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ELECTRICLAL ENERGY GENERATIOCONSERVATION AND UTILISATION
UNIT-IICONSERVATION
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DEFINITION:The rate of charging for electrical energy
supplied by the utility company to its consumer.Tariff= total actual charges(fixed+running)
Total energy supplied to the consumer
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OBJECTIVES1. ACCESSIBILITY
It must be such that it does not become a barrierto the effective use of, and derivation of benefitsfrom, electricity for ALL.
2. QUALITY OF LIFEIt should promote continual improvementin quality of life for ALL.
3. SUSTAINABILITY The tariff should be determined such that the
sustainability of electricity supply is assured, as
well the sustained promotion of access and quality
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OBJECTIVES
A tariff must cover the following items (i) capital investment in generating, transmitting
and distributing equipment(ii) operation, supplies and maintenance of equipment and
(iii) metering equipment, billing, collection andmiscellaneous services(iv) a satisfactory return on the total capitalinvestment.
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TYPES OF TARIFF (i) Flat Demand Tariff (ii) Simple Tariff (iii) Flat Rate Tariff (iv)Step Rate Tariff (v) Block Rate Tariff (vi) Hopkinson Demand Rate or Two Part Tariff (vii) Maximum Demand Tariff (viii) KVA Maximum Demand Tariff (ix) Doherty Rate or Three Part Tariff (x) Off Peak Tariff
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1. Flat Demand Tariff This is one of the earliest forms of tariffs This tariff is expressed as energy charges, y = Rs.
Ax A is the rate per lamp or kw of connected load x is the number of lamps or load connected in kw In these types of tariff the metering equipment,
meter reading, billing, and accounting costs areeliminated
Now-a-days such a tariff is restricted to use such as
in street lighting, signal systems, sign lightings etc.
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2.Simple Tariff/Uniform ratetariff
This is the simplest type of tariff according to which the cost o energy is charged on the basis of units consumed (energy meter)It can be expressed in the form y = Rs Ax
A is charges in rupees per unitx is the total electrical energy consumed in units orkwh.
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Draw backsThe cost per unit delivered is highThere is no discrimination between different typesof consumers since every consumer has to pay equally for the fixed charges.
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3. Flat Rate Tariff The different types of consumers are charged atdifferent rates.
i.e. the flat rate for light and fan loads is slightly higher than that for power load.The rate for each category of consumers is arrivedat by taking into account its load factor anddiversity factor.
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Draw backs
Separate meters are required for different types of supply.Difficult to derive the load factor and diversity factor for various types of loads to be employed indeciding tariff.
A particular class of consumers is charged at thesame rate irrespective of the magnitude of energy consumed.
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4.Step Rate Tariff
The step rate tariff is a group of flat rate tariffs of decreasing unit charges for higher range of
consumption.EX:Rs.4.00 per unit if consumption50KWh200KWh etc..
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Draw back
By increasing the energy consumption so as just toenter the next range from the final stage of previous range, the total energy cost is reduced.
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5.Block Rate Tariff In this type of tariff a given block of energy is
charged at higher rate and succeeding blocks of energy are charged at progressively reduced rates.
EX:
The first 25 units charged at Rs.5 per unit, the next40 units charged at Rs.4 per unit , consumptionexceeds 65 units at Rs.3 per unit etc.
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Draw backIt lacks the measure of consumers demand.
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6.Hopkinson Demand Rate /Two Part Tariff.
The total energy charge to be made to theconsumer is split into two components namely fixed charge and runign charge
tariff is expressed as Y = Rs a kw + b kwh Rs a is the charge per kw of maximum demand
assessed. Rs b is the charge per kwh of energy consumed. This tariff is mostly applicable to medium
industrial consumers.
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Draw back The consumer has to pay the fixed chargesirrespective of the fact whether he has consumedor not consumed the electrical energy.There is always error in assessing the maximum
demand of the consumer.
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7.Maximum Demand Tariff This tariff is similar to that of two part tariff except
that in this case maximum demand is actually measured by a maximum demand indicatorinstead of merely assessing it on the basis of rateable value.
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8.KVA Maximum Demand Tariff It is a modified form of two part tariff.
In tis case maximum demand is measured in Kvainstead of in kw.This type of tariff encourages the consumers tooperate their machines/equipment at improvedpower factor because low power factor will causemore demand charges
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9.Doherty Rate/Three PartTariff
In this tariff total energy charge is split into threeelements namely fixed charge, semi-fixed chargeand variable charge.
Such a tariff is expressed as y = Rs a + bkw + c kwh. a' is a constant charge. b is unit charge in Rs per kw of maximum demand
in kw during billing period (in some case it is also
charged in Rs per kva instead of Rs per kw) c is the unit charge for energy in Rs per kwh of
energy consumed. This type of tariff is usually applicable to bulk
su lies.
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10.Off Peak Tariff The load on the power station usually has
pronounced peak loads in the morning and early evening and a very low load during the night (from10 P.M. to 6 A.M.).
During the night, therefore, and other off-peakperiod which may occur, a large proportion of thegenerating and distribution equipment will belying idle.
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In case the consumers are encouraged to useelectricity during off peak hours by giving a special
discount, the energy can be supplied withoutincurring an additional capital cost and shouldtherefore prove very profitable.
This type of tariff is very advantageous for certain
processes such as water heating by thermalstorage, pumping, refrigeration etc.
10.Off Peak Tariff
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The Importance of SavingEnergy
What does ' energy conservation' mean ? We use electrical energy in our homes for cooking,
heating, TV. etc. We also use fuel energy in ourcars, and we may also use energy by burning woodor coal in our homes. The main ways most of uscan save energy are by:
using less electricity in the house, and by
using less fuel in cars.
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Why should we save energy ?
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Energy conservation 1.Save money : Typical mid-income households
spend R 150 to R 200 per month on electricity --500 to 800 kilowatt-hours (kWh). Mosthouseholds could save 20 - 30 % of this easily.
2. Reduce 'Greenhouse Gas' emissions : InSouth Africa electricity is generated from the coal-burning industries in Gauteng, which produces
carbon dioxide (CO2) when burnt. This iscontributing to Global Warming, which ispotentially catastrophic. Fuel combustion in cars isalso responsible for substantial CO2 emissions.
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Contd;3. Reduce air pollution caused by burning coal togenerate electricity, and from car fumes.4. Save water : Power stations use 2 litres of water forevery unit of electricity (kWh) generated.
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How does one use lesselectricity ?
There are several ways to use less electricity withlittle effort.
Priority 1: Your Geyser Your household geyser uses about 40 % or more of
the total electricity consumption, as is shown inthe following pie chart:
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Typical household electricityuse
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TO REDUCE ENERGYCONSUMPTION
Insulate the geyser and hot water pipes by wrapping a blanket or other material around them.
Install a timer on the geyser to avoid heating up water when you don't need it. A timer unit may cost R 150, but the estimated saving can be up to 10
% of your electricity bill. Install a solar water heater. If you are building anew house, this will be a sound economic choiceand can save up to 15-25 % of your total electricity
bill.
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Priority 2: Your Lighting
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Priority 2: Your Lighting Use 'compact fluorenscent' lights rather than
normal incandescent 'bulb' lights for any lights which stay on longer than about 4 hours per day.
These are especially good for outside fittings whichstay on all night.
CFLs are expensive (up to R 60 each), but they usually end up costing you half of what you wouldhave paid if you used a normal light bulb, because
they last much longer and use much less electricity for the same light output.
Each CFL installed saves about 500 kg of CO2 emissions over its lifetime by using lesselectricity.
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Priority 3: Heating
Heating is generally the third major cause of highenergy consumption in your household.
Insulate your ceiling. It is estimated that you cansave half of your heating electricity bill by doingthis.Include 'passive solar' features if you are designinga new house.Install roof hangings. These keep the summer sunout but let the winter sun in.
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ENERGY SAVING TIPS1. Turn off unnecessary lights, TVs, computers and
other electrical appliances when not in use.
2. When possible, replace older appliances withnewer, high-efficiency models.
3. Run only full (but not overloaded) loads in yourdishwasher.
4. Set the temperature in your refrigerator between37F and 40F.5. Keep your freezer section at 5F. If you have a
separate freezer for longer-term storage, itshould be kept at 0F.
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contd6. Unplug extra or unused appliances.
7. Get rid of that second refrigerator.8. Vacuum your refrigerators condenser coils (for
most models, once a year will do the job.)
9. Use small electric appliances or a microwave forcooking instead of your stove or oven.10. Do dishes and wash and dry clothes after 8pm.
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ENERGY CONSERVATIONFOR HT INDUSTRY
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ENERGY MANAGEMENT INHOSPITALS Energy use in Hospitals Hospitals and hospital
buildings are large consumers of energy Per square
meter, hospitals are the second highest energy intensive space type in the US In this part of the world it is the highest . They have an energy intensity nearly twice that of average building
Energy use in hospitals Energy has always been anessential element to the delivery of quality servicesExplosion in the use of technology by healthcarefacilities - increased energy demand
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contd Explosion ..Ten fold Lighting Lifts Laundry Air
conditioning ,refrigeration Advanced imagingsystems Diagnostic equipments
5. Hospital energy balance Air conditioning - 45%Hot water - 5% Lighting - 20% Kitchen - 5% Other- 20%
Power consumption daily SCT(250 beds) 15,000 units -60units/bed/day Rs.22 lakhs. pm -SUT(150 beds) - 5000 units 30units/bed/day. Rs 7.5lakhs /pm
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Contd;
Consumption Say 25 units /bed/day Keralahas more than 1,20,000 hospital beds >30,00,000units of electricity per day > Rs 1 crore a day
Kerala Scenario Healthcare facilities spend morethan Rs.380 crores annually.
10% Energy savings 25,000 tonnes of greenhousegases 750 acres of forest preserved from
deforestation Healthcare and Energy Impact Importance of
addressing climate changes Encouraging hospitalsto cut their Carbon emission Healthcare shouldnot create health problems
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Air Conditioning Minimize Energy Use Turn off AC right after use affix Save Energy
sticker near the exit Use natural ventilation or fan where possible Set AC at 24oC and suitable fan speed. Check
temperature regularly Air Conditioning Use Energy Efficiently
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contd Set up maintenance programme to ensure efficientoperation
Clean AC and dust filter Replace room coolers with more energy efficient
models Keep windows and doors closed to minimize air
infiltration when AC is running curtains to reduce direct sunlight during summer
time
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Air Conditioning Install Fresh Air Heat Exchanger Fresh Air Heat Exchanger Energy saving about 10 ~
15% Increase every 1oC of set point temperature will
save about 1.5% of electricity Use evaporative water-cooling for condensers
Energy saving about 10~15% Avoid pre-cooling. If pre-cooling is necessary,
switch on AC not more than 15 minutes in advance
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Lighting Turn off unnecessary lighting for area not in use
affix Save Energy sticker near the switch Turn off or dim lighting in perimeter area Set all computers and office equipment to energy
saving mode, and turn them off after use Screen Saver is actually Energy Waster &
should not be used when computer is idle Unplug equipment chargers and adapters when
these electronic equipment are not in use Arrange for last-man-out to turn off all equipment
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Lighting Lighting Replace tungsten lamps with fluorescent
tubes or compact fluorescent lamps (CFLs) Energy saving up to 80%
Lighting Replace conventional magnetic ballasts with electronic type Energy saving about 20~40%
Lighting Install separate control for lighting at
window perimeter to allow switch off duringbright days Energy saving about 10~15% Lighting LED is gradually replacing some
conventional lighting technologies
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LIFTS Use the stairs for 1 or 2 floors up or down affix SaveEnergy sticker near the lift
Shut down some of the lifts and escalators during non-peak hours
Switch off the lighting and ventilation fan inside the liftcar when the lift is in standby/idle mode
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Get People Into ActionGet support from all staff Explain energy policy and housekeeping practices
(and incentive scheme) through staff briefings, emails,newsletters or notice boards Affix Save Energy stickers at switches, doors, exits,lifts and escalators as a reminderKeep track of organizational performance in energy saving, and benchmark against targets.
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ENERGY MANAGEMENT/ENERGY AUDIT
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Definition An energy audit is an inspection, survey andanalysis of energy flows for energy conservation ina building, process or system to reduce the amountof energy input into the system without negatively affecting the output(s).
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Energy audit: DefinitionEnergy audit is a systematic study or survey to
identify how energy is being used in a building or plant, and identifies energy savingsopportunities. Using proper audit methods andequipment, an energy audit provides the energymanager with essential information on howmuch, where and how energy is used within anorganization (factory or building).
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Main issues of an audit
process The analysis of building and utility data, includingstudy of the installed equipment and analysis of energy bills
The survey of the real operating conditions; The understanding of the building behavior and of
the interactions with weather, occupancy andoperating schedules;
The estimation of energy saving potential; The identification of customer concerns and
needs.
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LAYOUT OF EEGCTU
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Stages of Energy Audit
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Energy audit-stages
Energy audit can be categorized into two types,1.walk-through or preliminary2. detail audit.
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Walk-through / preliminary audit
Walk-through or preliminary audit comprises oneday or half-day visit to a plant and the output is asimple report based on observation and historicaldata provided during the visit. The findings will
be a general comment based on rule-of-thumbs,energy best practices or the manufacturer's data.
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Preliminary Energy Survey Quick overview of energy use patterns
Provides guidance for energy accounting system
Provides personnel with perspectives of processes and equipment
Identify energy intensive processes andequipment
Identify energy inefficiency ,if any
Set the stage for detailed energy survey
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Detail audit Detail audit is carried out for the energy savingsproposal recommended in walk-through or
preliminary audit.It will provide technical solution options andeconomic analysis for the factory management todecide project implementation or priority.A feasibility study will be required to determinethe viability of each option.
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Contd;
It covers the estimation of energy input for different processes,losses,collection of past dataon production level and specific energyconsumption.
Review of equipment operatingcharacteristics
Evaluation of efficiencies
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Scope:
To formulate a detailed plan on the basis of qualitative and control evaluation, to reducetotal energy consumption for the productmanufactured.It should aim at 8 to 10% savings.
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Inputs and Outputs of Energy audit
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Benefits of energy auditThere is a lot of potential for energy savings fromenergy audits..
Technical solutions proposed in the energyaudits show massive potential for energy savingsin every sub-sector with an average of almost tenpercent of the energy usage.However, this can only materialize throughreplication at other factories within the respectivesub-sector.
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It also includes Energy savings Avoiding power factor penalties and
environmental compliance costs Quality improvements Productivity improvements Reduced maintenance Fewer breakdowns Better safety and protection A process for repeatable improvements
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Efficiency oportunities
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Process VS. EquipmentEquipment efficiency improvement : Max. 5%
Process efficiency improvement : 15% to30%
Focus on Processes
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Energy intensive
processes and equipmentExamples of processes Electrical furnace Rolling mills Gas furnace
Steam generation Feed water system Condensate return system Steam distribution s stem
Examples of equipment Electrical motor Pump Fan
Heater (gas,..,electric) Dryer (steam/electric) Motor / generator Com ressor
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Energy conservationopportunities
Electrical Reduce demand by load management
Electrical / thermal Reduce consumption by improving energy use
efficiency (reducing losses ,utilizing waste heat,etc..)
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Examples of conservationopportunities - processes
1.Electric furnaceAutomation of energy supply controlSubstitute electricity by thermal energy( mazout/solar/gas )Reduce radiation losses
2 S i
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2. Steam generation system
- Combustion efficiency improvement
- Waste heat recovery from flue gases
- Heat loss reduction from boiler surfaces
- Reduce leakage3. Condensate return system
4. Steam distribution system
- Pipe insulation
- Steam traps
- Steam leaks
Examples of conservation
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Examples of conservationopportunities equipment
1. Gas/air compression system
pre-cooling the gas/air
2. High efficiency motors
3. High efficiency lamps
4. High efficiency pump/fan
5. Change electric dryer and heater to oil/gas fuel
6. Replace motor/generator set with silicon
controlled rectifier (SCR)
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Energy Audit / step by step
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What is Power Factor?
Power Factor is an index used to compute theefficiency level of electricity usage. The index is
measured from 0 to 1. A higher index shows efficient usage of electricity and vice versa.Low power factor shortens the lifespan of electricalappliances and causes power system losses to TNB.
Basic terms
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Basic terms KW Working Power (also called Actual Power, Active
Power or Real Power).It is the power that powers equipment andperforms useful work.
KVAR Reactive Power.It is the power which magnetic equipment such astransformers, motors and relays need to producethe magnetizing flux.
KVA Apparent Power. It is the vectorial summation of KVAR and KW.
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Simple analogy Lets say you are at a park and it is a hot day. You
order a glass of a carbonated drink. The thirst-quenching portion of the drink is represented by KW.
Unfortunately, along with your drink comes a littlebit of foam. The foam does not quench your thirst.
This foam is represented by KVAR. The total content of your glass, KVA , is this
summation of KW (the carbonated drink)and KVAR (the foam).
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Power factor
Power Factor is the ratio of Working Power to Apparent Power.Power Factor = KW / KVA Looking at our carbonated drink analogy, powerfactor is the ratio of carbonated drink (KW) to thecarbonated drink plus foam (KVA).
Power Factor = KW / (KW + KVAR) = Carbonated drink / (Carbonated drink + foam)
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Contd;
Thus, for a given KVA:- i. The more foam you have, the lower your powerfactor.
ii. The less foam you have, the higher your powerfactor.
For efficient usage of electricity, power factor mustapproach 1.0. Power factor that is less than 0.85
shows inefficient use of electricity. Calculation for Power Factor =
KWh _(KWh 2 + KVARh2)
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Macs analogy Mac here is dragging a heavy load .Macs WorkingPower (or Actual Power) in the forward direction, where he most wants his load to travel, is KW.
Unfortunately, Mac cant drag his load on a perfecthorizontal (he would get a tremendous backache), sohis shoulder height adds a little Reactive Power, orKVAR.
The Apparent Power Mac is dragging, KVA, is thisvectorial summation of KVAR and KW.
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The effects of powerfactor.
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Consider a canal boat being pulled by a horse. If the horse could walk on water then the angle (Phi) would be zero and COSINE =1.
Meaning all the horse power is being used to pullthe load.However the relative position of the horseinfluences the power.
As the horse gets closer to the barge, angle 1
increases and power is wasted.But, as the horse is positioned further away, thenangle 2 gets closer to zero and less power iswasted
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Causes of Low Power Factor In our carbonated drink analogy, low power factor
resulted when the foam is large. Low power factoris caused by inductive loads, which are sources of
reactive power. Examples of inductive loads are:- Transformers Induction motors High Intensity Discharge (HID) lighting Inductive loads constitute a major portion of
power consumed by commercial and industrialsectors.
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Why to Avoid Low Power
Factor A system load with a low P.F. will draw morecurrent than a system with a higher P.F.. A systemdesigner considers the following:
A Low P.F. draws a higher internal current and theexcessive heat generated will damage and/orshorten equipment life
Increased reactive loads can reduce output voltageand damage equipment sensitive to reduced voltage
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contd Low P.F. requires equipment to be constructed
heavier to absorb internal energy requirements Low P.F. will result in a more expensive system
with equipment able to absorb internal loads andlarger load requirements A system designer looks to increase P.F. to lower
system costs, increase reliability and increase thesystems life cycle
Utilities will charge a higher cost to industrial andcommercial clients having a low P.F.
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How to Improve Power Factor?
Customers are advised to follow these steps:- Install capacitors (KVAR Generators) Capacitor Corrector Synchronous generators Synchronous motors
Minimize operations of idling or lightly loadedmotors.
Avoid operating equipment above its rated voltage. Replace standard motors as they burn out with
energy efficient motors.
f f
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Benefits of Improving Power
Factor Benefit 1: Reducing KW billing demand Low Power Factor requires high reactive
power (KVAR) and apparent power (KVA), whichis the power that TNB supplies. Therefore, afacilitys low power factor forces TNB to increaseits generation and transmission capacity in order
to handle this extra demand. By increasing power factor, customers use less
KVAR. This results in less KW, which equates toRM savings for TNB.
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Benefit 2: Eliminating power factor surcharge:
Utility companies all around the world chargecustomers an additional surcharge when theirpower factor is less than 0.95. In fact, some utilitiesare not obliged to deliver electricity to their
customers at any time the customers power factorfalls below 0.85. Thus, customer can avoid this additional surcharge
by increasing power factor. In Malaysia, TNB isallowed through the Malaysian Grid Code and theMalaysian Electricity Distribution Code, to imposea surcharge to the customer if the power factor is
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Benefit 3: Increased system capacity and reduced
system losses in your electrical system Low power factor causes power system losses inthe customers electrical system.By improving power factor, these losses can bereduced. With the current rise in the cost of energy,increased facility efficiency is important.
Moreover, with lower system losses, customers areable to add additional load in their electricalsystem.
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Benefit 4: Increased voltage level in yourelectrical system, resulting in more efficient
motors As mentioned before, low power factor causes
power system losses in customers electricalsystem. As power losses increase, customer may experience a voltage drop. Excessive voltage dropscan cause overheating and premature failure of motors and other inductive equipment.
Therefore, by raising the power factor, customerscan minimize these voltage drops along feedercables and avoid related problems. Motors willrun more efficiently, with a slight increase in
capacity and starting torque.
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Why Apply PFCs? Power Factor Correction Saves Money! Reduces Power Bills Reduces I 2R losses in conductors Reduces loading on transformers Improves voltage drop
Wh d I t ll
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Why do we Install
Capacitors? Capacitors supply, for free, the reactive energy required by inductive loads. You only have to pay for the capacitor ! Since the utility doesnt supply it (kVAR), you
dont pay for it!
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Other Benefits: Released system capacity: The effect of PF on current drawn is shown below:
Decreasing size of conductors requiredto carry the same 100kW load at P.F.ranging from 70% to 100%
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Reduced Power Losses:
As current flows through conductors, the conductorsheat. This heating is power loss Power loss is proportional to current squared
(PLoss=I2R)
Current is proportional to P.F.: Conductor loss can account for as much as 2-5% of
total load
Capacitors can reduce losses by 1-2% of the totalload
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Low Voltage Capacitor Unit Low Voltage Capacitor
Cubicle-type automaticcapacitor banks are
modular in structure.
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High Voltage Capacitor Unit High Voltage Capacitor Units
There are two types of fuses used for
capacitors; internal andexternal.
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High Voltage Capacitor High Voltage
Capacitors
High Voltage CapacitorsOne-Phase Units have all-film dielectric and areimpregnated with
dielectric liquid which isenvironmentally safe.
P F t C t ll
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Power Factor Controller
Power Factor Controllers
Power Factor controllers 6step or 12 step models aremanufactured for the controlof the automatic capacitorbanks.
P F t C ti
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Power Factor Correction
Capacitor PFC
Automatic capacitor banksare used for central powerfactor correction at main
and group distributionboards.
ff f
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Different Locations of
capacitor banks
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POWER FACTOR IMPROVEMENT
Improving power factor by reducing the kVAr load
requires the use of power factor equipment whichoperate at a leading power factor such as: Static capacitors Synchronous motors
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Synchronous motors which are either over-excitedor under loaded with full excitation so they will
supply kVAr to the electrical system.
Static capacitors which are electrical devices without
moving parts that have the ability to providemagnetizing current to the load. Their efficiency ishigh since losses are less than one-half of 1 percentof their kVAC (or kVAR) rating.
In the past two other types of equipment were usedto supply kVAr to a system: synchronous condensersand synchronous converters.
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Static Capacitors Static capacitors are the cheapest and the simplest
means for reactive power compensation . They areinstalled by power utilities in the transmission anddistribution network and also at the consumerspremises on to different loads such as motors,transformers, incoming supply, etc. In present daysautomatic switching of the capacitors enableskeeping a high power factor for heavily fluctuatingloads as well.
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connecting capacitor in parralel improves pf andconnecting series improves voltage profile. in somecases connecting capacitor increases the output voltage i.e. voltage acroos load may be greater than voltage accross source
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SYNCHRONOUS MACHINESBy Use of : Synchronous machines are excited by dc, and the power factor may be controlled by controlling the field excitation. The varioussynchronous machines available for power factorcorrection comprise synchronous motors,synchronous condensers, synchronous converters,synchronous phase modifiers, phase advancers,and synchronous-induction motors.
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Synchronous CondensersBy use of : An over-excited synchronous motorrunning on no load is called the synchronouscondenser or synchronous phase advancer andbehaves like a capacitor, the capacitive reactance of which depends upon the motor excitation.Power factor can be improved by using
synchronous condensers like shunt capacitorsconnected across the supply.
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Synchronous converters are used where dc supply is
needed. The pf of induction motor of rating exceeding 150kw may be improved by equipping the set with ac exciter orphase advancer which supplies the exciting current to therotor circuit at slip frequency.