1. Significant Deviation in Measurement Data: When the sensor's output value is significantly inconsistent with the actual physical quantity (such as temperature, pressure, etc.), and the deviation exceeds the allowable range, calibration is usually required. For example, a temperature sensor reading may be fixed, fluctuate abnormally, or deviate excessively from the actual temperature. This deviation may be due to sensor aging, environmental factors, or mechanical stress.
2. System Malfunction or Alarm: If the system associated with the sensor (such as industrial equipment or automotive control systems) triggers fault codes, alarms, or experiences performance degradation (such as equipment overheating or control failure) due to abnormal data, it may be a signal that the sensor is uncalibrated or damaged. For example, an air conditioner may fail to adjust the temperature correctly due to a faulty temperature sensor.
3. Physical Damage or Environmental Changes: If a sensor suffers physical damage (such as a cracked housing or corroded connecting wires) or is exposed to extreme environments (high temperature, high humidity, vibration) for a long period, its performance may degrade, requiring calibration to restore accuracy. Furthermore, mechanically assembled sensitive sensors (such as Hall effect sensors) must be calibrated after installation to avoid data deviations caused by assembly errors.
4. Regular Maintenance or Industry Standard Requirements
According to industry standards (such as ISO 9001, IEC 61508), sensors require regular calibration to ensure data accuracy and system reliability. Even without obvious faults, calibration should be performed as scheduled, especially in high-safety-requirement fields (such as oil drilling and aerospace).
5. After Repair or Replacement
After repair or replacement, the internal parameters of a sensor may change, necessitating recalibration to verify performance compliance. For example, a repaired pressure sensor needs to have its output signal compared with standard equipment to ensure that sensitivity, linearity, and other indicators meet requirements.
Calibration Method Reference
Calibration typically requires applying a known input quantity to the sensor using standard instruments (such as a constant temperature chamber or pressure testing machine), comparing the output signal with standard values, and generating calibration curves or data. Dynamic calibration also requires testing frequency response and stability.
