Burkert Type 8709 - Manual (Page 40)

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Operation and function
While the Autotune function is running, the LFC is not controlling.
The proportional valve is controlled according to an internally specified profile, resulting in flow-rate changes.
Thereby several control parameters are adjusted to the conditions present in the system.
These parameters are transferred into the non-volatile memory of the device at the end of a successfully run
Autotune function.
When the Autotune function ends, the LFC returns to the previous operating state.
Each LFC has run though the Autotune function during the final inspection in the factory, at the operating
pressure indicated in the calibration protocol and with the calibration fluid.
Therefore, the re-actuation of this function is not essential for a reliable controlled operation in the system.
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. •
safety function 8.3.3.
This function can be activated or reset depending on the device configuration via a binary input or field bus.
In this operating state the device behaves as in standard control mode. However, an external set-point value is
ignored and a defined safety value (standard setting: 0%, can be changed with “Mass Flow Communicator” PC
software) is used as the set-point value.
set-point value profile 8.3.4.
This function can be activated or reset depending on the device configuration via a binary input or field bus.
In this operating state the device behaves as in the standard control mode. However, the external set-point value
is ignored and a previously defined chronology of up to 30 flow-rate values is used as the set-point value (can be
configured with “Mass Flow Communicator” PC software).
When the set-point value profile has run through, the device drops back to the previous operating state, provided
this operating state was reset by a binary input during activation.
control mode 8.3.5.
This function can be activated or reset depending on the device configuration via a binary input or field bus
(can be configured with “Mass Flow Communicator” PC software).
In this operating state the set-point value is used as the output variable for the valve pulse-duty factor of the
proportional valve, e.g. set-point value 10% → Valve pulse-duty factor = 10%.
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Type 8718, 8719 / 8708, 8709