Siemens SIMATIC S7-1500T Function Manual

Principles for control
2.8 PID parameter settings
PID control
Function Manual, 03/2017, A5E35300227-AC
37
2.8
PID parameter settings
Rule of Thumb for the Parameter Setting
Controller structure
Setting
P
GAIN ≈ v
max
× T
u
[° C ]
PI GAIN ≈ 1.2 × v
max
× T
u
[° C ]
TI ≈ 4 × T
u
[ min ]
PD GAIN ≈ 0.83 × v
max
× T
u
[° C ]
TD ≈ 0.25 × v
max
× T
u
[ min ]
TM_LAG ≈ 0.5 × TD[ min ]
PID GAIN ≈ 0.83 × v
max
× T
u
[° C ]
TI ≈ 2 × T
u
[ min ]
TD ≈ 0.4 × T
u
[ min ]
TM_LAG ≈ 0.5 × TD[ min ]
PD/PID GAIN ≈ 0.4 × v
max
× T
u
[° C ]
TI ≈ 2 × T
u
[ min ]
TD ≈ 0.4 × T
u
[ min ]
TM_LAG ≈ 0.5 × TD[ min ]
Instead of v
max
= ∆
x
/ ∆
t
, you can use X
max
/ T
g
.
In the case of controllers with PID structure the setting of the integral action time and
differential-action time is usually coupled with each other.
The ratio TI / TD lies between 4 and 5 and is optimal for most controlled systems.
Non-observance of the differential-action time TD is uncritical at PD controllers.
In the case of PI and PID controllers, control oscillations occur if the integral action time TI
has been select by more than half too small.
An integral action time that is too large slows down the settling times of disturbances. One
cannot expect that the control loops operate "optimally" after the first parameter settings.
Experience shows that adjusting is always necessary, when a system exists that is "difficult
to control" with T
u
/ T
g
> 0.3.

Siemens SIMATIC S7-1500T Specifications

General

Brand	Siemens
Model	SIMATIC S7-1500T
Category	Controller
Language	English