HART VPT10-H, Руководство по установке, эксплуатации, настройке и обслуживанию, Страница: 22 / 40

VPT10-H HART
®
PRESSURE TRANSMITTER INSTALLATION, OPERATION, CONFIGURATION AND MAINTENANCE MANUAL
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Damping
It is an electronic pressure reading filter that changes the response time of the transmitter to smooth the variations in
the output readings caused by rapid variations in the input. The damping value can be set between 0 and 60 seconds
and its appropriate value should be based on process response time, output signal stability and other system
requirements.
Damping default value is 0.4 s.
The value chosen for damping affects the response time of the transmitter. When this value is set to zero, the damping
function will be disabled and the output of the transmitter will react immediately to changes in its input, so the response
time will be as short as possible.
Increasing the damping value leads to an increase in the transmitter response time. At the time the damping time
constant is set, the transmitter output will go to 63% of the input change value and the transmitter will continue to
approach the input value according to the damping equation.
Flow Measurement
VPT10-H can calculate mass or volumetric flow. For flow measurement, user must configure the Transfer Function for
Square Root Extraction (or Table + Square Root Extraction) and the Flow Unit to be used, according to the process.
According to Figure 3.10, note that there is a zero cutoff point that can be configured by the user through the Square
Root Cutoff parameter. This value refers to the Percent Pressure that will be converted to flow.
For example, if Square Root Cutoff is set to 1%, the flow values will only be different than zero when above 10%
(according to the equation in the graph below).
Figure 3.10 – Flow and square root cutoff measurement.
Once the transfer function has been defined according to the application, user can choose the output unit, with which
the pressure or flow value will be made available to the system.