Electronic measurement field, high resistanceresistanceAccurate measurement has always been a challenge. Due to the extremely large resistance value, problems such as instability and large fluctuations are prone to occur during measurement, which affects the reliability and accuracy of the test results. This article will focus on the problem of unstable high-resistance resistance measurements, analyze the main reasons, and propose corresponding solutions to help engineers and technicians improve the stability and accuracy of measurements.
1. Overview of unstable measurement of high-resistance resistorsHigh-resistance resistors generally refer to resistive components with resistances in the megohm level or higher, and are widely used in high-voltage circuits, electrostatic protection and precision instruments. Due to its extremely large resistance and extremely small current during measurement, it is easily interfered by various factors such as the environment, instrumentation, and operation, resulting in unstable measurement results. Understanding and mastering these influencing factors will help to take targeted measures to improve the reliability of measurement.
2. Impact of environmental factors on measurement stabilityAmbient humidity and temperature are the main environmental factors that affect the stability of high resistance resistance measurements. When the humidity is high, a thin water film may form on the surface of the resistance meter or the resistance being measured, causing the leakage current to increase and the measured value to be low and fluctuate significantly. Temperature changes will cause changes in the resistance of the resistor material itself, especially resistors with large temperature coefficients, making it difficult to maintain stable measurement results.
3. Test equipment and wiring issuesHigh resistance resistance measurement requires a high input impedance measuring instrument, otherwise the input impedance of the instrument itself will affect the measurement results. In addition, poor wiring, changes in contact resistance, and interference from test leads may cause unstable readings. Using a dedicated high resistance meter or a well-insulated test fixture to ensure firm wiring and avoid stray currents is an important step in ensuring stable measurement.
4. Improper selection of measurement methodsDifferent measurement methods have different adaptability to high resistance resistors. Due to the large current, the traditional direct ohmmeter measurement method may cause heating changes in the resistance, affecting the reading; while the static voltage method or the bridge method is more suitable for high resistance measurement. Choosing an appropriate measurement method and reasonably setting the measurement voltage and current can effectively reduce measurement errors and fluctuations.
5. Electrical interference and static electricity effectsWhen measuring high-resistance resistors, electromagnetic interference and electrostatic discharge in the environment can easily cause fluctuations in the measurement signal. Especially in laboratories or industrial sites, surrounding electrical equipment, wireless signals, etc. will interfere with measuring instruments. Taking shielding measures, using shielded wires and good grounding can significantly reduce interference and improve measurement stability.
6. Measurement time and stable waitingThe measurement of high-value resistors usually requires a certain amount of settling time, and capacitive effects in the circuit can cause initial fluctuations in readings. When measuring, you should wait enough time for the instrument and the resistance being measured to reach electrical balance before taking a reading. Reading data too early can lead to inaccuracies and instability.
7. The quality of the resistor being measured itselfSome high-resistance resistors have internal impurities or tiny cracks due to manufacturing processes or aging problems, resulting in unstable resistance values. Long-term use or moisture will also affect its performance. Pre-checking the resistance being measured to ensure its quality and stable performance is a prerequisite for accurate measurement.
Unstable measurement of high-resistance resistors is a comprehensive technical problem involving many factors including environmental conditions, test instruments, measurement methods, and components under test. By controlling the ambient humidity and temperature, using high input impedance instruments, rationally selecting measurement methods, reducing electromagnetic interference, extending the measurement waiting time, and ensuring the quality of the measured resistance, the stability and accuracy of the measurement can be effectively improved. Mastering these key points will help engineers obtain more reliable high-resistance resistance measurement results in actual work.
