POWER DISTRIBUTION & POWER
LOSS REDUCTION METHODS
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CONTENTS

Power Distribution System
 Equipment in Power Distribution
 Losses in the System
 Methods of Reducing Losses
POWER DISTRIBUTION
Classification of Power Distribution
1. According to type of current
a. DC Distribution
b. AC Distribution
2. According to construction
a. Over head distribution system
b. Underground distribution system
3. According to service
a. General lighting and power
b. Industrial power
c. Street Lighting
4. According to number of wires
a. Two wire
b. Three wire
c. Four wire
5. According to scheme of connections
a. Radial system
b. Ring system
c. Inter connected system
CONNECTION SCHEMES OF DISTRIBUTION
SYSTEM
Radial system: In this system feeders radiate from
single sub station and feed the distribution at one
end only.
Ring system: In this system each consumer is
supplied via two feeders. The arrangement is
similar to two feeders in parallel on different
routes.
Inter connected system: In this system the feeder
ring is energized by two or more generating
stations or sub stations.
POWER DISTRIBUTION AT NFC
 132kV MAIN RECEIVING STATION
132kV is step down to 33kV or 11kV over
two 3 windings transformer of capacity
20/31.5MVA 132kV/33kV/11kV.
The two feeders at 132kV are of 100%
capacity
An ON LOAD TAP CHANGER (OLTC)
which is controlled by automatic voltage
regulator to provide a constant secondary
voltage of 11kV irrespective of primary
incoming feeder voltage in a range of

33kV DISTRIBUTION SYSTEM
33kV is step down to 6.6kV by two 15/20MVA,
33kV/6.6kV transformer.
The step down secondary voltage is connected to
the switch board through a closed type bus duct
6.6kV switch board as 20 bulk oil circuit breaker to
feed the 1250kVA, 6.6kV/433V transformer.
 11kV DISTRIBUTION SYSTEM
11kV supply from 20/31.5MVA transformer is
drawn to the switch panel through XLPE cables.
SF6 gas circuit breaker
CAPTIVE POWER GENERATION PLANT
(CPGP)

Maximum demand of NFC made with
APTRANSCO is 10MVA.
 Total capacity of 7.5MVA, consisting of 3 DG
sets, each of 2.5MVA capacity.
 DG sets are connected to an 11kV bus of the
power plant which is linked with the 11kV with
board of MSDS-1 over to full capacity feeders.
 Every production unit is provided with a diesel
generator set of capacity 40kVA or 180kVA or
500kVA according to their emergency demand.
EQUIPMENT IN POWER DISTRIBUTION
Bus bars: Bus bars or buses are conductors to
which several local feeders or sources are
connected.
1. Outdoor Bus bars
2. Indoor Bus bar
3. Compound Immersed Bus bar
Various types of bus bar arrangements:
1. Single Bus bar Arrangement
2. Duplicate Bus bar Arrangement
3. Sectionalization of Bus bar
4. Ring Bus
Circuit breakers: Circuit breaker requires the separation
of contacts in a presence of a dielectric medium
which serves two functions as
1. It extinguishes arc between two contacts.
2. Provides adequate insulation between the
contacts and from each contact to earth.
Classification of Circuit Breaker:
1. Air Circuit Breakers
2. Oil Circuit Breakers
3. SF6 Circuit Breakers
Surge Arresters:
Surge arresters are used to protect the apparatus
insulation from lightning surges and switching
surges.
Surge arresters are usually connected between
phase and ground in distribution system; near the
terminals of the large medium voltage machines and
in HV, EHV, HVDC substations.
Two types of Surge Arresters:
1. Gapping Silicon Carbide Surge Arresters
2. Zinc Oxide Gapless Arresters.
EQUIPMENT IN POWER DISTRIBUTION
S.No
Equipment
Functions
1
Bus bars
Incoming and outgoing circuits are
connected to bus bars
2.
Lightening arrestors
To discharge lightning over voltages
and switching over voltages to
earth
3.
Shunt reactor in E.H.V
substations
Series reactors
4.
5.
6.
To
provide
reactive
power
compensation during low loads.
To reduce the short circuit currents
or starting currents.
Neutral Grounding Resistor To limit the earth fault currents.
Coupling Capacitor
To provide connection between high
voltage line and line carrier
currents equipment.
S.No
Equipment
Functions
7.
Line Trap
8.
Shunt Capacitors
9.
Power Transformers
To prevent high frequency signal
from entering other zones
To provide compensations to
reactive loads of lagging power
factors.
To step-up or step-down the voltage
and transfer power from one A.C
voltage to other A.C voltage at
same frequency.
10.
Series Capacitors
Compensation of series reactors of
long lines.
LOSSES IN THE POWER DISTRIBUTION





Distribution Line Losses
Transformer Losses:
1. Core Losses
2. Copper Losses
3. Dielectric Losses
4. Stray Magnetic Losses:
Losses due to Harmonics
Losses due to low power factor
Miscellaneous losses
IMPROVEMENTS IN POWER
DISTRIBUTION IN AN INDUSTRY

Energy Management System
 Power Factor Correction
 High Efficiency Transformers
1. Dry Type Transformer
2. Amorphous Core Type Transformer
 Lighting
Energy Management System
Industrial Energy
Management systems
are key factors in
energy cost
conservation.
 Monitoring and
reports
 Load shedding
 Load forecasting
Monitoring and Report
 Monitoring and reports also reveal at what times
there were particularly high loads.
 From here strategies can be developed to avoid such
critical situations.
Load Shedding
 Load shedding modules in an energy management
system offer the possibility of specifying a "turn-off
strategy" which states precisely which consumers
may be turned off at all and in which order.
Industrial load forecasting:
 Load forecasting gives you a preview of your
company’s load curve, it stores knowledge about
the production processes’ behavior in typical
production situations from several hours to several
days ahead.
Forecasting can be done in three modes:
1. Assistance Mode
2. Semi-automatic Mode
3. Automatic Mode
DRY TYPE TRANSFORMERS

Rating ranges from 100 to 20000 KVA
 They make use of flame-retardant inorganic
insulating materials which free these transformers
from all restrictions that apply to oil-filled
electrical equipment, such as oil-collecting pits,
fire walls, fire extinguishing equipment, etc.
 Dry Type Transformers are installed wherever oilfilled units cannot be used
 Their efficiency is rated at 99.02%
DRY-TYPE TRANSFORMERS
1,500 kVA
Standard
(Aluminum)
Load Factor**
High-Efficiency
(Copper)
Standard
(Aluminum)
65%
High-Efficiency
(Copper)
85%
Efficiency
98.64%
99.02%
98.47%
99.02%
Temp. Rise
(100% load)
150° C
80° C
150° C
80° C
Core Loss
4.3 kW
5.5 kW
4.3 kW
5.5 kW
Conductor
Loss
9.1 kW
4.1 kW
15.5 kW
7.1 kW
Total Loss
13.4 kW
9.6 kW
19.8 kW
12.6 kW
–
3.8 kW
–
7.2 kW
First Cost
Rs.7lacs
Rs.9lacs
Rs.7lacs
Rs.9lacs
Cost
Premium
–
Rs.2lacs
–
Rs.2lacs
Power Saving
Benefits of Using High-Efficiency Copper-Wound Dry-Type Transformers
Electrical
Energy Cost
Annual
Savings
Payback
Period
Annual
Savings
Payback
Period
Rs.2.25/kWh
Rs.57000
3.5 y
Rs.1.05lacs
1.9 y
Rs.3.15/kWh
Rs.80000
2.5 y
Rs.1.53lacs
1.3 y
Rs.4.05/kWh
Rs.1lacs
2.0 y
Rs.2.1lacs
1.0 y
AMORPHOUS TRANSFORMERS

Amorphous Transformer has become well
known after "Super amorphous transformer"
produced by Hitachi Ltd.,
 Amorphous transformer uses amorphous alloy
in the core.
 Core material is an alloy of Fe,B,Si.
 Low iron loss, High permeability, Low stress
sensitivity
Comparison between important transformer characteristics of
amorphous material and grain oriented electrical steel.
Performance of 315kVA and 630kVA 3 phase, demonstration
transformers with wound amorphous cores.
POWER FACTOR CORRECTION
The input power factor is the real power divided by
the apparent power
BENEFITS
1. Released System Capacity
2. Reduced Power Losses
3. Voltage Improvement