Reactance measurement

Reactance measurement can be used for self monitoring in carbon fiber reinforced mortar [62], whilst the effect of curing age on the self-monitoring behavior has been established [63]. 

Xuli Fu, Erming Ma, Chung DDL, Anderson WA, Self monitoring in carbon fiber reinforced mortar by reactance measurement, Cement Concrete Res, 27(6), 845-852, 1997. 

Because of a light interaction between the resistance and reactance measuring components, a correction mnst be made to the resistance measurement of a high Q circuit (low resistance and high reactance). The correction factor Cj can be computed from the following equation ... 

These reactances are measured by creating a fault, similar to the method discussed in Section 14.3.6. The only difference now is that the fault is created in any of the phases at an instant, when the applied voltage in that phase is at its peak, i.e. at Vni- so that the d.c. component of the short-circuit current is zero and the waveform is symmetrical about its axis, as shown in Figure 13.19,... 

The influence of skin effects in a multi-core cable is almost the same as that of a multiphase busbar system, discussed in Sections 28.7 and 28.8. However, unlike a busbar system, the resistance and inductive reactance for various sizes of cables can be easily measured and are provided by leading manufacturers as standard practice in their technical data sheets. To this extent, making an assessment of skin effects in cables is easy compared to a busbar system. Since all the phases in a cable, of a 3-core or 3 72-core are in a regularly twisted formation throughout the length of the cable, they represent the case of an ideal phase transposition (Section 28.8.4(3)) and almost nullify the effect of proximity. 

Tan 5 is a measure of dielectric loss in a capacitor unit and is represented by the ratio of equivalent series resistance and capacitive reactance of a capacitor unit at the rated voltage and frequency (Figure 9.7) i.e. 

Strictly, the strain gauges referred to above come into this category, since in such cases the change in the measured quantity causes a corresponding change in the resistance of the element. However, the principle has a much wider application, using changes in either the inductive or capacitive reactance of electrical circuit elements. 

All three of these terms have units of ohms as they are all measures of some form of resistance to electrical flow. The reactance of an inductor is high and comes specifically from the back electromotive force (EMF p. 46) that is generated within the coil. It is, therefore, difficult for AC to pass. The reactance of a capacitor is relatively low but its resistance can be high therefore, direct current (DC) does not pass easily. Reactance does not usually exist by itself as each component in a circuit will generate some resistance to electrical flow. The choice of terms to define total resistance in a circuit is, therefore, resistance or impedance. 

Further, the EIS of pyrite imder different polarization potential in the lime medium are measured and shown in Fig. 7.10. The relationship between polarization resistance and potential can be demonstrated in Fig. 7.11. It can be seen from Fig. 7.10 and Fig. 7.11 that when the anodic polarization potential is between 20 and 350 mV, all the curves appear as a single capacitive reactance loop. But surface process of pyrite electrode is controlled by a quite different... 

This expression has a form exactly analogous to Ohm s law in dc circuits. The quantity l/toCs is called the capacitive reactance Xc. It is a measure of the opposition to the flow of charge in a capacitor, and it is therefore measured in ohms. If we now substitute the definition of Xc into the expression for ec, it follows that... 

Reactance — In alternating current (AC) measurements, reactance is the imaginary part of impedance given by ... 

Since the reactance can be inductive or capacitive and can be parallel or in series with the resistance, there are many variations of the ac bridge. An arrangement suitable for conductivity measurements is discussed in Exp. 17, and an ac bridge used for capacitance determinations is shown in the following section. A more extensive treatment of ac bridges can be found in Refs. 8-10. 

A very similar result was found when we coated the resonator with a layer of collagen. In a typical experiment we measured an increase for A Zl of 236 18 relative to a medium-loaded resonator. Decomposing the complex load impedance in real and imaginary components revealed a load resistance of 43 15 compared to a load reactance of232 18 f2. Thus, the layer of purified collagen shows similar acoustic properties as the remaining ECM on the surface [16]. 

Quality factor (Q) - The ratio of the absolute value of the reactance of an electrical system to the resistance thus a measure of the energy stored per cycle relative to the energy dissipated. 

This eqnivalent circnit takes account of the tnrns ratio between the stator and the rotor if all the rotor resistances and reactance are given in the data as referred to the stator valnes. The circnit can be used with actual quantities such as ohms, amps and volts, or in their per-unit equivalent values which is often more convenient. This approach is customary since it easily corresponds to measurements that can be made in practice when tests are carried out in the factory. 

Scheltinga, M.R., Kimbrough, T.D., Jacobs, D.O., and Wilmore, D.W. (1990) Altered Cell Membrane Eunction in Critical Illness Can Be Characterized by Measuring Body Reactance, Surg. Forum 41,43-44. 

The electronic circuits used with variable capacitance transducers, are essentially the same as any other circuit used to measure capacitance. As with the inductance transducers, these circuits can take the form of a bridge circuit or specific circuits that measure capacitive reactance. One concern with capacitive sensors is that the sensor should be electrically shielded if there are electrically conductive objects in the vicinity of the sensor. Otherwise stray capacitances may affect the measurement. 

Also, deoxyribonucleic acid (DNA) molecules and their electrical conduction have been examined the electrical conduction through DNA molecules (Fink and Schonenberger 1999) and resonances in the dielectric absorption of DNA (Foster et al. 1987). Recently, the Pethig group (Chung et al. 2011) has shown that measurement results in a cell suspension up to iO MHz that is dependent on the cytoplasma membrane capacitance and resistance, the ceU diameter, and the suspension conductivity. By using special interdigitated electrodes, the ceU membrane capacitive reactance sort out the resistance above 100 MHz so that the electric field penetrates into the ceU interior and intracellular dielectric properties can be measured. 

The dissipation factor measures the inefficiency of an insulating material and is defined as the reciprocal of the ratio between the insulating material s capacitive reactance to its resistance at a specified frequency. ]... 

Measurement of Membrane Capacitance. A sufficiently high frequency of light modulation is chosen so that Rm is large compared to the AC impedance (i.e. capacitive reactance) of the membrane. Therefore, in depletion, I can still be described by the relative magnitudes of the internal and external capacitances (Equation 4). As long as Cm Ci (which can be controlled by the size of the illuminated region on the insulated semiconductor), Equation 4 can be transformed into a linear form (Equation 4a). 

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