Electronic transmitters

In a dhfribiifed control system (DCS) process loop with an eJeetronie transmitter. The DCS controller and the electronic transmitter have time constants that are dominant over the positioner response. Positioner operation is therefore beneficial in reducing valve-related nonlinearitv,... 

COMMENTS Sources do not specify between pneumatic and electronic transmitters... 

The oxygen absorber, the reactor, and the connecting tubing were immersed in a constant temperature oil bath whose temperature was controlled within 0.2°C. The oxygen uptake by the coal was recorded, and the pressure in the system was controlled with Swarthout electronic transmitters and recorders. Pressure control was within 10 3 atmospheres, while experiments were made up to 9 atmospheres total pressure. 

The predominant environment of the human body is one in which there is a redox potential that enhances the reception of electrons, resulting in a prevaifing presence of iodide (I ) as inorganic form of iodine. Thus, in many enzymatic reactions iodine can act as electron transmitter. Principally — according to the actual chemical status of iodine — enhancing, as well as inhibiting, influences are possible. The participation of in peroxidase reactions is... 

Factors influencing the choice of an instrument depend primarily on the pressure of the application and whether the gauge is required for control or simply as an indicator. For control, electronic transmitters are preferred whereas mechanical devices are suitable as indicators. Mechanical indicators are easy to read and interpret but may be difficult to install in tight areas or may require extensive tubing. Electronic transmitters may be easier to install in tight areas or remote connections but require a power supply and wire, as well as additional displays. The dynamic response of electrical instruments is superior to mechanical indicators since the data can be recorded at high frequency. 

Based on the biochemical and sequence data, we have proposed that 2-oxoacid ferredoxin oxidoreductases with different subunit compositions have an essentially similar catalytic mechanism with one TPP and at least one [4Fe-4S] cluster as the minimal set of redox centers, which will include the intermediacy of a hydroxyalkyl-TPP radical, and that the 8 subunit/domain carrying two [4Fe-4S] clusters may serve as (accessory) intramolecular electron transmitter from the [4Fe-4S] cluster in the p subunit/domain to the physiological electron acceptor... 

Transfer functions can also be used to describe the dynamic behavior of instruments, controllers, and valves. For a temperature transmitter the steady-state gain is simply the output span divided by the input span an electronic transmitter which has a 4 20 mA output and a 100-200 F temperature input range gives a gain of (20 — 4)/(200 — 100) = 0.16 mA/°F. Sensors usually have simple dynamics, typically described by a first-order transfer function. The characteristics of control valves are more complicated and are discussed in the next section. 

Differential pressure or AP cell transmitters come in two basic designs pneumatic or electronic. Controllers are typically mounted between 400 feet (closed loop) and 1,000 feet (open loop) from the transmitter. The signal from an electronic transmitter is proportional to the difference in the high-and low-pressure legs. Standard output signals are 4 to 20 mA, 10 to 50 mA, and 1 to 5 volts (V). 

Remote indication is possible via an electronic transmitter coupled to the indicator. However, this will not improve the rehability or accuracy of the mechanical gauge. 

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