Transmission line results

The losses, and hence the effective resistance, are also increased by passing the line in close proximity to a nonmsulatmg surface—for example, passing the line over seawater. The metal from which the conductor is made is also vei y important—for example, copper has a lower resistance, for the same geometry, than aluminum does. Also related to the losses of the transmission Hue is the shunt resistance. Under most circumstances, these losses are negligible because the conductors are so well insulated however, the losses become much more significant as the insulators supporting the transmission line become contaminated, or as atmospheric and other conditions result in corona on the line. 

Overhead transmission lines require that the area beneath them be cleared of trees or tall shrubs, which may result in erosion. When the transmission line right-of-way is not kept clear, the transmission line may come into contact with vegetation, causing a fault on the system and possibly starting a fire. Chemical contamination of soil may result from some types of transmission structures, such as treated wood. Burial of underground cables also can impact the environment due to erosion. 

Figure 2-32 is a convenient chart for handling most in-plant steam line problems. For long transmission lines over 200 feet, the line should be calculated in sections in order to re-establish the steam specific density. Normally an estimated average p should be selected for each line increment to obtain good results. 

Surface roughness is also expected to result in depression of the capacitance semi-circle. This phenomenon, which is indeed apparent in both Figures 1 and 2, is, however, unrelated to surface area. Rather, it is attributable to surface heterogeneity, i.e. the surface is characterized by a distribution of properties. Macdonald (16) recently reviewed techniques for representing distributed processes. A transmission line model containing an array of parallel R/C units with a distribution of values is physically attractive, but not practical. An alternative solution is introduction of an element which by its very nature is distributed. The Constant Phase Element (CPE) meets such a requirement. It has the form P = Y0 wn... 

The methods described above were tested at two sites in Hawaii The Nuuanu reservoir on Oahu, which is above downtown Honolulu, and the Waikoloa Dam on Hawaii Island, which is above the town of Waimea. In both cases the analyses were performed with and without topographic data obtained by a field survey crew. Detailed results from the ca e studies and results of a sensitivity analysis are reported elsewhere. The flood inundation maps produced for Waimea and Honolulu were overlaid onto several GIS infrastructure layers. These layers included major roads, secondary roads, schools, nursing homes, hospitals, police stations, fire stations, civil defense headquarters, chemical plants, electric plants and transmission lines, water plants, and wells (which could be contaminated by floodwaters). Critical facilities in the flood zone were identified and listed along with their mailing addresses and phone numbers of contact personnel. 

External noise denotes fluctuations created in an otherwise deterministic system by the application of a random force, whose stochastic properties are supposed to be known. Examples are a noise generator inserted into an electric circuit, a random signal fed into a transmission line, the growth of a species under influence of the weather, random loading of a bridge, and most other stochastic problems that occur in engineering. In all these cases clearly (4.5) holds if one inserts for A(y) the deterministic equation of motion for the isolated system, while L(t) is approximately but never completely white. Thus for external noise the Stratonovich result (4.8) and (4.9) applies, in which A(y) represents the dynamics of the system with the noise turned off. 

Pattle. Boyer (B12) has derived these results in a different way and applied them to the release of energy in an ionized gas, as well as to a transmission line problem. 

For the films and conditions we have used, the transmission line and lumped element models give indistinguishable results. Fitting of the data of Fig. 13.7 yields G as a function of time. These values increase at short times (due to nucleation phenomena) to long time limiting values of G = 1.9 x 106 dyne cm-2 and G" = 3.0 x 108 dyne cm-2. These values of the shear modulus components show that, in dichloromethane, the PVF film is a very rubbery polymer in which there is considerable viscoelastic loss when the film thickness exceeds 1 p.m. 

---