Alloys for resistance coils and measuring instruments. Scheme, description

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Conductor materials. Alloys for resistance coils and measuring instruments. Encyclopedia of radio electronics and electrical engineering

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The main and best representative of these alloys is copper-manganese alloy - manganin.

Manganin It is distinguished by high resistivity at a low temperature coefficient of resistance, low thermoelectric power in a pair with copper, high stability of resistance over time, high ductility and corrosion resistance. It is applied to production of exact exemplary resistances.

In order to maintain the constancy of the properties of the resistances, their operating temperature should not exceed 60 °C. For the stability of the properties of manganin over time, it is subjected to a special low-temperature heat treatment followed by long-term storage at room temperature; Manganin is produced in the form of wire and tape.

Less precision alloy than manganin is copper-nickel alloy - constantan, which is characterized by a very low temperature coefficient of resistance, corrosion resistance, satisfactory heat resistance and high mechanical properties.

The disadvantage of constantan when used for the manufacture of exemplary resistances is the high thermoEMF in a pair with copper, and therefore it has found wide application in the manufacture of thermocouples for measuring temperatures up to 900 °C.

For the manufacture of rheostats and other electrical devices, an alloy containing copper, nickel and zinc is sometimes used - nickel silver. This alloy is cheaper than constantan, however, due to the content of zinc, nickel silver wire becomes brittle after heating it to 200-250 ° C.

Author: Koryakin-Chernyak S.L.

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