Desin Instruments HS-7000 Series, General Instructions Manual

Page: 34 / 108

34
RELAY METHOD
The Relay method, is used in fast , unlinear or unknown processes. It is based on generating a pulse
once the process is controlled close to the setpoint SP.
The Autotuning pulse should be between -20% and -50% if negative pulse is required, or from
+ 20% to +50% if a positive pilse is required.
This means that the pulse applied to the process will be in the % and direction specified in
Pulse.
PROCEDURE TO RUN AUTOTUNING
Starting PID Autotuning by Ziegler Nichols method (recommended)
This metho allows to start the Autotuning sequence in any point of the process, even if the
process is starting (variable at ambient temperature) or if the process is controlling at the
setpoint SP.
From any point of the menu, proceed as follows:
Check that the Autotuning pulse value is 100%, as follows:
- Press until [0000] [PASS] are displayed.
- Introduce the password correspondent to level 2 to accede to the PID submenu.
- Enter to [MAn] [Pid n] pressing and then press until [100.0] [PuLS] are displayed
- If there were other value in [100.0] [PuLS] , modify the value as explained next:
- Press and modify using and then press and exit using
STARTING AUTOTUNING SEQUENCE
- If already located in PID submenu press and until [Auto] [Pid 1] are displayed
- If not, introduce the password to accede to PID submenu in [0000] [PASS] .
- Press , to accede to [Auto] [Pid 1 ] select the required Loop pressing until [Auto] [Pid
2 ] or [Auto] [Pid 3 ]
The message [Auto] will flicker indicating that we are in AUTOTUNING function .
- Start Autotuning sequence pressing .
In the upper display the Process Variable will be displayed and in the lower [Auto] will be
dispalyed indicating that autotuning sequence is in progress.
VERY IMPORTANT: Once the Autotuning is started, don’t press any key, since the autotuning
sequence will stop, indicating
[Erro] [Auto]
returning to the original PID parameters.
The message [donE] [Auto] indicates that the Autotuning sequence has been finished
successfully.
Units
Time
Variable
Autotuning pulse
Control output -20%
SP