With the economic growth and the increase in people's income, building intelligence and automation have led to an increase in the use of electricity in buildings. With the acceleration of urban integration construction, China’s building area is increasing at a rate of more than one billion square meters per year. According to the statistics of the Ministry of Construction and the National Building Materials Bureau, China's building energy consumption accounts for about 27% of the total energy consumption of the entire society. Building energy efficiency is imperative in the construction industry. All of these require the construction of electrical engineers to play their wisdom, not only to meet the functional requirements of the building, to provide residents with a comfortable and convenient living space, but also to reduce the energy consumption of the building as much as possible. From the following two aspects of the safety of the electrical design of buildings and energy conservation are analyzed.
1. Architectural electrical design principles
Building electrical design strictly complies with relevant design specifications. The design specification is a national or local design guideline. It embodies the country's policies and the quality requirements of the building. It is the design standard for building electrical designers.
The electrical design of the building should meet the functional requirements of the building, ensure the stable and continuous operation of the various functions of the building, and bring convenience and quickness to the daily life of residents.
The architectural electrical design is a part of the architecture. Comprehensive economic considerations must also be considered in the design process. It is necessary to consider both the initial investment and the future operating costs in order to obtain the lowest cost in the life cycle of the building.
2. Safety of building electrical design
The safety of building electrical design was analyzed from the aspects of power supply, power supply lines, grounding of electrical equipment, and building fire control.
2.1 Power Supply
Electricity plays an important role in current buildings. Without electricity, buildings will be paralyzed. To ensure the stable supply of building electricity is the basis for guaranteeing the normal life of residents. Therefore, in order to ensure the reliability of power supply, modern high-rise buildings should have at least two independent power sources, and the specific quantity should be determined according to the size of the load and the conditions of the local power grid. Two independent power sources are, in principle, two-way power supply and standby for each other. In addition, emergency backup diesel or gas-fired turbine generator sets must also be installed, which requires automatic restoration of power supply within 15 seconds to ensure accident lighting, computer equipment, fire fighting equipment, elevators and other accidents. For high-voltage switchgears that should be based on building standards, a vacuum switcher-type high-voltage switchgear with “five-prevention†function is selected. For power transformers, large-capacity oil-immersed power transformers are not permitted in the main building according to the fire protection requirements. For the outlet of the capacity low-voltage power distribution screen, it should be made into a handcart type.
2.2 Power Lines
There are many kinds of circuits in residential buildings. In order to ensure the stable and safe operation of various equipment circuits, the main line section of the power supply circuit cannot be arbitrarily changed. If you want to change, please refer to the specification for the corresponding calculation and then change. Otherwise, the cross section of the circuit becomes smaller, so that the resistance becomes larger, and the power overload will cause the circuit to generate heat or cause a fire.
2.3 Grounding of Electrical Equipment
There are a large number of electronic devices such as computers, televisions, and refrigerators in buildings. Electronic devices are connected to a common grounding body through repeated grounding of the protective grounding system. To ensure personnel safety, the resistance of this common grounding body should not exceed 1 Ω.
2.4 Building fire control
Building fire design means automatic fire alarm fire extinguishing system. Including fire detectors, district fire alarm controllers, fire centers and gas automatic fire extinguishing and automatic sprinkler systems, four parts, to achieve automatic fire alarm. Among them, the fire-fighting line requires the use of a metal pipe or concealer. The purpose is to maintain the normal use of the fire-fighting circuit after a fire has occurred and to ensure that signals and commands are effectively transmitted. The control of the fire pump is particularly important. To ensure safety, the fire pump control should be set up in two ways: one leading to the fire pump control cabinet and the other to the fire control room.
3. Energy Saving of Building Electrical Design
Architectural electrical design is part of the architectural design. In order to reduce the building's energy consumption, the building electrical designer should also consider the overall situation. It is necessary to consider both the initial investment and the energy consumption of the building's electrical operation. The following are given from the aspects of transformers, lines, and lighting.
3.1 The choice of transformer
Transformers should use energy-saving transformers. High-magnetization, high-quality cold-rolled grain-oriented silicon steel sheet and advanced technology make the magnetic field directions of silicon steel sheets nearly identical, and can cause core eddy current losses; good joint tightness can reduce leakage magnetic losses. . Compared with the old products, the no-load loss and short-circuit loss of energy-saving transformers decreased, and the 10kV series decreased by 41.5% and 13.93%, respectively. The average annual electricity consumption per kilovolt is 9kW/h. Energy-saving transformers have been widely used in recent years due to their advantages of low loss, light weight, high efficiency, impact resistance, and significant energy saving.
Transformer capacity selection. Theoretically, when the transformer load rate is 50%, the power consumption of the transformer has the smallest energy consumption. But at this time, the transformer's non-functional consumption increases, so it is necessary to consider the overall economic benefits to choose. After selecting the capacity of the transformer in the project, considering the initial investment and operating costs, the load rate of the general transformer is 80% of the capacity.
3.2 Loss of distribution lines
The power supply line in the building is long and many, due to the presence of resistance, when the current passes through it will produce power loss, the formula is: where ΔΡ - three-phase transmission line power loss; I-line current; R-line phase resistance . For the selected condition of the power supply line, the "R" value does not change. The larger the visible current, the greater the circuit loss. The resistance of the circuit is R=ÏL/S, and the resistance is proportional to the resistivity Ï and the length L of the wire, and is inversely proportional to the section S of the wire. To reduce the resistance loss should be considered from the following aspects:
Select a wire with a smaller resistivity Ï, such as a copper core wire, followed by aluminum wire. Reduce the length of the wire, in the design of the circuit should take a straight line less detours, and in addition, in the low-voltage distribution as far as possible or not to go back. Substations should be as close to the load center as possible to reduce the power supply radius. Increase the cross-sectional area of ​​the wire. For longer wires, increase the first-order wire cross-section when selecting the wire cross section under the premise of meeting the requirements of the current-carrying capacity, thermal stability, protection coordination, and voltage drop. This increased line cost can be offset by future operating expenses.
3.3 Energy Saving Analysis of Motor
The main way to reduce motor losses is to increase the motor's operating efficiency and power factor. However, in a specific project, motors are usually supplied by professional equipment such as plumbing and construction. Therefore, energy-saving measures for electrical design are mainly in operation. In addition to local capacitor compensation to reduce line losses, low-efficiency light and no-load operation of the motor should also be reduced. The main measure is to use frequency control to control the motor to adapt to changes in the load, in order to improve the efficiency of the motor light load to achieve the purpose of saving energy. For example, the air-conditioning system's circulation pump can save 30 to 40% of the operating cost of the air-conditioning system after frequency conversion control.
3.4 Lighting Energy Saving
Lighting energy-saving design is to reduce the loss of light energy in the lighting system under the premise of ensuring the visual requirements of the working surface and not reducing the quality of lighting, so as to maximize the use of light energy. The usual energy-saving measures are the following: (1) Full use of Natural light, in the design of electrical design personnel should be more with the architectural professional, to make full and reasonable use of natural light to make it with the indoor artificial lighting organically combined, thus saving artificial lighting power. (2) Use high-efficiency energy-saving lamps and high-efficiency electronic ballasts, energy-saving magnetic ballasts, electronic triggers, and electronic transformers. Fluorescent lamps in public buildings should use lamps with reactive power compensation. Compact fluorescent lamps are preferred. Electronic ballasts, gas discharge lamps should adopt electronic triggers. (3) Controlling lighting fixtures is also an effective power-saving method. According to the characteristics of lighting use can be taken to control the lighting zone or appropriately increase the lighting switch point. Bedside lights in bedrooms, sickrooms, rooms, etc. can use dimmer switches. Superior rooms use energy-saving key switches. Public places and outdoor lighting can be controlled by programs or photoelectric and voice-activated switches. Public places such as walkways and stairs can be used for short stays. Energy-saving self-extinguishing switch.
Conclusion
There are many safety and energy-saving measures for building electrical, and there is a great potential for energy saving in design. The majority of electrical designers should carefully consider the design, repeatedly compare design plans, and come up with a set of technical indicators that meet the functional requirements. , Effective and practical energy-saving measures, so as to achieve the purpose of real safety savings.
1. Architectural electrical design principles
Building electrical design strictly complies with relevant design specifications. The design specification is a national or local design guideline. It embodies the country's policies and the quality requirements of the building. It is the design standard for building electrical designers.
The electrical design of the building should meet the functional requirements of the building, ensure the stable and continuous operation of the various functions of the building, and bring convenience and quickness to the daily life of residents.
The architectural electrical design is a part of the architecture. Comprehensive economic considerations must also be considered in the design process. It is necessary to consider both the initial investment and the future operating costs in order to obtain the lowest cost in the life cycle of the building.
2. Safety of building electrical design
The safety of building electrical design was analyzed from the aspects of power supply, power supply lines, grounding of electrical equipment, and building fire control.
2.1 Power Supply
Electricity plays an important role in current buildings. Without electricity, buildings will be paralyzed. To ensure the stable supply of building electricity is the basis for guaranteeing the normal life of residents. Therefore, in order to ensure the reliability of power supply, modern high-rise buildings should have at least two independent power sources, and the specific quantity should be determined according to the size of the load and the conditions of the local power grid. Two independent power sources are, in principle, two-way power supply and standby for each other. In addition, emergency backup diesel or gas-fired turbine generator sets must also be installed, which requires automatic restoration of power supply within 15 seconds to ensure accident lighting, computer equipment, fire fighting equipment, elevators and other accidents. For high-voltage switchgears that should be based on building standards, a vacuum switcher-type high-voltage switchgear with “five-prevention†function is selected. For power transformers, large-capacity oil-immersed power transformers are not permitted in the main building according to the fire protection requirements. For the outlet of the capacity low-voltage power distribution screen, it should be made into a handcart type.
2.2 Power Lines
There are many kinds of circuits in residential buildings. In order to ensure the stable and safe operation of various equipment circuits, the main line section of the power supply circuit cannot be arbitrarily changed. If you want to change, please refer to the specification for the corresponding calculation and then change. Otherwise, the cross section of the circuit becomes smaller, so that the resistance becomes larger, and the power overload will cause the circuit to generate heat or cause a fire.
2.3 Grounding of Electrical Equipment
There are a large number of electronic devices such as computers, televisions, and refrigerators in buildings. Electronic devices are connected to a common grounding body through repeated grounding of the protective grounding system. To ensure personnel safety, the resistance of this common grounding body should not exceed 1 Ω.
2.4 Building fire control
Building fire design means automatic fire alarm fire extinguishing system. Including fire detectors, district fire alarm controllers, fire centers and gas automatic fire extinguishing and automatic sprinkler systems, four parts, to achieve automatic fire alarm. Among them, the fire-fighting line requires the use of a metal pipe or concealer. The purpose is to maintain the normal use of the fire-fighting circuit after a fire has occurred and to ensure that signals and commands are effectively transmitted. The control of the fire pump is particularly important. To ensure safety, the fire pump control should be set up in two ways: one leading to the fire pump control cabinet and the other to the fire control room.
3. Energy Saving of Building Electrical Design
Architectural electrical design is part of the architectural design. In order to reduce the building's energy consumption, the building electrical designer should also consider the overall situation. It is necessary to consider both the initial investment and the energy consumption of the building's electrical operation. The following are given from the aspects of transformers, lines, and lighting.
3.1 The choice of transformer
Transformers should use energy-saving transformers. High-magnetization, high-quality cold-rolled grain-oriented silicon steel sheet and advanced technology make the magnetic field directions of silicon steel sheets nearly identical, and can cause core eddy current losses; good joint tightness can reduce leakage magnetic losses. . Compared with the old products, the no-load loss and short-circuit loss of energy-saving transformers decreased, and the 10kV series decreased by 41.5% and 13.93%, respectively. The average annual electricity consumption per kilovolt is 9kW/h. Energy-saving transformers have been widely used in recent years due to their advantages of low loss, light weight, high efficiency, impact resistance, and significant energy saving.
Transformer capacity selection. Theoretically, when the transformer load rate is 50%, the power consumption of the transformer has the smallest energy consumption. But at this time, the transformer's non-functional consumption increases, so it is necessary to consider the overall economic benefits to choose. After selecting the capacity of the transformer in the project, considering the initial investment and operating costs, the load rate of the general transformer is 80% of the capacity.
3.2 Loss of distribution lines
The power supply line in the building is long and many, due to the presence of resistance, when the current passes through it will produce power loss, the formula is: where ΔΡ - three-phase transmission line power loss; I-line current; R-line phase resistance . For the selected condition of the power supply line, the "R" value does not change. The larger the visible current, the greater the circuit loss. The resistance of the circuit is R=ÏL/S, and the resistance is proportional to the resistivity Ï and the length L of the wire, and is inversely proportional to the section S of the wire. To reduce the resistance loss should be considered from the following aspects:
Select a wire with a smaller resistivity Ï, such as a copper core wire, followed by aluminum wire. Reduce the length of the wire, in the design of the circuit should take a straight line less detours, and in addition, in the low-voltage distribution as far as possible or not to go back. Substations should be as close to the load center as possible to reduce the power supply radius. Increase the cross-sectional area of ​​the wire. For longer wires, increase the first-order wire cross-section when selecting the wire cross section under the premise of meeting the requirements of the current-carrying capacity, thermal stability, protection coordination, and voltage drop. This increased line cost can be offset by future operating expenses.
3.3 Energy Saving Analysis of Motor
The main way to reduce motor losses is to increase the motor's operating efficiency and power factor. However, in a specific project, motors are usually supplied by professional equipment such as plumbing and construction. Therefore, energy-saving measures for electrical design are mainly in operation. In addition to local capacitor compensation to reduce line losses, low-efficiency light and no-load operation of the motor should also be reduced. The main measure is to use frequency control to control the motor to adapt to changes in the load, in order to improve the efficiency of the motor light load to achieve the purpose of saving energy. For example, the air-conditioning system's circulation pump can save 30 to 40% of the operating cost of the air-conditioning system after frequency conversion control.
3.4 Lighting Energy Saving
Lighting energy-saving design is to reduce the loss of light energy in the lighting system under the premise of ensuring the visual requirements of the working surface and not reducing the quality of lighting, so as to maximize the use of light energy. The usual energy-saving measures are the following: (1) Full use of Natural light, in the design of electrical design personnel should be more with the architectural professional, to make full and reasonable use of natural light to make it with the indoor artificial lighting organically combined, thus saving artificial lighting power. (2) Use high-efficiency energy-saving lamps and high-efficiency electronic ballasts, energy-saving magnetic ballasts, electronic triggers, and electronic transformers. Fluorescent lamps in public buildings should use lamps with reactive power compensation. Compact fluorescent lamps are preferred. Electronic ballasts, gas discharge lamps should adopt electronic triggers. (3) Controlling lighting fixtures is also an effective power-saving method. According to the characteristics of lighting use can be taken to control the lighting zone or appropriately increase the lighting switch point. Bedside lights in bedrooms, sickrooms, rooms, etc. can use dimmer switches. Superior rooms use energy-saving key switches. Public places and outdoor lighting can be controlled by programs or photoelectric and voice-activated switches. Public places such as walkways and stairs can be used for short stays. Energy-saving self-extinguishing switch.
Conclusion
There are many safety and energy-saving measures for building electrical, and there is a great potential for energy saving in design. The majority of electrical designers should carefully consider the design, repeatedly compare design plans, and come up with a set of technical indicators that meet the functional requirements. , Effective and practical energy-saving measures, so as to achieve the purpose of real safety savings.
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