A Basic Guide to Wirewound Resistors
The current market is rich in power resistors for your choosing. Wirewound resistors are among the oldest types of resistors but are still used in the current market. All wirewound resistors are created similarly. To create this resistor, you require an insulating material and wind a metallic wire around its core. Despite the fact that they are created in the same manner, you can expect variations in the application of the different types of resistors. Wirewound resistors can be classified into two accordingly. You have precision wirewound resistors and power wirewound resistors. The applications for these wirewound resistors are many. Some of the most common applications to them include the use in current and temperature sensors.
The most common uses of precision wirewound resistors include measuring bridges and accurate calibration devices. Since these resistors are very accurate, their tolerance levels should be under one-tenth percent. In terms of temperature coefficient, precision wirewound resistors are better with 5 ppm/C than with most metal film resistors with 25 ppm/C. Their stability is fairly good where their values of 30 ppm alterations function at full power rating for twelve months. If you require a resistor for temperature increases below 30C, then this is the kind of resistor for you. When you look at these wirewound resistors, they are coated by epoxy materials for this reason alone.
For the other type of wirewound resistor, you call them power wirewound resistors. Their power range is between 0.5 watts to 1000 watts. If you want to break down these power resistors by kind, you have to do so according to their coating type. When the lowest dissipation ranges, you have to go with silicone resins. These resistors are small and can endure temperature increases up to 300C above their normal levels. A porcelain enamel coat is another kind of coating for power wirewound resistors. This kind of coating is widely used for providing good insulation properties at low temperatures. You can expect the insulation to be less when the temperature goes up. This is why they are not so common in terms of power resistors. 400 degrees is basically the maximum operating temperature for this type of coating. Their resistance values range between 0.1 and 10 kOhm.
You have another coating type for power wirewound resistors, and they are ceramic coating. This is considered as the standard type of power wirewound resistors. To protect the wire, they come with a ceramic coating and core. When it comes to this coating, it can maintain good insulation properties while ensuring to have effective energy dissipation. In addition, it also offers good physical protection. You have a power rating from 5 to 18 watts for this kind of resistor. Even while warming up around three hundred degrees, this resistor will not have any problems at this range. Speaking of resistance, the range is from 10 to 20 kOhm.