2.ENERGY CONSERVATION IN MOTOR AND TRANSFORMER
Q..State the need of energy conservation in electric motor / induction motor ?
Conservation of energy is the most important area which is Focus in order to reduce production cost.
Industrial and commercial consumer identify the most energy consuming culprit which is found to be
Motors so that energy conservation measures can be applied.
43% to 46% of the world energy consumption and near about 70% Total energy consumption of the
industry due to motors and motor drives.
Inefficient Motors not only cause wastage of electrical energy but also more operational cost.
Most of the electricity to run this motor is generated from non renewable energy plants which also has an
incremental effect on greenhouse gasses.
So economic as well as an environmental aspect necessitates the conservation in electrical Motors.
Q..State the need of energy conservation in Transformer and material used to improve the design and
performance of transformer?
OR
Q.. State the need of energy conservation in transformer?
OR
Q..Why energy conservation techniques should be adopted in transformer even through its efficiency is
90%?
All the electrical power which consumer receive at his end passes through transformer.
Energy conservation in transformer obviously will be step forward when attempt to reduce the energy loss
related to Transformer operation in electrical power system are made.
Transformers specially in distribution network actually make up near about 40% of energy loss.
In some cases it may have to undergo numerous stages of transformations when passes through generator
to the consumer.
At each point, the Transformer energy loss is obvious , if this losses are given attention, it will considerable
e reduce greenhouse emission.
Modern distribution transformer operates at high efficiency in the range of 98.9 %.
However, the total number of Transformers used in Transmission and distribution systems, supplying
power to all class of consumers ,industrial, commercial, domestic and rural is very large.
Even small amount of loss in every transformer aggregately contributes a significant energy loss has well
as global warming and climate change.
Q..Explain how energy conservation can be achieved in induction motors by operating in star mode.
➢ Lesser than 30% load means torque required by load is less than 30%. Hence current requirement is
reduced.
➢ When connected in star, the phase voltage reduces to (1/ 3 ) times that in delta mode. As the torque
generated by motor is directly proportional to the (applied voltage per phase) 2 the torque produced falls to
1/3 compared to delta mode.
➢ Due to decreased phase voltage, the iron losses decrease to nearly 1/3, as total iron losses are proportional
to (applied voltage per phase) 2 before saturation.
➢ Due to reduction in phase voltage the current drawn in the lines also reduces leading to lower copper losses
in motor and decrease line losses.
,Q..List out the energy conservation techniques to be adopted to reduce losses in induction motor?
1}By improving power quality:-
Electrical energy can be conserved by improving the power quality. It can be achieved by avoiding voltage
unbalance, maintaining voltage & frequency value and avoiding harmonic distortion.
i) Voltage unbalance:
Three phase induction motors are designed to operate on a balanced three phase A.C. Supply. In unbalanced
condition the voltages in three phases are unequal which may cause a significant problem to motor such as
excessive heating and vibrations. This condition leads to increase in the I2R loss in motor. Voltage unbalance
produces negative sequence current which causes overheating.it reduces life of motor.
ii) Maintaining voltage & frequency value:
Maintaining the frequency and the required form factor minimizes the harmonics, and iron / mechanical losses as
the speed is maintained at specified value. As speed of motor is directly proportional to frequency, speed will
increase which will cause friction and windage losses and improper torque.
iii) Harmonic distortion :
Increased use of the power electronics devices in the system leads to add the harmonics in a supply frequency.
Undesirable effect of these higher frequencies related to the harmonic voltage distortion causes increase in iron
and copper losses in motor. Overheating due to harmonics leads to motor failure, lower life and improper torque
speed characteristics
2}By motor survey:-
To make motor perform optimally over the time it is necessary to develop and maintain a motor
management plan
This demands the serving of motor with respect to load by applying some methodology
Methodology
a .Sampling of Motors
b.Measurements of electrical / mechanical parameters
c.Analysis of observations
a.Sampling of Motors:-
Hours of operation- the motor drives which are continuously operated are given preference
On the basis of Illustrative sample:- one Motor out of a typical group of application is analysed and used as
an illustrative sample
b. Measurements of electrical / mechanical parameters:-
measurement on selected motor are carried out for Electrical parameters such as:
● voltages
● load currents
● power factor
● power drawn (KW,KVA)
measurement of mechanical parameter on the machine side includes:
, ● speed measurement
● pressure measurement
● mechanical load
● temperature measurement
c. Analysis of observations:-
analysis of the observation obtained from measurements on representative motor is done in order to:-
● find out probable energy consumption and motor load in KW
● identify the area in the monitoring system which can be improved
● search the aspect which can lead to energy conservation
● calculate benefits associated with identified conservation in term of money detail source of
information
Observation in motor surveying:-
● percentage loading in term of KW
● percentage voltage unbalance in case
● electrical parameters like voltage current power factor and frequency
● load on load condition of motor
Motor surveying fulfills the objectives of :-
● identification of efficiency areas in motor
● checking the efficiency of motor driven machines and Controller together in combined manner.
Motor load surveying can lead to saving in the range of 30% to 40% in driven machines or associated
system.
3}By matching motor:-
Power drawn by motor depends on load and not necessarily with size
10 KW 15 by 10 KW motor can be said a well match
That fan can also be driven by a 20 KW motor which will work but not with desired efficiency.
Over sizing causes:-
● lower efficiency
● lower power factor
● higher initial cost of motor as well as controls associated.
very reasons for unmatched of motor with load:-
● large safety factor
● use of large motor for high starting torque
● under utilization of equipments
● large motor even at low voltages
● rounding up to next size while designing.
in general , motor operating and load 40% less of its rated capacity it should be downsized especially
where motor load variation are rare.
on the contrary, if some motor is having capacity of 100 HP and generally operated at 35 HP but sometimes
required to operated 90hp it should not be considered for downsizing.
oversized video film motor work at low efficiency level so replacing an oversize motor should be preferred
to be replaced it is not failed because energy consumed and the cost of new motor.
however, suitable oversized margin offers the advantages of:-
● spare capacity in case of future expansion
● accommodation of an expected additional loads
in some cases of variable loads, to optimise the size of motor according to the load duration curve of that
particular application is referred and approach is:-
● operating little than the peak estimated or expected load is selected
● if motor of high ratings choosen it would be fully loaded for short duration of peak loading
4}By minimizing idle and redundant running of motor :-
Q..State the need of energy conservation in electric motor / induction motor ?
Conservation of energy is the most important area which is Focus in order to reduce production cost.
Industrial and commercial consumer identify the most energy consuming culprit which is found to be
Motors so that energy conservation measures can be applied.
43% to 46% of the world energy consumption and near about 70% Total energy consumption of the
industry due to motors and motor drives.
Inefficient Motors not only cause wastage of electrical energy but also more operational cost.
Most of the electricity to run this motor is generated from non renewable energy plants which also has an
incremental effect on greenhouse gasses.
So economic as well as an environmental aspect necessitates the conservation in electrical Motors.
Q..State the need of energy conservation in Transformer and material used to improve the design and
performance of transformer?
OR
Q.. State the need of energy conservation in transformer?
OR
Q..Why energy conservation techniques should be adopted in transformer even through its efficiency is
90%?
All the electrical power which consumer receive at his end passes through transformer.
Energy conservation in transformer obviously will be step forward when attempt to reduce the energy loss
related to Transformer operation in electrical power system are made.
Transformers specially in distribution network actually make up near about 40% of energy loss.
In some cases it may have to undergo numerous stages of transformations when passes through generator
to the consumer.
At each point, the Transformer energy loss is obvious , if this losses are given attention, it will considerable
e reduce greenhouse emission.
Modern distribution transformer operates at high efficiency in the range of 98.9 %.
However, the total number of Transformers used in Transmission and distribution systems, supplying
power to all class of consumers ,industrial, commercial, domestic and rural is very large.
Even small amount of loss in every transformer aggregately contributes a significant energy loss has well
as global warming and climate change.
Q..Explain how energy conservation can be achieved in induction motors by operating in star mode.
➢ Lesser than 30% load means torque required by load is less than 30%. Hence current requirement is
reduced.
➢ When connected in star, the phase voltage reduces to (1/ 3 ) times that in delta mode. As the torque
generated by motor is directly proportional to the (applied voltage per phase) 2 the torque produced falls to
1/3 compared to delta mode.
➢ Due to decreased phase voltage, the iron losses decrease to nearly 1/3, as total iron losses are proportional
to (applied voltage per phase) 2 before saturation.
➢ Due to reduction in phase voltage the current drawn in the lines also reduces leading to lower copper losses
in motor and decrease line losses.
,Q..List out the energy conservation techniques to be adopted to reduce losses in induction motor?
1}By improving power quality:-
Electrical energy can be conserved by improving the power quality. It can be achieved by avoiding voltage
unbalance, maintaining voltage & frequency value and avoiding harmonic distortion.
i) Voltage unbalance:
Three phase induction motors are designed to operate on a balanced three phase A.C. Supply. In unbalanced
condition the voltages in three phases are unequal which may cause a significant problem to motor such as
excessive heating and vibrations. This condition leads to increase in the I2R loss in motor. Voltage unbalance
produces negative sequence current which causes overheating.it reduces life of motor.
ii) Maintaining voltage & frequency value:
Maintaining the frequency and the required form factor minimizes the harmonics, and iron / mechanical losses as
the speed is maintained at specified value. As speed of motor is directly proportional to frequency, speed will
increase which will cause friction and windage losses and improper torque.
iii) Harmonic distortion :
Increased use of the power electronics devices in the system leads to add the harmonics in a supply frequency.
Undesirable effect of these higher frequencies related to the harmonic voltage distortion causes increase in iron
and copper losses in motor. Overheating due to harmonics leads to motor failure, lower life and improper torque
speed characteristics
2}By motor survey:-
To make motor perform optimally over the time it is necessary to develop and maintain a motor
management plan
This demands the serving of motor with respect to load by applying some methodology
Methodology
a .Sampling of Motors
b.Measurements of electrical / mechanical parameters
c.Analysis of observations
a.Sampling of Motors:-
Hours of operation- the motor drives which are continuously operated are given preference
On the basis of Illustrative sample:- one Motor out of a typical group of application is analysed and used as
an illustrative sample
b. Measurements of electrical / mechanical parameters:-
measurement on selected motor are carried out for Electrical parameters such as:
● voltages
● load currents
● power factor
● power drawn (KW,KVA)
measurement of mechanical parameter on the machine side includes:
, ● speed measurement
● pressure measurement
● mechanical load
● temperature measurement
c. Analysis of observations:-
analysis of the observation obtained from measurements on representative motor is done in order to:-
● find out probable energy consumption and motor load in KW
● identify the area in the monitoring system which can be improved
● search the aspect which can lead to energy conservation
● calculate benefits associated with identified conservation in term of money detail source of
information
Observation in motor surveying:-
● percentage loading in term of KW
● percentage voltage unbalance in case
● electrical parameters like voltage current power factor and frequency
● load on load condition of motor
Motor surveying fulfills the objectives of :-
● identification of efficiency areas in motor
● checking the efficiency of motor driven machines and Controller together in combined manner.
Motor load surveying can lead to saving in the range of 30% to 40% in driven machines or associated
system.
3}By matching motor:-
Power drawn by motor depends on load and not necessarily with size
10 KW 15 by 10 KW motor can be said a well match
That fan can also be driven by a 20 KW motor which will work but not with desired efficiency.
Over sizing causes:-
● lower efficiency
● lower power factor
● higher initial cost of motor as well as controls associated.
very reasons for unmatched of motor with load:-
● large safety factor
● use of large motor for high starting torque
● under utilization of equipments
● large motor even at low voltages
● rounding up to next size while designing.
in general , motor operating and load 40% less of its rated capacity it should be downsized especially
where motor load variation are rare.
on the contrary, if some motor is having capacity of 100 HP and generally operated at 35 HP but sometimes
required to operated 90hp it should not be considered for downsizing.
oversized video film motor work at low efficiency level so replacing an oversize motor should be preferred
to be replaced it is not failed because energy consumed and the cost of new motor.
however, suitable oversized margin offers the advantages of:-
● spare capacity in case of future expansion
● accommodation of an expected additional loads
in some cases of variable loads, to optimise the size of motor according to the load duration curve of that
particular application is referred and approach is:-
● operating little than the peak estimated or expected load is selected
● if motor of high ratings choosen it would be fully loaded for short duration of peak loading
4}By minimizing idle and redundant running of motor :-
