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CHAPTER 6 - DETAILED PARAMETER DESCRIPTION
NOTE!
When PID (P203 = 1) function is enabled:
Program one of the digital inputs DIX (P263 to P266 = 27). In this
manner, with closed DIX it operates in manual mode (without closing
the loop control – feedback) and opening the DIX the PID regulator
starts to operate (closed loop control – automatic mode). If there is
no digital input (DIx) selected for manual/automatic function (P263
to P266 = 27), the inverter operation always will be in automatic
mode.
If P221 or P222 is equal to 1, 2, 4, 5, 6 or 7 there will be an E24
indication.
Set P221 and P222 equal to 0 or 3 as need.
In manual mode the frequency reference is given by F* according
to figure 6.1.
When changed from manual to automatic, P525 = P040 is
automatically set if P536 = 0 (at the moment immediately before
the commutation). In this manner, if the set point is defined by P525
(P221 or P222 = 0) and changed from manual to automatic,
P525 = P040 is automatically set, since P536 parameter is active
(P536 = 0). In this case, the commutation from manual to automatic
is smooth (there is no abrupt speed variation).
The following figure 6.24 shows an application example of an in-
verter controlling a process in closed loop (PID regulator).
6.3.4.3 Start up Guide
Find below a start-up procedure for the PID regulator:
Initial Definitions
1) Process - To define the PID typeof action that the process requires:
direct or reverse. The control action must be direct (P527 = 0) when
it is required to increase the motor speed and so also increment
the process variable. Otherwise select reverse (P527 = 1).
Examples:
a) Direct: Pump driven by an inverter and filling a reservoir where the
PID regulates the reservoir level. To increase the reservoir level
(process variable) the flow must be increased and consequently
also the motor speed must be increased.
b) Reverse: Fan driven by an inverter to cool a cooling tower, with the
PID controlling the tower temperature.
When it is required to increase the temperature (process variable),
the cooling must be decreased by reducing the motor speed.
2) Feedback (process variable measurement):
It is always via analog input AI1.
Transducer (sensor) to be used for the feedback of the control
variable: it is recommended to use a full scale sensor with
minimum 1.1 times higher than the largest value of the process
variable that shall be controlled. Example: If a pressure control
at 20 bar is desired, select a sensor with a control capacity of at
least 22 bar.
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