forming the remainder, and a specific composition which has been found to give good results contains about 80% silver, about 10% manganese, and about 10%cadmium. The use .0 of cadmium in the diluent is highly desirable as this ingredient appears to have the characteristic of quenching arcing.

In making up a composition for use in the new contact, various factors are to be taken into 5 account. Thus, it may be said generally that an increase in the amount of manganese within the limits specified increases the antisticking properties of the contact and this is true, in general, of the amount of the diluent. Similarly, 30 an increase in the amount of diluent results in an increase in economy.

In the use of the diluent consisting of copper, cadmium, ora combination of both, total amounts up to about 23% may be employed and 5 the use of these materials in place of silver make available substantial economies without any important loss of the desired properties.

In all instances, the amount of manganese present should be not substantially less than 2%, 0 and an amount considerably in excess of that is preferred. Also, the new contact may be made of an alloy containing manganese in excess of 20%, but a manganese content exceeding 20% is not desirable. Similarly, the ranges of the 5 amounts of the members of the class of metals making up the diluent are not fixed but those given are the most desirable for ordinary purposes.

I claim: 60

1. A contact for electrical circuit breaker mechanisms composed of an alloy of silver in pre-' ponderating amount, manganese, and a diluent consisting of at least one member of the class made up of copper and cadmium.

2. A contact for electrical circuit breaker mecbaniamacompoaed oianalloyotlilverinan amount ranging from about 75% to about 95%, manganese in an amount ranging from about 2% to about 20%, and the remainder a diluent consisting of at least one member of the class made up oi copper and cadmium.

- 8. A contact for electrical circuit breaker mechanisms composed 01' an alloy of a prepondentin: amount oi silver. a less amount of man- :aneae, and a diluent consisting of at least one member of the class made up of copper and cadmium in an amount ranging from about 2% to about 23%.

4. A contact for electrical circuit breaker mechanisms, composed of about 80% silver, about 10% manganese. and about 10% cadmium.

CHESTER. PETERSON.