Brief Description :
Laboratory Experiment LTR700 Airstream and Temperature Control Plant
 

The laboratory experimental setup "Airstream and Temperature Control Plant" contains the technical realization of two different control plants (1st-order airstream control plant, temperature control plant of higher order) together with an accompanying actuator. An axial fan provides an airstream along a polypropylene tube. A heating element feeds heat into the airstream. A regulating flap mounted near to the fan allows for a step-wise disturbance of the airstream. The complete mechanical setup is protected against overheating by means of a bimetallic thermorelay. The heat element is switched off at a temperature of 87° Celsius. A PT100 temperature detector senses the temperature of the airstream. The volume 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 sensors (industrial standard) are mounted at distinct positions of the tube. The electrical connector box provides a disturbance of the heating capacity by means of an additional switch. The complete mechanical setup is mounted on top of an acrylic base plate. The accompanying actuator is connected to the mechanical setup by means of two leads. 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 input signals. The measured signals of the differential pressure sensor and of the PT100 sensor are provided as 4 ... 20 mA output signals. Two additional output sockets provide the 24 VDC supply voltage for external auxiliary. Any input or output signal is accessible by 4mm (security) sockets.  The laboratory experimental setup "Airstream and Temperature Control Plant" is extremely useful to demonstrate the behaviour 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 manipulating the volume of the air flow by means of the regulating flap at the input of the fan or by disturbing the heating capacity by means of the switch at the electrical connector box. After connecting additional external controllers the laboratory experimental setup "Airstream 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 independant temperature control and airstream control. Applying the laboratory experimental setup "Airstream and Temperature Control Plant", the following laboratory experiments are proposed in example: Identification of the static and dynamic behaviour of the control plant. Linearizing the characteristic of the pressure sensor and compensating effects on the measuring precision. 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. Technical data are subject to change (Date 08-February-1999)