1. Application errors in load cells are caused by operators and stem from various sources. Examples include errors arising from temperature variations, incorrect probe placement, or improper insulation between the probe and the measurement point. Other application errors may occur during the purification of air or other gases, or result from incorrect transmitter positioning, where positive or negative pressure affects reading accuracy.
2. Characteristic errors are inherent to the device itself, representing the difference between the device's recognized transfer function characteristics and its actual performance. Such errors include DC drift, slope inaccuracies, or slope non-linearity.
3. Dynamic errors arise because the characteristics and calibration of many sensors are based on static conditions-meaning the input parameters are static or quasi-static. Many sensors possess significant damping, preventing rapid responses to changes in input parameters; for instance, a thermistor requires several seconds to respond to a step change in temperature.
4. A thermistor does not instantly jump to a new impedance value or undergo an abrupt change; instead, it transitions gradually to the new value. Consequently, if a load cell with such lag characteristics responds to rapid temperature changes, the output waveform becomes distorted due to the inclusion of dynamic errors. Factors contributing to dynamic errors include response time, amplitude distortion, and phase distortion.
5. Insertion errors occur when a sensor is introduced into a system, thereby altering the measured parameters. While common in electronic measurements, similar issues arise in other measurement methods. For example, when a voltmeter measures voltage in a circuit, its inherent impedance-even if significantly higher than the circuit impedance-may still load the circuit, leading to substantial reading errors. Such errors may be caused by using a transmitter that is too large for the system (e.g., a pressure system), the system's dynamic response being too slow, or excessive thermal energy loading caused by self-heating.
6. Environmental errors stem from the operating environment of the load cell. Factors include temperature, oscillation, vibration, altitude, chemical vapors, and other elements that often affect the sensor's characteristics; consequently, in practical applications, these factors are typically grouped together.