CC608- BUILDING SERVICESLecturer : Mr. Rafikullah Deraman Department: Civil Engineering Department Topic 1: ELECTRICAL INSTALLATION SYSTEM IN BUILDINGS GENERAL OBJECTIVE To understand electrical installation in buildings LEARNING OUTCOMES 1 At the end of this topic students will be able to: Described the basic concept of electrical supply Described the 1 phase and 3 phases of electrical supply Identify the differences between 1 phase and 3 phases Explained the advantages and weakness of the 1 phase compared to the three phases AN OVERVIEW OF ELECTRICITY PRODUCTION Electrical energy is not a natural or primary source of energy an it cannot be stored very easily Electrical energy is generated by several ways: i) Stored energy (fossil fuel, nuclear and biomass) is converted to thermal energy to make steam that turns the turbine attached to the generator ii) Gravitational potential energy (Hydro) is converted to kinetic energy of water to turn the turbine iii) Kinetic energy of wind turns a wind turbine to generate electrical energy iv) Solar energy transforms directly into electrical energy by solar cells v) Chemical energy transform directly into electrical energy by accumulators BASIC CONCEPT OF ELECTRICAL SUPPLY Electricity arrives in your area from the national supply network (the National grid) at 275 kV or 400 kV. Then it’s reduced to 132 kV volts at a substation for distribution within each area of the country, travelling to further substations known as grid supply points From these, it is distributed an overhead lines or underground cables at 33kV to the intermediate substations National Grid At the intermediate substations, electricity at 33 kV is reduced to 11kV for secondary distribution The secondary distribution networks the carry it at 11kV to individual towns, industrial areas and group of villages Particularly heavy users such as manufacturing industries are supplied at 33kV Transmission (Penghantaran) THE SINGLE PHASE OF ELECTRICAL SUPPLY Electrical system supply consisting of 2 types of systems namely as Single Phase 240v and Three Phase 415v Single Phase supply system normally installed in small premises such as homes, small shops and so on, where the load on the premise that there is a small number. The overall total current load not exceeding 60 Amp. For Single Phase supply system comprises three wires namely live, neutral and protection (earthing). Live wires carried out electrical supply of 240Volt. Generally, single phase supply system is taken from a three phase supply system of the system Provider SINGLE PHASE TYPE the three phase electrical supply Three-phase electric power is the most common method use by electric power distribution grids worldwide to distribute power. For three phase supply systems are normally installed in medium to large premises such as two-storey house (bungalow), offices, restaurants and a workshop where current load more than 60 Amp. It is also installed on large premises such as factories, buildings and so on. For three phase supply system that were consists of five cables. Three cables namely Live (Red, Yellow and Blue)/(Red, Yellow, Blue),a neutral cable and a earthing / protection wire All three conductors carried-out supply of 415v. Three phase supply system can be distributed to 240 Volt single phase system. PURPOSE OF 3Ф The applications of the three-phase system is; a) To turn on the machines 3Φ b) To supply power to large factories. c) For the transmission and distribution system to the consumer. comparison Between Single Phase and Three Phase Single Phase Three Phase Use in residential Use for large and industrial building 240 voltage 415 voltage Single phase has two line voltage 3 phase has three line voltage wires, separate from each other. wires, actually saving more energy Each are 120V for total of 240V . and money for total of 415V Use more electricity. Expensive to Uses less conductor electricity. operate. Cheaper to operate. Use more conductor material to Uses less conductor material to transmit electric power. transmit electric power comparison Between Single Phase and Three Phase Nowadays three-phase system is more widely used in industries that require power level higher than a single-phase system. Among the advantages of three-phase systems than one phase are; a) More economical because less construction and maintenance costs. To provide significant amount of power equal to one phase of the system, the use of smaller conductors and copper requirements can be reduced further. b) Easy installation because of lines or cables are smaller and lighter. This resulted in a small supporting structure can be erected at a considerable distance between supports. c) equipment such as induction motors 3Φ have starting and operating characteristics are better because the power more stable and permanent. d) The electrical energy supplied by the system 3Φ higher than 1Φ e) Most of the large motor using induction motor 3Φ as may be came into being without the need for additional equipment such as capacitors, centrifugal switches or other additional circuits f) Production (output) and the quality of equipment work better than 1Φ whereby 3Φ to have efficiency and higher power factor.
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