red lion PXU10020, Instructions Manual

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Released 2018-01-12 Drawing No. LP0932
ON/OFF CONTROL
In this control mode, the process will constantly oscillate around the
setpoint value. The On/Off Control Hysteresis (balanced around the
setpoint) can be used to eliminate output chatter. Output Control Action
can be set to reverse for heating (output on when below the setpoint) or
direct for cooling (output on when above the setpoint) applications.
ON/OFF CONTROL -
REVERSE OR DIRECT ACTING FIGURES
Note: CHYS in the On/Off Control Figures refers to the On/Off Control
Hysteresis (
CY
) in parameter Module 2.
For heat and cool systems, Control Action parameter is used to
reverse (r) for heating and direct (d) for cooling. The Deadband/Overlap
in Cooling sets the amount of operational deadband or overlap between
the outputs. The setpoint and the On/Off Control Hysteresis applies to
both OP1 and OP2 outputs. The hysteresis is balanced in relationship to
the setpoint and deadband value.
Control Mode Explanations
ON
Output (d) :
ON
SP
OFF
INPUT
DEADBAND/OVERLAP
(db2) = 0
SP + 1/2 CHYS
SP - 1/2 CHYS
OFF OFF
Output (r) :
ON
CHYS
SP
SP + 1/2 (db-2) - 1/2 CHYS
SP + 1/2 (db-2) + 1/2 CHYS
SP - 1/2 (db-2) + 1/2 CHYS
SP - 1/2 (db-2) - 1/2 CHYS
DEADBAND/OVERLAP (db-2) < 0
db-2
CHYS
CHYS
ON
OFF
OFF
ON
Output (r) :
Output (d) :
db-2
Output (r) :
Output (d) :
SP - 1/2 (db-2) + 1/2 CHYS
SP - 1/2 (db-2) - 1/2 CHYS
OFF
SP
ON
OFF
OFF
ON
CHYS
OFF
DEADBAND/OVERLAP (db-2) > 0
SP + 1/2 (db-2) - 1/2 CHYS
SP + 1/2 (db-2) + 1/2 CHYS
CHYS
ON
ON
INPUT
INPUT
SP + 1/2 (db-2)
SP - 1/2 (db-2)
SP + 1/2 (db-2)
SP - 1/2 (db-2)
ON/OFF CONTROL - HEAT/COOL OUTPUT FIGURES
PID CONTROL
In PID Control, the controller processes the input and then calculates
a control output power value by use of Proportional Band, Integral Time,
and Derivative Time control algorithm. The system is controlled with the
new output power value to keep the process at the setpoint. The Control
Action for PID Control can be set to reverse for heating (output on when
below the setpoint) or direct for cooling (output on when above the
setpoint) applications. For heat and cool systems, the heat and cool
outputs are both used. The PID parameters can be established by using
Auto-Tune, or they can be Manually tuned to the process.
SP
TIME
P & I
P & I & D
P only
P & D
INPUT
TYPICAL PID RESPONSE CURVE
OFF Output (d) :
SP
OFF
INPUT
DIRECT ACTING
SP - 1/2 CHYS
SP + 1/2 CHYS
ON
OFF
Output (r) :
SP
OFF
INPUT
REVERSE ACTING
SP - 1/2 CHYS
SP + 1/2 CHYS
ON