Resistance-capacitor circuit

This is a significant loss. The resistance therefore should be connected during an interruption only, through a switch (or the no contact of the interrupting device which can easily carry this short time burden) and should not be left permanently in the capacitor circuit. 

Single phase motors do exhibit operational problems in pony motor applications. The capacitors in these motors store energy and the motors resist external attempts to rotate them. Single phase motors can be made to work on pony motor applications by splicing into the capacitor circuit and connecting it in series with an open auxiliary switch in the active motor starter. 

In studies of these and other items, the impedance method is often invoked because of the diagnostic value of complex impedance or admittance plots, determined in an extremely wide frequency range (typically from 104 Hz down to 10 2 or 10 3 Hz). The data contained in these plots are analyzed by fitting them to equivalent circuits constructed of simple elements like resistances, capacitors, Warburg impedances or transmission line networks [101, 102]. Frequently, the complete equivalent circuit is a network made of sub-circuits, each with its own characteristic relaxation time or its own frequency spectrum. 

Electrochemical reactions consist of electron transfer at the electrode surface. These reactions mainly involve electrolyte resistance, adsorption of electroactive species, charge transfer at the electrode surface, and mass transfer from the bulk solution to the electrode surface. Each process can be considered as an electric component or a simple electric circuit. The whole reaction process can be represented by an electric circuit composed of resistance, capacitors, or constant phase elements combined in parallel or in series. The most popular electric circuit for a simple electrochemical reaction is the Randles-Ershler electric equivalent... 

As discussed in Chapter 3, the electrolyte/interface and associated electrochemical processes can be treated as an electric circuit consisting of electrical elements, including resistance, capacitors, constant phase elements, and so on. Although the commonly used electrical elements have already been described in Chapters 2 and 3, the following section provides a brief review to preface the ensuing discussion of EIS equivalent circuits and their related PEM fuel cell processes. 

The impedance of the skin has been generally modeled by using a parallel resistance/capacitor equivalent circuit (Fig. 4a). The skin s capacitance is mainly attributed to the dielectric properties of the lipid-protein components of the human epidermis [5,8,9,12]. The resistance is associated primarily with the skin s stratum comeum layer [5,8,9,12]. Several extensions to the basic parallel resistor/capacitor circuit model have appeared in the literature [5,8,9,13]. Most involve two modified parallel resistor/capacitor combinations connected in series [5,8,9]. The interpretation of this series combination is that the first parallel resistor/capacitor circuit represents the stratum comeum and the second resistor/capacitor parallel combination represents the deeper tissues [5,8,9]. The modification generally employed is to add another resistance, either in series and/or in parallel with the original parallel resistor/capacitor combination [8,9]. Realize that because all of these circuits contain a capacitance, they will all exhibit a decrease in impedance as the frequency is increased. This is actually what is observed in all impedance measurements of the skin [5,6,8-15]. In addition, note that the capacitance associated with the skin is 10 times less than that calculated for a biological membrane [12]. This... 

RC constant The time constant of a resistor-capacitor circuit. The RC constant is the time in seconds required for current in an RC circuit to rise to 63 percent of its final steady value or fall to 37 percent of its original steady value, obtained by multiplying the resistance value in ohms by the capacitance value in farads. 

As can be observed, two semicircles were obtained for dense membrane/NaCl solution and the equivalent circuit is (ReCe)-(RmCm), that is, a series association of two resistance-capacitor subcircuits, one for the electrolyte solution and other for the membrane while data for the ultrafiltration membrane corresponds to a depressed semicircle (associated with a CPE) and the equivalent circuit for the total membrane system is (ReCe)-(RmQm)- However, for the porous membrane/NaCI solution and charged membrane/KCl solution systems, a unique relaxation process (a semicircle) was obtained, which makes it impossible to evaluate the separate contributions associated with the membrane and the electrolyte solution in both cases the equivalent circuit is given by a parallel association of resistance and capacitor representing the total membrane system (RsmQm)-Nevertheless, these two latter systems (shown in Figure 9.3e, f) represent two completely different situations, as can be seem when the corresponding impedance plots for 0.002 M NaCl and 0.01 M KCl solutions are also considered (measurements carried out without membranes in the test cell) ... 

Use of a switch which, in the open posiiion. can shori-circuit the capacitor with small resistance. 

If it is very high, so that its power loss Vf/Rj is low then it may be left permanently in the circuit. Otherwise it should be introduced into the circuit only during interruption through the switching device) (wired across the N(D contact of the switching contactor). This will provide the resistance across the capacitor banks when being interrupted and short-circuit it when closed. 

The above discharge is also possible through only an extra resistance in each capacitor switching circuit. Using equations (25.5) and (25.6),... 

The switching currents must be limited to as low a value as possible. However, in general, capacitors are designed for switching cuirents up to lOO/f (r.rn.s.) for milliseconds. If necessary, a series resistance or indtictance can be introduced into Ihe switching circuit to limit them to a desired level (Seetion 23.1 I ). 

Fig. 14-5 Circuit diagram for a higher resistance dc decoupling devices. (KE) insulated cable end seal, (E) grounding installation, (1) resistance ( 100 mQ), (2) grounding side bar or short-circuit-resistant grounding switch, (3) breakdown fuse, (4) capacitors (ca. 60 F), (5) choke.

One last factor is the physical layout of the output stage when more than one output filter capacitor is used. The capacitors should be located radially symmetric from the output rectifier, and the printed circuit traces for the rectified voltage and the grounds should be of similar trace-widths and lengths. Any dissimilarity of these traces causes more series resistance and inductance to the... 

Films have been used for insulating electric motors, in capacitors requiring a heat resistance not met by conventional polyester and polycarbonate dielectrics and as a soldering-resistant base for flexible printed circuits. 

Capacitors are often combined in series or parallel, with the resulting circuit capacitance calculated as depicted in Figure 4. An important relationship is the time constant of a capacitor. The time constant is based on the product of the resistance and capacitance and is known as the RC time constant. A capacitor in a dc circuit will charge or discharge 63.2 percent in one RC time constant. The time dependence of a capacitor is shown in the equations. 

---