EE482 ENERGY MANAGEMENT & AUDITING

MODULE 2

ENERGY MANAGEMENT OPPORTUNITIES IN LIGHTING, MOTORS,

ELECTROLYTIC PROCESS & ELECTRIC HEATING
TYPES OF INDUSTRIAL LOADS,
PEAK DEMAND CONTROLS AND METHODOLOGIES
 INTRODUCTION
• Energy management is the process of monitoring, controlling and conserving energy in a
building or organization
• Electrical energy is becoming increasingly important to industry due to the more prevalent use
of improved electric process systems and the development of new electro technologies.
• As a result, by increasing the electrical efficiency of equipments, more energy saving can be
achieved
Energy management opportunities in lighting systems
• In today’s cost-competitive, market-driven economy, everyone is seeking technologies or
methods to reduce energy expenses and environmental impact related to lighting systems
• Because nearly all buildings have lights, lighting retrofits are very common and generally offer
an attractive return on investment.
• Electricity used to operate lighting systems represents a significant portion of total electricity
consumed mainly in commercial buildings

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• Overall Electrical energy consumption in commercial
buildings is shown in figure
• From figure it is clear that Electric lighting is a major
energy consumer.
• Enormous energy savings are possible using energy
efficient equipment, effective controls, and careful design
• Using less electric lighting reduces heat gain, thus
saving air-conditioning energy and improving thermal
comfort.
• Electric lighting design also strongly affects visual performance and visual comfort by aiming
to maintain adequate and appropriate illumination while controlling reflection and glare.
• Lighting is not just a high priority when considering hotel design; it is also a high return, low-
risk investment.
• By installing new lighting technologies, hotels can reduce the amount of electricity consumed
and energy costs associated with lighting.

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• There are several types of energy efficient lighting and affordable lighting technology. The
following are a few examples of energy-saving opportunities with efficient lighting.
1. Installation of LED lamps in place of incandescent lamps & compact fluorescent lamps
(CFLs).
2. Installation of energy-efficient fluorescent lamps in place of “conventional” fluorescent
lamps.
3. Installation of occupancy/motion sensors to turn lights on and off where appropriate.
4. Use an automated device, such as a key tag system, to regulate the electric power in a
room.
5. Offer nightlights to prevent the bathroom lights from being left on all night.
6. Replace all exit signs with light emitting diode (led) exit signs.
7. Use high efficiency (hid) exterior lighting
8. Add lighting controls such as photo sensors or time clocks
9. Optimization of plant lighting
10. Maximum use of natural sunlight
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1. Installation of LED lamps in place of incandescent lamps & compact fluorescent lamps (CFLs).
- LED Lamps use a different, more advanced technology than incandescent light bulbs and come
in a range of styles, colour and sizes based on brand and purpose.
- They can replace regular, CFL & incandescent bulbs in almost any light fixture including globe
lamps for the bathroom vanity, lamps for recessed lighting, dimming, and 3-way functionality
lights.
- LEDs use about 80% less energy than standard incandescent bulbs, 30% less energy than CFLs
and give the same amount of light, and can last 6 to 10 times longer.
- LED prices range from ₹75 to ₹100 depending on the bulb, but you save about ₹300 to ₹500
per bulb on energy during the lifetime of the bulb.

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- When looking to purchase LEDs in place of incandescent bulbs, compare the light output, or
Lumens, and not the watts.
- Watts refers to the amount of energy used, not the amount of light. In other words, if the
incandescent bulb you wish to replace is 60 Watts, this is equal to 800 Lumens
- To get the same amount of light in a LED, you should look to find a LED that provides 800
Lumens or more.

2. Installation of energy-efficient fluorescent lamps in place of “Conventional” fluorescent

lamps.
- Many lodging facilities may already use fluorescent lighting in their high traffic areas such as
the lobby or office area.
- However, not all fluorescent lamps are energy efficient and cost effective.
- There are several types of fluorescent lamps that vary depending on the duration of their lamp
life, energy efficiency, regulated power, and the quality of color it transmits.

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- There are a few styles worth noting; these models are simply labelled as “T-12”, “T- 8”, or “T-
5”.
- The names come from the size of their diameter per eighth inch.
- For example, a T-12 lamp is 12/8 inch in diameter (or 1 1/2 inch); a T-8 lamp is 8/8 inch in
diameter (or 1 inch); a T-5 lamp is 5/8 inch in diameter.
- This is a simple way to identify the type of fluorescent lamps your
facility is using.
- The recommended style of fluorescent lighting is a T-8. T-8 lights
are the most cost-effective.
- They usually cost about 100 Rs a bulb and are 30% to 40% more efficient than standard T-12
fluorescent lamps, which have poor colour rendition and cause eye strain.
- T-8 lamps provide more illumination, better colour, and don't flicker (often exhibited by
standard fluorescent fixtures).
- T-5 lamps are the most energy efficient and also tend to transmit the best colour; however,
they usually cost about 250 Rs per bulb.

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3. Installation of occupancy/motion sensors to turn lights on and off where appropriate.
• Lighting can be controlled by occupancy sensors to allow operation whenever someone is
within the area being scanned.
• When motion can no longer be detected, the lights shut off. Passive infrared sensors react to
changes in motion.
• The controller must have an unobstructed view of the building area being scanned.
• Doors, partitions, stairways, etc. will block motion detection and reduce its effectiveness.
• The best applications for passive infrared occupancy sensors are open spaces with a clear view
of the area being scanned.
• Ultrasonic sensors transmit sound above the range of human hearing and monitor the time it
takes for the sound waves to return. A break in the pattern caused by any motion in the area
triggers the control.

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• Ultrasonic sensors can see around obstructions and are best for areas with cabinets and
shelving, restrooms, and open areas requiring 360-degree coverage.
• Some occupancy sensors utilize both passive infrared and ultrasonic technology, but are
usually more expensive. They can be used to control one lamp, one fixture or many fixtures.
• It can work in 3 modes: Time out, sensor mode and motion sensitivity settings.
• The table below provides typical savings achievable for specific building areas, by the
implementation of motion sensors.

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4. Use an automated device, such as a key tag system, to regulate the electric power in a room.
- The key tag system uses a master switch at the entrance of each guest room, requiring the use
of a room key-card to activate them.
- Using this technique, only occupied rooms consume energy because most electrical
appliances are switched off when the keycard is removed (when the guest leaves the room).
- Along with lighting, heating, air conditioning, radio and television may also be connected to
the master switch. This innovation has a potential savings of about $105.00 per room per year.

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5. Offer nightlights to prevent the bathroom lights from being left on all night
• Many guests opt to have a light on while they sleep.
• By turning the bathroom light on and leaving the bathroom door cracked open, guests are
able to find their way through an unknown room in the middle of the night.
• Those who are accompanied by children may often do the same to comfort their child.
• By offering a nightlight, the energy used to power a bathroom light during the night time can
be avoided and guests will still be able to feel comfortable in unfamiliar territory.
• One particular model uses six Light Emitting Diodes (LEDs) in the panel of a light switch to
provide light for guests.
• LEDs are just tiny light bulbs that fit easily into an electrical circuit. They are different from
ordinary incandescent bulbs because they don’t burn out or get really hot.

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6. Replace all exit signs with light emitting diode (LED) exit signs.
• The development of light emitting diodes (LEDs) has allowed the replacement of exit sign
lighting with a more energy efficient alternative.
• Multiple LEDs, properly configured, produce equivalent lighting and consume 95% less
electricity than incandescent bulbs and compact fluorescent lamps is 75% less energy-efficient
than LED.
• A major benefit is the 20-year life cycle rating of LEDs; they virtually eliminate maintenance.
Of the three different styles of exit signs, incandescent signs are the least expensive, but are
inefficient and use energy releasing heat instead of light.
• Fluorescent signs are also inexpensive and have an expected life of about 10,000 hours.
• LED exit signs are the most expensive, but are also the most efficient exit signs available. Their
payback time is usually about four years. The table on the following slide offers an easy
comparison of the three models of exit signs.

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7. Use high efficiency (hid) exterior lighting
• High intensity discharge (HID) lighting is much more efficient and preferable to incandescent,
quartz-halogen and most fluorescent light fixtures.
• HID types (from least to most efficient) include mercury vapour, metal halide and high
pressure sodium. Mercury vapour is seldom used anymore.
• Both metal halide and high pressure sodium are
excellent outdoor lighting systems.

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• High pressure sodium has a pink-orange glow and is used when good color rendition isn’t
critical.
• Metal halide, though less efficient, provides clean white light and good color rendition.
• HID lighting is mostly utilized in floodlight, wall pack, canopy and area fixtures outdoors.
• The best type for any application depends on the area being lit and mounting options.

8. Add lighting controls such as photo sensors or time clocks

• Photo sensor controls monitor daylight conditions and allow fixtures to operate only when
needed.
• Photo sensors detect the quantity of light and send a signal to a main controller to adjust the
lighting.
• Photo sensors are commonly used with outdoor lighting to automatically turn lights on at dusk
and off at dawn, a very cost-effective control device. This helps to lower energy costs by
ensuring that unnecessary lighting is not left on during daytime hours.

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• Photo sensors can be used indoors, as well. Building areas with lots of windows may not
require lights to be on all of the time.
• Photocells can be used to ensure fixtures operate only when the natural light is inadequate by
either controlling one light fixture, or a group of lights.
• Time controls save energy by reducing lighting time of use through preprogramed
scheduling.
• Time clock equipment ranges from simple devices designed to control a single electrical load
to sophisticated systems that control several lighting zones. They are one of the simplest, least
expensive, and most efficient energy management devices available.

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Time controls could include:
• Simple time switches: automatically turn lights, fans or other electronic devices off after a pre-
set time.
• Multi-channel time controls: have the ability to control from 4 to 16 duties.
• Special-purpose time controls: include cycle timers for repetitive short duration cycling of
equipment or outdoor lighting time controls that combine time clock and photo sensor
technologies.

9. Optimization of plant lighting (Lux optimization)

• If the lighting provided is higher than the standard (required lux) for any part of the
production, this results in a waste of electricity.
• Therefore, the plant engineers should optimize the lighting system based on the standard lux
specific for each process step

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10. Optimum use of natural sunlight
• Many plants do not use natural sunlight to an optimum level.
• In addition to optimizing the size of the windows, transparent sheets can be installed at the
roof in order to allow more sunlight to penetrate in to the production area.

Energy Management Opportunities in electric motors

• Motors convert electrical energy into mechanical energy by the interaction between the
magnetic fields set up in the stator and rotor windings.
• Industrial electric motors can be broadly classified as induction motors, direct current motors
and synchronous motors.
• All motor types have the same four operating components: stator (stationary windings), rotor
(rotating windings), bearings and frame (enclosure).

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• Two important attributes relating to efficiency of electricity use by AC Induction motors are
efficiency (η), defined as the ratio of the mechanical energy delivered at the rotating shaft to
the electrical energy input at its terminals and power factor (PF).
• Motors, like other inductive loads, are characterized by power factors less than one.
• As a result, the total current draw needed to deliver the same real power is higher than for a
load characterized by a higher PF.
• An important effect of operating with a PF less than one is that resistance losses in wiring
upstream of the motor will be higher, since these are proportional to the square of the
current.
• Thus, both a high value for η and a PF close to unity are desired for efficient overall operation
in a plant.
• Squirrel cage motors are normally more efficient than slip-ring motors, and higher-speed
motors are normally more efficient than lower-speed motors.
• Efficiency is also a function of motor temperature. Totally-enclosed, fan-cooled (TEFC) motors
are more efficient than screen protected, drip-proof (SPDP) motors.

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• Also, as with most equipment, motor efficiency increases with the rated capacity.
• The efficiency of a motor is determined by intrinsic losses that can be reduced only by
changes in motor design.
• Intrinsic losses are of two types: fixed losses - independent of motor load, and variable losses -
dependent on load.
Energy-Efficient Motors
- Energy-efficient motors (EEM) are the ones in which,
design improvements are incorporated specifically to
increase operating efficiency over motors of standard
design (see Figure).
- Design improvements focus on reducing intrinsic motor
losses.

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- Improvements include the use of lower-loss silicon steel, a longer core (to increase active
material), thicker wires (to reduce resistance), thinner laminations, smaller air gap between
stator and rotor, copper instead of aluminum bars in the rotor, superior bearings and a smaller
fan, etc.
- Energy-efficient motors now available in India operate with efficiencies that are typically 3 to 4
percentage points higher than standard motors.
- In keeping with the stipulations of the BIS, energy-efficient motors are designed to operate
without loss in efficiency at loads between 75 % and 100 % of rated capacity.
- This may result in major benefits in varying load applications.
- The power factor is about the same or may be higher than for standard motors. Furthermore,
energy efficient motors have lower operating temperatures and noise levels, greater ability to
accelerate higher-inertia loads and are less affected by supply voltage fluctuations.

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 Different losses in motors
- Measures adopted for energy efficiency to address each loss specifically as under:
a) Stator and Rotor I2R Losses or Copper losses
• These losses are major losses and typically account for 55% to 60% of the total losses.
• I2R losses are heating losses resulting from current passing through stator and rotor
conductors.
• I2R losses are the function of a conductor resistance, the square of current.
• Resistance of conductor is a function of conductor material, length and cross sectional area.
• The suitable selection of copper conductor size will reduce the resistance.
• Reducing the motor current is most readily accomplished by decreasing the magnetizing
component of current.
• This involves lowering the operating flux density and possible shortening of air gap.
• Rotor I2R losses are a function of the rotor conductors (usually aluminum) and the rotor slip.
• Utilization of copper conductors will reduce the winding resistance.
• Motor operation closer to synchronous speed will also reduce rotor I2R losses.
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b) Core Losses or iron losses
• Core losses are those found in the stator-rotor magnetic steel and are due to hysteresis effect
and eddy current effect during 50 Hz magnetization of the core material.
• These losses are independent of load and account for 20 – 25 % of the total losses.
• The hysteresis losses which are a function of flux density, are be reduced by utilizing low loss
grade of silicon steel laminations.
• The reduction of flux density is achieved by suitable increase in the core length of stator and
rotor.
• Eddy current losses are generated by circulating current within the core steel laminations.
These are reduced by using thinner laminations.

c) Friction and Windage Losses

• Friction and windage losses results from bearing friction, windage and circulating air through
the motor and account for 8 – 12 % of total losses.

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• These losses are independent of load.
• The reduction in heat generated by stator and rotor losses permit the use of smaller fan.
• The windage losses also reduce with the diameter of fan leading to reduction in windage
losses.

d) Stray Load-Losses
• These losses vary according to square of the load current and are caused by leakage flux
induced by load currents in the laminations and account for 4 to 5 % of total losses.
• These losses are reduced by careful selection of slot numbers, tooth/slot geometry and air
gap.
Energy efficient motors cover a wide range of ratings and the full load efficiencies are higher by 3
to 7 %. The mounting dimensions are also maintained as per IS1231 to enable easy replacement.
• As a result of the modifications to improve performance, the costs of energy-efficient motors
are higher than those of standard motors.

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• The higher cost will often be paid back rapidly in saved operating costs, particularly in new
applications or end-of-life motor replacements.
• In cases where existing motors have not reached the end of their useful life, the economics
will be less clearly positive.
• Because the favourable economics of energy-efficient motors are based on savings in
operating costs, there may be certain cases which are generally economically ill-suited to
energy efficient motors.
• These include highly intermittent duty or special torque applications such as hoists and
cranes, traction drives, punch presses, machine tools and centrifuges.
• In addition, energy efficient designs of multi-speed motors are generally not available.
• Furthermore, energy- efficient motors are not yet available for many special applications, e.g.
for flame-proof operation in oil-field or fire pumps or for very low speed applications (below
750 rpm).
• Also, most energy-efficient motors produced today are designed only for continuous duty
cycle operation.

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• Given the tendency of over sizing on the one hand and ground realities like ; voltage,
frequency variations, efficacy of rewinding in case of a burnout, on the other hand, benefits of
EEM's can be achieved only by careful selection, implementation, operation and maintenance
efforts of energy managers.
• A summary of energy efficiency improvements in EEMs is given in the Table

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 Factors Affecting Energy Efficiency of Electric Motors
a) Power Supply Quality
• Motor performance is affected considerably by the quality of input power, that is the actual
volts and frequency available at motor terminals in comparison with rated values as well as
voltage and frequency variations and voltage unbalance across the three phases.
• Motors in India must comply with standards set by the Bureau of Indian Standards (BIS) for
tolerance to variations in input power quality.
• The BIS standards specify that a motor should be capable of delivering its rated output with a
voltage variation of +/- 6 % and frequency variation of +/- 3 %.
• Fluctuations much larger than these are quite common in utility-supplied electricity in India.
• Voltage fluctuations can have detrimental impacts on motor performance.

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b) Power Factor Correction
• As noted earlier, induction motors are characterized by power factors less than unity, leading
to lower overall efficiency (and higher overall operating cost) associated with a plant's
electrical system.
• Capacitors connected in parallel (shunted) with the motor are typically used to improve the
power factor.
• The impacts of PF correction include reduced kVA demand (and hence reduced utility demand
charges), reduced I2R losses in cables upstream of the capacitor (and hence reduced energy
charges), reduced voltage drop in the cables (leading to improved voltage regulation) and an
increase in the overall efficiency of the plant electrical system.
• It should be noted that PF capacitor improves power factor from the point of installation back
to the generating side.
• It means that, if a PF capacitor is installed at the starter terminals of the motor, it won't
improve the operating PF of the motor, but the PF from starter terminals to the power
generating side will improve, i.e., the benefits of PF would be only on upstream side.

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• The size of capacitor required for a particular motor depends upon the no-load reactive kVA
(kVAR) drawn by the motor, which can be determined only from no-load testing of the motor.
• In general, the capacitor is then selected to not exceed 90 % of the no-load kVAR of the motor.
(Higher capacitors could result in over-voltages and motor burn-outs).
• Alternatively, typical power factors of standard motors can provide the basis for conservative
estimates of capacitor ratings to use for different size motors.
• The capacitor rating for power connection by direct connection to induction motors is shown
in Table.

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• From the above table, it may be noted that required capacitive kVAr increases with decrease
in speed of the motor, as the magnetizing current requirement of a low speed motor is more
in comparison to the high speed motor for the same HP of the motor.
c) Maintenance
• Inadequate maintenance of motors can significantly increase losses and lead to unreliable
operation.
• For example, improper lubrication can cause increased friction in both the motor and
associated drive transmission equipment.
• Resistance losses in the motor, which rise with temperature, would increase.
• Providing adequate ventilation and keeping motor cooling ducts clean can help dissipate heat
to reduce excessive losses.
• The life of the insulation in the motor would also be longer: for every 10°C increase in motor
operating temperature over the recommended peak, the time before rewinding would be
needed is estimated to be halved

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• A checklist of good maintenance practices to help insure proper motor operation would
include:
 Inspecting motors regularly for wear in bearings and housings (to reduce frictional losses)
and for dirt/dust in motor ventilating ducts (to ensure proper heat dissipation).
 Checking load conditions to ensure that the motor is not over or under loaded. A change in
motor load from the last test indicates a change in the driven load, the cause of which
should be understood.
 Lubricating appropriately. Manufacturers generally give recommendations for how and when
to lubricate their motors. Inadequate lubrication can cause problems, as noted above. Over
lubrication can also create problems, e.g. excess oil or grease from the motor bearings can
enter the motor and saturate the motor insulation, causing premature failure or creating a
fire risk.
 Checking periodically for proper alignment of the motor and the driven equipment.
Improper alignment can cause shafts and bearings to wear quickly, resulting in damage to
both the motor and the driven equipment.
 Ensuring that supply wiring and terminal box are properly sized and installed. Inspect
regularly the connections at the motor andEEEstarter
MITS to be sure that they are clean and tight.
30
d) Age
• Most motor cores in India are manufactured from silicon steel or de-carbonized cold-rolled
steel, the electrical properties of which do not change measurably with age.
• However, poor maintenance (inadequate lubrication of bearings, insufficient cleaning of air
cooling passages, etc.) can cause a deterioration in motor efficiency over time.
• Ambient conditions can also have a detrimental effect on motor performance. For example,
excessively high temperatures, high dust loading, corrosive atmosphere, and humidity can
impair insulation properties; mechanical stresses due to load cycling can lead to misalignment.
However, with adequate care, motor performance can be maintained.
e) Rewinding of motor
• It is common practice in industry to rewind burnt out motors
• Careful rewinding can sometimes maintain motor efficiency at previous levels, but in most
cases losses in efficiency results
• Rewinding can affect a number of factors that contribute to deteriorated motor efficiency :
winding & slot design, winding material, insulation performance and operating temperature

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• For eg, a common problem occurs when heat is applied to strip old windings, the insulation
between laminations can be damaged, thereby increasing eddy current losses
• A change in the air gap may affect power factor & output torque
• If proper measures are taken, motor efficiency can be maintained and in some cases increased
after rewinding
• The impact of rewinding on motor efficiency & pf can be easily assessed if the no load losses
of the motor are known before & after rewinding
f) Proper sizing of the motor to avoid under loading
g) Provide proper ventilation
- for every 10 degree rise in motor operating temperature over recommended peak, the motor
life is estimated to be halved
h) Use energy efficient motors where economical

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Classification of motors based on energy efficiency (International efficiency classes for motors)
- Based on energy efficiency of motors, they are classified
1. Eff classification
- In 1998, the European Committee of Manufacturers of Electrical Machines and Power
Electronics (CEMEP) developed three classes (i.e. EFF1, EFF2 and EFF3) to describe the energy
efficiency of motors.
- It is a voluntary agreement between the electrical motor manufacturers and the European
Commission.
- The EFF has 3 classes, i.e. EFF1, EFF2 and EFF3 respectively.
- EFF1 is the most energy efficient, while EFF3 is the least energy efficient.
- In other words, the lower class number represents the higher motor efficiency.

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2. IE Classification
• The IE Classification is defined by IEC 60034-30-1. The latest version of IEC 60034-30-1 was
published in June 2014.

Class type Class number

Standard efficiency IE 1
High efficiency IE 2
Premium efficiency IE 3
Super premium efficiency IE 4

• IE4 represents the highest energy efficiency whilst IE1 represents the least energy efficiency.
• In other words, the higher the class number, the higher the motor efficiency.

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 Loading of motor
- Motor loading is a measure of the net load on the motor
- It can be expressed as the ratio of actual electrical input to motor & rated electrical input to
motor or the ratio of actual output of motor (mechanical) & rated output of motor
(mechanical)
- % loading of the motor = [Input power drawn by the motor (kW) at existing load/(Name plate
full load kW rating/name plate full load efficiency)] x 100
- i.e, Motor loading % = (Actual operating load of the motor /rated capacity of motor) x 100
Under loading of motors
- A motor is said to be under loaded if it is operated continuously at a load less than 70% of full
load
- Under loading of motor is one reason that contribute to sub optimal motor efficiency
- The power factor of the motor decreases when it is under loaded
- When power factor decreases, efficiency also decreases
- Under loading is common due to following reasons
 If motor manufacturer use a large safety factor in motors, then it may result in under loading
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 Under loading may occur due to under utilization of equipment. For example, in machine tool
equipment, the manufacturer may provide a motor having rating suitable for full capacity load
of equipment. But the user may need this full capacity rarely and it result in under loading of
motor
 Another common reason for under loading of motor is selection of larger motor for enable the
output to be maintained at desired level even when input voltages are abnormally low.
 Under loading also results from selecting a large motor for an application requiring high
starting torque. If a motor, specially designed for high torque is used for this purpose, the
under loading can be avoided
Steps to improve operating efficiency of under loaded motors
1. Improving motor loading by operating in star mode
• for motors operating at loads below 40% of rated capacity, the motor loading can be improved
by operating in star mode.
• Operating in star mode leads to a reduction in voltage by a factor of √3 and power by a factor
of 3, but the performance characteristics remains the same.
• For example, if a motor is rated for 15kW in delta mode, its derated capacity is 5kW in star
mode. Thus full load operation in star mode gives higher efficiency and power factor than
partial load operation in delta
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2. Sizing to variable load
• Industrial motors frequently operates under varying load conditions due to process
requirements
• In such a case, a common practice is to select a motor based on highest anticipated load
• This may result in under loading of motor
• To avoid this, rather than selecting a motor of high rating that would operate at full capacity for
only a short period, a motor will be selected with a rating slightly lower than the peak
anticipated load and would operate at overload for a short period of time
3. Power factor correction
• If a motor is under loaded, its power factor decreases and as a result the efficiency of motor
also decreases
• Capacitors connected in parallel with the motor is used to improve the power factor
• The impact of power factor improvement include reduced kVA demand, reduced I2R losses in
cable, reduced voltage drop in cables and increase in overall efficiency of the plant electrical
system
• The size of the capacitor required for a particular motor depends upon the no load kVAR
drawn by the motor
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Criteria for selection of motors
- While choosing a motor for a particular application, the following points need to be
considered
1. Type of power supply available: The motor should be chosen by considering whether DC/AC
supply or 1phase or 3phase AC supply available
2. Power rating of the motor: The power rating of motor should be chosen by considering the
actual power requirement of the application to avoid under loading/over loading of motor
3. Starting of motor: The motor should be chosen by considering whether the motor is started
on load or on no load condition
4. Speed of motor: The motor should be chosen by considering whether the speed of the motor
is compatible with the required speed in the application
5. Bearing type: The type of bearing of motor should be considered
6. Base type: The method of fixing the motor need to be considered while choosing the motor.
i.e, rigid base, sliding adjustable base etc.
7. Environment where the motor is installed: While choosing the motor the place where it is
going to be installed need to be considered. According to the environment we need to
choose the motor enclosure type.
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Example 1
A three phase 10kW motor has the name plate details as 415V, 18.2A and 0.9 pf. Actual input
measurement shows 415V, 12A and 0.7 pf which was measured with power analyzer during
motor running. Determine the motor loading?
Rated full load output (Mechanical power) = 10kW
Rated full load input (Electrical power) = √3 x V x I x Cosφ = √3 x 415 x 18.2 x 0.9
= 11800W
Actual input (measured) of motor = √3 x V x I x Cosφ = √3 x 415 x 12 x 0.7
= 6000W
Motor loading % = (Measured kW/Rated kW) x 100 = (6000/11800)x100
= 51.2%
Example 2
An electric heater of 230V, 5kW rating is used for hot water generation in an industry. Find
electricity consumption/hour a) at rated voltage b) at 200V
a) Electricity consumption at rated voltage = 5kW x 1 hour = 5kWh
b) Electricity consumption at 200V = (200/230)2 x 5kW x 1 hour
= 3.78kWhEEE MITS 39
 Electrolytic process
• An electrolytic process is the use of electrolysis industrially to refine metals or compounds at a
high purity and low cost.
• Some examples are the Hall- Héroult process used for aluminum, the production of hydrogen
from water, production of chlorine and caustic soda etc.
• Electrolysis is usually done in bulk using hundreds of sheets of metal connected to an electric
power source.
• Electrolysis process uses an electric current to drive a chemical reaction which otherwise
would not occur spontaneously.
Hydrogen production
• Electrolytic hydrogen production has been scientifically studied for more than a century.
• According to the literature, hydrogen has been used by for military, industrial and commercial
purposes since late 19th century.
• Nowadays, electrolytic hydrogen has a share of only 4% in the global production of the most
abundant element of the universe.
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• Electricity expense constitutes the largest fraction of hydrogen production costs.
• High hydrogen production expenses count as the main deficiency of commercial and industrial
electrolyzers.
• Hence electrolytic methods are usually outperformed by other approaches such as steam methane
reformation.
• An electrolyzer is usually subjected to massive current values in order to break the water molecules
into oxygen and hydrogen.
• Electrolysis involves movement of positively or negatively charged ions within an electrolyte between
an anode (positively-charged electrode) and a cathode (negatively-charged electrode).
• These familiar processes involve electrolysis:
 Storage batteries.
 Welding.
 Corrosion.
 Electrowinning (refining of metals such as aluminum).
 Plating and anodizing.
 Electroforming, electrochemical machining, and etching.
 Fuel cells. EEE MITS 41
Corrosion
• Corrosion occurs as a result of oxidation-reduction reactions between a metal or alloy and a
corroding agent.
• Corrosion can occur as a result of chemical reactions, which usually require high temperatures
and a corrosive environment, or due to electrochemical reactions, which are more common.
• Note that corrosion is an important indirect use of energy.
• The electrochemical reactions resemble the processes that take place in a battery.
• They can arise when dissimilar metals occur in the presence of an electrolyte or in the
presence of external electric currents.
• A common electrolyte is water with trace amounts of dissolved salts, acids, or alkalis.
• The rates of corrosion reactions are dependent on the concentration of salts, acids, or alkalis
in the electrolyte, and on the surface, temperature, and chemical constituents of the
corroding metal.
Welding
• Where possible, AC welders are preferred as they offer a better power factor and more
economical operation.
• Automated systems reduce standby power losses compared to manual welding because they
place the weld bead more consistently (lessEEE
start/stop).
MITS 42
Electrowinning
• An important use of electrolysis is the refining of metals such as aluminum.
• Basically the original process involved the electrolysis of a solution of aluminum oxide in
molten cryolite, using carbon anodes and electrodes.
• In the electrolyte solution, aluminum oxide disassociates into aluminum and oxygen ions.
• As currents on the order of 105 amperes pass through the cells (at potentials of 5.0-5.4 V), the
aluminum ions migrate to the cell lining (cathode) where they are reduced to metallic
aluminum. This process required 15-20 kWh of electricity per kg
• New processes have been developed that reduce the amount of electricity required.
Plating and Anodizing
• An electric current flows in a tank where the object to be plated or anodized serves as one of
the electrodes.
• In plating, the plated object serves as the cathode and the anode has the material to be
electrodeposited.

EEE MITS 43
• Alternatively, the anode may be non consumable carbon and the plating material may be
drawn from the bath.
• In anodizing (typical for aluminum), the object to be anodized is the anode and a direct
current produces a build-up of aluminum oxide on the surface.
• By use of various organic acids, coloured finishes can be produced.
Electroforming, Electrochemical Machining
• Electroforming is a process whereby a thin layer of metal is deposited on an object to be
coated or on a mould that is later removed.
• The classic example is copper plated baby shoes.
• Electrochemical machining is the reverse of plating; a high current is passed between an
electrolyte and the part, removing metal.
• This process is used for fine, intricate parts or hard, difficult-to-machine metals.

EEE MITS 44
 Energy Management Opportunities in Electrolytic Processes
• The points below summarizes typical energy management possibilities for electrolytic
processes.
• The greatest users of energy in this field (aside from the large indirect use caused by
corrosion) are in primary metals production, particularly aluminum and magnesium.
Factors to improve electrical efficiency in electrolytic hydrogen production process
1. Electrolyte quality
2. Temperature
3. Pressure
4. Electrical resistance of the electrolyte
a. Space between electrodes b. Size and alignment of the electrodes
5. Electrode material
6. Separator material
7. Applied voltage waveform
Corrosion protection
• Use protective films, paints, epoxy
• Provide cathodic protection (sacrificial anodes)
EEE MITS 45
• Cathodic protection with an applied voltage
• Electroplating and anodizing
• Use chemical water treatment (corrosion inhibitors)
• Avoid contact of dissimilar materials (dielectric unions)
Storage batteries
• Provide adequate maintenance (replace electrolytes, clean terminals, etc.)
• Use efficient charging techniques, charge at proper rates
• Avoid overheating, provide adequate ventilation
Other Electrolytic processes
• Insulate plating tanks
• Provide proper maintenance of electrodes and rectifiers
• Recover waste heat
• Use more efficient rectifiers (semiconductor vs. mercury arc)
• Use more efficient controls
• Develop improved electrode design and materials
EEE MITS
to increase efficiency 46
 Electric heating Applications
Electric Heating Applications
• Due to its relatively higher cost, electricity is not used extensively for process heat.
• However, there are some types of applications where electricity offers advantages for heating.
• Electric heating can take several forms:
 Resistance heating.
 Induction heating.
 Dielectric heating.
 Electric arc heating.
 Microwave heating.
 Infrared heating.
 Heat pumps.
Resistance heating
• Resistance heating makes use of the I2R law; i.e., power dissipated is proportional to the
square of the current times resistance. EEE MITS 47
• An example of this is a conventional residential electric water heater, which has two resistance
heating elements, nominally rated at 3800W and 240 V, single phase.
• This form of resistance heating has a high first law efficiency because all the heat is transferred
to the material being heated; i.e., the water.
• Losses result from conduction through the tank walls and distribution piping.
Induction heating
• Induction heating is similar to resistance heating in that the actual heating is caused by current
flowing through resistance.
• However, in the induction heater, the heating current is induced in the work piece.
• An example is the heating of transformers, cores, and motor windings.
• Even though they are laminated to produce high resistance to the flow of such currents,
transformers are in effect inductance heaters.
• In an induction furnace, a coil surrounds the work piece, which must be a conductor.
• A variable frequency power source (oscillator) is connected to this coil, inducing eddy currents
that in turn heat the work piece.
• The eddy currents exhibit a “screening” effect; i.e., the current density at the surface of the
work piece is maximum and decreases exponentially with depth.
EEE MITS 48
• A “penetration” depth can be defined, wherein the current has decreased to about 37% of the
surface value. Approximately 90% of the heating occurs within the penetration depth.
• Since the penetration depth is inversely proportional to frequency, a low frequency would be
used for heating a large piece and a high frequency for a smaller size.
Example - A forge heater. Billets of steel are brought by a conveying system into a water-cooled
copper coil. The frequency is in the range of 1_10 kHz; specific power is about 300 kWh/ton.
Advantages of induction heating include excellent temperature control and no surface
decarburization. The disadvantage is a low power factor (typically 0.1_0.5), which can be
corrected with capacitors.
Dielectric heating
• Dielectric heating refers to the heating of non conducting materials by an electric field.
• Basically, this is similar to the heating that occurs in the dielectric of a capacitor on which a
high-frequency voltage is impressed.
• The electromagnetic fields excite the molecular makeup of material, thereby generating heat
within the material. As a result, the heat is distributed uniformly throughout the work piece.
• Dielectric heating can be applied to wood, paper, food, ceramics, rubber, glues, and resins.
EEE MITS 49
• The heating effect is proportional to the dielectric loss factor, the applied frequency, and the
electric field strength.
• Dielectric systems can be divided into two types: RF (radio frequency) and microwave.
• RF systems operate in the 1-100 MHz range, and microwave systems operate in the 100-10,000
MHz range.
• RF systems are less expensive and are capable of larger penetration depths because of their
lower frequencies and longer wavelengths than microwave systems, but they are not as well
suited for materials or products with irregular shapes.
Electric arc furnace
• The electric arc furnace has three electrodes connected to the secondary windings of a three-
phase transformer.
• The principle is the same as in electric arc welding. When an arc is struck, the nearby gas is
raised to such a high temperature (in excess of 5000°C) that it becomes highly ionized.
• In this state, it is a sufficiently good conductor to be maintained at high temperature by the
resistive heating produced by the current.
EEE MITS 50
• The high temperature of the plasma permits very efficient heat transfer.
• Arc furnaces with capacities in the range of a few tons to hundreds of tons are in use.
• The primary application of electric arc furnaces is for melting and processing recycled steel.
Microwave heating
• Microwave heating (a form of dielectric heating) is a highly efficient technique for heating by
high-frequency electromagnetic radiation.
• Typically, frequency bands are 896 or 915 MHz and 2450 MHz, corresponding to wavelengths
of about 0.33 and 0.12 m.
• Energy is deposited in the work piece according to the same principles as the dielectric heater
described above.
• Furnaces can be designed to be resonant or non resonant.
• The microwave oven found in many homes is an example of a resonant cavity device.
• Resonant systems have efficiencies generally in excess of 50%. Again, because the heat is
deposited in the work piece, losses are minimized.

EEE MITS 51
Infrared heating
• Infrared heating is generated by I2R losses in heating lamps or devices, and this is a special case
of resistance heating.
• The difference, however, is that infrared energy can be generated in a narrow bandwidth.
• This can be applied more efficiently in some cases than combustion energy that spans a
broader bandwidth.
• To be most efficient, infrared heaters should concentrate their output at the peak of the
absorption spectrum for the material being heated.
• For water, this corresponds to a wavelength of about 2.8X1026 m.
• There are applications in papermaking, drying paints and enamels, and production of
chemicals and drugs.
Heat pump
• The heat pump is basically a refrigerator operating in reverse.
• An evaporator receives heat from a low temperature heat source (the air, waste heat, ground,
water, etc.).
• This causes evaporation of the working fluid;EEEthe
MITS vapor is then compressed by the compressor.
52
• In the condenser, it gives up the heat collected at the evaporator as well as the heat of
compression.
• As this heat is delivered, the vapor condenses, and the hot condensate passes through the
expansion valve.
• Heat pumps fall into the several categories, depending on the type of heating and the purpose.
• Those used for residential HVAC and water heating are primarily air-source or ground-source
heat pumps, meaning they extract heat either from the air or from underground pipes.
• Therefore they use air-to-air or liquid-to-air heat transfer. Larger units for commercial and
industrial applications employ liquid-to-liquid heat transfer.

EEE MITS 53
 Energy Management Opportunities in Electric heating
- It can be divided into three categories
1. Reduce heat losses
2. Use more efficient processes or equipment
3. Recover heat
1. Reduce heat losses
 Insulate furnace walls, ducts, piping
 Put covers over open tank.
 Reduce time doors are open
 Avoid cooling time for heated products
 Shutdown heating systems on tanks and ovens when not in use, or at least lower
temperatures (reduce standby losses)
2. More efficient equipment or processes
 Use alternative processes (microwave, dielectric rather than fuel-fired)
 Employ recuperators, regenerators, or preheaters
 Use direct-fired rather than indirect-fired systems
 EEE MITS 54
  Use less energy-intensive materials and processes
 Use heat pumps for low temperature process heat
 Reduce moisture content mechanically in materials used in drying processes
 Use lower temperature processes (cold rinses, etc.)
3. Recover heat
 There are multiple sources: stacks, processes, building exhaust streams, cooling towers,
compressors, etc.
 Recovered heat can be used for space heating, water heating, process preheating,
cogeneration, etc.
 Many types of heat recovery systems are commercially available (heat wheels, run-around
systems, heat pipes, heat exchangers, heat pumps, etc.)

EEE MITS 55
 Types of loads in power systems
• A device which taps electrical energy from the electric power system is called a load on the
system.
• Electrical loads can be classified according to their nature as Resistive, Capacitive, Inductive
and combinations of these.
Resistive Load
• The resistive load obstructs the flow of electrical energy in the circuit and converts it into
thermal energy, due to which the energy dropout occurs in the circuit.
• The lamp and the heater are the examples of the resistive load.
• The resistive loads take power in such a way so that the current and the voltage wave remain
in the same phase.
• Thus the power factor of the resistive load remains in unity
Inductive Load
• The inductive loads use the magnetic field for doing the work.
• The transformers, generators, motor are the examples of the load.
• The inductive load has a coil which stores magnetic energy when the current pass through it.
• The current wave of the inductive load is lagging behind the voltage wave, and the power
factor of the inductive load is also lagging.
EEE MITS 56
Capacitive Load
• In the capacitive load, the voltage wave is lagging the current wave.
• The examples of capacitive loads are capacitor bank, three phase induction motor starting
circuit, etc.
• The power factor of such type of loads is leading.
Combination Loads
• Most of the loads are not purely resistive or purely capacitive or purely inductive.
• Many practical loads make use of various combinations of resistors, capacitors and inductors.
• Power factor of such loads is less than unity and either lagging or leading
• Examples: Single phase motors often use capacitors to aid the motor during starting and
running, tuning circuits or filter circuits etc.
• The load may be resistive (e.g., electric lamp), inductive (e.g., induction motor), capacitive or
some combination of them.

EEE MITS 57
The various types of loads on the power system according to the application are:
1. Domestic load
• Domestic load consists of lights, fans, refrigerators, heaters, television, small motors for
pumping water etc.
• Most of the residential load occurs only for some hours during the day (i.e., 24 hours) e.g.,
lighting load occurs during night time and domestic appliance load occurs for only a few hours.
• For this reason, the load factor is low (10% to 12%).
2. Commercial load
• Commercial load consists of lighting for shops, fans and electric appliances used in restaurants
etc.
• This class of load occurs for more hours during the day as compared to the domestic load.
• The commercial load has seasonal variations due to the extensive use of air conditioners and
space heaters.

EEE MITS 58
3. Municipal load
• Municipal load consists of street lighting, power required for water supply and drainage
purposes.
• Street lighting load is practically constant throughout the hours of the night.
• For water supply, water is pumped to overhead tanks by pumps driven by electric motors.
• Pumping is carried out during the off-peak period, usually occurring during the night.
• This helps to improve the load factor of the power system.
4. Irrigation load
• This type of load is the electric power needed for pumps driven by motors to supply water to
fields.
• Generally this type of load is supplied for 12 hours during night.

EEE MITS 59
5. Traction load
• This type of load includes tram cars, trolley buses, railways etc.
• This class of load has wide variation.
• During the morning hour, it reaches peak value because people have to go to their work place.
• After morning hours, the load starts decreasing and again rises during evening since the
people start coming to their homes.
6. Industrial load.
• Industrial load consists of load demand by industries.
• The magnitude of industrial load depends upon the type of industry.
• Thus small scale industry requires load up to 25 kW, medium scale industry between 25kW
and 100 kW and large-scale industry requires load above 500 kW.
• Industrial loads are generally not weather dependent.

EEE MITS 60
According To Load Nature
 Linear loads
 Non-linear loads
According to Importance
 Vital electrical loads (e.g. required for life safety)
 Essential electric loads
 Non-essential / normal electric loads
According To Phases
 Single phase loads
 Three phase loads

EEE MITS 61
 Electrical Load Management and Maximum Demand Control
Need for Electrical Load Management
• In a macro perspective, the growth in the electricity use and diversity of end use segments in
time of use has led to shortfalls in capacity to meet demand.
• As capacity addition is costly and only a long time prospect, better load management at user
end helps to minimize peak demands on the utility infrastructure as well as better utilization
of power plant capacities.
• The utilities (State Electricity Boards) use power tariff structure to influence end user in better
load management through measures like time of use tariffs, penalties on exceeding allowed
maximum demand, night tariff concessions etc.
• Load management is a powerful means of efficiency improvement both for end user as well as
utility.
• As the demand charges constitute a considerable portion of the electricity bill, from user
angle too there is a need for integrated load management to effectively control the maximum
demand.

EEE MITS 62
 Step By Step Approach for Maximum Demand Control
1. Load Curve Generation
• Presenting the load demand of a consumer against time of the day is known as a ‘load curve’.
• If it is plotted for the 24 hours of a single day, it is known as an ‘hourly load curve’ and if daily
demands plotted over a month, it is called daily load curves.
• A typical hourly load curve for an engineering industry is shown in Figure below
• These types of curves are useful in predicting patterns of drawl, peaks and valleys and energy
use trend in a section or in an industry or in a distribution network as the case may be.

EEE MITS 63
2. Rescheduling of Loads
• Rescheduling of large electric loads and equipment operations, in different shifts can be
planned and implemented to minimize the simultaneous maximum demand.
• For this purpose, it is advisable to prepare an operation flow chart and a process chart.
• Analyzing these charts and with an integrated approach, it would be possible to reschedule
the operations and running equipment in such a way as to improve the load factor which in
turn reduces the maximum demand.
3. Storage of Products in process material/ process utilities like refrigeration
• It is possible to reduce the maximum demand by building up storage capacity of products/
materials, water, chilled water / hot water, using electricity during off peak periods.
• Off peak hour operations also help to save energy due to favorable conditions such as lower
ambient temperature etc.
• Example: Ice bank system is used in milk & dairy industry. Ice is made in lean period and used
in peak load period and thus maximum demand is reduced.

EEE MITS 64
4. Shedding of Non-Essential Loads
• When the maximum demand tends to reach preset limit, shedding some of non-essential
loads temporarily can help to reduce it.
• It is possible to install direct demand monitoring systems, which will switch off non-essential
loads when a preset demand is reached.
• Simple systems give an alarm, and the loads are shed manually.
• Sophisticated microprocessor controlled systems are also available, which provide a wide
variety of control options like:
 Accurate prediction of demand
 Graphical display of present load, available load, demand limit
 Visual and audible alarm
 Automatic load shedding in a predetermined sequence
 Automatic restoration of load
 Recording and metering

EEE MITS 65
5. Operation of Captive Generation and Diesel Generation Sets
• When diesel generation sets are used to supplement the power supplied by the electric
utilities, it is advisable to connect the D.G. sets for durations when demand reaches the peak
value.
• This would reduce the load demand to a considerable extent and minimize the demand
charges.
6. Reactive Power Compensation
• The maximum demand can also be reduced at the plant level by using capacitor banks and
maintaining the optimum power factor.
• Capacitor banks are available with microprocessor based control systems.
• These systems switch on and off the capacitor banks to maintain the desired Power factor of
system and optimize maximum demand thereby.

EEE MITS 66
 Optimal load scheduling
• The electrical load scheduling is the process of estimating the instantaneous loads operating in an
installation.
• Optimal load scheduling is the process of scheduling the loads in an industry/power system in a way to
operate it at minimum energy cost and without affecting the quality of product/service.
• The load schedule provides the load for the particular installation in terms of apparent, reactive and
active power (kVA, kVAR and kW).
• The load schedule preparation should ideally be the first task to perform during the electrical system
design stage since it relates to the equipment sizes and other power system requirements.
• In particular, it provides information about the equipment ratings during normal and peak operations,
thereby guiding the electrician in determining the conductor sizes.
• Load scheduling is one form of load management action that allows companies to save energy by
minimizing their demand.
• In order to have an efficient load schedule operation, the energy manager or business should conduct
power logging and record all sessions so as to measure the usage of energy over a specific time.
• This enables the consumer to identify large loads that may be operating concurrently.

EEE MITS 67
• There is no standard methodology and various methods can be used based on type of
installation and person carrying out the load scheduling exercise.
• One of the methodology is the economic load dispatch.
• The economic load dispatch means the real and reactive power of the generator vary within
the certain limits and fulfils the load demand with less fuel cost.
• The sizes of the electric power system are increasing rapidly to meet the energy requirement.
• So a number of power plants is connected in parallel to supply the system load by an
interconnection of the power system.
• In the grid system, it becomes necessary to operate the plant units more economically.
• The economic scheduling of the generators aims to guarantee at all time the optimum
combination of the generator connected to the system to supply the load demand.
• The economic load dispatch problem involves two separate steps.
• These are the online load dispatch and the unit commitment.

EEE MITS 68
• The unit commitment selects that unit which will anticipate load of the system over the
required period at minimum cost.
• The online load dispatch distributes the load among the generating unit which is parallel to
the system in such a manner as to reduce the total cost of supplying.
• It also fulfils the minute to the minute requirement of the system.
Standards and labelling scheme by Bureau of Energy Efficiency (BEE)
- The Bureau of Energy Efficiency initiated the Standards & Labeling program for equipment and
appliances in 2006 to provide the consumer an informed choice about the energy saving and
thereby the cost saving potential of the relevant marketed product.
- The energy efficiency labeling programs under BEE are intended to reduce the energy
consumption of appliance without diminishing the services it provides to consumers.
- The scheme is invoked for 21 equipment/appliances including 10 for which it is mandatory.
The other appliances are presently under voluntary labeling phase.
- The estimated savings from these labeling programs have been about 12000 MW since 2007.

EEE MITS 69
- The following products have been notified under mandatory labelling.
1. Frost Free (No-Frost) Refrigerator
2. Tubular Fluorescent Lamps
3. Room Air Conditioners
4. Distribution Transformers
5. Room Air Conditioners (Cassette, Floor Standing Tower, Ceiling, Corner AC)
6. Direct Cool Refrigerator
7. Electric Geysers
8. Color TV
9. Room Air Conditioners (Inverter type)
10. LED lamps
- The following products have been notified under voluntary labelling.
1. Induction Motors 2. Pump sets 3. Ceiling fans 4. Liquefied Petroleum Gas (LPG) Stoves
5. Washing machine 6. Computer (Notebook/Laptops) 7. Ballast (Electronic/Magnetic)
8. Office equipment's (Printer, Copier, Scanner, MFD’s)
9. Diesel Engine Driven Monoset Pumps for Agricultural Purposes
10. Solid State Inventor 11. Diesel Generator 12. Chillers 13. Microwave Ovens
14. Deep Freezers 15. Light Commercial Air ConditionersEEE(LCAC)
MITS 70
- A star label and its description is shown below

EEE MITS 71
 Previous University Questions
1. Explain the criteria for selection of motors.
2. Explain the energy management opportunities in motor.
3. Explain the lighting controls used for energy saving.
4. Explain the energy management opportunities in electric heating.
5. Explain the energy saving opportunities in lighting system.
6. What are the energy management opportunities in electrolytic processes?
7. What is meant by loading of motor? Why does the efficiency of motor reduce when it
operates at lower loading? List down any 2 steps to improve the operating efficiency of
under-loaded motors.
8. Explain the types of losses in electric motor. List down the various opportunities for energy
saving in case of underloaded motors?
9. What is Optimal Load Scheduling? Explain.
10. Explain how standards and labelling scheme introduced by BEE is helpful as a demand side
management strategy.
11. Explain peak demand control methods used for energy management.
12. Explain different types of industrial loads. EEE MITS 72