Red Lion TSC - Manual (Page 17)

OPERATION OVERVIEW
CONTROLLER POWER-UP
Upon applying power, the controller delays control action and temperature
indication for five seconds to perform several self-diagnostic tests and
displays basic controller information. Initially, the controller illuminates both
displays and all annunciators to verify that all display elements are
functioning. Following, the controller displays the programmed input sensor
type in the Main display (verify that the input select sensor jumper matches the
programming). Concurrently, it displays the current revision number of the
operating system software in the bottom display. The controller checks for
correct internal operation and displays an error message (E-XX) if an internal
fault is detected (see Troubleshooting).
A profile can be programmed to Start (run mode), Stop (off mode), or Pause if
itwasrunningonpower-up(see“ProfilePowerCycleStatusParameter”section).
Upon completion of this sequence, the controller begins control action by
displaying the temperature and updating the outputs based upon the PID
control value.
CONTROLLER POWER DOWN
At power down, the steady state control value as well as all parameters and
control modes are saved, to provide a quick and predictable temperature
response on the next power-up.
When powering down the process, it is important to power down the
controller at the same time. This prevents the reset action of the controller
from shifting the proportional band while the temperature is dropping, which
prevents excessive overshoot on the next process start-up.
PROCESS START-UP
After starting the process, the controller’s PID settings must be initially
“tuned” to the process for optimum temperature control. Tuning consists of
adjusting the Proportional Band, Integral Time, and Derivative Time
parameters to achieve the optimum response to a process disturbance. Once
the controller is tuned, it may need to be re-tuned if the process has been
changed significantly. Several options exist for tuning these parameters:
A) Use the controller’s built-in Auto-Tune feature (see Auto-Tune).
B) Use a manual tuning technique (see manual tuning).
C) Use a third party tuning software package (generally expensive and not
always precise).
D)Usevaluesbasedoncontrolloopexperienceorvaluesfromasimilarprocess.
If the controller is a replacement, the PID settings from the unit being
replaced may be used as good initial values. Be sure to consider any
differences in the units and the PID settings when replacing. The PID settings
may be fine tuned by using the techniques outlined in the PID Control section.
After tuning the controller to the process, it is important to power the load and
the controller at the same time for best start-up response.
MANUAL (USER) & AUTOMATIC OPERATION
The controller can be transfered between Automatic control (closed loop;
PID or ON/OFF control) and Manual control (open loop). Placing the
controller in the Manual Mode does not impede the advancement or operation
of a running profile. In the Hidden Function Mode, the “trnf” parameter allows
the operator to select the desired operating mode. To allow front panel
switching between control modes, program the transfer (trnf) parameter to
“Enbl” in the Lockout module. The User Input or RS-485 serial interface
option may also be used to perform the auto/manual transfer function,
independent of the setting in the Lockout module.
Manual operation provides direct control of the output(s) from 0 to +100%,
or -100% to +100% if cooling output is installed. The MAN (manual)
annunciator flashes to indicate that the unit is in manual operation.
In the Manual Mode, the output power can be adjusted using the front panel
arrow buttons when % output power is viewed in the lower display. If the %
output power is locked or read only, then the output power can be adjusted in
the unprotected parameter mode when OP is viewed. With the serial option,
the % output power can be modified independent of what is viewed in the
display as long as the unit is in the manual mode.
When transferring the controller mode from/to automatic, the control
power output(s) remain constant, exercising true “bumpless” transfer. When
transferring from manual to automatic, the power initially remains steady but
integral action will correct (if necessary) the closed loop power demand at a
rate proportional to the Integral Time. The programmable high and low power
limit values are ignored when the unit is in manual operation.
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