There are two types of performance characteristics of measuring instruments which are: Static characteristics and Dynamic characteristics. First, let’s discuss static characteristics, these set of characteristics used to measure quantities which slowly vary with time or mostly constant with time.
Now, let’s discuss individual characteristics in detail.
- Accuracy: It is the degree of closeness of readings from an instrument to the true value. Always accuracy is measured relative to the true value or actual value.
- Sensitivity: It refers to the least change in measured value to which instrument or device responds. The ratio of change in the output of an instrument to a change in the value of the quantity to be measured is known as sensitivity.
- Precision: It is the degree of closeness of reading with the previous reading. An instrument is said to be precise when there is negligible difference between successive readings.
- Linearity: The linearity is defined as the ability to give the input characteristics symmetrically and linearly (Straight line). In other words, the ability to measure maximum deviation from the ideal linear line. Instruments are said to be linear when there is an increment in input and output are constant over the specified range.
- Resolution: It refers to a small change in input value does not affect the output value of an instrument. This continues until both the increment value and output value exceed the threshold value. This increment is called a resolution.
- Repeatability: It defines how consistent is the output of an instrument for the same input tried again and again under the same conditions.
- Range: The left extreme and right extreme values of a quantity for which the instrument is designed to function. The range is equal to Maximum value minus minimum value.
- Tolerance: It is the highest allowable error that is specified in terms of certain values while measurement, it is called tolerance.
- Hysteresis: It is defined as an instrument showing different output values during loading and unloading conditions.