Power resistors are resistor devices that can withstand high power, and they come in various types. The following provides a detailed introduction from different dimensions:
Classified by materials and processes
Wire wound power resistor
Production method: It is made by winding a resistance wire (usually made of nickel chromium alloy or manganese copper alloy) around a ceramic, plastic or glass fiber core, with metal caps and leads connected at both ends of the winding for circuit connection, and the winding coated with non-conductive plastic or enamel coating to protect the resistor.
Types: There are three types: spiral winding, double wire winding, and edge winding. Spiral winding is easy to manufacture but has inductive inductance; Double wire winding can offset the total inductance caused by the winding; Edge windings usually do not have magnetic cores and have air cooling devices.
Features: Known for high precision and stability, some can withstand temperatures up to 450 ° C. Wide power range, typical spiral wound power resistors can be used for power dissipation up to 50W, and edge wound resistors can be used for power dissipation up to 3.5kW. But it is bulky, has inductors, is not suitable for high-frequency applications (usually not used in circuits with signal frequencies higher than 50KHz), and has poor reliability and uneven quality.
Application: Suitable for high-power, high-precision application scenarios, such as industrial equipment that requires high current stability.
Membrane power resistor
Production method: It mainly refers to the planar power resistor of thick film technology, usually made by printing thick film resistor paste on aluminum oxide or aluminum nitride substrate.
Type: There are mainly thin film and thick film SMD resistors, and the resistance materials used in construction can be carbon, metal, metal oxide, metal ceramic, or metal foil.
Features: High power density, no inductance or capacitance, very suitable for use in situations with limited space but good heat dissipation conditions. The resistance range is wide, ranging from milliohms to megaohms. However, the overload capacity is limited and it is prone to damage in high-energy pulse applications such as discharge circuits, resulting in low reliability; And the requirements for heat dissipation conditions are very high, and suitable heat sinks must be added to achieve the rated power.
Power resistors are resistor devices that can withstand high power, and they come in various types. The following provides a detailed introduction from different dimensions:
Power resistors are resistor devices that can withstand high power, and they come in various types. The following provides a detailed introduction from different dimensions:
Application: Commonly used in electronic devices with high space requirements and certain power demands, such as specific circuits in computers and servers.
Solid ceramic resistor
Production method: After mixing powdered resistor materials, they are formed, sintered at high temperature, treated with electrodes, and finally packaged and tested.
Characteristics: The biggest difference between it and wire wound resistors and film type planar power resistors is that it conducts electricity throughout the body, so it can withstand high-energy and high pulse impacts, making it very suitable for energy discharge, such as capacitor charging and discharging. No sensitivity, extremely high reliability. According to different applications, it can be divided into two types: power type and pulse type.
Application: Suitable for scenarios that require withstanding high-energy pulses, such as battery pack pre charging, capacitor charging and discharging, starting current limiting, arc protection, and other applications.
Cement resistance
Production method: Wrap nickel chromium resistance wire or constantan resistance wire around heat-resistant ceramic material, and then package it with special heat-resistant material.
Characteristics: High power, generally capable of producing tens or even tens of watts. For example, the RX27-3 model has a power range of around 5-15 watts, while the RX27-4 model has a power range of around 10-40 watts. Good heat resistance, excellent moisture resistance and heat dissipation, and relatively affordable price.
Application: Widely used in power adapters for laptops, switch mode power supplies for desktop computers, power amplifiers, industrial instruments, and many other electronic products.
Aluminum shell resistor
Production method: The outer surface is encapsulated with aluminum alloy or gold aluminum shell, with grooves on the aluminum shell to increase heat dissipation performance.
Features: relatively small size, good heat resistance, high power, high precision. But the cost is relatively high, and the price is also high. The highest power can reach over 200 watts.
Application: Commonly used in circuits such as power supplies, frequency converters, and motor control.
Grid resistance
Production method: Constructed by assembling a matrix of resistive metal strips between two electrodes.
Characteristics: It is a bulky resistor with a rated current of up to 500A, only used for guiding heat dissipation in railway vehicle braking or for harmonic filtering in substations.
Application: Mainly used in railway vehicle braking systems and substations that require handling high currents.
water resistance
Production method: Made from a tube filled with salt water or copper sulfate solution, the tube is connected between two electrodes.
Characteristic: As water is a good conductor of electricity, it can be used as a resistive material by changing the concentration of appropriate salts in water. Water is also a good conductor of heat, which gives water resistors high thermal conductivity and high power dissipation capability. High power waterproof resistors use copper sulfate solution instead of salt solution.
Application: Used in electrical applications that require typical power consumption exceeding 500mW, it will not dissipate rated power instantly, but will dissipate a large amount of power (heat) within a specified time period.
liquid rheostat
Manufacturing method: It is a variable water resistor constructed by immersing the electrode in a salt solution, which can change the position of the electrode to alter the effective resistance.
Features: It has a variable resistance value and can adjust the resistance size according to demand.
Application: Still used in some generators to regulate the resistance in circuits.
Classified by power level
Low power resistor: usually refers to a resistor with a withstand power of less than 1/4 watt, mainly used in low-power electronic products such as calculators, remote controls, etc. Its size is usually small and its price is relatively low.
Medium power resistor: refers to a resistor that can withstand power between 1/4 watt and 5 watts, mainly used for applications that require high power, such as household appliances, automotive electronics, audio equipment, etc. The volume of medium power resistors is relatively large, and their price will also be relatively high.
High power resistor: capable of withstanding power above 5 watts, usually used in high-power equipment or some environments that require high temperature resistance, such as engine control, aerospace and other fields. The size of high-power resistors is relatively large and the price is also expensive.
Classified by structure
Alloy type resistor: a resistor made by pulling or rolling block shaped resistance alloy into resistance alloy wire or resistance alloy foil, including wire wound power resistors made of alloy wire and block metal film resistors made of alloy foil, with excellent functions of block metal.
Thin film resistor: made by depositing a layer of resistive film on a glass or ceramic substrate using different processing methods, with a thickness ranging from tens of angstroms to several micrometers, including thermally differentiated carbon film, metal film, metal oxide film, and other types.
Synthetic resistor: The resistor is a mechanical mixture of conductive particles and organic (or inorganic) adhesives, which can be made into thin films and solid cores, such as forming carbon films, forming solid cores, and metal glass glaze resistors.
Function
Power circuit: It can be used for current limitation, voltage stability, and power overload protection in power circuits.
Industrial control: used for current limiting, voltage stabilization, and preventing electrical overheating in industrial control.
Communication equipment: used for current limiting and preventing electrical overheating in communication devices.
Household appliances: used for current limiting, voltage stabilization, preventing overheating, and extending the service life of household appliances.