Response time of SMART trasmitter = dead time + time constant. Another parameter called Damping is closely related to response time. What is the relation between response time & damping in SMART transmitters? Is there any mathematical relation?
Hello avik_ic,
The more a transmitter is damped, the slower the transmitter's response time. In some applications, pumps or other process noise must be 'damped out' to get good control or indication. Damping is the ability of an instrument to prevent rapid or excessive corrections in response to process noise that may result in measurement instability or oscillation. Regarding your question of an equation - here is an example:
Damping may be “adjustable between 0.2 and 255seconds.” In other words, the transmitter can be set to respondto changes in the process (i.e., reflect a change in output) every0.2 seconds, every 255 seconds, or at any interval in between.Figure 5.6 shows the time required to change a transmitter’soutput reading with 5-second damping. The time before theoutput starts to change is called dead time. After the first5-second interval, 63.2% of the process variable’s true value isreflected in the transmitter’s output. This time interval is calledthe time constant (the time required [after dead time] for theoutput to reach 63.2% of the input’s true value). After 25seconds, almost 100% of the process variable’s true value isregistered in the output. The dead time plus one time constantequals total response time.
Hope that answers your question
Regards,
Caitlin