2 Voltage Drop
3 Distance between the service pole to energy meter
1 Current carrying capacity
2 Voltage Drop
For single Phase Supply permissible voltage drop is equal to
2% of Voltage + 1 Volt
For example: If a house is energized with single phase 230 volts supply then permissible voltage drop is equal to : 2% X 230 + 1 v
= 5.6 volts
For three Phase Supply permissible voltage drop is equal to
5% of Voltage applied
For example: If a house is energized with three phase 430 volts supply then permissible voltage drop is equal to : 5% X 430
= 21.5 volts
3 Relation between voltage drop of wire and permissible voltage drop
Voltage drop Should be less than Permissible voltage drop
Voltage drop < Permissible Voltage drop
Friends this topic is based all numarical so see this carefully and step by step
Numaricals:
Problem 1
A residential building is energized with single phase 230 volts 50 hz supply. The total current requirement by load is 13 amps. The distance between the service main to energy meter is 10 meters. Find out the size of aluminum wire lying between service mains to energy meter.
Ans
Supply voltage = 230 volts
Frequency = 50 hz
I = 13 Amps
Length = 20 meters ( both phase and neutral)
Permissible voltage drop = 2 X 230/100. + 1 volt
= 5.6 volts
For 2.5 square mm wire voltage drop @ 15 A = 20/2.5
@ 1 A. = 20/(2.5 X 15)
@ 13 A. = (20 X 13) / (2.5 X 15)
= 6.9 volts
For 4 square mm wire voltage drop @ 20 A = 20/2.9
@ 1 A. = 20/(2.9 X 20)
@ 13 A. = (20 X 13) / (2.9 X 20)
= 4.48 volts
Problem 2
A residential building is energized with single phase 230 volts 50 hz supply. The total current requirement by load is 5 amps. The distance between the service main to energy meter is 20 meters. Find out the size of aluminum wire lying between service mains to energy meter.
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