To safely use good electrical equipment, can not be separated from the protection of safety devices. Electrical equipment safety device is the safe use of electrical equipment, electrical accidents to prevent the occurrence of safety protection devices. Such as: fuses, circuit breakers, etc.. Electrical equipment safety device is the safe production of the “God of protection”, in the daily work, due to the failure of protective devices and accidents are not uncommon. Therefore, safety guards should always be sensitive and reliable, otherwise it is easy to accident.
1. Fuse. Fuse is generally installed in the power grid and electrical lines, is one of the most basic safety devices. When the electrical equipment short circuit or overload work, the fuse of the fuse will fuse itself to cut off the circuit and avoid electrical equipment accidents or casualties. Fuse fuse fusing, should still be configured according to the original specifications, can not be replaced by other metal wire or super-spec fuse, otherwise it will not play the role of safety protection, prone to accidents.
2. Circuit breaker. Circuit breaker, also known as overload protection switch, when the circuit is overloaded, exceeding the allowable limit or short circuit, can automatically disconnect the current circuit safety device. Circuit breaker such as tension porcelain vase and support porcelain vase damage rupture or simultaneous grounding, barrel fire explosion, serious leakage, switch jump vibration, casing terminal fuse or melting, access side casing blowing, fire or continuous occurrence of large sparks and other faults, emergency measures should be taken immediately to repair or replace the processing.
3. Leakage protector. Leakage protector is to prevent electrical equipment or lines due to accidental leakage of electricity set up a protective switch device. When the leakage of electrical equipment, the switch device can quickly cut off the power supply to prevent the housing, rack accidentally energized endangering human safety. The device should match the rating of the equipment or line, and can be highly sensitive to the correct action. Usually installed in the conductive iron plate, electric rack, water, liquid, wet material and other places and the voltage to ground higher than 150V movable circuit and electrical equipment.
4. Safety voltage. Safety voltage is to prevent electric shock accidents and the use of a specific power supply voltage series. China’s safety voltage rating of 42V, 36V, 12V, 6V, the general safety voltage of 36V and 12V, such as portable lighting, portable power tools, etc.. If there is no special safety structure and safety measures, the safety voltage of 36V should also be taken. In the workplace narrow, difficult to move and around a large grounded body and other environments, such as metal containers, tunnels, mines, portable lighting should be used in the safety voltage of 12V.
5. Screen protection. Screen protection is to prevent electric shock, electric short-circuit and electric burns effective protection measures. In some electrical equipment is not convenient insulation or low strength, can not ensure safe operation, we must take cover, shield and other measures, such as the use of cover rod. Shield, box box, etc. Shelter bar (also known as the shelter bar), is used to prevent operators from unintentionally touching or excessively close to the live body, in the safety distance is not enough to operate the screen protection device. Generally with dry wood, rubber or other tough insulating materials, the height shall not be less than 1.7m, the following from the ground shall not exceed 10cm. between the shield rod and the charged body, according to the voltage of the high and low, should leave a corresponding safety distance, such as the special needs of the work, can use a high degree of insulation performance of the shield, part of the shielded charged body. All the parts of the use of the shield bar (shield bar), are to hang “high voltage danger” or “electric danger” warning, warning signs, and the use of lights or sound and other signaling devices, that there is electricity do not approach, and when the human body over the screen close to the charged body, can make the screen guard The charged body automatically cut off the power of the interlocking device to ensure the safety of personnel. Screen material should have sufficient mechanical strength and good fire resistance, metal materials made of screen protection to pay attention to insulation and reliable grounding or zeroing.
6. Insulation. The use of non-conductive gases, liquids and solids, the electrically charged body isolated or wrapped screen up, known as insulation. Insulation is an important measure to ensure the safe operation of electrical equipment lines, to prevent electric shock accidents. In general, the resistance of insulation should not be less than 0.5MΩ; operating low-voltage lines and equipment insulation strength in accordance with the provisions of the electrical equipment handover test regulations: 1V working voltage correspondingly have not less than 1kΩ insulation resistance; in the wet occasion of the line and equipment insulation strength requirements 1V working voltage correspondingly have not less than 500Ω insulation resistance; control line insulation resistance general requirements Should not be less than 1MΩ.
7. Protective grounding and zeroing. Protective grounding and zeroing is an important precautionary measure to prevent electrical equipment leakage or accidental electrocution. Grounding is a protective measure in the event of a fault, the metal part of the ground voltage may present a danger connected to the ground; zero is the normal state of electrical equipment is not charged metal part of the grid connected to a protective measure of the zero line. Grounding should meet the safety requirements, the connection must be secure, the depth into the ground shall not be less than 0.6m, and the building to maintain a distance of more than 1.5m. To safely and efficiently use good electrical equipment, in addition to intact electrical equipment and reliable safety devices, but also to have the corresponding safety procedures and systems, and in the daily work of the implementation of serious.
Source：Basic Electrician Knowledge Network