LTR701
Airstream and Temperature Control Plant
for your student practicals and your research laboratory
The laboratory experimental setup
"Airstream and Tempera- ture Control Plant" contains the technical
realization of two dif- ferent control plants (1st-order airstream control plant,
temper- ature control plant of higher order) together with an integrated actuator.
A fan provides an airstream along a tube. A heating element feeds heat into
the airstream. A regulating flap mounted near to the fan allows for a stepwise
dis- turbance of the airstream. The complete mechanical setup is protected against
overheating by means of a bimetallic thermo- relay. The heat element is switched
off at a temperature of 140° Celsius. Two NiCr-Ni temperature detectors
with different time constants sense the temperature of the airstream. The temperature
can be measured at four different locations of the tube. The vol- ume of the
air flow is measured by a differential pressure sensor which detects the pressure
in front of a metering orifice in comparison with the constant supply pressure.
The two sen- sors (industrial standard) are mounted at distinct positions of
the tube.
The electronics is contained in a robust sheet steel case and forms one unit
together with the mechanical set-up. The heating capacity as well as the air
flow may be manipulated at the front panel of the actuator either by potentiometers
or by external 4... 20 mA or 0...10V input sig- nals. The measured signals of
the position of the regulating flap, the differential pressure sensor and of
the temperature sensors are provided as 4 ... 20 mA and 0...10V output signals.
Any input or output signal is accessible by 4mm (security) sockets.
All control resp. measuring signals can also be sent resp. received via a processor
con- trolled RS232 serial interface. The microprocessor displays all control
and measuring signals on a LCD screen. Bar graph or oscilloscope function are
selectable for the graphic representation of the signals.
The laboratory experimental setup "Airstream and Tempera- ture Control
Plant" is extremely useful to demonstrate the behav- iour of the following
control plants:
a 1st-order control plant by manipulating
the volume of the air flow by means of the regulating flap at the input of the
fan.
a 2nd-order temperature control plant by manipu- lating the volume of the
air flow by means of the regu- lating flap at the input of the fan or by variation
of the heating capacity.
After connecting additional external
controllers the labora- tory experimental setup "Air- stream and Temperature
Control Plant" may realize the following closed control loops:
A simple control loop with a 1st-order control plant (Airstream control with
uncontrolled temperature).
A simple control loop with a 2nd-order control plant (Temperature control
with uncontrolled airstream).
A cascaded control loop with temperature control and cascaded airstream control.
Two separated control loops with independent temperature control and airstream
control.
Applying the laboratory ex- perimental setup "Airstream and Temperature
Control Plant", the following laboratory experi- ments are proposed in
example:
Identification of the static and dynamic behaviour of the control plants.
Implementing simple closed control loops with control plants of 1st or 2nd-order
and evaluating its dynamic behaviour.
Implementing cascaded closed control loops with airstream and temperature
control and evaluating its dynamic behaviour.
Implementing separated closed control loops with airstream and temperature
control and evaluating its dynamic behaviour.
The laboratory set-up is extendable by the following options:
The Option 701-02 extends the standard version of the LTR701 by an adapter card
ready to plug in a PC with ISA slot and MCON as the controller program (MS-
WINDOWS). MCON comes along with corresponding configuration files for the realization
of different realtime closed control loops. A separate information sheet is
available for MCON.
The Option 701-03 contains a air mass sensor which is mounted at the end of
the tube. The measuring signal is processed by the electronics and can be accessed
via the current, voltage or serial RS232 interface.