Watt types of load

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  • 1. TYPES OF ELECTRICAL LOAD Compiled By : M.G. Wath EET, MSEDCL, Nagpur LOAD DEMAND  Load Demand defines requirement of load concern to particular category.  Load requirements depends upon its terrain, its population and living standard. Following figures indicates utilization of the energy by different category of the loads. Type of load Utilisation of Energy % Industries 37 Domestic 23 Commercial 7 Agriculture 27 Max Demand  Electricity is bought and sole on the basis of demand  Demand is in fact the average demand registered over a fixed time period.  Fixed time period is also known as integration period.  Integration period is usually 15 /30 /60 min.  30 min demand is recommended for –  There is no undue penalty for short duration  From consideration of thermal time constant of m/c.  Most of the meters having facility of 30 min integration Demand factor = MD/CL
  • 2. Load Factor : Statement of the load factor is meaningless unless  Interval of time period of max demand  Time over which average is taken are specified. e.g. Daily / Monthly / yearly Load Factor = Units Consumed during given period /Max Demand X Hours in period Diversity Factor:         Ratio of sum of Max Demand of the consumer to Max Demand of whole system. Diversity factor is always Greater than unity. Diversity Factor = sum of individual MD / Total MD Coincidence Factor is reciprocal of Diversity factor Diversity factor at Distribution T/F --- 1.00 – 1.5 S/s ------ 1.1 -- 1.60 Ehv s/s ------- 1.1 -- 1.25      Annual Diversity factors for five regions are -Northern Region 1.08 Western Region 1.07 Southern region 1.04 Eastern region 1.04 North Eastern region 1.08 Power factor : it is a Ratio of Active power to Apparent Power     Low PF means more current and greater loss in system Less pf --- less efficient PF = KWH / KVAH KVAH = √ KWH ² + KVARH ² System Load Diversity  Electrical load diversity factor is the probability that a particular piece of equipment will start at the time when the load is at its peak.  To plan for peak power demand. For ex.- During Summer season J&K state have lean power demands so they sell power to Punjab & adjoining state as these state have larger Power demand. And situation is reverse during winter.
  • 3. Connected Load ::  Installed load of the consumer is the sum of rated inputs of the all electrical equipments installed in the consumer premises.  Connected load is that part of the installed load which have been calculated by the utility.  Definition of the connected load is different in different utilities. Street Light : load of the street light is depend upon illumination required on road.  Small town --- bulb of 40w ---- 250V --- span 45-50m -- Height 7.5 to 9 m Large town ---- lamp of 40 – 100 W -- – 30m-35m Incandescent / Florescent / Mercury /SodiumVapour Lightening Intensity depends upon Traffic speed , safety criteria Lamps with better eff., longer life, good colour rendering index are available. Water supply : Load estimated from water requirement in a specified area such as -Rural --- 50 ltr /day/person Semirural – 70 ltr / day / person Urban – 90 ltr / day / person Metropolitian city -- 120 ltr /day / person As per WHO min water required per person per day 23 Liters in very small villages. Irrigation Load : - Power requirement depends on ----Nos of watering required for each kind of crop Area under the crop Nature of the soil Depth of the ground water level. HP requirement for electric motor used for irrigation is on the basis of average discharge of centrifugal hydraulic pump.  Efficiency of the pump is depends on --------Specific speed Discharge head Stuffing box friction Size of pump Internal running clearance Inlet head Surface roughness For efficient pump – water level should not be more than 5-6m below pump, For level more than 15m – submersible pump are used.
  • 4. Sensitive Load : The load which is sensitive to the fluctuation of system parameter are called sensitive load. e.g. Computer based product. Testing equipment Thyrister controlled devices Parameters to be within limits of ---Voltage unbalance Frenquency -- < 3 % ------ < +/- 0.5 Hz Voltage waveform distortion -- < 5 % Dirty Loads : Dirty loads are known for the load which produce –  Harmonics  Voltage fluctuation  Light flickering  Large variation in reactive power demand This phenomenon creates ----Extra system losses Thermal over loading Dielectric stress control & protection relaying disturb Dirty loads are ---Computer TV discharge lamp X-ray m/c Arc furnace induction furnace welding m/c Re-rolling mills Traction speed drive Remedial measures against the dirty loads are ------to provide—  Filters, Delta – star T/F, U/G feeders --- Harmonics  Supply consumer on HV /EHV level / parallel transformer / conditioning equip.--Voltage fluctuation  Thyristor controlled capacitors --- to reduce voltage fluctuation due to less pf.
  • 5. Q 1 : A 50 MW Hydro generator delivers 350 million units during the year. Calculate the plant load factor? Ans : PLF = Actual energy generated / max energy that could have been generated = 350x 106 / 50x 103 x8760 = 0.8 Q 2 : A generating station has Max demand of 20 MW, plant capacity factor 48%, a load factor of 60 % , Plant use factor of 80% find -- a) daily Energy produced b). The max energy that could be produced daily if the plant run for all the time. C) the max energy that could be produced daily if the plant when running as per operating scheduled were fully loaded. Ans : LF = AD/MD = 0.6 hence AD = 20x0.6 = 12 MW Daily Energy produced = 12 x 24 = 288 MWH Installed capacity = AD/PCF = 12/0.48 = 25 MW Energy per day as per plant capacity = 25 x 24 = 600MW Max energy as per scheduled= Actual energy produced/PUF = 288/0.8 =360MWH ---------------------------------------------------------------------------------------------------