scope:

Objective and scope

The series of guidelines, VDI 3500 through 3508, gives guidance on the proper design of the control circuits for steam generators in fossil fired power stations. Each of the guidelines is an independent document, but their contents are largely coordinated. Following the description of the controlled system, the control task is defined. A subsequent paragraph describes appropriate circuitry for the control circuits, and a further part deals with the measuring instruments and actuators needed to realise the control unit. The findings and experience contained in these guidelines are widely known and acknowledged, but the information has not previously been compiled in this form.

The terms and notations used are in accordance with the definitions and symbols as given in the standards DIN 19 227 "Control technology; Graphical symbols and identifying letters for process control engineering", DIN 2481 "Thermal power stations", and ISO 3511-3 "Process measurement control functions and instrumentation - Symbolic representation - Part 3: Detailed symbols for instrument interconnection". This guideline describes measures serving to maintain the negative pressure in the combustion chamber of fossil fired steam generators.