During the measurement of resistors, environmental conditions are critical to obtaining accurate results. The ideal ambient temperature is set to 25±2°C or 23±2°C because small changes in temperature can have a significant impact on the resistance value. In addition, humidity control cannot be ignored, especially when testing high-value resistors. In practice, the humidity of the test environment should be controlled below 50%, and when storing resistors, the relative humidity should be kept below 80%. These conditions are strictly controlled to avoid adverse effects of humidity on resistor performance, thus ensuring the accuracy of measurement results and the long-term stability of the resistor.
Critical requirements for test instrument accuracy
The accuracy of the test instrument is critical to ensuring the reliability of resistance measurements. According to industry standards, the accuracy of the test instrument should be at least one-tenth the accuracy of the resistor under test. For example, if a resistor has an accuracy of ±1%, the test instrument used must have an accuracy of ±0.1% or better. For those resistors with resistance accuracy as high as ±0.1%, the accuracy requirements of the test instrument are more stringent, and should reach one-quarter of the resistor accuracy, that is, no less than ±0.025%. When measuring the DC resistance of high-precision alloy foil resistors, it is recommended to use a digital meter with at least 7½ digits and use the four-terminal measurement method. This method can effectively reduce measurement errors and ensure high accuracy of measurement results.
Technical details when measuring resistors
Resistor measurements also need to consider the test voltage and test duration. In order to maintain the sensitivity of the test while avoiding possible damage or reading errors, the test voltage should be kept as low as possible and the test time should be as short as possible. Especially when measuring high-resistance resistors, the influence of the surrounding electromagnetic field is a factor that cannot be ignored. To this end, the support frame in the test fixture must have good insulation and shielding properties to isolate external electromagnetic interference. In addition, the grounding of test instruments also requires special attention to ensure the stability and reliability of the measurement process.
For the measurement of low-resistance resistors, the four-terminal measurement method has become a must-have. This method can effectively reduce the measurement error caused by the resistance of the test line by connecting the current and voltage leads to both ends of the resistor respectively, thus providing more accurate measurement results. The adoption of this method further reflects the extremely high accuracy requirements in resistor measurement work and the professional measures taken to ensure the accuracy of measurement results.