Key technical specifications for measuring instruments include accuracy, sensitivity, and response time. Accuracy indicates the degree of agreement between the instrument's measurement result and the true value of the quantity being measured. Instrument accuracy is commonly expressed via accuracy classes-such as Class 0.1, 0.2, 0.5, 1.0, or 1.5-where, for instance, a Class 0.1 instrument has a total error not exceeding ±1.0%. A lower accuracy class number indicates smaller systematic and random errors, signifying higher precision.
Sensitivity is defined as the ratio of the change in the instrument's indicated value to the corresponding small increment in the measured quantity; it reflects the instrument's ability to detect the smallest measurable change. Response time refers to the interval required for the output to reach its final steady-state value for the first time following a step input; this is typically measured as the time taken to reach 95% of the steady-state value. Other performance specifications include repeatability, linearity, hysteresis, dead zone, and drift.
