Current meter

Gup and Vane Anemometers. A number of flow meter designs use a rotating element kept in motion by the kinetic energy of the flowing stream such that the speed is a measure of fluid velocity. In general, these meters, if used to measure wind velocity, are called anemometers if used for open-channel Hquids, current meters and if used for closed pipes, turbine flow meters. 

Current Meters. Various vane designs have been adapted for open-channel flow measurement. The rotating element is partially immersed and rotates rather like a water wheel. Operation is similar to that of vane anemometers. 

The current meter is generally used for measuring velocities in open channels such as rivers and irrigation channels. There are two types, the cup meter and the propeller meter. The former is more widely used. It consists of six conical cups mounted on a vertical axis pivoted at the ends and free to rotate between the rigid arms of a... 

U-shaped clevis to which a vaned tailpiece is attac-hed. The wheel rotates because of the difference in drag for the two sides of the cup, and a signal proportional to the revolutions of the wheel is generated. The velocity is determined from the count over a period or time. The current meter is generally usebil in the range of 0.15 to 4.5 m/s (about 0.5 to 15 ft/s) with an accuracy of 2 percent. For additional information see Creager and Justin, Hydroelectric Handbook, 2d ed., Wiley, New York, 1950, pp. 42-46. 

Strength. -messer, m. current meter specif., (Elec.) ammeter, amperemeter,... 

Radiation detection circuit currents or pulse rates vary over a wide range of values. The current output of an ionization chamber may vary by 8 orders of magnitude. For example, the range may be from 10"13 amps to 10"5 amps. The most accurate method to display this range would be to utilize a linear current meter with several scales, and the capability to switch those scales. This is not practical. A single scale which covers the entire range of values is used. This scale is referred to as logarithmic. 

Current leads, in superconducting electromagnets, 23 855—856 Current meters, 11 666 Current Patents Fast Alert service, 18 235 Current percolation, through grain boundaries, 23 842-845... 

Electrical problems related to barrel heaters, band heaters, and instruments occur constantly in most production lines. In most cases, the problem is easily identified and fixed. For example, most barrel heaters are configured with a current meter on the control panel. If the controller is calling for heat on the zone and the meter... 

The basic elements needed for demineralization experiments are a demineralization cell, solution reservoir and pump, constant voltage power supply, conductivity cell (with temperature regulation) and bridge and voltage and current meters. A typical demineralization assembly is shown in Figure 2. 

Current meter and rotating anemometer. These two, which are the same in principle, determine the velocity as a function of the speed at which a series of cups or vanes rotate about an axis either parallel to or normal to the flow. The instrument used in water is called a current meter, and when designed for use in air it is called an anemometer. As the force exerted depends on the density of the fluid as well as on its velocity, the anemometer must be so made as to operate with less friction than the current meter. 

Another way of investigating the depth in energy to which charges are trapped (a measure of the stability towards thermal decay) may be obtained by thermally stimulated currents (TSC). In this technique, electrodes on the two sides of the electret are connected via a sensitive current meter and the specimen is then heated at a constant, slow rate (1 Cmin-1, say). Discrete current peaks are observed as a function of temperature as successively more deeply trapped charges are released (Fig. 7.22). Dipolar relaxation may also give peaks in the TSC spectrum (van Turnhout, 1975). 

Bidstrup P, Bonnell J, Harvey DG, et al. 1951. Chronic mercury poisoning in men repairing direct current meters. Lancet 856-861. 

---