Contenu connexe


SG PPT.pptx

  1. ELECTRICAL INSTALLATIONS By Dr. Gireesh Kumar Devineni
  2. Components of LT switch gear  The apparatus used for switching, controlling and protecting the electrical circuits and equipment is known as switchgear.  The term ‘switchgear’ is a generic term encompassing a wide range of products like circuit breakers, switches, switch fuse units, off- load isolators, HRC fuses, contactors, earth leakage circuit breakers (ELCBs), etc...
  3. excessive through current sufficient flows time. whenever the current flowing through increases fuse element beyond its rated capacity then short circuit or overload occurs. This raises the temperature and the fuse element melts, disconnecting the circuit is protected by it. FUSE A fuse is a short piece of wire or thin strip which melts when
  4. • The Switched Fuse Unit has one switch unit and one fuse unit. • When we operate the breaker, the contacts will get close through switch and then the supply will passes through the fuse unit to the output. SWITCH FUSE UNIT (SFU)
  5. MCB Mminiature Circuit Breaker (MCB) is an electromechanical device which guards an electrical circuit which automatically switches off electrical circuit during abnormal condition of the network means in over load condition as well as faulty condition. The normal current rating is ranges from 0.5-63 A with a symmetrical short circuit breaking capacity of 3-10 KA, at a voltage level of 230 or 440V. Characteristics of MCB The characteristics of an MCB mainly include the following • Rated current is not more than 100 amperes • Normally, trip characteristics are not adjustable • Thermal magnetic operation
  6. ELCB • Early earth leakage circuit breakers are voltage detecting devices, which are now switched by current sensing devices (RCD/RCCB). • An ECLB is one kind of safety device used for installing an electrical device with high earth impedance to avoid shock. There are two types of Earth Leakage Circuit Breaker (ELCB) 1. Voltage Operated ELCB 2. Current Operated ELCB Characteristics of ELCB • This circuit breaker connects the phase, earth wire and neutral • The working of this circuit breaker depends on current leakage
  7. Molded case circuit breakers are a type of electrical protection device that is commonly used when load currents exceed the capabilities of miniature circuit breakers. They are also used in applications of any current rating that require adjustable trip settings, which are not available in plug-in circuit breakers and MCBs. The main distinctions between molded-case and miniature circuit breaker are that the MCCB can have current ratings of up to 2,500 amperes, and its trip settings are normally adjustable. MCCB
  8. Wire is a single electrical conductor, whereas a cable is a group of wires swathed in sheathing. Types of wires and cables
  9. CABLES • The main requirements of the insulting materials used for cable are:  High insulation resistance.  High dielectric strength.  Good mechanical properties i.e. tenacity and elasticity.  It should not be affected by chemicals around it.  It should be non-hygroscopic because the dielectric strength of any material goes very much down with moisture connect.
  10. TYPES OF CABLES RUBBER: used for house wiring, buildings, factories and low power work. PVC(Polyvinyl chloride): It is a thermo insulating material. up to plastic These 1.1kv especially in are used voltages concealed wiring system. TRS (Tough sheathed) or sheathed(CTS): rubber Cab type These are used 250/ 500v circuits.
  11. Electrical Earthing The process of transferring the immediate discharge of the electrical energy directly to the earth by the help of the low resistance wire is known as the electrical earthing. Mostly galvanised iron is used for earthing.Earthing provides simple path to the leakage current. Earthing is an important component of electrical systems because of the following reasons: • It keeps people safe by preventing electric shocks • It preventsdamage to electrical appliances and devices by preventing excessive current from running through the circuit • It prevents the risk of fire that could otherwise be caused by current leakage
  12. Types of Electrical Earthing: •Neutral Earthing: In neutral earthing, the neutral of the system is directly connected to earth by the help of the GI wire. The neutral earthing is also called the system earthing. Ex. Generator, T/F, Motor etc., •Equipment Earthing: Such type of earthing is provided to the electrical equipment. The non- current carrying part of the equipment like their metallic frame is connected to the earth by the help of the conducting wire.
  13. Elementary calculations for energy consumption STEP I : Calculate Watts Per Day In this step, simply multiply your device’s wattage by the number of hours you use it in a day. This will give you the number of watt-hours consumed each day. For example, say you use a 125-watt television for three hours per day. By multiplying the watts (125) by the hours used (3), we find that the television is consuming 375 watt-hours per day. 125 watts X 3 hours = 375 watt-hours per day
  14. Cont., STEP II : Convert Watt-Hours to Kilowatts Electricity is measured in kilowatt-hours on your bill, not watt-hours. One kilowatt is equal to 1,000 watts. so to calculate how many kWh a device uses, divide the watt-hours from the previous step by 1,000. Using our previous example, this means you would divide 375 watt-hours by 1,000, resulting in 0.375 kWh. 375 watt-hours per day / 1000 = 0.375 kWh per day
  15. Cont., STEP III : Find Your Usage Over a Month Now that you know the kWh used per day, multiply that by 30 to find your approximate usage for the month. So, if your daily usage is 0.375 kWh, your monthly usage would be 11.25 kWh. 375 watt-hours per day X 30 days = 11.25 kWh per month
  16. Cont., STEP IV : Figure Out the Cost For the final step, refer to your last electric bill to see how much you pay per kWh, i.e. Tariff. Let’s say, according to your bill, your electric rate is 3 rupees per kWh. Multiply your electric rate (₹3) by your monthly usage (33.75) to find out how much your TV is costing you in a month (₹33.75). 11.25 kWh per month X ₹5 per kWh = ₹33.75 per month
  17. What about devices that use more electricity? • For refrigerator, for instance, runs 24 hours a day. Most refrigerators consume anywhere between 300 to 780 watts of electricity. Let’s say your model only uses 300 watts.  300 watts X 24 hours = 7,200 watt-hours per day  7,200 watt-hours per day / 1000 = 7.2 kWh per day  7.2 kWh per day X 30 days = 216 kWh per month  216 kWh per month x ₹3 per kWh = 648 per month
  18. Cells and Batteries • A device which is used as a source of e.m.f. and which works on conversion of chemical the principle of energy into electrical energy is called a cell. • But practically the voltage of a single cell is not sufficient to use in any practical application. • Hence various cells are connected in series or parallel to obtain the required voltage level. • The combination of various cells, to obtain the desired voltage level is called a battery.
  19. Types of Cells • There are two types of cells,  Primary Cells: • The chemical action in these cells is not reversible and hence the entire cell is required to be replaced by a new one if the cell is down. • The primary cells can produce only a limited amount of energy. • Mostly the non electrolytes are used for the primary cells. • The various examples of primary cells are i. Dry Cell (zinc-carbon) ii. Mercury cell iii. Zinc chloride cell iv. Lithium cell v. alkaline cells
  20. Dry Cell (zinc-carbon) • The zinc container is lined with paper to avoid direct reaction of zinc with carbon. • The container is sealed with an insulator called pitch. • The tin plates are used at top and bottom which are positive and negative terminals of the cell. • Applications are Used in torch lights, Electronic apparatus and toys, wall clocks etc.
  21. Mercury cell Applications These cells are preferred for providing power to small devices like Electronic calculators, Audio devices, Cameras etc.,
  22. Types of Cells  Secondary Cells: • The chemical action in this cells is reversible. • Thus if cell is down, it can be charged to regain its original state, by using one of the charging methods. • The electrical energy is stored in the form of chemical energy. • Secondary cells are also called storage cells, accumulators or rechargeable cells. • The various types of secondary cells are i. Lead-acid cell. ii. Alkaline cell (Nickel-cadmium )
  23. Lead-acid cell Applications • In emergency lighting systems • In automobiles for starting. • Uninterrupted power supply systems. • Railway signalling. • Electrical substations and the power stations.
  24. Characteristics of Lead-acid cell • During charging of the lead acid cell, the voltage increases from 1.8V to 2.5V- 2.7V, when cell is completely charged. • If the discharge rate is high, the curve is more drooping as voltage decreases faster.
  25. Alkaline cells • The secondary cells can be alkaline cells. These are of two types 1. Nickel – iron cell or Edison cell 2. Nickel – cadmium or Nife cell or Junger cell
  26. 1. Nickel – iron cell or Edison cell Applications • Mine locomotives and mine safety lamps Space ship • In the railways for Lighting and air conditioning purposes. • To supply power to tractors, submarines, aeroplanes etc.
  27. Electrical Characteristics of Nickel Iron cell  The Characteristics will show the variations in the terminal voltage of cell against the charging or discharging hours.  When fully charged its voltage is about 1.4V and during discharging it reduces to 1.1 to 1V. During charging, the average charging voltage is 1.7 to 1.75 V.
  28. Nickel – cadmium cell Applications • Millitary aero planes, helicopters and commercial airlines for starting engines and provide emergency supply. • In Electric Shavers. • In the railways for Lighting and air conditioning purposes etc.