Siemens SPS starter kit 6ED1057-3BA00-0AA8 12 Vdc, 24 Vdc 6ED1057-3BA00-0AA8 Ficha De Dados
Códigos do produto
6ED1057-3BA00-0AA8
Reference material
5.3 Special functions
LOGO!Soft Comfort Online Help
Operating Instructions, 06/2014
Operating Instructions, 06/2014
297
● It cannot correct faults with the control process > lasting loop error.
● It reacts immediately to a change in the process value.
● It is stable.
● It reacts immediately to a change in the process value.
● It is stable.
I Controller
An integral-action controller (I controller) changes the manipulated variable M proportional to
the loop error and to the time. The I controller works by delayed action. It completely
remedies a loop error.
In order to calculate the value of the manipulated variable at a period of time n, the time up
In order to calculate the value of the manipulated variable at a period of time n, the time up
until this period of time must be divided into small time slices. The loop errors at the end of
each time slice must be added up (integrated) and they are then entered in the calculation.
M
M
In
= k
I
× (T
S
/ T
I
) × (e
n
+ e
n-1
+ e
n-2
+ e
n-3
+ … + e
0
) = k
I
× (T
S
/ T
I
) × e
n
+ M
In-1
M
In
: Manipulated variable of the I controller at the time n
M
In-1
: Manipulated variable of the I controller at the time n-1; also called integral sum
k
I
: Gain of the I controller
T
S
: Sampling time, duration of a time slice
T
I
: Integral time: by means of this time, the influence of the integral part is controlled on the
manipulated variable, also known as integral-action time
e
e
n
: Loop error at the time n
e
n-1
: Loop error at the time n-1; etc.
e
0
: Loop error at the beginning of the calculations
The following picture shows a jump in process value and step response of the controller:
Summary
The I controller has the following characteristics:
● It sets the process value exactly to the command variable.
● By so doing, it tends to oscillate and is unstable.
● It requires more time to carry out the control action than the P controller .
The I controller has the following characteristics:
● It sets the process value exactly to the command variable.
● By so doing, it tends to oscillate and is unstable.
● It requires more time to carry out the control action than the P controller .
PI controller
A PI controller reduces the loop error immediately and will eventually drive the loop error to
zero.