The resistance coils in D.C. motor starters are wound using wire made of_______________?
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Answer: C. manganin
Explanation
Manganin has an extremely low temperature coefficient of resistance and high thermoelectric stability. These unique physical properties make manganin ideal for winding precision resistors and D.C. motor starter coils. Using manganin ensures that starter resistance values remain stable despite self-heating during motor acceleration. Manganin is a copper-manganese-nickel alloy specifically engineered for exceptional electrical resistance stability. Low temperature coefficient of resistance means electrical resistance changes negligibly with temperature fluctuations. D.C. motor starters require robust resistance coils to limit high starting currents safely during initial startup.
Industrial motor control systems rely on stable starter resistors to prevent damaging overcurrent conditions in DC motors. Electrical instrumentation manufacturers use manganin wire for precision shunt resistors and calibration standards. Engineers select resistance alloys carefully to ensure reliable equipment performance in varying thermal environments. Copper possesses a high temperature coefficient of resistance and low resistivity, making it unsuitable for starter resistance coils. Kanthal is an iron-chromium-aluminium alloy typically utilized in high-temperature industrial heating furnaces rather than motor starters. Nichrome is commonly used for heating elements rather than precision motor starter resistance coils.
- Subject
- Engineering
- Category
- Electrical Engineering
- Topic
- —
- Difficulty
- medium
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