A Basic Guide to Wirewound Resistors
There are different types of power resistors that you can choose from in the market. If you are wondering about wirewound resistors, you should know that they are one of the oldest types of resistors that are used and sold in the market. All wirewound resistors are created similarly. Usually, a metallic wire is winded around the center of an insulating material. Though they are created similarly, each type of wirewound resistor has different applications. There are basically two kinds of wirewound resistors. These two are precision wirewound resistors and power wirewound resistors. All of them can be used for a wide array of applications. They can be used for current and temperature sensors.
The most common uses of precision wirewound resistors include measuring bridges and accurate calibration devices. Owing to the fact that these resistors are very accurate, their tolerance should only 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. With values such as 30 ppm, their stability is fairly good for twelve months of alteration and functioning at full power rating. This is the kind of wirewound resistor that you need if you will be requiring temperature increases below 30C. For this reason alone, these wirewound resistors are often coated with epoxy materials.
Power wirewound resistors are the second kind of wirewound resistor. 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. You can make use of silicone resins when you need to provide for the lowest dissipation ranges. These resistors are small and can endure temperature increases up to 300C above their normal levels. Another kind of power wirewound resistors is the one that has a porcelain enamel coat. 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. That is why this makes these resistors less common. This type of coating can operate at maximum temperatures of only 400 degrees. If you talk about their resistance values, they are within 0.1 and 10 kOhm.
Ceramic coating is another kind of power wirewound resistors. This is considered as the standard type of power wirewound resistors. From these resistors, you will see that they have a ceramic coating and core to provide wire protection. This coating boasts of its good insulation properties and effective energy dissipation. Moreover, you get good physical protection with it. Their power ratings range between 5 and 18 watts. Without any problem, this kind of resistor can warm up around three hundred degrees. Their resistance falls within the range of 10 and 20 kOhm.