WEG CFW100 Programming Manual page 148

APPLICATIONS
This parameter enables the PID controller and defines how the control action will be.
P928
0 It defines that the PID controller will be disabled
It defines that the PID controller will be enabled, and the regulation or control action will be in direct mode. In other words, the
1
error will be the control setpoint value (P911) minus the control process variable value (P916)
It defines that the PID controller will be enabled, and the regulation or control action will be in reverse mode. In other words, the
2
error will be the control process variable value (P916) minus the control setpoint value (P911)
✓
NOTE!
When enabling the PID controller, that is, changing the content of parameter P928 from 0 to 1 or 2,
the following parameters related to the PID controller application will be loaded: P100, P101, P133,
P134, P205, P207, P208, P209, P210, P213, P220, P221, P224, P231, P232, P233, P234, P235,
P263, P264, P510, P511, P911, P912, P913, P914, P915, P918, P920, P921, P922, P923, P924,
P925, P926, P927, P929, P930, P931, P932, P933, P934, P935, P936, P937, P938, P939.
✓
NOTE!
The control action of the PID controller must be selected for direct mode when it is necessary to
increase the PID controller output in order to increase the process variable value. E.g.: Pump driven
by an inverter and filling a tank. For the level of the tank (process variable) to increase, it is necessary
that the flow increase, which is accomplished by increasing the speed of the motor.
The control action of the PID controller must be selected for reverse mode when it is necessary to
decrease the PID controller output in order to increase the process variable value. E.g.: Fan driven by
inverter cooling a refrigeration tower. When an increase in temperature is desired (process variable),
it is necessary to reduce the ventilation by reducing the motor speed.
P929 - PID Controller Operation Mode
Range:
Description:
This parameter defines the operation mode of the inverter PID controller.
P929
It defines that the PID controller will always operate in manual mode. In other words, the process variable will not be controlled
0 according to the control setpoint required by the user, and the PID controller output value will be the setpoint value in manual
mode programmed in parameter P918
It defines that the PID controller will operate in automatic mode, that is, the process variable will be controlled according to the
1
control setpoint required by the user and the PID controller output value will behave according to the settings defined by the user
It defines the PID controller will be able to operate in manual or automatic mode according to the state of digital input DI2. In other
2
words, if the digital input is in logical level "0", the PID controller will operate in manual mode; if the digital input is in logical level
"1", the PID controller will operate in automatic mode
✓
NOTE!
The change from an operation mode to another with the motor running may cause disturbances
on the system control. That can be optimized according to the automatic adjustment mode of the
PID controller setpoint defined in parameter P930 together with the bumpless transfer characteristic
14
from the manual mode to the automatic mode of the PID block of the SoftPLC function. Bumpless
transfer is merely making the transfer from the manual mode to the automatic mode without causing
variation in the PID controller output. In other words, when the transition from the manual mode to the
automatic mode occurs, the PID controller output value in manual mode is used to start the integral
part of the PID controller in automatic mode. That ensures that the output will start from this value.
14-12 | Micro Mini Drives
Table 14.8: Description of the PID controller control action
0 = Manual
1 = Automatic
2 = Select Control to Manual (0) or Automatic (1) via digital input DI2
Table 14.9: Description of the PID controller operation mode
Description
Description