Characteristic curve deviation

The characteristic curve of a measuring instrument is the graphical representation of the relation between the physical value being measured, e.g. pressure, and the resulting electrical value. Ideally, the characteristic curve would be linear. The characteristic curve deviation, usually specified at room temperature, indicates the precision of a measuring instrument. Small characteristic curve deviation implies high precision of the instrument. When measuring pressure, thermal drift must also be accounted for in addition to the characteristic curve deviation. It is caused by changes in the temperature of the medium.

External influences affect the measuring instrument. For this reason, the characteristic curve does not remain constant over years of use. The long-term stability (also long-term drift) is determined by manufacturers under laboratory conditions and listed in data sheets as a percentage of full scale per annum.