BEEME 2 Protection devices
UNIT – 3
Utilization of Electrical Power
Need for earthing
Earthing is used to protect you from an electric shock. It does this by providing a path (a protective conductor) for a fault current to flow to earth. It also causes the protective device (either a circuit-breaker or fuse) to switch off the electric current to the circuit that has the fault.
What is circuit breaker?
Electrical circuit breaker is a switching device which can be operated automatically or manually for protecting and controlling electrical power systems.
Applications of Circuit breakers:
The circuit breaker is a switching device which also offers protection by tripping & cutting off the supply to load in case of fault. Primarily the circuit breakers are used for switching of different kinds of load in Industries, Buildings, Commercial Complexes, and Hotels, etc.
BEEME 2 Comparisons
UNIT – 3
Utilization of Electrical Power
Compare fuse and circuit breaker
Fuse
|
Circuit breaker
|
Detects and interrupts the fault current
|
Only interrupts the fault current. Detection is done by relay system
|
Automatic operation
|
Not automatic. Relay system is required to operate it
|
Breaking capacity is less
|
Has large breaking capacity
|
Arc interruption is simple
|
Arc interruption is complicated
|
Operating time is small. Operating speed is high
|
Operating time is large. Operating speed is comparatively less
|
Replacement / rewiring required after each operation
|
No replacement needed. Easy to reset
|
Simple design. Cheap
|
Complicated design. expensive
|
Comparing Horizontal and vertical axis wind turbines
Horizontal axis wind turbines
|
Vertical axis wind turbines
| |
Axis of rotation
|
Axis of rotation is parallel to ground and wind steam
|
Axis of rotation is perpendicular to ground and wind stream
|
Mount point
|
Gearbox and generator are mounted above the ground with a tower to support them
|
Gearbox and generator are mounted at ground level. Hence does not require any support tower.
|
Output energy
|
Overall energy output is more
|
Overall energy output is less
|
Efficiency
|
Overall efficiency is more
|
Overall efficiency is less
|
Stress
|
Higher stress is put at the base of the blade by the wind
|
Higher stress is put at the center of the blade by the wind
|
Structural support
|
Requires more structural support
|
Requires less structural support
|
Installation and maintenance
|
Installation and maintenance is hard
|
Installation and maintenance is easy
|
Yaw control
|
Yaw control is necessary to turn rotor so that the blades face the wind
|
Yaw control not needed as rotor reacts to wind from any direction
|
BEEME 2 Batteries
UNIT – 3
Utilization of Electrical Power
General applications of Batteries
1. Batteries are used in starting, lightning and ignition systems.
2. They are used in back up power supply.
3. Batteries are used in portable equipment like wrist watches, mobile phones, tablets, laptops.
4. They are used in military and aerospace science.
Advantages of Ni-Cd battery
1. Only battery that can be ultra-fast charged with little stress.
2. It has long shelf life; can be stored in a discharged state.
3. Simple storage and transportation.
4. Available in wide range of sizes and performance options.
Disadvantages of Ni-Cd battery:
1. Relatively low specific energy compared with newer systems.
2. Cadmium is a toxic metal ,cannot be disposed of in landfills.
3. It has high self-discharge.
4. It has memory effect;needs full discharges.
Advantages of lead acid battery:
1. It is less expensive.
2. It is robust and tolerant to abuse.
3. It can deliver very high currents.
4. Wide range of sizes and capacities available.
Disadvantages of lead acid battery:
1. It is very bulky and heavy.
2. It has danger of over heating during charging.
3. It is not suitable for fast charging.
4. Must be stored in a charged state once the electrolyte has been introduced to avoid deterioration of the active chemicals.
Advantages of lithium battery
1. It is Eco friendly
2. It is less weight and compact.
3. It needs low maintenance.
4. It needs more charge cycles.
Disadvantages of lithium battery
1. Requires protection circuit to maintain voltage and current within safe limits.
2. It is expensive to manufacture-storage in a cool place at 40% charge reduces the aging effect.
3. It is not fully mature -metals and chemicals are changing on a continuing basis.
4. Shipment of larger quantities may be subject to regulatory control.
1.
BEEME 2 AC
UNIT – 3
Utilization of Electrical Power
Air conditioning
ADVANTAGES
1. Simple to design & control.
2. Smaller ductwork.
3. Less mechanical space.
4. Less maintenance.
5. Increase comfort.
DISADVANTAGES
1. Power consumption is high.
2. Higher construction cost.
3. Designing and Construction is complex.
APPLICATIONS
1. For human comfort – Used to maintain a cool temperature and control the moisture content in offices, hotels, residential buildings etc.,
2. Transportation/Automobiles – used in vehicles like buses, cars, trains, flights, etc., for cooling.
3. Used in textile industries to control moisture.
4. Industrial air conditioning – used to control temperature and humidity in chemical plants
BEEME 2 Refrigeration
UNIT – 3
Utilization of Electrical Power
REFRIGERATION
Advantages
1. The cooling temperature of refrigerator enables user to preserve food for longer time.
2. A huge variety of models along with different design refrigerator are there.
3. Works on the basis of direct cool technology which is most energy efficient.
4. Single door refrigerators are compact in size and it is best for a small family.
Disadvantages:
1. Refrigerator needs proper power supply for running.
2. It is not eco-friendly. The refrigerant (CFC) depletes the ozone layer.
BEEME 2 Wind
UNIT
– 3
Utilization
of Electrical Power
WIND ENERGY
Advantages
1. It has huge potential
2. Wind energy has low running costs.
3. Wind technology is becoming cheap
4. It provides power to remote locations.
Disadvantages
1. The wind fluctuates.
2. Wind turbines create noise pollutions.
3. Safety concerns are required.
4. Wind turbines are expensive.
Applications
1. Generation of Electricity – Windmills harness wind energy to create electricity. It is a clean & green form of energy.
2. Pumping water – Similar to windmills the energy from the wind is used to drive a pump.
3. Milling Grain – Grain milling is certain locations are done using wind energy.
4. Transportation – The power of wind is used for propulsion in sailing boats.
5. Wind energy based Sports – like parasailing, hang gliding, air ballooning
Horizontal axis wind turbine [HAWT]
Advantages
1. It has variable balde pitch.
2. It has optimum angle of attack.
3. It has high efficiency.
4. It has tall tower to access stronger winds.
Disadvantage:
1. It is more difficult to transport and install.
2. It needs stronger tower construction.
3. it needs additional yaw control mechanism.
4. It needs high installation and equipmental costs.
Vertical axis wind turbine [VAWT]
Advantages:
1. it accepts winds from any directions.
2. All the components are placed at the ground level itself.
3. It is easy to service and lighter towers.
4. It has low maintenance costs.
Disadvantages:
1. At ground level, there is very poor wind power.
2. It has poor self-starting capabilities.
3. It requires support at the top of turbine rotor.
4. The entire rotor has to be removed to replace bearings.
BEEME 2 Solar
UNIT
– 3
Utilization
of Electrical Power
Solar Energy
Advantages:
1.
Solar energy is available as long as we have the
sun
2.
Wide range of applications
3.
It is free source. Can be utilized effectively.
4.
It requires very low level of maintenance.
Disadvantages:
1.
Solar modules are very expensive to buy and
install.
2.
It requires lot of space for labels, equipment and
batteries.
3.
It is very expensive to store solar energy in
batteries.
4.
Solar modules are made of hazardous materials.
Applications:
1.
Solar Water Heating, solar heating of buildings, solar
distillation, solar furnaces,
2.
Solar energy for drying agricultural land animal
products
3.
Solar panels for generating electricity.
Flat plate
solar collectors
Advantages
1.
Absorbs
both direct and diffused radiations
2.
Does
not need to be oriented towards the sun
3.
Requires
less maintenance
4.
Mechanical
design and arrangement is simpler
5.
Comparatively
less expensive
Disadvantages
1.
More
material required for reflecting surface
2.
Power
generation is limited by the area of absorber surface
3.
Heat
loss is also more
4.
Temperature
attained by fluid is comparatively less
Parabolic
solar collector:
Advantages
1.
It is the most efficiet type since it can focus the
sun’s energy on a small heat exchanger.
2.
Less collector surface is required.
3.
It doesn’t cause pollution which is one of the
biggest advantage.
4.
High heat gain.
Disadvantages
1.
The installation cost of the parabolic collection
is high.
2.
Construction cost of parabolic collection is high.
3.
Solar plant use lot of water which is major problem
in dessert.
4.
They track sun in only one direction.
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