Fundamental of Electrical Loads

Chapter 7

04/19/23 Prof. Magdi El-Saadawi 1

The Load Curve • It gives the following information

– Variation of load during different hours of day– Max. and Min. value s of daily load– Average annual load of the station– Information whether the installations is

working efficiently or not

04/19/23 Prof. Magdi El-Saadawi 2

04/19/23 Prof. Magdi El-Saadawi 3

04/19/23 Prof. Magdi El-Saadawi 4

5

حكومى لحمل توضيحى شكل

الحمل يمثل الرأسى المحوروات بالكيلو

الزمن يمثل األفقى المحوربالساعات

04/19/23 Prof. Magdi El-Saadawi

Difference between load curves of summer and winter

04/19/23 Prof. Magdi El-Saadawi 6

04/19/23 Prof. Magdi El-Saadawi 7

04/19/23 Prof. Magdi El-Saadawi 8

04/19/23 Prof. Magdi El-Saadawi 9

Load Duration Curve

04/19/23 Prof. Magdi El-Saadawi 10

Load Duration Curve

04/19/23 Prof. Magdi El-Saadawi 11

Load Curve and Load Duration Curve

04/19/23 Prof. Magdi El-Saadawi 12

• Average Demand: the ratio of kWh delivered by the station in a particular period divided by the hours in that period

• Load FactorMonthly L.F. =

kWh supplied in a month

Maximum demand * 24 * 30Annual L.F. =

kWh supplied in a year

Maximum demand * 8760

04/19/23 Prof. Magdi El-Saadawi 13

• Diversity of Load

فترة فى تعمل ال المختلفة األحمال أن يعنىتتبع الكهرباء شركات أن أو واحدة زمنية

ذلك إلى تدفع سياسات

• Diversity Factor

the ratio of the sum of maximum demands of the individual category to the maximum demand of the power station

04/19/23 Prof. Magdi El-Saadawi 14

Practical Example on Diversity Factor

04/19/23 Prof. Magdi El-Saadawi 15

Solution 1:

Transformer Size (Assuming Diversity Factor of 1.0)

2,000 + 1,500 + 1,000 = 4,500 kVA

Solution 2:

Transformer Size (Assume Diversity Factor of 1.2) Choose 3,750 kVA

(4,500 kVA divided by 1.2 = 3,750 kVA)

?Which is better and why

High or Low load factor value

High or Low diversity factor value

04/19/23 Prof. Magdi El-Saadawi 16

• Plant Factor

Indicates how best the plant capacity has been utilized

Station output in kWh

kW1*h1 + kW2*h2 + kW3*h3 + …….

• Capacity Factor is a value used to express the average percentage of full

capacity used over a given period of time. Average demand on the Station

Maximum Installed Capacity of the Station

04/19/23 Prof. Magdi El-Saadawi 17

• Connected Load Factor

Average kWh

Connected load * 8760

04/19/23 Prof. Magdi El-Saadawi 18

Load Duration Curve

04/19/23 Prof. Magdi El-Saadawi 19