Endress+Hauser Topclean S CPC30, Руководство по эксплуатации

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Topclean S 6 Commissioning
Hauser 75
PID controller Used for processes where a P, PI or PD controller does not control sufficiently.
Configuration options of the PID controller
• Change control gain K
p
(P influence).
• Set integral action time T
n
(I influence).
• Set derivative action time T
v
(D influence).
Laplace transformation The Laplace transformation is an integral transformation that transforms a given function f(t) from
the time domain into the spectral domain yielding a function f(s).
Due to its differentation principle, the Laplace transformation is useful to solve differential
equations. The differential equation is transformed into the spectral domain, the resulting algebraic
equation is solved and the solution is re-transformed into the time domain.
Batch or inline process
arrangement: With active control, batch and inline processes differ in their relationship to the medium flow:
Pure batch process: the batch container is filled with the medium. During the subsequent batch
process, no additional medium is fed in. The change in pH value is determined only by the
controller. To be able to compensate for possible so-called "overshoots", use a two-sided controller.
For as long as the actual value is within the neutral zone, no additional dosing agent is added.
Pure inline process: Here, the control works with the medium flowing past. The pH value of the
medium in the inflow may be subject to strong deviations for which the controller should
compensate. The volume of medium which has already flowed past can no longer be influenced by
the controller. For as long as the actual value corresponds to the set point, the set value has a
constant value.
In practice, the most common option is the semi-batch process . Depending on the ratio of inflow to
tank size, this process shows the behaviour of an inline or a batch process.
The Mycom controller takes this differing behaviour into account. The difference for these settings
is the internal handling of the integral part of the PI or PID controller.
Controlling the actuators
The CPM153 has four different methods for controlling the actuators (see above).
1. PWM (Pulse-width modulation, "pulse-length controller")
Pulse-width-modulated outputs are intended to control solenoid valves, for example. With PWM,
the internal, continuous actuating variable is output to a relay as a rhythmic signal.
The larger the calculated actuating variable, the longer the corresponding contact remains picked
up (i.e. the longer the switch-on period t
ON
; see fig. 39). You can set the period length freely
between 1 and 999.9 seconds. The minimum switch-on period is 0.4 seconds.
For a two-sided process, you can combine PWM with a second controlling method as follows:
• a PWM relay
• a PFM relay
• a three-point step controller
A single PWM relay can only output one actuating variable for a solenoid valve.
To avoid pulses which are too short, enter a minimum switch-on period. Pulses which are too short
are not given to the relay/or the actuators. This benefits the actuator.