Process Controls RESET (INTEGRAL) CONTROL SYSTEMSThe positive 0.5% per second indicates that the controller output increases from its initial pointof 50% at 0.5% per second. This causes the control valve to open further at a rate of 0.5% persecond, increasing flow.Figure 21 Reset Controller ResponseThe controller acts to return the process to the setpoints. This is accomplished by therepositioning of the control valve. As the controller causes the control valve to reposition, themeasured variable moves closer to the setpoint, and a new error signal is produced. The cyclerepeats itself until no error exists.The integral controller responds to both the amplitude and the time duration of the error signal.Some error signals that are large or exist for a long period of time can cause the final controlelement to reach its "fully open" or "fully shut" position before the error is reduced to zero. Ifthis occurs, the final control element remains at the extreme position, and the error must bereduced by other means in the actual operation of the process system.Rev. 0 Page 31 IC-07
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