Training Session on Energy
Equipment
Electricity
Presentation from the
“Energy Efficiency Guide for Industry in Asia”
www.energyefficiencyasia.org
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© UNEP 2006
Training Agenda: Electricity
• Future electricity scenario
• Generation & distribution
• Phase of electricity
• Active and reactive power
• Power factor correction
• Electrical load management
• Electrical billing mechanisms
• Transformers
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Electricity
General Electricity Scenario
• Development can be measured by a
nation’s electricity consumption
• Electricity usage is divided into:
a) Industrial
b) Commercial and residential
c) Agriculture and irrigation
• Electricity important input for
industry
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© UNEP 2006
Electricity
General Electricity Scenario
International Energy Agency predicts for 2030:
•
78% of population in developing countries
has access to electricity
•
1.4 billion people no access
•
665 billion US$ needed to overcome this
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Electricity
General Electricity Scenario
• How can electricity supply shortage
be solved?
a) Renovation and modernization of plants,
transmission and distribution systems
b) Demand side management with the
utilization of energy efficiency
technologies
c) Awareness raising among energy users
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© UNEP 2006
Electricity
Generation & Distribution
• Electricity generation: fossil fuels and
uranium
• Renewable energy is growing
World electricity generation by
energy
Renewable 21%
Nuclear 16%
Fossil fuels 63%
(US Energy Information Administration, 2004)
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Electricity
Generation & Distribution
Transmission
system
Power plant
Distribution system
Generator
GT
10.6 KV
220 KV
Distribution
Step down
transformer
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Electricity
Generation & Distribution
• AC generators (“alternators”) generate
electricity
• Electricity generated at 9-13 KV
• Power generated from 67.5 to 1000 MW
• Power stations: generating transformers
(GTs) to increase voltage to 132-400 KV
• Substations: step-down transformers to
reduce voltage before distribution
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Electricity
Generation & Distribution
Benefits of high voltage transmission
• Less voltage drop: good voltage regulation
• Less power loss: high transmission
efficiency
• Smaller conductor: lower costs
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Electricity
Phase of Electricity
Single phase AC circuit:
• Two wires connected
to electricity source
• Direction of current
changes many times
per second
3-phases of an electric system
(Wikipedia contributors, 2005)
Three phase systems:
• 3 lines with electricity from 3 circuits
• One neutral line
• 3 waveforms offset in time: 50-60 cycles/second
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Electricity
Phase of Electricity
Star connection
Delta connection
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Electricity
Active and Reactive Power
• Active power (kW): real power used
• Reactive power (kVAR): virtual power that
determines load/demand
• Utility pays for total power (kVA)
kVA =  (KW)2 + (KVAR)2
Source: OIT
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Electricity
Power Factor Correlation
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Figure: Power factor of electric circuit
© UNEP 2006
Electricity
PF Correction: Capacitors
• kVAR demand should be as low as
possible for the same kW output
Figure: Capacitor as kVAR generator
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Electricity
PF Correction:
Capacitors
• Act as reactive
power
generators
• Reduce reactive
power
• Reduce total
power generated
by the utilities
Figure: Fixed capacitor banks
Source: Ecatalog
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Electricity
PF Correction: Capacitors
Advantages for company:
•
One off investment for capacitor
•
Reduced electricity costs:
•
Total demand reduced
•
No penalty charges
•
Reduced distribution losses
•
Increased voltage level at load end, improved
motor performance
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© UNEP 2006
Electricity
PF Correction: Capacitors
Advantages for utility:
•
Reduced reactive component of network
•
Reduced total current in the system from
the source end
•
Reduced I2R power losses
•
Reduced need to install additional
distribution network capacity
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© UNEP 2006
Electricity
Electrical Load Management
• Goal: reduce maximum electricity demand
to lower the electricity costs
KVA
• Load curve predicts patterns in demand
Daily load curve of an
engineering industry
(National Productivity
Council, India)
18
Hours
© UNEP 2006
Electricity
Electrical Load Management
Strategies to manage peak load demand:
•
Shift non-critical / non-continuous process
loads to off-peak time
•
Shed non-essential loads during peak time
•
Operate in-house generation or diesel
generator (dg) sets during peak time
•
Operate AC units during off-peak times and
utilize cool thermal storage
•
Install power factor correction equipment
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© UNEP 2006
Electricity
Electricity Billing Mechanism
• Energy charges
• Actual charges based on active power
• Charge based on apparent power
• Maximum demand charges
• Based on maximum demand registered
• Penalty for peak load
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© UNEP 2006
Electricity
Electricity Billing Mechanism
• Power factor penalty or bonus
• Fuel costs
• Electricity duty charges
• Meter rentals
• Lighting & fan power consumption
• Time of Day (TOD) rates
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Electricity
Electricity Billing Mechanism
Utility uses trivector meter for measurement
during billing cycle (usually month):
• Maximum demand
• Active energy in kWh
• Reactive energy in kVArh
• Apparent energy in kVAh
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Electricity
Electricity Billing Mechanism
•
Demand
measured in
time intervals
•
Maximum
demand is
highest reading
•
Customer
charged on
highest
maximum
demand value!
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A Typical Demand Curve
(National Productivity Council)
© UNEP 2006
Electricity
Transformer
•
Static electrical device that
transforms electrical energy
from one voltage level to
another
•
Two or more coils linked
magnetically but electrically
insulated
•
Figure 12: A view of a
transformer
(Indiamart.com)
Turns Ratio: turns on 2nd coil (connected to load)
turns on 1st coil (connected to power source)
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Electricity
Transformer types
Transformers are classified based on:
• Input voltage
• Operation
• Location
• Connection
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Electricity
Transformer Losses & Efficiency
PTOTAL = PNO-LOAD+ (% Load/100)2 x PLOAD
PTOTAL = PNO-LOAD+ (Load KVA/Rated KVA)2 x PLOAD
Transformer loss versus percent loading (BEE, 2004)
• Transformer losses: constant and variable
• Best efficiency: load where constant loss =
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variable loss
© UNEP 2006
Electricity
Electricity Formulae
•
Resistance (Ohm)
•
Power factor
•
Voltage (Volts)
•
Efficiency
•
Reactance
•
Transformer ratio
•
Impedance
•
•
Real power (Watt)
Voltage drop in a
line
•
Star connection
•
Delta connection
•
•
Reactive power
Apparent power
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© UNEP 2006
Training Session on Energy
Equipment
Electricity
THANK YOU

FOR YOUR ATTENTION
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© UNEP GERIAP
Disclaimer and References
• This PowerPoint training session was prepared as part of
the project “Greenhouse Gas Emission Reduction from
Industry in Asia and the Pacific” (GERIAP). While
reasonable efforts have been made to ensure that the
contents of this publication are factually correct and
properly referenced, UNEP does not accept responsibility for
the accuracy or completeness of the contents, and shall not
be liable for any loss or damage that may be occasioned
directly or indirectly through the use of, or reliance on, the
contents of this publication. © UNEP, 2006.
• The GERIAP project was funded by the Swedish
International Development Cooperation Agency (Sida)
• Full references are included in the textbook chapter that is
available on www.energyefficiencyasia.org
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© UNEP 2006