What is a wire-wound resistor?

2018-06-15 19:11:16 post by microhm


A wire wound resistor is a resistor where a wire with a high resistivity is wrapped around an insulating core to provide the resistance. It is an electrical passive component that limits current.

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Wire wound resistor are made by winding a wire around a core. The resistance value is dependent on the resistivity of the wire, the cross section and the length. The resistance value is measured to determine exactly the length of the wire. The wire material has a high resistivity, and is usually made of an alloy such as Nickel-chromium (Nichrome) or a copper-nickel-manganese alloy called Manganin. Silver alloys, iron chromium alloys and iron chromium aluminum alloys are also used.Common core materials include ceramic, plastic and glass.

For low power ratings, very thin wire is used. To create a high resistance, the wire diameter needs to be very small and the length very long. They are not only precision but also with high power rating for 50W or more. Compared to other resistor types like metal film, the wire diameter is relatively big and therefore more robust.

Wire wound resistors are the oldest type of resistors that are still manufactured today. They can be produced very accurate, and have excellent properties for low resistance values and high power ratings. But it has the worst high frequency properties of all the resistor type. Wire wound resistors can roughly be classified as precision and power. They are often used in circuit breakers or as fuses.

 


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TAG:   wirewound resistor electrical passive component