Red Lion P16 - Manual (Page 14)

14
2

CYCLE TIME

to
2
seconds
OUTPUT POWER DAMPENING

to
2
seconds
The Cycle Time is entered in seconds with one tenth of a second resolution.
It is the total time for one on and one off period of the time proportioning
control output O1. With time proportional control, the percentage of power is
converted into an output on-time relative to the cycle time value set. (If the
controller calculates that 65% power is required and a cycle time of 10.0
seconds is set, the output will be on for 6.5 seconds and off for 3.5 seconds.)
For best control, a cycle time equal to one-tenth or less, of the natural period of
oscillation of the process is recommended. When using the Analog Output
signal for control, the Cycle Time setting has no effect. If the O1 output is not
being used, a cycle time of 0 can be entered to prevent the output and indicator
from cycling.


CONTROL ACTION

Direct (cooling)

Reverse (heating)
This determines the control action for the PID loop. Programmed for direct
action (cooling), the output power will increase if the Process value is above the
Setpoint value. Programmed for reverse action (heating), the output power
decreases when the Process Value is above the Setpoint Value. For heat and cool
applications, this is typically set to reverse. This allows O1 or A1 (models with
Analog Output) to be used for heating, and A2/O2 to be used for cooling.


OUTPUT POWER LOWER LIMIT

to
1
percent O1
1
to
1
percent O1/O2
This parameter may be used to limit controller power at the lower end due to
process disturbances or setpoint changes. Enter the safe output power limits for
the process. If Alarm 2 is selected for cooling, the range is from -100 to +100%.
At 0%, both O1 and O2 are off; at 100%, O1 is on; and at -100%, O2 is on.
When the controller is in Manual Control Mode, this limit does not apply.
1
I
OUTPUT POWER UPPER LIMIT

to
1
percent O1
1
to
1
percent O1/O2
This parameter may be used to limit controller power at the upper end due to
process disturbances or setpoint changes. Enter the safe output power limits for
the process. If Alarm 2 is selected for cooling, the range is from -100 to +100%.
At 0%, both O1 and O2 are off; at 100%, O1 is on; and at -100%, O2 is on.
When the controller is in Manual Control Mode, this limit does not apply.
AUTO-TUNE CODE

fastest to
2
slowest
Prior to starting Auto-Tune, this code should be set to achieve the necessary
dampening level under PID Control. This value allows customization of the PID
values that Auto-Tune will calculate. For the process to be controlled aggressively
(fastest process response with possible overshoot), set the Auto-Tune Code to 0.
For the process to be controlled conservatively (slowest response with the least
amount of overshoot), set this value to 2. If the Auto-Tune Code is changed,
Auto-Tune needs to be reinitiated for the changes to affect the PID settings. For
more information, see PID Tuning Explanations Section.

F
SENSOR FAIL POWER LEVEL
This parameter sets the power level for the control outputs in the event of a
sensor failure. If Alarm 2 is not selected for cooling, the range is from 0% (O1
output full off) to 100% (O1 output full on). If A2 is selected for cooling, the
range is from -100 to +100%. At 0%, both O1 and O2 are off; at 100%, O1 is
on; and at -100%, O2 is on. The alarm outputs are upscale drive with an open
sensor, and downscale drive with a shorted sensor (RTD only), independent of
this setting. Manual Control overrides the sensor fail preset.
The Dampening Time, entered as a time constant in seconds, dampens
(filters) the calculated output power. Increasing the value increases the
dampening effect. Generally, dampening times in the range of one-twentieth to
one-fiftieth of the controller’s integral time (or process time constant) are
effective. Dampening times longer than these may cause controller instability
due to the added lag effect.
ON/OFF CONTROL HYSTERESIS
1
to
2
The controller can be placed in the On/Off Control Mode by setting the
Proportional Band to 0.0%. The On/Off Control Hysteresis (balanced around
the setpoint) eliminates output chatter. In heat/cool applications, the control
hysteresis value affects both Output O1 and Output O2 control. It is suggested
to set the hysteresis band to Factory Setting prior to starting Auto-Tune. After
Auto-Tune, the hysteresis band has no effect on PID Control. On/Off Control
Hysteresis is illustrated in the On/Off Control Mode section.



1

T16
P16
2
2

T16
P16
7.2 module 2 - o
utput
p
ArAmeterS
(
2-OP
)
CYCt OPLO OPAC OPHI OPFL OPdP CHYS
CYCLE
TIME
CONTROL
ACTION
OUTPUT
POWER CONTROL
ON/OFF OUTPUT
POWER
2-OP
CNFP
UPDATE
ANAS
OUTPUT
ANALOG
ANUt
ANALOG ANALOG
ANHI
HIGH
ANLO
LOW
ANALOG SENSOR FAIL
POWER CODE
AUTO-TUNE
OUTPUT
ANALOG
tcod ANtP
LOW LIMIT HIGH LIMIT
POWER
OUTPUT
LEVEL DAMPENING HYSTERESIS RANGE ASSIGNMENT TIME SCALING SCALING
PARAMETER MENU

to
1
percent O1
1
to
1
percent O1/O2