Burkert Type 8715 - Manual (Page 9)

9
Descriptionofthesystem
Type 8710, 8711, 8713, 8715
5.3.1. control electronics
The control electronics:
• process the mass flow-rate set-point values and measured values,
• control the solenoid valve.
set-point value
The set-point value (w) is either transmitted either by an analogue,
normalized input signal, or digitally via the serial interface or the field bus
interface. If the set-point value is supplied by analogue transmission,
the following assignments are applied:
signal
range set-point associated
with the range min. set-point associated
with the range max.
4...20 mA 4 mA, w = 0 % 20 mA, w = 100 %
0...20 mA 0 mA, w = 0 % 20 mA, w = 100 %
0...5 V 0 V, w = 0 % 5 V, w = 100 %
0...10 V 0 V, w = 0 % 10 V, w = 100 %
For the control of a system where quick flow-rate changes are not
permitted, a ramp function can be activated. The settings for an
ascending and a descending set-point value can be set separately.
More detailed information on the ramp function and on all
other functions can be found in the software documentation
for the MFM / MFC.
control settings
The initial control settings are set at the factory.
• Amplification factors:
After start-up, the controller operates with amplification factors
dependent on the loop properties. When the autotune function runs,
these are determined automatically. This function enables the control
settings to be optimized for the system's actual conditions.
• Control dynamics setting:
The device has a setting which can change the control dynamics
with the aid of the "Mass Flow Communicator" software
(see chap. 10.1.3). Its extreme effects are:
1. a very quick adjustment in which overshoots are possible. This
enables the controller to respond immediately to very low control
deviations, causing the control to be very turbulent,
2. a slower adjustment to the required flow-rate. If the system is less
dynamic, the behavior of the controller may be damped so that
minor fluctuations of the measured value or set-point value are
adjusted slowly.
English