Fundamentals of Electricity Distribution Jammu

7/29/2019 Fundamentals of Electricity Distribution Jammu

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)

12-14th March ,2012

Venue: JKPDD Jammu


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Er. A.K. BhagatREC New Delhi


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BasicsofElectricity


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The production of electricity and its transmission and

distribution to our houses, factory or place of work

involves a long process, which consists of operation

of power machines and system network. The whole

process is referred to as the Power System.

The power system can be divided into three broad

sections Generation, Transmission & Distribution

and utilisation


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Types of Generations

- Thermal (Coal, Gas & Diesel)

- Hydro

- Non-Conventional Energy i.e. Wind,

Tidal, Solar, Biomass Gassifiers,Fuel

Cells etc


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Transmission system

It is a process by which the power istransmitted over long distances.

Consists of transmission lines and substationsat EHV &HV (66kv & above)

Connects two substations at the same voltage

Transmission substation Consists of transformers, bus bars, circuit

breakers,isolators, protection andcommunication equipments and a control room.


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Distribution system

Involves distribution of Power received at HV substations

to consumers through distribution system which operates

at voltages at 33 KV and below.

Consists of electrical sub stations, distribution

transformers and distribution lines.

Primary distribution system

It connects the transmission system with secondary

distribution network, at 33 kV or 11 kV voltage levels and

form the back bone of the distribution system.


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Secondary distribution system Supplies power to consumers at voltages of 415 volts

and/or 240 volts and constitutes the first contact of utilityauthorities with the consumers.

Distribution lines Consists of over head lines and/or cables. Lines in rural area are mostly radial in nature Lines in city area are mostly a mesh-like networks often

called ring mains which are used to increase the reliabilityof supply and to meet the high density of loads.


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Utilization-It refers to the process through

which the electricity is put to different uses such

as- Power for industrial units

Power for different kinds of household

appliances and gadgets

Power for communication and electrical traction

Use in medical equipments, Electrolysis, etc.


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VoltageVoltage can be best explained by the example given

below. Consider two water tanks, one above the other,

with a water wheel in between them as shown in below

figure. These tanks are placed in such a way that water

falling from the upper tank through a water tap will turn

the wheel


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Before splashing down to the lower tank. The wheel will go on

rotating as long as there is water in the upper tank if the upper tank is

taken higher the water flow will increase and the wheel will turn

faster. If the upper tank is kept at the same place and the tap turn to

increase the flow of water the wheel will turn faster.

Now if a person draw water from the lower tank and keep pouring it

back to upper tank to replenish the water there, the wheel will turn

continously.If the person stop working, the tank will be empty after

sometime and wheel will stop turning.

Water falling on the wheel makes the wheel turn because there is

energy in water stored in upper tank.

There is water pressure at the outlet of upper tank.

The energy associated with water in the upper tank is called

potential energy and it depends on the different in the height of the

upper tank and lower tank.


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Water in the upper tank has potential energy because of the work

done by the person.

The height from the lower tank to the upper tank is the measure of

the potential energy and,therefore, the pressure.

The equivalent of water pressure in electric circuit is called the

voltage.

The voltage may also be defined as the energy difference between

the positive and negative terminal of a battery.

The energy difference is measured in volts and represented

symbolically as V.


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CurrentCurrent is the flow of electrons. Just as pressurecauses water to flow in the pipe, Voltage causes

current to flow in the conductor. the symbol of

current is I Current is measured in amperes,

and is denoted by the symbol A.


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Resistance Resistance is like friction. It is an inherent property of

all materials to oppose the flow of electricity.

Some materials offer more resistance than others.

Metals such as silver ,copper alumunium and iron

offer less resistance and are good conductors of

electricity.

Materials like plastic,glass,mica, and rubber offer highresistance and are bad conductors of electricity and,

therefore, good insulators.

The symbol of resistance is R,and it is measured in

ohms by a measuring instrument ohmmeter.


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Power is related to the voltage and current by the formula,Power = voltage x current

Replace voltage with current x resistance in the above

equation.Therefore, Power=current x current x resistance

Power is measured in watts, denoted by W 1000 w = 1 kW 1000kW=1MW(megawatt)


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Unlike resistive loads in which the current is used to create heat for the work output,

inductive loads like motors in a factory use require the current to create a magnetic

field, and the magnetic field produces the desired work.This total ( or apparent ) power required by an inductive device comprises the

following:

Real power (measured in kilowatts, kW)

Reactive power, the nonworking power caused by the magnetizing current,required to operate & sustain the magnetism in the device (measured inkilovars,kVAR)

Reactive power required by inductive loads increases the amount of apparent power

(measured in kVA) in the distribution system. The increase in reactive and apparent

power causes the power factor to decrease.

Power factor is defined as the ratio of the real power to the apparent power. As seenfrom the simplest diagram below representing the same,


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Energy is the product of power and time, that is,energy = power x time.

We say that one unit of electricity is consumed when welight a 1000-W bulb for one hour.

Since 1000 W is equal to 1kW,the unit of energy isKWh(kilowatt-hour).

Electricity consumption of any appliance in units can becalculated by the following formula.

Unit consumed = number of hours of operation xpower in kW


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T&D losses can be broadly categorised as:

Technical losses

Commercial losses


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Technical Losses are attributed to:Energy dissipation in the conductors and

equipments used for transmission, transformationand distribution of power.

Improper operation of power system.Can be reduced to a certain minimum level but

cannot be eliminated completelyThe Technical losses in the distribution feeder(line)

increases with (i) an increase in the length of feeder

(ii)a rise in the current flowing through thefeederand(iii)increase in resistance of theline/feeder due to decrease in the cross section ofthe conductor


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Commercial Losses are attributed to:Pilferage of energy by tapping/hooking.

Theft of energy by Tampering ofmeters

Defective energy meters.

Un-metered supply.


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Amount billed to

Consumers

( C = Rs. 240)

Units billed to

consumers

(B =60 units)

Amount realized by utility

(D=Rs. 220)

Units Collected (E=B/C*D

=55 units)

Units purchased

(A =100 units)

AT&C LOSSES

AT&C losses = units input-units collected100-55 =45 units or 45%

Collection losses Technical & Commercial losses


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Thank You

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Fundamentals of Electricity Distribution Jammu