Losses Resistive

Solid Oxide Fuel Cell In SOF(7s the electrolyte is a ceramic oxide ion conductor, such as vttriurn-doped zirconium oxide. The conduetKity of this material is 0.1 S/ern at 1273 K (1832°F) it decreases to 0.01 S/ern at 1073 K (1472°F), and by another order of magnitude at 773 K (932°F). Because the resistive losses need to be kept below about 50 rn, the operating temperature of the... 

Since the resistive loss would vary in a square proportion of the current, the motor will overheat on lower voltages (drawing higher currents). At higher voltages, while the stator current may decrease, the core losses will be higher. 

Resistive losses within the current-carrying conductors, i.e. within the electrical circuit itself, caused by the leakage flux (Figure 2.6), as a result of the deep conductor skin effect. This effect increases conductor resistance and hence the losses. For more details refer to Section 28.7. 

A very important feature of solid-state technology is energy conservation in the process of speed control. The slip losses that appear in the rotor circuit are now totally eliminated. With the application of this technology, we can change the characteristics of the motor so that the voltage and frequency are set at values just sufficient to meet the speed and power requirements of the load. The power drawn from the mains is completely utilized in doing useful work rather than appearing as stator losses, rotor slip losses or external resistance losses of the rotor circuit. 

The design of the C-R combination maintains a negligible level of leakage current through the suppressor in healthy conditions (to contain resistance loss). It is easily achieved, as C provides a near-open circuit in these conditions and permits only a very small leakage current to flow through it. 

If the closing period is only 15 seconds, the required discharge resistance will become 50 kii. The resistance loss in 100 kiJ, discharge resistance... 

To improve the efficiency of a switching power supply, one must be able to identify and roughly quantify the various losses. Tosses within a switching power supply roughly fall into four categories switching, conduction, quiescent, and resistive losses. These losses usually occur in combination within any lossy component and are treated separately. 

There are three major losses assoeiated with transformers and induetors hysteresis loss, eddy eurrent loss, and resistive loss. These losses are eontrolled during the transformer or induetor s design and eonstruetion. 

Resistive losses are those losses associated with the resistance of the windings contained within the transformer or inductor. There are two forms of resis-... 

Underground transmission lines are preferred in places where rights-of-way are severely limited because they can be placed much closer together than overhead lines. They are also favored for aesthetic reasons. They may be directly buried in the soil, buried in protective steel or plastic pipes, or placed in subterranean tunnels. The conductors are usually contained within plastic insulation encased in a thin metallic sheath. The conductors enclosed in steel pipes may be immersed in oil, which may be circulated for cooling purposes. For all types of underground lines, the capacitance is higher than for overhead lines, and the power transfer capability is usually limited by the resistive losses instead of the inductance. Wliile not exposed to environmental... 

An air-moving device such as a fan will be required to increase the static pressure in order to overcome this resistance loss (see Figure 27.1). 

The application of superconductivity in electrical engineering offers revolutionary possibilities huge current densities with no resistive loss very high magnetic fields with no power supply required the possible elimination of iron in electrical machines and the reduction in size and cost of plant. The first wide-scale application of superconductivity has... 

As shown in Fig. 13.3, fuel cells theoretically have higher efficiencies at lower temperatures, whereas engines are the best choice for higher temperatures. In reality, however, the efficiency in existing systems is much lower due to resistance losses in the system. 

Lifetime performance degradation is a key performance parameter in a fuel cell system, but the causes of this degradation are not fully understood. The sources of voltage decay are kinetic or activation loss, ohmic or resistive loss, loss of mass transport, or loss of reformate tolerance (17). 

In DMFCs, Scott, Taama, and Argyropoulos [117] changed the PTFE content (from 0 to 40 wt%) of the anode DL (E-TEK type A CC) in order to observe how this affected the methanol and carbon dioxide transport through the DL. At very high levels of PTFE, the performance of the cell decreases due to an increase in resistance losses. On the other hand, when an untreated CC was used, the observed performance was the lowest of all the materials investigated. In this study it was concluded that the ideal amount of hydro-phobic agent for the anode DL is around 13-20 wt% (see Figure 4.17). 

All acidic proton conductors discussed so far in this review have relied on the presence of large amounts of water (A = 10—30) as a mobile phase for the conduction of protons. Current targets for automotive use of hydrogen/air fuel cells are 120 °C and 50% or lower relative humidity. Under these conditions, the conductivity of the membrane decreases due to low water uptake at 50% relative humidity and thus creates large resistive losses in the cell. To meet the needs of advanced fuel cell systems, membranes will have to function without large amounts of absorbed water. Organic—inorganic composites are one preferred approach. ... 

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