Burkert Type 8715 - Manual (Page 37)

37
Operationandfunction
Type 8710, 8711, 8713, 8715
8.3.1. standard control mode
In this operating mode, the flow-rate is corrected to the specified set-
point value at a high dynamic.
The MFC is in this operating mode once energized, after a brief
initialization phase. The green power indicator is on.
The set-point value is specified via the analogue input or the field bus,
depending on the device version.
The controller settings are set in such a way that set-point value
changes or actuating variables are corrected as quickly as possible
without appreciable overshoot occurring.
The measured flow-rate value is available on the analogue output or
the field bus, depending on the device version.
For the MFC:
If the blue Limit (y) LED is on, this means that the control
signal of the proportional solenoid valve is approaching the
100% limit (see chap. 9.3).
The cause may be:
• either an insufficient pressure difference around the MFC,
for example an insufficient inlet pressure,
• or a dirty inlet filter
• This means that the set point cannot be achieved and a
difference between the set point and the measured value
(w-x) persists.
For the MFM:
If the blue Limit (y) LED is on, the measured mass flow is
approaching the nominal flow-rate or has even exceeded it
(see chap. 9.3).
If a high exceeding of the nominal flow rate occurs, a
difference between the measured and the real flow rates
may appear.
To permit an external reaction to this gap, a binary output is
activated.
8.3.2. Autotune function
The Autotune function is run through during the final
inspection in the factory, at the operating pressure and with
the calibration fluid indicated in the calibration protocol.
Therefore, the re-actuation of this function is not essential.
However, the
Autotune function should be activated if:
• the pressure conditions in the system have changed
significantly,
• the calibration fluid does not correspond with the
operating fluid.
In this operating mode, the device calculates and optimizes the control
settings to the conditions present in the system.
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