Electro-hydraulic analogy

The electro-hydraulic analogy , also known as hydraulic analogy , establishes relationships in the laws between hydraulic and electrical systems. In this way, hydraulic systems can be described and developed using the methods of electrical circuit technology, and the circuit diagrams common with electrical systems can be converted into hydraulic counterparts, as well as the reverse direction of description from hydraulic circuit sketches to electrical circuits. The electro-hydraulic analogy goes back to the work of the British physicist Oliver Heaviside under the name of drain-pipe theory , who used these relationships to illustrate the new electrical circuit technology at the end of the 19th century with the help of pipelines and the liquids in them.

Analogy relationships

Analogy relationship between a hydraulic and an electrical circuit

In the hydraulic analogy, electrical lines are described as pipelines of a closed system through which a liquid medium such as water flows (hence the name water model , especially in introductory lessons). The electrical current in the electrical line corresponds to the volume flow of the fluid in the pipeline. ${\ displaystyle I}$ ${\ displaystyle Q}$

The potential difference or electrical voltage between two points, such as points A and B in the adjacent sketch, correspond to the pressure difference between two points. The flow resistance of a bottleneck corresponds to the electrical resistance . Electrical voltage sources can be modeled by suitable pumps in the hydraulics, electrical switches by hydraulic gate valves , electrical consumers such as an electric motor by a turbine in the pipeline. ${\ displaystyle U}$ ${\ displaystyle \ Delta p}$ ${\ displaystyle R}$

Analogy of the electrical condenser in hydraulics: elastic shut-off in the pipeline

Special electrical components such as the condenser correspond to an elastic shut-off in the pipeline, which can bend up to a certain pressure difference and does not allow a continuous mass flow through the pipeline. The electrical inductance is described by the hydraulic inductance . The function of electronic components such as a diode , which allows the electric current to pass in only one direction, corresponds to the check valve in hydraulics .

Not only can individual components be implemented, legal relationships can also be established as an analogy. Ohm's law , which is common in electrical engineering and establishes the relationship between electrical voltage, current strength and the proportionality factor, corresponds to the Hagen-Poiseuille law in the case of a laminar flow .

literature

Horst-Walter Grollius: Basics of hydraulics . 6th edition. Hanser, 2012, ISBN 978-3-446-43081-5 .
Helmut Haase, Heyno Garbe, Hendrik Gerth: Fundamentals of electrical engineering . 3. Edition. Schöneworth, 2009, ISBN 978-3-9808805-5-8 .

Individual evidence

^ Paul J. Nahin: Oliver Heaviside: The Life, Work, and Times of an Electrical Genius of the Victorian Age . Johns Hopkins University Press, 2002, ISBN 0-8018-6909-9 .

Web links

Commons : Hydraulic analogy - collection of images, videos and audio files

[heaviside1-1] Paul J. Nahin: Oliver Heaviside: The Life, Work, and Times of an Electrical Genius of the Victorian Age . Johns Hopkins University Press, 2002, ISBN 0-8018-6909-9 .