Burkert 8630 Instructions De Service page 157

Characteristics:
A pure I controller eliminates the effects of occuring disturbances completely. Therefore, it has a favorable static response. Owing
to its finite manipulating speed, it operates more slowly than the P controller and tends to oscillate. Therefore, it is relatively unfavorable
from the dynamic point of view.
D component:
Function: Y = Kd d Xd/dt
Kd is the derivative action coefficient.
The higher Kd is, the stronger the D influence is.
Fig. 8.3: Characteristics and step response of the D component of a PID controller
Characteristics :
A controller with a D component reacts to changes in the controlled variable and is accordingly capable of dissipating occurring
deviations faster.
Supperposition of P-, I- and D components:
Y = Kp Xd +
Where Kp · Ti = Tn and Kd/Kp = Tv, results with regard to functioning of the PID controller:
Y = Kp (Xd +
Kp: Proportional action coefficient / gain
Tn: Reset time
(the time needed to achieve the same manipulated variable change by the I component as is produced as the
result of the P component)
Tv: Derivative action time
(the time to achieve a specific manipulated variable on the basis of the D component earlier than when using a
pure P controller)
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Step response
1
∫ ∫ ∫ ∫ ∫ Xd dt + d Xd/dt
Ti
1
∫ ∫ ∫ ∫ ∫ Xd dt + Tv dXd/dt)
Tn
Rise response
Operating instructions no. 800607