Weight and Force Measurement Terminology
Understanding the fundamental terms used in industrial weighing and force measurement systems is critical for defining measurement accuracy and system performance. Below are the basic definitions in accordance with OIML (International Organization of Legal Metrology) standards.
Load Cell Terms
Maximum Capacity (Emax)
The maximum load value that the load cell is designed to measure while remaining within specified error limits. In system design, this value should be calculated with a 20-50% safety margin.
Sensitivity (Rated Output)
The output signal per unit of excitation voltage measured at maximum capacity. It is typically expressed in mV/V (millivolts per volt). Standard values are 2mV/V or 3mV/V.
Vmin (Minimum Load Cell Verification Interval)
The smallest load value that can be distinguished by the load cell. It is calculated using the Emax / Y formula. A higher 'Y' value indicates higher resolution capabilities.
Creep
The change in output signal occurring over time while under a constant load. Typically measured over a 30-minute period. Low creep is essential for long-term static weighing applications.
Weighing System Terms
Division (d - Actual Scale Interval)
The value of the smallest weight difference visible on the digital display. For instance, if a scale increments as 0, 5, 10, 15g, the division is d=5g.
Verification Interval (e - Verification Scale Interval)
The value used for the classification of a scale (e.g., Class III) in legal metrology. Often configured as e=d or e=10d in commercial applications.
Zero Stability
The ability of the scale to maintain its zero point despite environmental factors (temperature, humidity) when no load is applied.
Hysteresis
The difference in output at the same load between increasing and decreasing directions (loading and unloading).
Stabilization Time
The time required for the display (or data) to become stable after a load is applied. In high-speed devices like the ZMA Series, this time is in the millisecond range.