- Wire Wound Resistor Definition: A wire wound resistor is defined as a resistor made by winding a wire with high resistivity around an insulating core, used for precise and stable resistance.
- Need for Wire Wound Resistor: Wire wound resistors are necessary for applications requiring high power and stability, as they perform better than carbon resistors in these areas.
- Construction of Wire Wound Resistor: They are constructed using high resistivity materials like Constantan or manganin, often insulated for safety and accuracy.
- Applications: These resistors are used in high-power circuits and as variable resistors in devices like potentiometers and rheostats.
- Advantages and Disadvantages: They offer high power handling and thermal stability but are more expensive and larger than carbon resistors.
Wire has a specific resistance, which varies based on the material. The resistance depends on the wire’s length and material. These principles are key in making wire wound resistors.
Now, for metal or conductor the resistance directly proportional to the temperature, so when the temperature is increased, its resistance also increases. We do not want the resistance to be varying with the temperature and it is not possible to construct a material which has no variation with temperature. However, that can be minimized by the use of the material which has a low-temperature coefficient. For the construction of wire wound resistor, we generally use material which has high resistivity.
Need for Wire Wound Resistor
Carbon resistors are cheap and small, but they have a low power rating and are sensitive to temperature and noise. Wire wound resistor overcome these issues, though they are more expensive.
Construction of Wire Wound Resistor
Wire wound resistors are made from high-resistivity, low-temperature coefficient materials, often alloys like Constantan or manganin. Insulation ensures safety, and tinned alloy is used for terminals. Accuracy varies, with special alloys used for high accuracy and stability, achieving tolerances as low as ±0.0005%.
The wire wound resistor has a resistance which varies from 1 ohm to 1 Mega Ohm and power dissipation may vary from .5 watt to 250 watt. The tolerance level may be there from 5 % to 10 %.
Application of Wire Wound Resistor
The wire wound resistor has a very wide range of application, especially when we need variable or adjustable resistor, or if we need a fixed resistor which has to dissipate larger power, this may be used. We can construct variable resistor, such as potentiometers, rheostat.
Rheostat is a three terminal device which has two fixed contacts and one sliding contact which is used to adjust the resistance value. If we connect only two fixed point then rheostat acts as a potential divider. When all three are used, then it can vary the resistance with the help of a sliding contact.
In case of a potentiometer we have wires and a rotating shaft so that the resistance can be adjusted.
Advantages of Wire Wound Resistor
- It can be used in higher power circuits compared to carbon resistors.
- It is not that sensitive to noise compared to carbon resistor.
- It is thermally stable.
Disadvantages of Wire Wound Resistor
- It is costlier compared to carbon size
- It has large size
Conclusion of Wire Wound Resistor
It can be said that this resistance are costlier so they may be used wherever it is desired to use. These resistors cannot be used in electronic circuits also. But it is a very important type of resistor we have and mostly used in high power application whenever we cannot use carbon resistors and also they provide excellent thermal stability also.
