source: Powerful
article summarizes the basic knowledge about strong and weak electricity in buildings. introduces three-phase AC power, wire types, lighting installation methods, wire laying symbols, line graphic symbols, distribution equipment graphic symbols, and lamps. and sockets and other graphic symbols are for everyone’s communication and learning only!
accident level
alternating current
three-phase alternating current : three-phase alternating current is composed of three parts with the same frequency, potential equal amplitude and phase difference A power system composed of AC circuit with an angle of 120° from each other. At present, my country's production and distribution are all three-phase AC .
star (Y-shaped) connection of three-phase power supply: star connection of -phase motor is to connect one end of each phase power supply or load to one point, and their other ends are used as lead wires, respectively Three phase lines of three-phase electricity.
For the star connection method, the midpoint (called the neutral point) can be led out as the neutral line to form a three-phase four-wire system. It can also be left out to form three-phase three-wire system . Of course, whether there is a neutral wire or not, you can add ground wire to become three-phase five-wire system or three-phase four-wire system respectively. The advantage is that two different levels of voltage can be obtained at the same time to supply power to three-phase electrical equipment and single-phase electrical equipment.
Wire type
①BBLX, BBX: Cotton yarn braided rubber insulated aluminum core, copper core wire.
②BLV, BV: plastic insulated aluminum core, copper core wire.
③BLVV, BVV: plastic insulated plastic sheathed aluminum core and copper core wires.
④BLXF, BXF, BLXY, BXY: rubber insulated neoprene sheath, polyvinyl chloride sheath, aluminum core and copper core wire.
⑤VLV, VV: PVC insulated, PVC sheathed aluminum core, copper core power cable , also known as all-plastic cable.
⑥YJLV, YJV: Cross-linked polyvinyl chloride insulated, polyvinyl chloride sheathed aluminum core, copper core power cable.
⑦XLV, XV: Rubber insulated, PVC sheathed aluminum core, copper core power cable.
Wiring type
The installation height of the lighting distribution box should comply with the requirements of the construction drawings. If there is no requirement, the bottom edge is generally 1.5m from the ground, and the vertical deviation of the installation should not be greater than 3mm. The name of the electrical circuit should be marked on the distribution box.
Wire laying
Lightning protection level
Lightning protection device
Wire representation method
Common wire markings
device representation method
a: device number;
b: device rated capacity ;
c: line melt or low-voltage circuit breaker tripping current (A);
d: elevation.
line graphic symbols
power distribution equipment graphic symbols
lamp graphic symbols
socket graphic symbols
switch graphic symbols
Electric meter graphic symbol
Lamp installation method
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