Average Load, Load+factor, Demand Factor And Diversity Factor Easy Slides s2y6u

Load Factor Examples  A 100 MW generating station delivers  100 MW for 2 hours  50 MW for 6 hours  Shut down for the remaining day  It is also shut down for maintenance for 45 days/year  Calculate the annual load factor?

 Total energy produced = {(100 x 2) + (50 x 6)} x 320  = 160000 MWh  Max. demand = 100 x 24 x 320 = 768000 MWh

 Load Factor = 160000/768000 = 0.208 = 20.8%

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Load Factor Examples  One of the simplest

methods to improve the load factor is to “shave the peaks”  “Shaving” means shifting some of the load at peak times to non-peak times

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Demand Factor  Demand Factor = Max. Demand/Connected Load  Demand Factor is less than 1  Knowing Demand Factor is vital in determining the capacity of the plant equipment  A household has total connect load = 10000 W  Maximum demand of house hold = 4500 W

 Demand Factor = 4500/10000 = 0.45  Feeder cable required to supply load to household from

power utility company should be of 4500 W 3

Demand Factor  A household has ten, 100 W bulbs  What is the total connected load of light bulbs?  Total connect load of light bulbs = 1000 W  Only six bulbs are turned on at any time, what is the 

  

Maximum Demand? Maximum demand of household = 600 W What is the Demand Factor? Demand Factor = 600/1000 = 0.6 Feeder cable required to supply light bulb load to household should be of 600 W 4

Use of Demand Factor  Feeder conductors should have sufficient Ampere

Capacity to carry the load  The Ampere Capacity does not always be equal to the total of all loads on connected branch-circuits  Demand factor must be applied to each individual load, with particular attention to electric motors, which are very rarely operated at full load

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Use of Demand Factor  As per National Electrical Code (NEC) demand factor may

be applied to the total load  The demand factor permits a feeder ampearcity to be less

than 100 percent of all the branch-circuit loads connected to it

 Demand factor can be applied to calculate the size of the

sub-main which is feeding a Sub or a fixed load like a motor etc  If the have total load of 250 kVA , considering a Demand factor of 0.8, we can size the feeder cable for 250 x 0.8= 200 kVA 6

Use of Demand Factor  Demand factors for buildings typically range between

0.50 and 0.80 of the connected load  In an industrial installation this factor may be estimated on an average at 0.75 for motors  For incandescent-lighting loads, the factor always equals 1

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Demand Factor Demand Factor For Industrial Load Text Book of Design of Elect. Installation- Jain Electrical Load

Demand Factor

1 No of Motor

1

Up to 10 No’s of Motor

0.75

Up to 20 No’s of Motor

0.65

Up to 30 No’s of Motor

0.6

Up to 40 No’s of Motor

0.5

Up to 50 No’s of Motor

0.4

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Demand Factor Demand Factor Text Book of Design of Elect. Installation- Jain Utility

Demand Factor

Office ,School

0.4

Hospital

0.5

Air Port, Bank, Shops,

0.6

Restaurant, Factory,

0.7

Work Shop, Factory (24Hr Shift)

0.8

Arc Furnace

0.9

Compressor

0.5

Hand tools

0.4

Inductance Furnace

0.8 9

Demand Factor Demand Factor Text Book of Principal of Power System-V.K.Mehta Utility Demand Factor Residence Load (<0.25 KW) 1 Residence Load (<0.5 KW) 0.6 Residence Load (>0.1 KW) 0.5 Restaurant 0.7 Theatre 0.6 Hotel 0.5 School 0.55 Small Industry 0.6 Store 0.7 Motor Load (up to 10HP) 0.75 Motor Load (10HP to 20HP) 0.65 Motor Load (20HP to 100HP) 0.55 Motor Load (Above 100HP) 0.50 10

Demand Factor

Demand Factor Saudi Electricity Company Distribution Standard Utility Demand Factor Residential 0.6 Commercial 0.7 Flats 0.7 Hotel 0.75 Mall 0.7 Restaurant 0.7 Office 0.7 School 0.8 Common Area in building 0.8 Public Facility 0.75 Street Light 0.9 Indoor Parking 0.8 Outdoor Parking 0.9 Park / Garden 0.8 Hospital 0.8 Workshops 0.6 Ware House 0.7 Farms 0.9 Fuel Station 0.7 Factories 0.9

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Demand Factor and Load Factor Introduction to Power Requirement for Building – J. Paul Guyer, Utility Demand Factor (%) Load Factor (%) Communications – buildings 60-65 70-75 Telephone exchange building 55-70 20-25 Air enger terminal building 65-80 28-32 Aircraft fire and rescue station 25-35 13-17 Aircraft line operations building 65-80 24-28 Academic instruction building 40-60 22-26 Applied instruction building 35-65 24-28 Chemistry and Toxicology Laboratory 70-80 22-28 Materials Laboratory 30-35 27-32 Physics Laboratory 70-80 22-28 Electrical and electronics laboratory 20-30 3-7 Cold storage warehouse 70-75 20-25 General warehouse 75-80 23-28 Controlled humidity warehouse 60-65 33-38 Hazardous/flammable storehouse 75-80 20-25 Disposal, salvage, scrap building 35-40 25-20

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Demand Factor and Load Factor Introduction to Power Requirement for Building – J. Paul Guyer, Utility Demand Factor (%) Load Factor (%) Hospital Laboratory K-6 schools 7-12 schools Churches Post Office Retail store Bank Supermarket Restaurant Auto repair shop Hobby shop, art/crafts

38-42 32-37 75-80 65-70 65-70 75-80 65-70 75-80 55-60 45-75 40-60 30-40

45-50 20-25 10-15 12-17 5-25 20-25 25-32 20-25 25-30 15-25 15-20 25-30

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Demand Factor and Load Factor Introduction to Power Requirement for Building – J. Paul Guyer, Utility Demand Factor (%) Load Factor (%) Bowling alley Gymnasium Skating rink Indoor swimming pool Theatres Library Golf clubhouse Museum

70-75 70-75 70-75 55-60 45-55 75-80 75-80 75-80

10-15 20-45 10-15 25-50 8-13 30-35 15-20 30-35

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Diversity Factor  Diversity Factor =

Sum of individual Max demands Max.demand on Power Station

 A power station supplies load to various types of consumers

whose maximum demands generally do not occur at the same time  The maximum demand on the power station is always less than the sum of individual maximum demands of the consumers  Diversity factor will always be greater than 1  Greater the diversity factor, lesser is the cost of generation of power 15

Diversity Factor Example 1  Two primary feeders supplied by

a transformer  One of the feeders supplies an industrial load  The other one feeds residential loads  Determine the Diversity Factor of the load connected to the transformer 16

Diversity Factor Example 1  Total max. demand  = 2000 + 2000  = 4000 kW  Max. Demand on

transformer  = 3000 kW  Diversity Factor  = 4000/3000 = 1.33

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Diversity Factor Example 2  Diversity Factor is used for main feeders supplying a   

  

number of secondary feeders Feeder supplies five s with the following load conditions On Monday 1 reaches max. demand of 100 A On Tuesday 2 reaches max. demand of 95 A On Wednesday 3 reaches max. demand of 85 A On Thursday 4 reaches max. demand of 75 A On Friday 5 reaches max. demand of 65 A 18

Diversity Factor Example 2  Feeders max. demand is 250 A  Sum of total demands = (100 + 95 + 85 + 75 + 65) = 420  Diversity Factor = 420/250 = 1.68

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Diversity Factor Example 3  Calculate the size of a main feeder from substation

switchgear that is supplying five feeders with connected loads of 400, 350, 300, 250 and 200 kilovolt-amperes (kVA) with demand factors of 95, 90, 85, 80 and 75 percent respectively. Use a diversity factor of 1.5

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Diversity Factor Example 3  Calculate demand for each feeder  400 kVA × 95% = 380 kVA  350 kVA × 90% = 315 kVA  300 kVA × 85% = 255 kVA  250 kVA × 80% = 200 kVA  200 kVA × 75% = 150 kVA

 The sum of the individual demands is equal to 1,300 kVA  Feeder size = 1300/1.5 = 866.67 kVA

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Diversity Factor Example 4  Use the data

given in load curve to determine the diversity factor of primary feeder

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Diversity Factor Example 4  Sum of max. individual demands ?  = 2300 kW  100 kW street lighting load  1000 kW residential load  1200 kW industrial load  Max primary feeder load ?

 = 1800 kW  Diversity Factor = 2300/1800 = 1.27

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Use of Diversity Factor  The Diversity Factor is applied to each group of loads (e.g.

being supplied from a distribution or sub-distribution board)  Diversity factor is used to estimate the load of a particular node in the system, the total load required for a facility or to size the Transformer  Diversity factors have been developed for main feeders supplying a number of feeders, and typically 1.2 to 1.3 for Residence Consumer and 1.1 to 1.2 for Commercial Load, 1.50 to 2.00 for power and lighting loads 24

Use of Diversity Factor  Note: Reciprocal of the above ratio (will be less than 1) 



 

also is used in some other countries (Coincidence Factor) Diversity factor is mostly used for distribution feeder size and transformer as well as to determine the maximum peak load The residential load has the highest diversity factor Industrial loads have low diversity factors usually of 1.4 Street light practically unity and other loads vary between these limits 25

Diversity Factor in Distribution Network (Standard Handbook for Electrical Engineers” by Fink and Beaty) Elements of System

Residential

Commercial General Power

Large Industrial

Between individual s

2.00

1.46

1.45

Between transformers

1.30

1.30

1.35

1.05

Between feeders

1.15

1.15

1.15

1.05

Between substations

1.10

1.10

1.10

1.10

From s to transformers

2.00

1.46

1.44

From s to feeder

2.60

1.90

1.95

1.15

From s to substation

3.00

2.18

2.24

1.32

From s to generating station

3.29

2.40

2.46

1.45 26

Diversity Factor in Distribution Network  Coincidence Factor % (ks)

Diversity Factor for Apartment block Apartment Diversity Factor in % (ks) 2 To 4 1 5To 19 0.78 10To 14 0.63 15To 19 0.53 20To 24 0.49 25To 29 0.46 30 To 34 0.44 35 To 39 0.42 40To 40 0.41 50 To Above 0.40

Diversity Factor as per IEC 60439 Circuits Function Diversity Factor in % (ks) Lighting 90% Heating and air conditioning 80% Socket-outlets 70% Lifts and catering hoist For the most powerful motor 100% For the second most powerful motor 75% For all motors 80%

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Diversity Factor in Distribution Network

Diversity Factor for Apartment block Apartment Diversity Factor in % (ks) 2 To 4 1 Diversity Factor as per IEC 60439 5To 19 0.78 Circuits Function Diversity 10To 14 Factor in % (ks)0.63 Lighting 90% 0.53 15To 19 Heating and air conditioning 80% 0.49 20To 24 Socket-outlets 70% 0.46 25To 29 Lifts and catering hoist 30 To 34 0.44 For the most powerful motor 100% 0.42 35 To 39 For the second most powerful motor 75% 0.41 40To 40 For all motors 80% 0.40 50 To Above

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Classroom Group Assignment 01  Topic: Calculation of Demand and Diversity Factor  Wednesday, 23rd August 2017

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