Burkert Type 8709 - Manual (Page 39)

39
Operation and function
standard control mode 8.3.1.
The LFC / LFM is in this operating state immediately after the device is switched on, after a brief initialisation
phase. The green Power LED is lit.
The flow-rate is corrected for the LFC to the specified set-point value at a high dynamic.
Malfunctions, e.g. due to pressure changes, are quickly counterbalanced by a corresponding adjustment of the
proportional valve position.
The set-point value is specified in this operating state depending on the device version via the analogue input
(standard signal input) or the field bus.
The controller parameters 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 actual flow-rate value can be read depending on the device version via the analogue output (standard signal
output) or the field bus.
Please note!
if the blue limit (y) led lights up, this means
for the lfc •
the control signal of the proportional valve is approaching the 100% limit.
The cause is usually
- a too low pressure difference via the LFC,
e.g. due to an inadequate pressure supply or
- a heavily soiled filter.
This may cause the specified set-point value not to be reached and result in a permanent positive
control deviation (w – x).
for the lfM •
the current flow-rate is approaching the nominal flow-rate or has exceeded it.
If the nominal flow-rate is greatly exceeded, this may cause the output flow-rate to deviate from the
actual flow-rate.
to give an external response to the deviations, a binary output is switched.
autotune function 8.3.2.
A prerequisite for the automatic adjustment of the controller, to the conditions of the system, is that typical
pressure conditions prevail.
Activate the Autotune function by briefly actuating (> 0.5 s) the binary input 1.
→
The Autotune function runs automatically.
While the Autotune function is running, the green Power LED flashes.
Warning!
While the autotune function is running, note the following:
Different flow-rate changes occur.
The power supply of the LFC must not be switched off. •
The supply pressure should be kept constant. •
english
Type 8718, 8719 / 8708, 8709