Who can tell me something about weak current?

Weak current generally refers to DC circuits or audio, video lines, network lines and telephone lines, and the DC voltage is generally within 32V. Telephone, computer, TV signal input (cable TV line), audio equipment (output line) and other electrical appliances in household appliances are all weak current electrical equipment.

There are two main types of weak current in buildings: one is the national safe voltage level, which controls weak current.

Low-voltage electric energy such as voltage can be divided into AC and DC, such as 24V DC control power supply or emergency lighting standby power supply. The other is information sources including sound, images and data, such as telephone, television and computer information.

narrow sense

In a narrow sense, building weak current mainly refers to: security (monitoring, perimeter alarm, parking lot), fire control (electrical part), building control, network integrated wiring, sound system, etc.

Edit the difference between this paragraph and strong electricity.

Conceptually, strong electricity and weak electricity are generally easy to distinguish, and the main difference is the different uses. Strong electricity is used as power supply and weak electricity is used for information transmission. Roughly as follows:

Different AC frequencies

The frequency of strong electricity is generally 50Hz, which is called "power frequency", which means the frequency of industrial electricity. The frequency of weak current is often high frequency or ultra-high frequency, which is measured by KHz and MHz.

Different transmission modes

Strong electricity is transmitted through transmission lines, and weak electricity is transmitted through wires or wireless. Radio is transmitted by electromagnetic waves.

Different power, voltage and current.

Strong electric power is measured in KW (kilowatt) and MW (megawatt), voltage is measured in V (volt) and KV (kilovolt), and current is measured in A (ampere) and kA (kiloampere); Weak current is measured in W (Watt) and mW (Milliwatt), voltage in V (Volt) and mV (Millivolt), and current in mA (mA) and uA (Microampere), so its circuit can be composed of printed circuit or integrated circuit. There are also high frequency (hundreds of KHz) and intermediate frequency devices in high voltage, but the voltage is higher and the current is larger. Due to the development of modern technology, weak current has penetrated into high voltage fields, such as power electronic devices and wireless remote control. But these can only be regarded as the weak current control part of high voltage, which is different from charged high voltage.

Edit this paragraph classification

There are two main types of weak current in buildings: one is low-voltage electric energy such as safe voltage grade and control voltage specified by the state, which is divided into AC and DC, such as 24V DC control power supply or emergency lighting standby power supply. The other is information sources including sound, images and data, such as telephone, television and computer information. The intelligent system consists of building equipment monitoring system, safety prevention system, communication network system, information network system, automatic fire alarm and fire linkage system, which is a comprehensive system of centralized monitoring, control and management. All kinds of data collection, control, management, communication control or network system lines in the home are called intelligent lines (that is, weak current in home decoration). Weak current generally refers to DC circuits or audio, video lines, network lines and telephone lines, and the DC voltage is generally within 24V. Telephone, computer, TV signal input (cable TV line), audio equipment (output line) and other electrical appliances in household appliances are all weak current electrical equipment.

Edit this weak current system

The weak current system of intelligent building is the basic weak current of intelligent group in intelligent building.

Staff, also a key component of intelligent building, is the main object of daily work of building electrical professionals. Before 1970s, the weak current design was only telephone and broadcast design, but after 1980s, fire alarm and linkage control, * * * antenna, security monitoring, air conditioning DDC control and so on were added. The design content of weak current design is expanding step by step, the technology is getting newer and newer, and the workload is getting bigger and bigger. The weak current system of intelligent building generally includes the following subsystems: building automation management subsystem (BAS), automatic fire alarm subsystem (FAS), security monitoring subsystem (CCTV), satellite receiving and CATV subsystem (CATV), underground garage management subsystem (CPS), public broadcasting and emergency broadcasting subsystem (PAS), program-controlled exchange subsystem (PABX) and structured integrated wiring. The subsystems of intelligent building provide monitoring and management of all kinds of mechanical and electrical equipment for buildings, create a safe, healthy, comfortable and pleasant office environment for building users, provide modern communication means and office conditions, and meet the requirements of various users for different environments and functions. Building Automation Management Subsystem (BAS) The building automation management subsystem is the core of the weak current system of intelligent buildings, and its high reliability is the cornerstone of the whole weak current system, so BAS system adopts three-level control mode. The automatic fire alarm subsystem (FAS) adopts intelligent smoke-sensing probe and temperature-sensing probe, which can intelligently sense smoke and heat and give corresponding simulation values. Through advanced algorithm, the system can distinguish between true alarm and false alarm interference. The display screen of the system can graphically display the exact location of the fire and the nature of the alarm. After the fire alarm is confirmed, the system can automatically send out the corresponding fire emergency broadcast and fire linkage control, which lays the foundation for safe evacuation and correct and effective fire fighting. The security monitoring system (CCTV) consists of closed-circuit television monitoring system, entrance control system, patrol system and burglar alarm system. Satellite receiving and CATV subsystem Satellite receiving and CATV subsystem is a basic system widely established now. Satellite receiving system is a system that directly relays TV signals through satellites, which plays the role of space relay station and is the best way to solve the problem of TV coverage and transmit TV image signals with high quality. Cable TV (public antenna) system uses a group of high-quality antennas to distribute TV signals to all users of the TV system in a wired way. It has the functions of two-way communication, videophone and graphic transmission, and can be networked with home computer terminals. The underground garage management system (CPS) takes the computer network as the core, and is equipped with all kinds of necessary equipment for modern parking lots, such as invoice/ticket checking machine, automatic fence machine, vehicle induction coil, toll collecting machine, etc. The system can adopt full-automatic or semi-automatic management modes. Public address system (PAS) is mainly used in shopping malls, business centers, lobbies, restaurants, public walkways and other building parts, which can provide FM and AM broadcast programs, dual-card playback signals, CD player signals and microphone signals. You can select any one of the above audio sources through the mixer, adjust the volume to an appropriate level through the volume control circuit, and then output it to a given area through the area selector for playback. When there is a fire alarm signal, the system will automatically turn off the public broadcast and automatically switch the fire floor and its upper and lower floors to emergency broadcast. If necessary, it can also be controlled manually through the microphone attached to the machine. PABX (Digital Program-Controlled Telephone Exchange System) provides enough session capacity to meet the needs of all users in the building, and leaves room for future expansion. The system can realize ISDN function by simple interface configuration, and realize data communication by selecting X..25 interface or other interfaces. Through software setting, the function of establishing private virtual network in the system can be realized. The system has many functions, such as dialing, calling special service, conference call, call back in case of busy, call confidentiality, e-mail, voice mail and so on. The system also has the functions of daily automatic detection, diagnosis, positioning and automatic switching to standby machine when the main engine is seriously faulty. Structured Integrated Wiring System (PDS) is the "nervous system" of the whole building, which improves the networking application of voice communication, fax and other image materials, video conference and other video signals and data communication. Structured integrated wiring system consists of six independent subsystems, namely, workspace subsystem, horizontal subsystem, management subsystem, vertical backbone subsystem, equipment subsystem and building complex subsystem.

Edit this paragraph function and application

According to the intensity of power transmission, power applications can be divided into two categories: strong electricity and weak electricity. Building and building electricity generally refers to high-voltage alternating current above 220 V and 50 Hz. It mainly provides people with electric energy and converts it into other energy sources, such as air conditioning electricity, lighting electricity, power electricity and so on. There are two main types of weak electricity in intelligent buildings. One is low-voltage electric energy such as safe voltage grade and control voltage specified by the state, which is divided into AC and DC, with AC below 36V and DC below 24V, such as 24V DC control power supply or emergency lighting standby power supply. The other is information sources including sound, images and data, such as telephone, television and computer information. People used to call weak current technology weak current technology. It can be seen that the basic meaning of weak current technology in intelligent buildings is still weak current technology in the original sense. However, with the rapid development of modern weak current technology, weak current technology is more and more widely used in intelligent buildings. Generally speaking, weak current system engineering refers to the second application. Mainly includes: 1, TV signal engineering, such as TV monitoring system and cable TV. 2. Communication engineering, such as telephone. 3, intelligent fire engineering. 4. Sound reinforcement and sound engineering, such as community background music broadcasting and building background music. 5, integrated wiring engineering, mainly used for computer networks. With the rapid development of computer technology, the rapid and powerful functions of software and hardware, and the perfect combination of various weak current system engineering and computer technology, the previous classification is no longer as clear as before. The integration of various projects is system integration. The common working voltages of weak current systems are: 24VAC, 16.5VAC, 12VDC, and sometimes 220VAC is also considered as a weak current system. For example, the working voltage of some cameras is 220VAC, so we can't classify them as high-voltage systems. Weak current system is mainly aimed at buildings, including buildings, residential areas, airports, docks, railways, expressway and so on. Common weak current systems include: ccTV monitoring system, burglar alarm system, entrance guard system, electronic patrol system, parking lot management system, visual intercom system, home intelligent system and security system, background music system, LED display system, plasma splicing screen system, DLP large screen system, three-meter CC system, building automatic control system, lightning protection and grounding system, paging intercom and professional intercom system, weak current pipeline system, UPS uninterrupted power supply system, Computer room system, integrated wiring system, computer local area network system, property management system, multifunctional conference room system, cable TV system, satellite TV system, satellite communication system, fire protection system, telephone communication system, hotel management system, video-on-demand system, human resource management system, etc.

Edit this weak current project

According to the intensity of power transmission, power applications can be divided into two categories: strong electricity and weak electricity. Building and building electricity generally refers to high-voltage alternating current above 220 V and 50 Hz. It mainly provides people with electric energy and converts it into other energy sources, such as air conditioning electricity, lighting electricity, power electricity and so on. There are two main types of weak electricity in intelligent buildings. One is low-voltage electric energy such as safe voltage grade and control voltage specified by the state, which is divided into AC and DC, with AC below 36V and DC below 24V, such as 24V DC control power supply or emergency lighting standby power supply. The other is information sources including sound, images and data, such as telephone, television and computer information. People used to call weak current technology weak current technology. It can be seen that the basic meaning of weak current technology in intelligent buildings is still weak current technology in the original sense. However, with the rapid development of modern weak current technology, weak current technology is more and more widely used in intelligent buildings. Generally speaking, weak current system engineering refers to the second application. Mainly includes: 1, TV signal engineering, such as TV monitoring system and cable TV. 2. Communication engineering, such as telephone. 3, intelligent fire engineering. 4. Sound reinforcement and sound engineering, such as community background music broadcasting and building background music. 5, integrated wiring engineering, mainly used for computer networks. With the rapid development of computer technology, the rapid and powerful functions of software and hardware, and the perfect combination of various weak current system engineering and computer technology, the previous classification is no longer as clear as before. The integration of various projects is system integration. The common working voltages of weak current systems are: 24VAC, 16.5VAC, 12VDC, and sometimes 220VAC is also considered as a weak current system. For example, the working voltage of some cameras is 220VAC, so we can't classify them as high-voltage systems.