Causes and preventive measures of electrical accid

2022-08-07
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Causes and preventive measures for underground electrical accidents I. forms of electrical hazards the guide for the development of new material industry (hereinafter referred to as the guide) is an important document for the implementation of made in China 2025. As the underground electrical equipment is restricted by the harsh natural environment and geological conditions, the equipment starts frequently, changes greatly in load and fluctuates greatly in voltage during use due to overload, short circuit, electric leakage, electric arc Equipment burnout, mine fire, gas and coal dust explosion, electric shock casualties caused by electric spark failure may occur at any time. In addition, distribution lines, switches, fuses, pin seats, electric heating equipment, lighting fixtures, motors, etc. may cause electrical injury, become the ignition source of fire, or cause electric shock

II. Hazards of electric shock and preventive measures

1. Hazards of electric shock

an electric shock occurs when a human body touches a live conductor or an equipment shell or cable or wire charged due to insulation damage. Due to the special working environment conditions underground, there is a great possibility of electric shock. The destructiveness of electric shock to human tissues is very complex. Generally, the injury to human body can be divided into electric shock and electric injury. Electric shock means that when electric shock occurs, the current passes through the human body, and the respiratory organs, heart and nervous system are damaged and destroyed under the action of thermochemistry and electrolysis. In most cases, electric shock can kill people, so it is the most dangerous. Electric injury refers to the damage to external organs caused by electric current passing through a part of the human body or electric arc burning the human body, mainly physical damage, such as burns. When the burn area is small, it will not be life-threatening. Usually, the human body is injured by electric shock and electric injury at the same time

the danger of electric shock to people is determined by many factors, but the current flowing through the human body is the main factor. The maximum current that the human body can extricate itself from is 16mA (called extrication current). Generally, when the electric shock current passing through the human body is less than 15 ~ 20 mA, and the DC is less than 50 Ma, there is no danger to life. However, when the electric shock current of the human body exceeds the current for a long time and is not rescued, life is in danger. When the electric shock current of the human body reaches more than 100 Ma (roughly equivalent to the current flowing when a 25W bulb is connected with a voltage of 220 V), life is absolutely dangerous

2 of the current flowing through the human body is to support the entrepreneurship and innovation of new materials based on interconnection. The size of innovation is related to the resistance of the human body. The greater the resistance of the human body, the smaller the current passing through the human body, and vice versa. The resistance of human body is a value with a large range of variation. When the human body has a wound, is sweating and wet, its value is greatly reduced compared with the normal value, and decreases with the extension of the electric shock time. Therefore, the electric shock in this case is more dangerous

the electric shock current flowing through the human body is related to the voltage acting on the human body. The greater the electric shock voltage, the greater the electric shock current and the more dangerous it is

the longer the electric shock current flows through the human body, the greater the degree of injury caused by electric shock. Therefore, even if the safety current flows through the human body for a long time, it will also cause casualties. China stipulates that it is safe for a current of 30 Ma to flow through the human body for 1 second. Therefore, when an electric shock occurs to the human body, it is very important to save the lives of the electric shock victims that how to make the electric shock victims disconnect from the power supply in the shortest time

2. Prevention and control measures for electric shock

(1) underground live maintenance and relocation of electrical equipment (including cables and wires) are not allowed. Before maintenance or relocation, the power supply must be cut off and inspected with an electric pen corresponding to the power supply voltage. The inspection can be carried out only after there is no power. All switch handles shall be locked when the power supply is cut off, and a warning sign of "no power transmission when someone is working" shall be hung. Only the personnel performing this work have the right to remove this sign for power transmission. Strictly implement the principle of "the one who cuts off power, the one who assists in the work of normalized power transmission". It is strictly forbidden to "send electricity at appointed time"

(2) when operating the underground electrical equipment, the following regulations must be observed:

2 automatic shutdown function: ① after the sample is broken, part-time or on duty electrical personnel shall not operate the electrical equipment without authorization

② when operating the main circuit of high-voltage electrical equipment, the operator must wear insulating gloves and electrical insulating boots or stand on the insulating platform

③ the operating handle of 127 V hand-held electrical equipment and the parts that must be contacted during operation shall have good insulation

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