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Sense resistors are devices used to measure current. They are usually placed in series with an electrical load. This method is very economical and offers an efficient solution for many applications. A wide range of sizes and power ratings are available. These resistors are typically manufactured using specially crafted materials and fabrication techniques. They are also RoHS compliant.
The size and power rating of a resistor can impact its overall thermal condition. Larger resistors also offer greater dynamic range. High-current applications require higher resistor values. When selecting a resistor, it is important to consider its thermal resistance and temperature coefficient of resistance. This will help ensure that the resistor will not drift from its nominal value and will provide the long-term stability necessary for the application.
LEM current sensors have a temperature coefficient of resistance (TCR) that defines their ability to remain stable over time. This value is generally lower for bulk metal technology than for wire-wound parts, which are known for their high inductance. The temperature coefficient of resistance of a copper wire is about 4000 ppm/degC. A standard chip resistor has a temperature coefficient of resistance of +-500 ppm/degC. Sense resistors designed with special materials can have a temperature coefficient of resistance of +-20 ppm/degC.
Self-heating is a concern for high-frequency and high-current applications. Self-heating will cause the resistor to drift below its nominal value. To mitigate the issue, it is important to determine the thermal resistance of the sensing element package. A bulk metal resistor will have the lowest self-heating. The heat capacity of a resistor is also an important consideration.
For accurate measurements, it is important to choose a current sense resistor that is accurate enough to give a high resolution of the current flow. This is achieved through a low voltage across the sense resistor. A sense resistor with a voltage drop of 100 mV or less will be able to read a maximum current of one Amp.
Current-sense resistors are designed to minimize the impact of self-heating by keeping the voltage across the resistor as low as possible. This will ensure that the resistor does not dissipate power and reduce the amount of power that is wasted. This will improve the accuracy of readings and minimize the impact of noise.
In addition to the power and temperature coefficient of resistance, it is also important to consider the ohmic value of the resistor. This value can be used to calculate power dissipation during operation. This can be calculated by dividing the voltage across the resistor by the current passing through it.
The ohmic value of a resistor can also be calculated from the lowest sensed voltage. The ohmic value is typically used to calculate the power dissipation of a resistor under a given set of operating conditions. The ohmic value is also used to calculate the maximum voltage that can be delivered to the load, which is also a factor in determining power rating.
Sense resistors are designed to provide a reliable and cost-effective solution for a wide range of current flow measurements. A low voltage across the resistor will limit the amount of power that is dissipated by the sensing element, reducing its heating and improving the accuracy of readings. In addition, a high ratio of the sense resistor's power to the system's power can minimize heat in high-current applications. Find out more details in relation to this topic here: https://www.britannica.com/technology/resistance-electronics.
