Building services II-2

SYLLABUS

• REFERENCE BOOKS • 1. E.R.Ambrose, Heat pumps and Electric Heating, John and Wiley and Sons Inc, New York, 1968. • 2. Handbook for Building Engineers in Metric systems, NBC,New Delhi, 1968. • 3. Philips Lighting in Architectural Design, McGraw Hill, New York, 1964. • 4. R.G.Hopkinson and J.D.Kay, the Lighting of Buildings, Faber, and Faber, London, 1969Text books

Current

voltage

• The greater the voltage, the greater the flow of electrical current (that is, the quantity of charge carriers that pass a fixed point per unit of time) through a conducting or semi conducting medium for a given resistance to the flow.  • Voltage is symbolized by an uppercase italic letter V or E. • The standard unit is the volt, symbolized by a non-italic uppercase letter V.  • One volt will drive one coulomb (6.24 x 1018) charge carriers, such as electrons through a resistance of one ohm in one

Power • In general physics terms, power is defined as the rate at which energy is transferred (or transformed). • A battery supplying power to a circuit is an example of a power producer. • Energy is measured in terms of joules (J). Since power is a measure of energy over a set amount of time, we can measure it in joules per second. The SI unit for joules per second is the watt abbreviated as W.

Important components • Resistance (R) - ohms • Inductance (L) -Henry • Capacitance (C) -Farads

Electrical supply • Electrical supply can be broadly classified as 1. DC supply (direction does not change with respect to time or scalar quantity) 2. AC supply (direction changes with respect to time or vector quantity) DC supply can be taken through static components like battery, DC generators. Similarly AC supply can be taken through AC generators or alternators.

Direct Current (DC) • An electric current that flows through a circuit in only one direction, although the rate of flow may vary • Most common household items and appliances operate on DC power

AC supply • AC voltage is generated by AC generators or alternators. • AC voltages are sinusoidal in nature ie their magnitude is changing with respect to time with a specified frequency. • The voltage is represented as V = Vmsinωt. • Current I = Imsinωt • Power P = V I cosф

Classification of AC supply • AC supply can be classified as Single phase AC Three phase AC

Single phase AC • Single phase AC is generated by single phase ac generator or alternator. • The voltage level is of 230V, 50Hz. • This voltage level is used where the consumption of power is less. • So it is used for less wattage motors/ equipments like fan, refrigerator, etc.. • The voltage is represented as V = Vmsin(ωt+ф)

Three phase AC • Three phase supply is generated by 3ф generator. • The voltage level is 440V, 50 Hz. • A single phase generator is an alternator with a single set armature coil producing a single voltage waveform. • A three –phase alternator has three sets of coils spaced at 120o apart and generates three sets of voltage waveforms

Types of three phase system. 1. 3phase 3 wire 2. 3phase 4 wire  Star/wye connected system  Delta connected system

• Star connected system. phase current = line current Iph = IL phase voltage = line voltage/√3 Vph = VL /√3 • Delta connected system phase current = line current Iph = IL /√3 phase voltage = line voltage Vph = VL

Key Differences Between Single Phase and Three Phase • In single phase supply, the power flows through one conductor whereas the three phase supply consists three conductors for power supply. • The single phase supply requires two wires (one phase and one neutral) for completing the circuit. The three phase requires three phase wires and one neutral wire for completing the circuit. • The single phase supplies the voltage up to 230V whereas the three phase supply carries the voltage up to 415V. • The maximum power is transferred through three phases as compared to single phase supply. • The single phase has two wire which makes the network simple whereas the three phase network is complicated as it consists four wires.

• The single phase system has only one phase wire, and if the fault occurs on the network, then the power supply completely fails. But in three phase system the network has three phases, and if the fault occurs on any one of the phases, the other two will continuously supply the power. • The efficiency of the single phase supply is less as compared to three phase supply. Because the three phase supply requires less conductor as compared to single phase supply for the equivalent circuit. • The single phase supply requires more maintenance and become costly as compared to three phase supply. • The single phase supply is mostly used in the house and for running the small loads. The three phase supply is used in large industries and for running the heavy loads.

Single-phase power is: Used in most homes in North America Able to supply ample power for most smaller customers, including homes and small, nonindustrial businesses Adequate for running motors up to about 5 horsepower; a single-phase motor draws significantly more current than the equivalent 3phase motor, making 3-phase power a more efficient choice for industrial applications

Advantages of three phase system • Three phase system has the following advantages as compare to single phase system: 1. Power to weight ratio of 3-ø alternator is high as compare to 1-ø alternator. Means for generation for same amount of Electric Power, the size of 3-ø alternator is small as compare to 1-ø Alternator. Hence, the overall cost of alternator is reduced for generation of same amount of power. 2. For electric power transmission and distribution of same amount of power, the requirement of conductor material is less in 3-ø system as compare to 1-ø system. Hence, the 3-ø transmission and distribution system is economical as compare 1-ø system

– In single phase circuit, the power delivered is pulsating. Even when the single phase voltage and current are in phase, the power is zero twice in each cycle. There is no problem with light loads and small motors but with large motors. It causes excessive vibrations. Whereas, in poly phase system power delivered is almost constant when the load is balanced. – For transmission of electrical power three phase supply requires less copper or less conducting material than that of single phase system for given volt amperes. To transmit same amount of power over a given length, a three phase transmission system requires less conductor. So the three phase system is more economical than single phase system.

– The output of 3-phase machine is higher than the single phase machine of the same size. It is nearly 1.5 times the rating of a single phase machine. It means smaller machine is required in case of three phase machine as compare to single phase machine for same output. – Single phase induction motor has no self-starting torque. Some auxiliary means are required to start the single phase induction motors. But three phase induction motor has self-starting torque except synchronous motors. – Parallel operation of poly phase alternators is simple as compared to that of single phase alternators. – Three phase system gives steady output. – Power factor of single phase machines is poor as compared to three phase machines. – Single phase supply system can be obtained from three phase supply system, but vice-versa is not possible

Wire • Wire is a Solid conductor or Insulated conductor which has strength and with cover or without cover. and Cable means Insulated conductor (Solid or Stranded) or two more than insulated conductor are kept together in insulated layer.

• Types of Wire and Cable:  1. P.V.C Wire (polyvinyl chloride) 2. V.I.R.Wire( Vulcanized Insulated Rubber Wire) 3. C.T.S. Wire (Cab tire sheathed) or T.R.S. Wire (Tough rubber sheathed) 4. W.P.C. Wire (weatherproof wire) 5. flexible wire 6. A.C.S.R. Wire (Aluminium Conductor Steel Reinforce) 7. Lead Covered Wire (L.C. Wire)

• P.V.C Wire: In this cable the wire is coated with strong layer of PVC. This wire is not effected by petrol and oil As well as waste likely to be very less probability. It is not used where temperature is change breaks down. The wire is widely used. • It is available in sizes 1mm , 1.5mm , 2.5mm , 4mm etc. It is available in single core, twin core and three core. It have a long lifetime. It can be used in PVC conducts PVC casing capping, overhead wiring etc. • These are not sensitive to mild dose of water, heat, oil, acid, alkalis, sunrays, ultraviolet rays etc. It is available in 600, 660, 1100 Voltage grade. 2

2

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• C.T.S. Wire (Cab tire sheathed) or T.R.S. Wire (Tough rubber sheathed) C.T.S. wire-(Cable Tyre Sheath wire) In this type of wires, a tinned copper conductors are used. • These conductors are covered by red and black colour rubber. It is then coated with a layer of hard rubber. It is available in sizes 1/18, 3/20, 7/22 etc. • It does not absorb moisture. It is used in batten wiring service lines and short distance overhead lines. • It is available in 250/440 voltage grade only.

• T.R.S. wires-(Tough Rubber Sheath) In this type of type of cable which normally consists of a black outer sheath of rubber with several conductors inside. The rubber provides an abrasion-resistant, corrosion-resistant, waterproof, protective covering for an insulated electric cable. that wires are old types wires which are not used in market.

Cab tyre sheathed or tough rubber sheathed wiring

HT transformers • Each and every component of the HT transformer is manufactured and assembled with precision and utmost care. • The main process lines of the transformers are: Core: The core is made with laminated and low loss electrical steel sheets that are imported, grain oriented, cold rolled and sheets of high-grade steel. • The cores are assembled in a manner that they reduce the noise caused by vibration; individual stamping is coated with insulation varnish which is resistant to heat and oil on both sides. The core is connected to the clamp which ensures that it is effectually earthed. The core legs are bounded with heavy duty insulating tape. • The yokes are rigidly and securely clamped between the folded steel channels. Clamps on top and bottom are firmly attached to each other by the means of tie rods. • Tie rods serves the duel purpose of transferring the load from the bottom to the top clamps and securing the winding in place. This prevents tensile stress being setup in the core legs, which could adversely affect the iron losses.

Electrical panel • An electrical panel is also called a load center. It is a metal electrical service box that accepts the main power to the home and distributes electrical current to the various circuits within the home. • The distribution of power to the various circuits are protected from over-current by the use of circuit breakers or fuses. • Once you open the door to the panel you can access all the circuit breakers or fuses. • Usually one of these panels feeds all the circuits in the home but there may be a situation where there is another "sub-panel" serving a dedicated area like a new kitchen.

• You will find the circuit breakers stacked in the panel and controlled with a lever that places it in the "On" or " Off" position. You will also see a double pole circuit breaker at the top of the panel called the "Main". • That breaker controls all the power to panel in the circuit breakers. The main breaker is used to power all the circuits on or off at one time. At the main circuit breaker you can also see the amperage capacity of the electrical panel. • The main breaker will have a number on it identifying its ampere capacity, for example, "100" or "150". Today, 100 amp service is the minimum allowed by code in residential construction so 150 amp is very common. Electrical panels also come in 200 amp and 400 amp configurations. • To identify a circuit you should find stickers placed next to each breaker or a sheet adhered to the inside of the panel door that identifies the circuit served by a particular fuse or circuit breaker.

Electrical panel room

Panel room requirement • Electrical Short Circuit is the primary reason for big, fatal fires in most premises today. In such fires these short circuits occur mostly inside the electrical panels as this is where high voltage lines terminate.  In seconds, what is a small spark turns into a flame and then a fiery blaze in a matter of few minutes. Lives are lost and property is gutted.   Presenting Ceasefire's Quick Response System(CQRS) that is designed to fight fires that occur in the enclosed space of electric panels.  The CQRS system's split second detection and activation ensures that the fires are killed in the nascent stage inside the most vulnerable spaces i.e. the electrical panels.

• Clean Agent Fire Extinguisher Eco-friendly multipurpose fire extinguishers that reduce post-fire collateral damage and leave no residue behind. Perfect for areas where there's an abundance of ultra-sensitive electronic equipment. • CCTV Systems Ceasefire's CCTV systems bring you a wide range of cameras to guard your premises round the clock and state of the art DVRs that receive images from the camera and store those for future reference. • Alarm Solutions Ceasefire’s detection’s range is the result of extensive hardware and software product design and development. • Evacuation Designed to ensure safe passage through limited visibility conditions, Ceasefire’s Evacuation Solutions are put together with one aim in mind: to save lives. 

Cable trench • A trench is a type of excavation or depression in the ground that is generally deeper than it is wide and narrow compared with its length. • Open trench cable laying is often used as opposed to laying cables directly into cable ducts. This method of laying cables into the ground tends to be used where the cables in use are of a higher voltage and therefore have a greater outside diameter. • Cable laying into open trenches is a key part of cable installation in many industries, mainly utilities, construction, offshore, oil, gas, petrochemical and power. • When a trench is to be dug, it should be sufficient to allow the installer to install the cables and ducting at depth for the cable being used.

Switch controls • Switches control most of the circuits. Originally, switches were used to open and close circuits by hand. Modern technology and the demand for convenience has greatly expanded this role of switches. Switches can be simple or complex depending on the needs of the user. • The main switch is used to cut off the main supply when carrying out major repair works in the wiring system. The main switch is there to help prevent electrical fires. If you overload a circuit, and it tries to draw more current than the wire is supposed to have, it will pop the fuse, causing an open circuit, and electricity stops flowing. The main switch allows you to disconnect all electricity coming into the home.

Meter box • DOMESTIC ELECTRIC METER BOX - SINGLE PHASE • The standard electric meter box is used to house all single-phase electric meters within the UK. Single-phase meters can only be housed in meter boxes complying with ESI Standards. Electricity suppliers will not connect to boxes outside of these specifications. Where it is not possible to install a recessed meter cabinet into the wall cavity, a surface mounted box is available.

• ELECTRIC METER BOX - THREE PHASE • Homes and industrial premises requiring high power distribution will install a threephase meter. Three phase meters are housed in a different meter box to the single-phase meters. The three phase meter box is recessed into the wall cavity and complies with ESI standards. Electricity suppliers will not connect to boxes outside of these specifications.

Meter box

Circuit breakers • Electrical circuit breaker is a switching device which can be operated manually and automatically for controlling and protection of electrical power system respectively. • As the modern power system deals with huge currents, the special attention should be given during designing of circuit breaker for safe interruption of arc produced during the operation of circuit breaker.

Uninterrupted power supply • UPS is the abbreviation for Uninterruptible Power Supply, and is a device which supplies power to devices for a fixed amount of time without stopping even when there are problems occurring with utility power and other power sources. • Power situation is extremely stable and there are virtually no power outages or voltage abnormalities.

• However, regardless of the status of power supply and power transmission, power outages, voltage fluctuations, and the like can occur due to natural phenomena such as lightning or snow affecting power cables and the breakdown of power generation or power distribution equipment, therefore it is necessary for users to take appropriate measures or appropriate measures should be taken to load devices. • UPS is essential to avoid this kind of power trouble and enable the stable operation of systems.

Lightning protection

Need for lightning protection