Hello learners.Hope in the self-learning module, you got brief idea about civil engineering in substation engineering. We already discussed some of civil engineering aspects in the self-learning module. Let us discuss about few more critical civil engineering aspect here. This session will cover the topics on civil engineering in MV substation such as, various civil activities involved in substation, preliminary works for substation and layout finalization, detailed design of buildings and substation, autos, steel structures in substation, foundation for steel structures, infrastructure works like road, and civil underground system. Now, let us look at what are the various civil activities involved in a substitution. It is majorly classified into two categories, site data, and engineering. Before we start up with any activity, basic and primary details about the land allocated for substation shall be collected by doing contour survey. Survey can be done by using total station equipment are by drone. The data to be collected in contour survey where already covered in detail in the self-learning module. Here is the quick recap. The following data are collected during contours survey. Profile of land, coordinates of plot, spot levels, approach road from existing road, utilities, like transmission line, nallah, etc. Engineering properties and hydrological conditions of soil are obtained by doing the detailed geotechnical engineering using various field test at site under laboratory test. After the collection of contour survey input and geotechnical data. First and foremost, in an engineering activity is preparation of layer, followed by detailed engineering. Based on the contour input, the layout for substitution and site grading is to be finalized. Substation shall generally be placed in the flat ground with uniform level are in certain cases, multiple ground level maybe proposed by meeting the electrical requirement. The various factors and key parameters to be considered in designing the FGL of any station, that already discussed in our self-learning module. Finished ground level, shall be about maximum flood level, our existing road level. Once the layout engineering is completed, the detailed engineering is performed for substructure, superstructure, and infrastructure of works based on that site data. and project requirement. The substructure, that is foundation for doubles equipment support structures, transformers, and various other buildings, are designed considering the geotechnical information. After the completion of the foundation, the superstructure in the form of towers, girders, equipment support structures, and building, it's constructed as per the design, and connected with the foundation with the help of anchor, or foundation bolts. Infrastructure works comprise of, substitution routes for access to the equipment during erection and maintenance. Gravel filling, minimize step potential, and touch potential voltages. Storm water drain, to drain out the rainwater from switch yard, cable trenches, gate, fence, and compound wall. Once the site grading with about jellies is decided, finalization of substitution layout proceeds with the collection of primary details, like orientation of incoming and outgoing lines, source substation details, location, and orientation of means such as entrance, existing, high tension, and low tension lines, proneness of area towards flood, existing nallah, and plot boundary. Secondary details like keeping the provisions of possible repair and maintenance of equipment without interrupting the power supply, requirement of future expansion off switch yard and the provision for the same shall be considered. Last but not the least, the outgoing transmission line should not cross each other. The pictorial view in the figure shown here demonstrates the layout of substation. MV substation consist of two types of buildings, electrical buildings, and utility buildings. Electrical buildings are of two categories. Control building and GIS building. Control comes with your building is also called as main electrical building. As the substitution is a restricted area, a security room or guard room, is usually built as utility building near the entrance road to restrict unauthorized access. Building dimensions and arrangements are considered, as per the final equipment layout. Substation building is designed as reinforced concrete frame structure with reinforced concrete roof are steel roof based on project procurement. Plan view of the control building frame is shown in the figure for illustrations, various electrical rooms accommodated in the control building are HV and LV, switchgear room, control and relay panel room, and battery room. Other rooms in control building are, office room, store room, pantry, toilet, and staircase. Substation building shall be planned or arranged by considering the following aspects. One, architectural aspects, minimum passage or corridor area should be provided for movement of persons on panels. Rooms shall be properly arranged and staggered arrangement should be minimized as much as possible for effective utilization of the floor area. The building should be aesthetically pleasant, and shall comply with the air conditioning, and false ceiling requirements. Two, structural aspects, spacing of columns and beams should be such that, it satisfies the requirements, like optimization and interfacing with the electrical discipline. Panels are provided with the minimum spacing of 0.8 meters around, for proper access. Arrangement of beams and openings and clear hydrocarbons based on panel, or equipment height shall be taken care of. Third, executional aspects, cutouts, and openings should be appropriately designed for cable entry to panels. Placing of cutouts in floors shall be planned, keeping the cross beams in view. The openings should be continuous and requirements for considering the equipment maintenance shall be satisfied.
