Paralleled windings

Precision wire-wound resistors are used for critical applications in which low noise and resistance stability are important, but since they are coils, they have an inductive reactance that must be taken into account for ac circuits. By folding the insulated wire in the middle and carefully forming parallel windings, the inductive component can be reduced by about a factor of 100. Precision standard resistors with an accuracy of about 50 ppm in the range of 1 fl to 10 Mfl are available from Electro Science Industries and other companies. These are often combined in the form of decade resistance boxes to provide a wide range of fixed values. 

Roving, collimated Made using a process permitting parallel winding so that the strands are more parallel than in standard roving. 

Collimated roving n. Roving with strands that are more nearly parallel than those in standard roving, usually made by parallel winding. 

Cup anemometers have shaped cups mounted on the spokes of a wheel. The cups, under the action of the fluid forces, spin in a horizontal plane about a vertical shaft mounted in bearings. Vane or propeller types use a multibladed rotor, the axis of which is parallel to the flow direction as the rotating member. Both designs are commonly used for wind speed measurement or similar appHcations such as the velocity in ventilation ducts. Because of inertia, anemometers are most accurate under steady conditions. Velocity fluctuations cause readings that are too high. 

CT with a primary winding (4) CT with two secondary windings, in 2 sections which may be each with its own magnetic core, connected in series or parallel... 

When the isobars are essentially straight, the balance between the pressure gradient force and the coriolis force results in a geostrophic wind parallel to the isobars. 

When the isobars are curved, an additional force, a centrifugal force outward from the center of curvature, enters into the balance of forces. In the case of curvature around low pressure, a balance of forces occurs when the pressure gradient force equals the sum of the coriolis and centrifugal forces (Fig. 17-12) and the wind continues parallel to the isobars. In the... 

Because at higher latitudes the coriolis force deflects wind to a greater extent than in the tropics, winds become much more zonal (flow parallel to lines of latitude). Also in contrast to the persistent circulation of the tropics, the mid-latitude circulations are quite transient. There are large temperature contrasts, and temperature may vary abruptly over relatively short distances (frontal zones). In these regions of large temperature contrast, potential energy is frequently released and converted into kinetic energy as wind. Near the surface there are many closed pressure sys-... 

One of the effects of wind speed is to dilute continuously released pollutants at the point of emission. Whether a source is at the surface or elevated, this dilution takes place in the direction of plume transport. Figure 19-2 shows this effect of wind speed for an elevated source with an emission of 6 mass units per second. For a wind speed of 6 m s", there is 1 unit between the vertical parallel planes 1 m apart. When the wind is slowed to 2 m s there are 3 units between those same vertical parallel planes 1 m apart. Note that this dilution by the wind takes place at the point of emission. Because of this, wind speeds used in estimating plume dispersion are generally estimated at stack top. 

In this section a selection procedure will be developed for injection moulding, since this process is used for the widest range of materials. The choice available for other processes such as, for example, compression moulding, filament winding and vacuum forming, is much more restricted. The approach described will be less mechanistic than the systems described in the two previous sections, requiring the prospective user to be aware of the properties of the various materials available. Because the approach is somewhat different, it would be instructive to run it parallel to the above processes and compare the results. 

The net aerodynamic force exerted on a body is illustrated in Figure 2 by the arrow labeled R. The direction and speed of the airflow ahead of the body is denoted by V, called the relative wind. The body is inclined to V . by the angle of attack, a. The resultant aerodynamic force R can be resolved into two components lift, L, perpendicular to V. and drag, D, parallel to V,. In Figure 2, R is shown acting through a point one-quarter of the body length from the nose, the quarter-chord point. Beacuse the aerodynamic... 

There are two major types of wind turbines horizontal-axis and vertical-axis. A wind turbine that rotates about an axis parallel to the wind is a horizontal-axis wind turbine (IIAWT). Although IIAWTs have not been proven clearly superior to Vertical-Axis Wind Turbines (VAWTs), they have dominated recent... 

Split-Phase Motor. A split-phase motor is a single-phase induction motor equipped with an auxiliary winding, displaced in magnetic position from, and connected in parallel with, the main winding. Note Unless otherwise specified, the auxiliary circuit is assumed to be opened when the motor has attained a predetermined speed. The term split-phase motor, used without qualification, described a motor to be used without impedance other than that offered by the motor windings themselves, other types being separately defined. 

Straight Shunt-Wound Motor. A straight shunt-wound motor is a direct-current motor in which.the field circuit is connected either in parallel with the armature circuit or to a separate source of excitation voltage. The shunt field is the only winding supplying f ield excitation. 

Each time the external lines of flux are drawn into the core, they pass through the sense windings B-B to generate a voltage pulse whose amplitude is proportional to the intensity of that component of the external field that is parallel to the centerline of the sense winding. The polarity, or direction of this pulse, will be determined by the polarity of the external field with respect to the sense windings. When the flux lines are expelled from the core they cut the sense... 

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