A Basic Guide to Wirewound Resistors
The current market is rich in power resistors for your choosing. 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. The construction of all kinds of wirewound resistors is more or less the same. Around the core of an insulating material, a metallic wire will then be winded. Despite the fact that they are created in the same manner, you can expect variations in the application of the different types of resistors. There are basically two kinds of wirewound resistors. You have precision wirewound resistors and power wirewound resistors. All of them can be used for a wide array of applications. 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. Owing to the fact that these resistors are very accurate, their tolerance should only be under one-tenth percent. Unlike most metal film resistors that have a 25 ppm/C temperature coefficient, precision wirewound resistors have a 5 ppm/C temperature coefficient, which is better. In terms of stability, these wirewound resistors are fairly good with values like 30 ppm alternating for twelve months upon functioning with the use of full power. This type of wirewound resistor is often made for temperature increases that is just below 30C. Epoxy materials are often used as coating because of this reason.
Another kind of wirewound resistor is the power wirewound resistors. These wirewound resistors have a power range between 0.5 watts and 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. They are known for being small resistors and can withstand temperature increases to a maximum of 300C above normal levels. A porcelain enamel coat is another kind of coating for power wirewound resistors. This is a coating type that provides good insulation properties when there are low temperatures. If the temperature goes up, the insulation will considerably be less. This is one of the reasons why this kind of resistor is 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.
Another coating type for power wirewound resistors is ceramic coating. This is the standard type of power wirewound resistor that is used. 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. Furthermore, its physical protection is also good. The power rating for this resistor is between 5 and 18 watts. Even while warming up around three hundred degrees, this resistor will not have any problems at this range. Their resistance falls within the range of 10 and 20 kOhm.