Endress+Hauser TopClean S CPC 30, Руководство по эксплуатации

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TopClean S CPC 30 6 Commissioning
Hauser 51
Batch or inline process
arrangement: With active control, the batch and inline processes are different in their relationship to
the medium current:
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 actuating variable has a constant value.
The Mycom controller takes this differing behaviour into account. It is the internal
handling of the integral part of the PI or PID controller which is different for these
settings.
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.
Controlling the actuators
The CPM 153 has four different methods for controlling the actuators (see above).
1. PWM (pulse-width modulation, "pulse-length controller")
Pulse-width modulated outputs serve as control e.g. of solenoid valves. With PWM, one
side (i.e. acid
or
alkali) of the internal, analogue actuating variable is output to a relay
as a rhythmic signal.
The larger the calculated actuating variable, the longer the appropriate contact remains
picked up (i.e. the longer the switch-on period t
ON
; s. fig. 21). You can set the period
length freely between 1 and 999.9 seconds. The minimum switch-on period is 0.4
seconds.
A two-sided process requires two PLM relays or one PLM and a three-point step
controller (see below). One PLM relay on its own can only output an actuating variable
of
•
–100% ... 0%
or
•
of 0% .... +100%.
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.
2. PFM (pulse-frequency modulation; "pulse-frequency controller")
Pulse-frequency modulated outputs serve as control e.g. of solenoid dosing pumps. As
with PWM, PFM is output as a rhythmic signal by the relay.
The greater the calculated actuating variable, the higher the frequency of the related
contact. The maximum settable frequency 1/T is 120 min
-1
. The switch-on period t
ON
is
a constant factor of the entered frequency (s. fig. 21).
Here too, two PFM relays are required for a two-sided process.