MA7200 PLUS Operating Manual
TECO – Westinghouse Motor Company App-1 Main PID Control
PID Control Invalid (Setting: 15)
PID Control Invalid 2 (Setting: 30)
OFF PID control valid (close-loop)
ON PID control invalid (open-loop)
1- If the PID function is enabled (Sn-64
≠
0), the setting can be used to disable PID function. It is often
Used in the changeover of test run.
2- When the PID function is disabled (PID control invalid is “ON”), an open-loop operation or jog operation
can be performed for system testing. The system can then be changed to PID control.
3- Setting Sn-25 – 28 = 15 disables the PID function and sets the previous PID target as the frequency
command.
4- Setting Sn-25 – 28 = 30 disables the PID function and sets parameter An-16 as the frequency
command.
5- Table1.4.2 below shows a list of the frequency command sources available while the PID function
is invalid.
Table 1.4.2
Sn-05
Sn-29
Frequency Command Source with PID control invalid
Sn-25 - 28 = 15
Sn-25 - 28 = 30
0
-
From Keypad
An-16
1
9
From Terminal AUX (0 -10V / 0 -100%)
Other
Value
From Terminal VIN (0 -10V / 0 -100%)
2
- From
RS-485
Communication
3
-
From Pulse Input
6- If both PID control invalid (Sn-25 - 28 = 15 and 30) are set, PID control invalid 2 (30) has the priority.
1.5 Adjusting the PID Control Functions
The following procedure can be used to initially set up the PID loop and then adjustments can be made while
monitoring the response.
1- Enable PID control by setting Sn-64 = 1 to 8 (select for the application)
2- Adjust the Proportional Gain Bn-17 until continuous oscillations in the Controlled Variable are at a
minimum.
3- Adjust the Integral Time Bn-18 so that the steady-state error will approach zero. The time should be
adjusted so that a minimal error is attained as fast as possible without making the system oscillate.
4- If necessary, adjust Derivative Time Bn-19 to reduce overshoot during acceleration. Parameters
Bn-01 (Acceleration time) and Bn-02 (Deceleration time) may also be adjusted for this purpose.
All of these parameters are interactive, and will need to be adjusted until the control loop is properly
Set so that stability is achieved with minimal steady-state error. A general procedure for adjusting these
parameters is as follows:
Reducing Overshoot
If overshoot occurs, decrease the derivative time (D) and lengthen the integral time (I).
Cont.
