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Control valve with pneumatic diaphragm actuator and "smart" 4–20 mA positioner which will also feed back the actual valve position and status over the current loop. The 4–20 mA convention was born in the 1950s out of the earlier highly successful 3–15 psi pneumatic control signal standard, when electronics became cheap and reliable enough ...
A digital current loop uses the absence of current for high (space or break), and the presence of current in the loop for low (mark). [1] This is done to ensure that on normal conditions there is always current flowing and in the event of a line being cut the flow stops indefinitely, immediately raising the alarm of the event usually as the heavy noise of the teleprinter not being synchronized ...
The net electric current I is the surface integral of the electric current density J passing through Σ: =, where dS denotes the differential vector element of surface area S, normal to surface Σ. (Vector area is sometimes denoted by A rather than S , but this conflicts with the notation for magnetic vector potential ).
In the 1950s, when high gain electronic amplifiers became cheap and reliable, electronic PID controllers became popular, and the pneumatic standard was emulated by 10-50 mA and 4–20 mA current loop signals (the latter became the industry standard). Pneumatic field actuators are still widely used because of the advantages of pneumatic energy ...
This page was last edited on 13 March 2007, at 22:35 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may ...
4/20 is an annual event taking place on 20 April (the date is 20/4 or in the American date format 4/20), in celebration of cannabis. While 4/20 is widely used in common vernacular in reference to ...
The crash was reported about 3:30 a.m. Oct. 27 on westbound Northwest Loop 820 just past Marine Creek Parkway. The family’s Ford Focus caught fire after the collision, and a couple and their two ...
Police in Hartford, Connecticut, are searching for the suspect who opened fire at a 12-year-old who threw a snowball at a car. Officers responded to a report of a shooting around 7:15 p.m ...