69
Integral Time
With the proportional band alone, the process tends to reach equilibri-
um at some point away from the main setpoint. This offset is due to the
difference between the output needed to maintain setpoint and the out-
put of the proportional band at setpoint. Since the proportional band is
equidistant from the main setpoint, the output is around 50%. If anything
more or less than 50% output is required to maintain setpoint, an offset
error will occur. Integral action eliminates this offset. See the diagrams
below.
Integral action eliminates offset by adding to or subtracting from the
output of the proportional action alone. This increase or decrease in
output corrects for offset error within the proportional band in estab-
lishing steady-state performance at setpoint. It is not intended to cor-
rect for process disturbances. See the following diagram.
Summary of Contents for CN4321
Page 33: ...32 SYSTEM WIRING DIAGRAMS Example 1 Example 2...
Page 45: ...44 Deadband Overlap...
Page 48: ...47 Table of Input Type Codes...
Page 50: ...49...
Page 53: ...52 Table of Alarm Action Type Codes CN4321...
Page 54: ...53 Table of Alarm Action Type Codes CN4431...
Page 59: ...58 Table of Output Type Codes...