Power distribution fault levels

Figure 13.29 A power distribution scheme illustrating the procedure to assign fault level to a device, component or a bus system...

For more clarity we have reproduced in Figure 14.3 an actual test circuit and in Figure 14.4, the oscillograms of the test results of a short-circuit test successfully carried out on an LT power distribution panel (Figure 14.8) for a system fault level of 50 kAfor 1 second, at CPRI (Central Power Research Institute). From a study of these oscillograms (Figure 14.4), we can infer the following test results ... 

The subjects covered aim at providing methods to form specihcations and then design a switchgear assembly for all power distribution needs. It also provides coverage of draw-out asseinblies. Establishing the fault level of a system is described including the electrodynamic and electromagnetic forces that arise. 

The penetration level of this SOFC plant is set at 20 %. A faults occurs that disconnects the utility supply from the distribution system. The fault clearing is after 0.4 s. The comparison between Figs. 28 and 29 shows the advantage of a fast power controller. Since the SOFC inverter has the capability to adjust its angle Sp quickly, the inverter maintains constant power output imder fast transient disturbances. In addition, SOFC inverter has power modulation capabilities that enhance transient stability of the system. 

The computer system of the station control and data acquisition is a distributed micro processer based systems. A digital multiplexed control system takes the place of hard wired analogue control. This accounts for a significant reduction in cable usage. Built-in diagnostics and board level maintenance makes restoration of operability of any fault in the system a matter of replacement of printed circuit cards. Automatic control systems and procedures are deployed to simplify these procedures and power level manoeuvers. In case of unsafe conditions the reactor protection system (PMS) takes over and automatically scrams the reactor and actuates the relevant safety systems. Diverse methods are used to assure the shutdown of the reactor in hypothetical situations. The systems also provide for post-accident monitoring. 

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