Distribution network

Distribution networks in towns have been built over periods of decades with various phases of pipeline technology. Networks can consist of welded steel pipes, steel pipes with lead sockets, different types of cast iron and plastic pipes. 

A similar danger of corrosion lies in cell formation in steel-concrete foundations (see Section 4.3). Such steel-concrete cells are today the most frequent cause of the increasing amount of premature damage at defects in the coating of new steel pipelines. The incidence of this type of cell formation is increased by the connection of potential-equalizing conductors in internal gas pipelines and domestic water pipelines [25], as well as by the increased use of reinforcing steel in concrete foundations for grounding electrical installations [26]. 

The requirements derived in Eq. (10-5) are relevant in the cathodic protection of distribution networks for low and as uniform as possible values of resistance and leakage loading. The second requirement is often not fulfilled with old pipeline networks on account of their different ages and the type of pipe coating. When setting up cathodic protection, a distinction must be made between old and new steel distribution networks. 

Insulating connections or joints are used in new distribution networks for gas service pipes. Their installation in these pipes has been compulsory in Germany since 1972 [28]. Therefore, use of cathodic protection here is no problem and is 

In distribution networks installed before 1972, all service pipes must be provided with insulating connections. The following documents are useful in addition to those given in Section 10.3.1  

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Sales gas would be piped directly into the national gas distribution network (assuming one exists) and NGL products such as propane and butane can be stored locally in pressurised tanks. NGL products are often distributed by road or rail directly from the gathering station, although if ethane is recovered it is normally delivered by pipeline. 

Lin, M., Hsieh, J., Du, D. H. C., Thomas, J. P., MacDonald, J. A. Distributed network computing over local ATM networks. In Proceedings of Supercomputing 94. IEEE Computer Society Press, Los Alamitos, California, 1994. Greengard, L., Rokhlin, V. A fast algorithm for particle simulation. J. Comp. Phys. 73 (1987) 325-348. 

Bags of various constmctions are used in the storage and transportation of dry chemicals. The choice of which type of bag to use should be based on the needs of the product for adequate protection and the requirements of the distribution network. To a certain degree, bags can be custom-made for a particular product indeed, almost any shipping requirement can be satisfied by one of many combinations of paper, plastic, and natural fibers incorporated in the design of bags. 

The selection should be such as to provide proper discrimination at the various levels of a multi-distribution network. Our discussions generally take account of the recommendations in lEC 60947-4-1 regarding coordination between the short-circuit protection and the main components such as switching devices [switch, breaker. 

Secondary transmission line (J) H.T. distribution transformer H.T. distribution network ( L.T. distribution transformer L.T. distribution network... 

Figure 13.15 Typical layout of a typical transmission and distribution network and significance of circuit impedances at various points...

We illustrate a typical powerhouse generation and transmission system layout in Figure 13.21, and reproduce in Table 13.10 the typical fault levels of different transmission and distribution networks in practice for different voltage systems. 

Table 13.10 Typical fault levels for an integrated transmission and distribution network...

Figure 18.15 A power generation, transmission and distribution network and strategic locations for the surge arresters...

For an industrial power distribution network, if the setting of the protection reiay is considered to be 20% of I, then... 

In view of the considerable increase in power distribution networks and their overutilization to meet increasing constinier and industrial demands it has become imperative to optimize the use ol available power through efficient trtuismission and distribution. 

The power factor of a motor decreases sharply at loads lower than rated as discussed in Section 1.8. All the above factors, contribute to reducing the overall system power factor, which is sometimes seen to reach a low of 0.6 or even less on an LT distribution network. 

It is pertinent to note that since a filter circuit will provide a low impedance path to a few harmonic currents in the circuit (in the vicinity of the harmonic, to which it has been tuned) it may also attract harmonic currents from neighbouring circuits which would otherwise circulate in those circuits. This may necessitate a slightly oversized filter circuit. This aspect must be borne in mind when designing a filter circuit for a larger distribution network having more than one load centre. 

A distribution network 33 kV, three-phase 50 Hz feeding an industrial belt with a number of medium-sized factories some with non-linear loads and some with static drives and some with both. It was observed that while the lines were apparently running reasonably loaded, the active power supplied was much below the capacity of the network. Accordingly, a harmonic study of the network was conducted and it was found that despite localized p.f. control by most factories, the p.f. of the network itself was well below the optimum level and the voltage was also distorted by more than was permissible. To improve this network to an acceptable level, we have considered the following load conditions, as were revealed through the analysis. 

Refer to a typical distribution network shown in Figure 2.5..5 I. The capacitor is of maximum use when located as near to the load-point as possible, especially in induction motors, because ... 

It can also be applied to an HT distribution network that has a high series inductive reactance to improve its receiving-end voltage. 

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