Time Constant: Same as lag time.

Time Response: How the output of a system varies with time (not very exciting if there hasn't been a change in the system input!).

Tracking: When a controller changes a process variable to move the process variable in response to a setpoint change, it is called tracking.

Transfer Function: A convenient way of representing a dynamic system. Rather than working with differential equations, which is difficult even for simple systems, they are converted into the Laplace domain (also called s-domain, since the equations are transformed from written in t (time) to s, which is related to frequency) using a Laplace Transform. This turns the difficult to analyse integration and differentiation functions into multiply and divide functions, making system analysis very much simpler. A transfer function is the ratio of output signal to input signal, so that the output of a system can be calculated by multiplying the input signal by the transfer function. A transfer function usually has numerator and denominator polynomials in powers of s, with the numerator polynomial being of an equal or lower order than the denominator. A discrete time transfer function can also be derived, but this is based on the Z-Transform and is written in powers of z.

Transport Delay: This term is often used instead of dead time.

Tuning: The procedure of setting the controller gains to correctly work with a certain process.

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All of the information in this glossary has been carefully compiled and we believe it to be accurate. However, since any such definitions need to be placed in the context of specific applications, we assume no liability for the usage of information contained in this glossary.

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