Electrical and fire safety technology

First, electrical safety technology

1.    Zero, ground protection system. According to whether the neutral point of the power system is grounded, the protection zero-connection system or the protection grounding system is adopted respectively. In the construction project, the TN - S and TN - C - S protection systems should be given priority in the neutral-grounded low-voltage power grid .

2.    Leakage Protection. According to "Installation and operation of leakage protector" ( GB/13955 - 1992 ) requirements.

3.    insulation.

4.    Electrical isolation. The insulation of the isolation transformer should be reinforced between the primary and secondary sides, and the secondary loop must not have any connection with other electrical circuits, ground, and protection ground (ground) lines; the voltage ( U ) of the isolation loop (secondary) should be guaranteed to be U ≤ 500V and the line length L ≤ 200M , and the product of secondary voltage and line length U • L ≤ 100000VM ; when the secondary loop is longer, insulation monitoring device shall also be installed; when the isolation loop has more than one electrical equipment, the metal shell of each device Equipotential bonding measures shall be taken. The socket used shall have a dedicated socket for equipotential bonding.

5.    Safe voltage (or safety extra low voltage). Safe voltage power supply ( 42V , 36V , 24V , 12V , 6V ,) (ie 12V safe voltage in wet, narrow metal containers, tunnels, mines, etc. ). The pins and sockets used in the safety voltage circuit shall use special pins and sockets, and shall not be provided with zero or grounding plugs and jacks. The primary and secondary sides of the safety voltage power supply shall be equipped with fuses for short circuit protection. When the electrical equipment uses a safe voltage of more than 24V , protection measures must be taken to prevent direct contact with the live body.

6.    Screen protection and safety distance. Covers, shields, covers, boxes and other devices isolate the live parts from the outside world. Screen protection hanging warning signs, but also set up sound and light alarm signals and interlocking protection devices. The safety distance refers to the safety measures that must be maintained between the live parts and the ground, buildings, human bodies, other equipment, other charged bodies, and pipes.

7.    Chain protection. Substation program operation control lock, dual power supply automatic switching interlock protection device, open high-voltage dangerous equipment screen protection, alarm and live device automatic power-off protection device, welding machine no-load power-off or reduce no-load voltage device.

Second, electrical fire protection and explosion protection measures

1. Prevent the formation of flammable and explosive systems

Prevention of the presence of flammable substances, combustible substances (air, strong oxidants), ignition energy (open flames, impacts, hot objects, chemical reaction heat, etc.); prevention of combustible substances, combustible substances mixed explosive mixture (in explosive limits) Concurrent with the ignition of energy.

Replacing flammable materials with non-combustible or flame-retardant materials does not allow flammable materials to leak and accumulate to form an explosive mixture; secondly, it prevents air and other oxidizing substances from entering the equipment or preventing leakage of combustible materials and air.

- Replace or control usage;

- strengthen confinement;

- Ventilation exhaust;

- Inert.

2. Elimination and control of ignition energy

The main sources of fire and explosion accidents are open flames, high-temperature surfaces, friction and impact, adiabatic compression, chemical reaction heat, electrical sparks, static sparks, lightning strikes, and photo-thermal rays.

In production sites with fire and explosion hazards, full attention should be paid to the following sources of ignition and strict control measures should be taken:

- open flames and hot surfaces;

- friction and impact;

- Prevent electrical sparks.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.