Temperature coefficient: The amount of drift, in percent of full scale output, that might result from a 1°C change in ambient temperature.
Thermal shock: An abrupt temperature change applied to a device.
Time constant: The value “T” in an exponential term A(-t/T). For the output of a first-order system forced by a step or an impulse, T is the time required to complete 63.2% of the total rise or decay. For higher order systems, there is a time constant for each of the first-order components of the process.
Transducer: An element or device that receives information in the form of one quantity and converts it to information in the same or another quantity or form. Primary elements and transmitters are also referred to as transducers.
Transfer function: Mathematical, graphical, or tabular statement of the influence which a system or element has on a signal or action compared at input and at output terminals.
Transient: The behavior of a variable during transition between two steady-states.
Transmitter: A transducer which responds to a measured variable by means of a sensing element, and converts it to a standardized transmission signal which is a function only of the values of the measured variable.
Upper range limit (URL): The highest value of a measured variable that a device can be adjusted to measure. (This value corresponds to the top of the range.)
Upper range value (URV): The highest value of a measured variable that a device is adjusted to measure. (This value corresponds to the top of the span.)
Vapor pressure: The pressure exerted by a vapor which is in equilibrium with its own liquid.
Variable: Any condition that is measured, controlled (directly or indirectly) or manipulated.
Velocity limit: A limit on the rate of change which a particular variable may not exceed.
Vibration: The periodic motion or oscillation of an element, device, or system.
Volt (V): The electrical potential difference between two points in a circuit. One volt is the potential needed to move one coulomb of charge between two points while using one joule of energy.
Warm-up period: The time required after energizing a device before its rated performance characteristics start to apply.
Zero offset: The non-zero output of an instrument, expressed in units of measure, under conditions of true zero.
Zero suppression: For a suppressed-zero range, the amount by which a measured variable’s zero is less than the lower-range value; can be expressed as a percentage of either the measured variable or of the span.
Zone, neutral: A predetermined range of input values that do not result in a change in the previously existing output value.