Location of Faults

In the lower part of Fig. 3-20 the types and approximate positions of defects can be recognized from the potential and pipe current curves. Only in the region of the protection station is an off potential more negative than achieved, as a result of the 

Contacts with other pipelines or grounds can be localized to within a few hundred meters by pipe current measurements. Contacts with foreign pipelines or cables can also be found by measuring potential at the fittings of the other line while the protection current of the cathodically protected pipeline is switched on and off. While the potential of unconnected pipelines will assume more positive values when the protection current is switched on, the cathodic current may also enter any line in contact with the cathodically protected pipeline and thus shift its potential to more negative values. Should the contacting line not be located by this method, fault location can be attempted with direct or alternating current. 

---

Other information that can be obtained from such map is the location of faults, the status and location of wells and the location of the fluid contacts. Figure 5.45 shows some of the most frequently used map symbols. Structural maps are used in the planning of development activities such as well trajectories/targets and the estimation of reserves. 

Location of faults by the direct current method is based on the application of Ohm s Law. It is assumed that, because of the good pipe coating, virtually no current passes into the measured span and that the longitudinal resistance R is known. When the fault-locating current, I, is fed in and takes a direct path via the foreign line to the protected pipeline, the fault distance is determined from the voltage drop AU over the measured span ... 

L. Van Biesen, J. Renneboog, and A.R. Barel, Hi accuracy location of faults on electrical lines using digital signal processing, IEEE Transactions on Instrumentation and Measurement, vol. 39, no. 1, pp. 175-179,1990. 

The first table. Table 7, shows the influence of the various factors which may be grouped under the heading of Functional Testability. The importance of fault detection and failure location was discussed in section 5 however, as Table 7 shows, these factors extend beyond the detection and location of faults. The need for special test equipment influences logistic time. The presence of test points and BITE also affects preparation for changeover or repair because of the need to ensure a safe system state before proceeding with these activities. 

DSHA/NDSHA requires fault geometry and geographic location of faults which can be readily obtained from tectoiuc maps and earthquake locations from seismicity maps. In a nutshell, input MCEs for sources are estimated as staled above and ground motion hazards can be obtained by using input GMPE in DSHA and by direct computation in NDSHA. 

Below we briefly discuss the criteria and theory of selecting a grounding system to achieve a desired level of fault current to suit a predetermined ground fault protection scheme, i.e. type of grounding and grounding impedance to suit the system voltage, type of installation, and location of installation. 

Tlte value of / can thus be varied in magnitude and phase displacement to suit a particular location of installation or pi otective scheme by introducing suitable R and /Y into the neutral circuit. When the impedance is inductive, the fault current will also be inductive and will offset the ground capacitive current /". In such a grounding, the main purpose is to offset the fault current as much is possible to immunize the system from the ha/ai ds of an arcing ground. This is achieved by providing an inductor coil, also known as an arc suppression coil, of a suitable value in the neutral circuit. 

Voltage polarization depends upon the location of the relay and the location of the fault. It is possible that the residual voltage, at a particular location in the system, is not sufficient to actuate the voltage coil of the directional G/F relay. In such an event, current polarization is used to supplement voltage polarization. Current polarization is possible, provided that a star point is created on the system, even through a A/t> power transformer, if such a transformer is available in the same circuit. Figure 21.20. Else a grounding transformer may be provided as... 

Z = positive sequence equivalent system impedance, Q/phase at the location of the fault = negative sequence equivalent system impedance, fj/phase at the location of the fault. 

Quaternary sulfur deposits are distributed along the present volcanic front. Intersections of transverse faults proposed by Carr et al. (1973) and the present volcanic front coincide with the locations of clusters of the sulfur deposits (Nishiwaki and Yasui, 1974). 

The probable route and structures included are identified using the following hierarchical criteria 1) direct and shortest structural connection, 2) interconnection of faults, 3) average breakthrough time of tracer which is directly correlated to tracer concentration and 5) the location of major and minor feed zones within the respective wells. 

It is partly the fault of statistics that experimenters have misconstrued the value of the number and precision of data points relative to the value of the location of the points. The importance of the location of the data in the model specification stage can be seen from Fig. 1, which represents literature data (M3) on sulfur dioxide oxidation. The dashed and solid lines represent the predicted rates of two rival models, and the points are the results of two series of experimental runs. It can be seen that neither a greater number of experimental points nor data of greater precision will be of major assistance in discriminating between the two rival models, if data are restricted to the total pressure range from 2 to 10 atm. These data simply do not place the models in jeopardy, as would data below 2 atm and greater than 10 atm total pressure. This is presumably the problem in the water-gas shift reaction, which is classical in terms of the number of models proposed, each of which adequately represent given sets of data. 

Related studies to the diagnosis of bioprocess have been limited and have used mainly heuristic approaches. Moreover, they have been concerned with the detection of a disfunction of the bioprocess (detection of a desestabiliza-tion, state of the biomass, etc.) rather than the detection and the location of sensor and/or actuators faults. The interested reader will be able to refer to the following references [4], [5], [12], [14], [27], [28], [43], [45], [47], [52], [59], [60], [61], [63], [64], [71]. 

System diagnosis frequently lies on a model that represents the normal behavior of a particular process to be supervised. The fundamental problem comes then from the inaccuracies associated with the model, either related to the ignorance of the kinetics or its parameters, or related to the ignorance of its inputs. Within the framework of this chapter, the interest is focused on the detection and location of sensor faults in the presence of unknown inputs. Among the existing solutions based on observers, one can distinguish the approaches based on non-linear unknown inputs observers (see for example, [21],... 

Location of samples and content of Zn, ppm i-" - Mineral deposits LIti - Prospective areas for next stage. - Faults... 

Fig. 4. Geological map of the Elmtree Inlier showing the Elmtree (ED) and Guitard Brook deposit (GB) located near faults (NBDNRE, 2005).

In order to locate the fault, one normally proceeds by separating the evacuated vessel from the pump system (where this is possible) and checking the vessel alone for leaks and contamination using the pressure rise method, for example. If it has been found that the vessel is free of defects in this regard, then the measurement system w/ill be checked for cleanliness (see Section 8.38) and ultimately - if required - the pump or the pumping system itself w/ill be examined. 

Several kinds of failures may compromise safety and productivity of industrial processes. Indeed, faults may affect the efficiency of the process (e.g., lower product quality) or, in the worst scenarios, could lead to fatal accidents (e.g., temperature runaway) with injuries to personnel, environmental pollution, and equipments damage. In the chemical process fault diagnosis area, the term fault is generally defined as a departure from an acceptable range of an observed variable or a parameter. Fault diagnosis (FD) consists of three main tasks fault detection, i.e., the detection of the occurrence of a fault, fault isolation, i.e., the determination of the type and/or the location of the fault, and fault identification, i.e., the determination of the fault profile. After a fault has been detected, controller reconfiguration for the self-correction of the fault effects (fault accommodation) can be achieved in some cases. 

Figure 15.5 Distribution of faults in the Bagnoli-Fuorigrotta Plain and location of the thermal springs (spas).

Answer 4.4 The fault in Fig. 4.6 was plotted on the basis of abrupt changes in recorded lithologies between wells 6 and 7 (Table, Fig. 4.6a). An alternative interpretation The calcareous sandstone was deposited on a limestone relief with a steep paleo-erosional face between the locations of wells 6 and 7. 

---