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State four factors that affect the output of a solar module. (4 marks)craft1 electrical June/July 2020
Solar irradiance: The amount of solar irradiance, or the intensity of solar radiation, that the solar module receives can affect its output. Solar modules will typically produce more electricity on sunny days with high solar irradiance than on cloudy days with low solar irradiance. Temperature: TheRead more
- Solar irradiance: The amount of solar irradiance, or the intensity of solar radiation, that the solar module receives can affect its output. Solar modules will typically produce more electricity on sunny days with high solar irradiance than on cloudy days with low solar irradiance.
- Temperature: The temperature of the solar module can also affect its output. Solar modules tend to produce less electricity at higher temperatures, as the heat can reduce the efficiency of the solar cells.
- Orientation: The orientation of the solar module, or the direction it is facing, can affect its output. Solar modules that are oriented towards the sun will typically produce more electricity than those that are oriented away from the sun.
- Shade: Solar modules that are shaded by trees, buildings, or other objects can produce less electricity than those that are in full sun. This is because the shade can block some of the solar radiation that the module would otherwise receive.
See lessState three merits of direct solar drier. (5 marks)craft1 electrical June/July 2020
Renewable and clean: Solar energy is a renewable and clean energy source, and using a direct solar dryer does not produce any greenhouse gas emissions or air pollution. Cost-effective: Solar drying systems can be cost-effective to operate, as they do not require any fuel or electricity to operate. VRead more
- Renewable and clean: Solar energy is a renewable and clean energy source, and using a direct solar dryer does not produce any greenhouse gas emissions or air pollution.
- Cost-effective: Solar drying systems can be cost-effective to operate, as they do not require any fuel or electricity to operate.
- Versatility: Solar dryers can be used to dry a wide range of materials, including fruits, vegetables, grains, and herbs.
- Sanitation: Solar dryers can improve the sanitation of dried products, as they do not require the use of fossil fuels that can contaminate the drying process.
- Durability: Solar dryers can be durable and long-lasting, as they do not have moving parts that can wear out over time.
See lessExplain two methods of solar energy conversion.craft1 electrical June/July 2020
Photovoltaic cells: Photovoltaic (PV) cells, also known as solar cells, convert solar energy into electricity through the photovoltaic effect. When sunlight is absorbed by the PV cells, it excites the electrons in the cells and generates an electric current. Solar thermal systems: Solar thermal systRead more
- Photovoltaic cells: Photovoltaic (PV) cells, also known as solar cells, convert solar energy into electricity through the photovoltaic effect. When sunlight is absorbed by the PV cells, it excites the electrons in the cells and generates an electric current.
- Solar thermal systems: Solar thermal systems use the heat from the sun to generate electricity or to provide hot water or space heating for buildings. These systems can include solar collectors, such as flat-plate collectors or concentrating collectors, which absorb and collect solar energy, and heat exchangers, which transfer the collected heat to a fluid or gas for use.
- Solar water heaters: Solar water heaters use solar collectors to absorb the sun’s energy and heat water, which can then be used for domestic hot water or space heating.
- Solar cookers: Solar cookers use the sun’s energy to cook food, often by focusing the sun’s rays onto a cooking pot or container.
- Solar pumps: Solar pumps use solar panels to power an electric pump, which can be used to pump water for irrigation or other purposes.
See lessDefine each of the following as used in solar systems: (a) irradiance; (i) diffuse radiation. (4 marks)craft1 electrical June/July 2020
(a) Irradiance: Irradiance is the measure of the intensity of solar radiation received by a surface, typically measured in watts per square meter (W/m²). (b) Diffuse radiation: Diffuse radiation is solar radiation that has been scattered by the atmosphere and is not directly aligned with the sun. ItRead more
(a) Irradiance: Irradiance is the measure of the intensity of solar radiation received by a surface, typically measured in watts per square meter (W/m²).
(b) Diffuse radiation: Diffuse radiation is solar radiation that has been scattered by the atmosphere and is not directly aligned with the sun. It is often referred to as “sky radiation” and can contribute significantly to the total solar radiation received by a surface, especially on cloudy days.
See lessState four advantages of A.C over D.C system. (4 marks)craft1 electrical June/July 2020
Ease of transmission: AC voltage can be easily transformed to higher or lower values using transformers, making it more suitable for long-distance transmission over high-voltage power lines. Safety: AC voltage is less likely to cause electric shock than DC voltage, as it oscillates rapidly and is leRead more
- Ease of transmission: AC voltage can be easily transformed to higher or lower values using transformers, making it more suitable for long-distance transmission over high-voltage power lines.
- Safety: AC voltage is less likely to cause electric shock than DC voltage, as it oscillates rapidly and is less likely to pass through the human body.
- Efficiency: AC motors are more efficient than DC motors, as they do not suffer from the losses associated with brush and commutator wear.
- Widespread adoption: AC electrical systems have been widely adopted in the power industry, and there is a wide range of AC electrical equipment available.
- Compatibility with power grid: AC electrical systems are compatible with the power grid, which allows for the easy exchange of electricity between different power generation sources.
See lessOutline the stages of a typical power system from a generating station to the consumer and for each case state the voltage levels. (6 marks)craft1 electrical June/July 2020
Generating station: At the generating station, electricity is produced using a power source such as a coal-fired power plant, hydroelectric dam, or wind farm. The voltage level at the generating station is typically high, in the range of 11 kV to 33 kV. Transmission: The electricity produced at theRead more
- Generating station: At the generating station, electricity is produced using a power source such as a coal-fired power plant, hydroelectric dam, or wind farm. The voltage level at the generating station is typically high, in the range of 11 kV to 33 kV.
- Transmission: The electricity produced at the generating station is transmitted over long distances to the distribution system using high-voltage transmission lines. The voltage level at this stage is also typically high, in the range of 132 kV to 765 kV.
- Substation: At the substation, the voltage of the transmitted electricity is reduced to a level that is suitable for distribution to the consumer. The voltage level at the substation is typically medium, in the range of 11 kV to 33 kV.
- Distribution: The electricity is then distributed to the consumer via medium-voltage distribution lines. The voltage level at this stage is typically medium, in the range of 4 kV to 33 kV.
- Service entrance: At the service entrance, the voltage of the electricity is reduced to a level that is safe for use in the consumer’s premises. The voltage level at the service entrance is typically low, in the range of 120 V to 480 V.
- Consumer premises: The electricity is then distributed throughout the consumer’s premises using low-voltage wiring. The voltage level at this stage is typically low, in the range of 120 V to 240 V.
See lessExplain the function of a water turbine in hydro-electric power plant. (5 marks)craft1 electrical June/July 2020
A water turbine is a mechanical device that converts the kinetic energy of flowing water into rotational mechanical energy, which can then be used to generate electricity. In a hydroelectric power plant, the water turbine is a key component that is used to generate electricity from the movement of wRead more
A water turbine is a mechanical device that converts the kinetic energy of flowing water into rotational mechanical energy, which can then be used to generate electricity. In a hydroelectric power plant, the water turbine is a key component that is used to generate electricity from the movement of water.
The water turbine works by channeling water through a system of pipes and channels to a turbine runner, which is a rotating shaft with blades or vanes attached to it. As the water flows over the blades of the runner, it causes the runner to rotate, generating mechanical energy. This mechanical energy is then transmitted through a series of gears and shafts to a generator, which converts it into electricity.
See lessState three merits of hydro-electric generating plant.craft1 electrical June/July 2020
Renewable and clean: Hydroelectric power is a renewable energy source, as it generates electricity from the movement of water, which can be replenished through natural processes such as rain and snowmelt. It is also a clean energy source, as it does not produce any greenhouse gas emissions or air poRead more
- Renewable and clean: Hydroelectric power is a renewable energy source, as it generates electricity from the movement of water, which can be replenished through natural processes such as rain and snowmelt. It is also a clean energy source, as it does not produce any greenhouse gas emissions or air pollution during operation.
- Reliable: Hydroelectric power plants can operate consistently and reliably, as they are not dependent on weather conditions or fuel supply.
- Low operating costs: Hydroelectric power plants have low operating costs, as they do not require fuel to generate electricity.
- Long lifespan: Hydroelectric power plants have a long lifespan, with many plants operating for several decades before requiring major maintenance or upgrades.
- Adjustable: The power output of a hydroelectric power plant can be easily adjusted by controlling the flow of water through the turbine, making it a flexible source of electricity.
- Low land use: Hydroelectric power plants often have a small footprint, as they do not require large amounts of land for fuel storage or transportation.
- Versatility: Hydroelectric power can be used for a variety of applications, including large-scale electricity generation, irrigation, and water supply.
See lessExplain four reasons for carrying out the polarity test in electrical installation. (4 marks)craft1 electrical June/July 2020
The polarity test is carried out in electrical installations to ensure that the electrical system is properly wired and that the electrical current is flowing in the correct direction. There are several reasons for carrying out this test: Safety: The polarity test helps to ensure that the electricalRead more
The polarity test is carried out in electrical installations to ensure that the electrical system is properly wired and that the electrical current is flowing in the correct direction. There are several reasons for carrying out this test:
- Safety: The polarity test helps to ensure that the electrical system is safe to use, as it checks that the electrical current is flowing in the correct direction and that there are no incorrect connections that could potentially cause an electrical shock.
- Compliance with regulations: The polarity test is required by electrical regulations to ensure that the electrical installation is installed and maintained in a safe and compliant manner.
- Prevention of damage: Incorrect polarity can cause damage to electrical equipment, as it can cause the electrical current to flow in the wrong direction. The polarity test helps to prevent this type of damage.
- Efficiency: Properly wired electrical systems are more efficient, as they allow the electrical current to flow in the correct direction without any unnecessary resistance. The polarity test helps to ensure that the electrical system is wired correctly for maximum efficiency.
See lessList in correct sequence the equipment at consumer’s intake point. (4 marks)craft1 electrical June/July 2020
The equipment at the consumer's intake point, also known as the service entrance, is typically installed in the following sequence: Meter box: The meter box houses the electrical meter, which measures the amount of electricity consumed by the consumer. Main switch or fuse box: The main switch or fusRead more
The equipment at the consumer’s intake point, also known as the service entrance, is typically installed in the following sequence:
- Meter box: The meter box houses the electrical meter, which measures the amount of electricity consumed by the consumer.
- Main switch or fuse box: The main switch or fuse box provides a means of isolating the electrical supply to the consumer’s premises in case of an emergency or for maintenance purposes.
- Surge protection device: A surge protection device helps to protect the consumer’s electrical equipment from damage caused by sudden increases in voltage, such as those caused by lightning strikes.
- Earth rod: An earth rod is a copper or galvanized steel rod that is driven into the ground and used to provide an earth connection for the consumer’s electrical installation.
- Earthing conductor: An earthing conductor is a conductor that is used to provide an electrical connection between the consumer’s electrical installation and the earth rod.
- Main earthing terminal: The main earthing terminal is a terminal block that is used to connect the earthing conductor to the consumer’s electrical installation.
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