What is a Wire Wound Resistor : Types and Applications

The first type of resistor was a wire wound resistor. Over the years, the structure of this resistor has changed. We know that the carbon resistor is very small in size as well as inexpensive but why we use these types of resistors also?? Because the carbon type resistor includes a small amount of power rating, sensitive to temperature differences, not reliable, extremely responsive to noise whereas in wire wound, the disadvantages of carbon type resistor can be reduced but it expensive when compared with carbon type. This article discusses an overview of the wire-wound resistor.

What is a Wire Wound Resistor?

Definition: A resistor that is designed using a conductive wire to limit or restrict the flow of current within a circuit. The designing of this resistor can be done using a conductive wire by wounding around a non-conductive core. Generally, the material of the wire can be made with like Nichrome (Nickel-chromium alloy) or Manganin (copper-nickel-manganese alloy). These resistors generate very accurately, excellent properties for high power ratings & low resistance values. These resistors are used in industrial and high-power applications like fuses, circuit breakers. The wire-wound resistor symbol is similar to a normal resistor.

Construction of Wire Wound Resistor

The wire-wound resistor diagram is shown below. It is designed with the material including low-temperature coefficient and high resistivity. The construction of any resistor can be done by using alloys like manganin or constantan. The two terminals of the resistor are fabricated with tinned alloy. The construction of the resistor changes based on the accuracy needed, however for the highly accurate system design, the resistor cost will be increased.

The resistance of this resistor changes from 1ohm-1Mega Ohm as well as power dissipation can change from 5- 250 watt. The range of tolerance may range from 5% to -10 %.

This resistor can be designed by winding the metal wire in the region of a metal core. In this resistor, metal wire can be used as the resistance element whereas the metal core is used as the non-conductive material

The wire wounded around the resistor can be enclosed with an insulating material like vitreous enamel to block or oppose the exterior heat.

These resistors range from small to a large tubular power resistor and they are used within the electronic equipment & instruments wherever power dissipation & accuracy are more required. This resistor is more prefer compare with the metal oxide resistors due to its features like smaller size & high stability.

Types of Wire Wound Resistors

These resistors are classified into two types based on their construction and application like the following.

Power Type Resistor

These kinds of resistors are the non-inductive type and they function at high temperatures. The applications of these resistors mainly include in high power applications.

Precision Type Resistor

These kinds of resistors work with high accuracy by using a low temperature and are used in instrumentation due to its high accuracy.

Properties

These resistors are applicable in a wide range of areas due to their properties like the following.

• High power applications
• Fewer noise applications
• Extremely high tolerance applications
• Where customized requirements are needed
• Capability to absorb pulses
• High-temperature strength is needed
• Lasting stability

The Resistance of the Wire Wound Resistor

The resistance of this resistor mainly depends on three factors like

• The resistivity of the metal wire,
• Length of the metal wire
• The cross-sectional area of the metal wire

The Resistivity of the Metal Wire

The metal wire’s resistivity and the resistance of the resistor are directly proportional. If a metal wire has high resistance then it opposes huge electric current. Thus, the wire gives high resistance to the electric current. In contrast, a metal wire including less resistance can block less quantity of electric current. Thus, this resistor supplies less resistance for the electric current.

Length of the Metal Wire

The resistance of the wire-wound resistor is directly proportional to the length of the metal wire. If the length of the wire is long, then the resistance will be high due to the electrons flow up to the large distance. Therefore, the possibility of collision of electrons with the atoms is high so they lose their energy in the heat form. Thus, a small amount of energy will flow through the resistor.

Cross-Sectional Area of the Metal Wire

The resistor and cross-sectional area of the metal wire are inversely proportional. If the metal wire has a small cross-sectional area provides less space for the electrons flow. So there is a high chance of electrons collision through the atoms. So, a small amount of electric current will supply through the resistor.

Similarly, if the metal wire has a small cross-sectional area, then they provide enough space for the electrons flow. So there is a low chance of electrons collision through the atoms. So, a large amount of electric current will supply through the resistor.

Advantages of Wire Wound Resistor

The advantages are

• This resistor is employed in high power circuits
• It will not affect by the noise
• It is thermally constant.

Disadvantages of Wire Wound Resistor

The disadvantages are

• These resistors are used for only low frequencies because it works as an inductor at high frequencies
• Therefore, non-inductive type resistors are used for high frequencies.
• It is expensive as compared with carbon size resistor
• It is larger in size

Applications

The applications of the wire-wound resistors include the following.

• Space and defense
• Transducer devices
• Medical devices
• Audio devices
• Video devices
• Balancing of voltage & current
• Computers
• Telecommunication
• Current sensing
• Telephone switching systems

FAQs

1). What is the use of a wire-wound resistor?

The main use of this resistor is where a huge amount of power needs to be dissipated.

2). What are the types of the wire-wound resistor?

They are precision and power.

3). What are the properties of the wire-wound resistor?

Extremely high tolerance, high power, the stability of high temperature, long term, etc.

Thus, this is all about an overview of wire wound resistor. These resistors are available in different packages and some of them are mostly applicable in power resistor applications. Some types of resistors are available in ceramic packages, whereas some others are obtainable in metallic packages. These can be bolted to other types of a heat sink or metallic chassis. Here is a question for you, what is the main function of a wire-wound resistor?