Sterlco M2B, Руководство пользователя

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Appendix C
Control Modes:
On-Off:
Action takes place if any deviation from set point occurs. The output is either
full on or full off depending on the direction of deviation. Because the on-off
controller can cause rapid cycling around the set point, hysteresis (dead
band) is built in to suppress fast control action.
Temp
Proportional:
Referred to as “P” or GAIN.
The controller switches the output based on the difference between the set
point value and the process variable, and controls the output proportional
to the deviation. This proportional action is active within a zone around the
set point called the proportional band. The output becomes gradually
smaller as the process variable nears the set point. Note that the process
seldom reached the set point, but stabilizes at some deviation offset.
Temp
Integral:
Referred to as “I” or RESET.
Expressed by integral time in seconds, the purpose of the integral action is
to automatically compensate for any offset due to proportional action. The
integral moves or resets the proportional band up or down to obtain set
point. It is not intended to correct for process disturbances.
Temp
P.B. too small
TIME
S.P.
P.V.
TIME
P.B.
S.P.
P.V.
OFFSET
TIME
P.B.
S.P.
P.V.
OFFSET
PB SHIFTED UP