Control and Monitoring

Measuring systems are aimed at determining physical quantities with the help of various devices. It provides data for assessing the properties of technical devices and equipment.

A distinction can be made between direct and indirect measuring methods, as well as between analog and digital measuring methods. The direct measuring method is a comparative method, whereas with the indirect method the desired measuring value of a variable is determined on the basis of a different physical variable. With the analog measuring method, the incoming variable is converted by the method into a corresponding value which is proportional to the incoming variable. Digital means that a measured variable is converted into a digital value and displayed as such.

Control systems are aimed at strategically influencing certain variables in technical systems. These variables are either to be kept as constant as possible under the influence of disturbances or to be influenced in such a way that they follow a specified change over time. Control means measuring the variable to be influenced in the system controlled and continuously comparing it with the desired value. Depending on the deviation, the controller determines a regulating variable which acts on the controlled variable in such a way that it minimizes the deviation and the controlled variable assumes a desired time response despite the presence of disturbance variables. Generally speaking, control systems work according to a setpoint mechanism.

An electronic temperature controller uses a temperature sensor to measure the current temperature and attempts to produce the specified target temperature. It therefore compares the current temperature to the target temperature. The temperature sensor reports the current temperature to the controller and the controller constantly tries to reach the target temperature (closed control circuit).

The temperature sensor makes temperatures of different media measurable and changes when temperature conditions vary. For example, it reacts to variable input values with variable shapes, resistances, current and voltage values. The sensors are needed to control certain variables or processes depending on temperature.

The eltherm portfolio consists of two types of controllers. While one temperature controller is oriented to the ambient temperature, with the other the pipeline temperature is the decisive measured variable.

The Pt100 (platinum measuring resistor) is connected to the transmitter or to the measuring device by means of a wire. There are 2-wire circuit, 3-wire circuit and 4-wire circuit for this purpose.

With the control system, there is no adjustment of setpoint and current values. It is only a matter of achieving a certain state. Disturbance variables are not taken into account, whereas the measuring system tries to compensate for these.