When AT is executed, control operates in ON-OFF mode Output response is used to calculate
new PID parameter. When auto tuning is completed, new PID value is stored, auto tuning ends
and AT lamp goes off.
Stop Auto Tuning
To stop auto tuning in the middle of execution, select OFF by using the
button on the auto
tuning. Press the
button to confirm the new setting.
Unexecutable Conditions of Auto Tuning
In following conditions, auto tuning is unable to be executed:
1. Control output in manual mode.
2. Control in standby mode.
3. OFF is selected for proportional band (P) of output.
4. Lock number 2 or 3 is selected on the key lock screen.
Manual PID Tuning
Tuning the controller requires adjusting the proportional band (P), Integral (I) and Derivative (D)
for the process conditions. With the heater load at 25% rated load, the following procedure will
permit good control for a given set of conditions.
1. Set the (I) and (D) to the factory settings, I = 120 and D = 0. Set the (P) to a large value
approximately 100.
2. Decrease the (P) until the process oscillates.
3. Add 10% to the (P) value to stop oscillation. Note the offset (difference between Setpoint
and the Outlet temperature value.
4. Increase or decrease the (I) to eliminate or minimize the offset. When the offset is
minimized, note the value.
5. With a minimum or no offset, increase the (P) 10~20%, then decrease the (P) until
control oscillates. Increase (P) 10% and repeat number 4 and 5 until minimum offset and
no control oscillation.
6. Add (D) if system does not respond to load changes fast enough.
7. If the Outlet temperature over shoots on initial start up or large Setpoint changes, change
the PID control coefficient (SF) parameter on the Setup Mode to minimize this condition.
The factory default setting is 0.4.
Note: These settings may have to change for different loads on the heater. Check the operation
of the heater at minimum and maximum loads. A constant supply pressure and temperature of
the input heat source to the heater is required.
Key Lock
Key lock setting can be used to prevent unauthorized personnel from changing the settings.
Changing Lock Setting
While in the Setup Mode, press the
button to scroll to the Lock screen. When on this screen,
use the
and buttons to change the key lock setting and press the button to confirm
new setting. The Table 3 – Key Lock Level Description describes different lock settings.
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