What it refers to in simple terms: weak current mainly refers to below 36VAC and below 24VDC.
Weak current systems include:
1. Building equipment system
2. Security system
- CCTV surveillance system
- security alarm system
- Perimeter Defense System
- access control system
- visitor intercom system
- Electronic patrol system
3. Intelligent property management system
- Smart Parking System
- Smart card system
- Broadcasting and background music system
- Three tables in one
4. Network information service system
- Satellite reception and cable TV system
- Integrated wiring system
- Broadband Network Information Service System
5. Fire alarm system (I also saw it elsewhere)
In fact, there is no obvious boundary for the weak current system. As society progresses, the size and size of various systems are more and more obvious. It is difficult for a single system to exist and meet human requirements (personal opinion)
What does it mean in terms of complexity:
Weak current generally refers to DC circuits or audio, video lines, network lines, telephone lines, and the DC voltage is generally within 32V. Household electrical appliances such as telephone, computer, TV signal input (cable TV line), audio equipment (output end line) and other electrical appliances are all weak current electrical equipment.
Conceptually speaking, strong electricity and weak electricity are generally easy to distinguish, and the main difference lies in their different uses. Strong electricity is used as a power source , and weak electricity is used for information transmission . They roughly have the following differences:
(1) AC frequency is different
The frequency of strong electricity is generally 50Hz (hertz), which is called " power frequency ", which means the frequency of industrial electricity: the frequency of weak electricity is often high frequency or ultra-high frequency, measured in KHz (kilohertz) and MHz (megahertz).
(2) Different transmission methods
Strong electricity is transmitted through transmission lines, while weak electricity transmission can be divided into wired and wireless. Radio transmits in electromagnetic waves.
(3) The power, voltage and current are different
Strong electric power is measured in KW (kilowatt), MW (megawatt), voltage is measured in V (volt), KV (kilovolt), current is measured in A (ampere), kA (kiloampere); weak electric power is measured in W (watt) , mW (milliwatts), voltage in V (volts), mV (millivolts), current in mA (milliamps), uA (microamperes), so its circuit can be composed of printed circuits or integrated circuits .
There are also high-frequency (hundreds of KHz) and intermediate-frequency equipment in strong electricity, but the voltage is higher and the current is also larger. Due to the development of modern technology, weak current has penetrated into the field of strong current, such as power electronic devices, wireless remote control, etc., but these can only be counted as the weak current control part of strong current, which is still different from the charged strong current.
There are two main types of weak electricity in buildings:
- One is low-voltage electric energy such as safety voltage level and control voltage stipulated by the state, which can be divided into AC and DC, such as 24V DC control power supply, or emergency lighting backup power supply.
- The other type is information sources that carry information such as voice, images, and data, such as information from telephones, televisions, and computers.
Conceptually speaking, strong electricity and weak electricity are generally easy to distinguish, and the main difference lies in their different uses. Strong electricity is used as a power source, and weak electricity is used for information transmission. Specifically, they roughly differ as follows:
1. The frequency of communication is different
The frequency of strong electricity is generally 50Hz, which is called "power frequency", that is, the frequency of industrial electricity; the frequency of weak electricity is often high frequency or ultra-high frequency, measured in kilohertz (KHz) or megahertz (MHz).
2. Different transmission methods
Strong electricity is transmitted by transmission lines, weak electricity is transmitted by wire and wireless, and radio is transmitted by electromagnetic waves.
3. The power, voltage and current are different
- Strong electric power is measured in kilowatts (KW) and megawatts (MW), voltage is measured in volts (V) and kilovolts (KV), and current is measured in amperes (A) and kiloamps (KA);
- Weak electric power is measured in watts (W) and milliwatts (mW), voltage is measured in volts (V) and millivolts (mV), and current is measured in milliamps (mA) and microamps (μA).
Thus its circuit can be formed by printed circuit or integrated circuit. Of course, there are also high-frequency (several megahertz) and intermediate-frequency equipment in strong electricity, but the voltage is higher and the current is also larger.
Another example is flashlights and electric shavers, although the voltage is very low, the power and current are very small, they are still strong electricity. Due to the development of modern technology, weak current has penetrated into the strong current field, such as power electronic devices, wireless remote control, etc., but these can only be counted as the weak current control part of the strong current, which is still different from the charged strong current.
Electronics are used to be divided into two parts: strong electricity ( electricity ) and weak electricity ( information ). There are both connections and differences between the two. Generally speaking, the processing object of strong electricity is energy (electricity), which is characterized by high voltage, high current, high power, and low frequency. The main consideration is to reduce losses and improve efficiency. Weak electricity The main object of processing is information, that is, the transmission and control of information, which is characterized by low voltage, low current, low power, and high frequency. The main consideration is the effect of information transmission, such as the fidelity, speed, and breadth of information transmission. , Reliability.
Generally speaking, weak current projects include TV projects, communication projects, fire protection projects, security projects, video projects, etc. and integrated wiring projects serving the above projects. Weak electricity is for strong electricity. Strong electricity = (380/220), regardless of high voltage.