Abstract: After the economizer, an injection water pipe branches off the connecting pipe between economizer and evaporator in order to control the steam temperature. The injection water pipe is provided with a control device for controlling the injection water flow. The injection water flowing through the injection water pipe is injected into the steam coming from the evaporator at a mixing point located before the superheater. In order to control the position of the control device in the injection water pipe, the enthalpy at the superheater outlet is calculated from the parameters pressure and temperature and is compared with a desired enthalpy resulting from the desired parameters.

Abstract: The plant has a controlled section through which water flows, for example, for cooling or heating purposes. The operation of the controlled section is controlled by obtaining temperature measurements of the flow via a pair of temperature sensors and emitting a control signal in response to a difference to a valve in a connecting line which is in parallel with the heat exchanger. The same signal is also directed to a comparator in a control circuit within which a second process variable, i.e. flow quantity, is measured. A comparison between these latter signals is made and a resulting difference signal is used by a controller to adjust a valve in the feed line to the heat exchanger to adjust the flow of medium.

Abstract: The control circuit is provided with a signal transmitter for feeding a temporary disturbance signal to the controller 16, a selector which is selectively connected to the signal transmitter and a function transmitter and a disturbance indicator which switches the selector to the function transmitter in response to a signal from the signal transmitter falling outside a certain preset range of threshold values. The control of the circuit may be constructed in various manners.

Abstract: The method serves to control sluggishly reacting plants by controllers in which rapid changes in set value occur. The controller has an integral section and a proportional section separate from the I-section. The I-section receives a control deviation signal formed from the actual value and the set value, whereas the P-section is supplied with the set value. The output signals of the I-section and of the P-section act on the plant. The I-section is blocked for the duration of an abrupt change in the set value.As a result of this relatively short interruption in operation of the I-section, the control of the plant is improved.

Abstract: The PI controller for a blockable servo motor comprises a selector having a first, normal operating position in which a difference signal is fed to the I network. In the other position, the output of a subtraction member is fed to the I network. The inputs of the subtraction member receive the input and output of the servo motor. The selector is actuated by means of a comparator which also blocks the servo motor when the difference signal is of small absolute value. In this way, the servo motor is not operated as frequently and yet this does not appreciably impair the control accuracy.