Urumqi Nantianya Electrical Complete-sets Equipment Co.,Ltd.
Add : 366 Tongbaishan Street, Economic and Technological Development Zone, Urumqi
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Grounding and zeroing of electrical equipment

The so-called grounding is a good connection between any part of the electrical equipment and the soil. Here, the grounding system can be divided into four types: protective grounding, working grounding, protective zeroing and repeated grounding according to its equipment and function. In normal or accidental state, in order to ensure the reliable operation of electrical equipment, a certain point in the power system is grounded, whether it is directly grounded or grounded by special equipment, it is called working ground; when the electrical equipment is insulated from the live part of the metal casing due to Insulation damage may be charged, causing electric shock accidents. In order to prevent the danger of electric shock, the metal casing or frame is well connected with the grounding body, so that the equipment casing is kept at the same potential as the ground, which is called protective grounding; Is the metal enclosure or frame insulated from the live part connected to the neutral line in the neutral point direct earthing system (called protective earth)? If the metal casing or frame insulated from the live part is connected to the neutral line in the direct point system, it is called protection zero; the point or point of the zero line is again metal-connected to the ground, called repeat Grounding, in short, whether it is grounding or zeroing, its purpose is nothing more than two: First, the electrical equipment is in any range, its metal casing and its close to the metal structure of the scale are always low, to avoid the risk of electric shock To ensure personal safety. The second is to provide reliable electrical access. That is, there is no spark or other obvious overheating when the grounding short-circuit current passes, to avoid igniting flammable substances or gases, which may cause fire hazard.

1 safety voltage

The safety voltage is a voltage that does not endanger life and safety under certain conditions and for a certain period of time. The limit of the safe voltage is the voltage value that must not be exceeded between any two conductors under any circumstances. The limit of the effective value of the power frequency safety voltage specified by China's standard is 50V. China's specified power frequency RMS values ​​are 42V, 36V, 24V, 12V, and 6V. Portable power tools used in particularly hazardous environments should use a 42V safety voltage; hand-held and partial illumination lamps used in hazardous environments should be 36V and 24V safe; large areas in metal containers, tunnels, water wells, and surrounding areas. Grounding conductors and other places with narrow working places and inconvenient movements should use 12V safety voltage; special places such as water operations should use 6V safety voltage.

2 single phase electric shock

When the human body directly touches one of the charged devices, current flows into the earth through the human body. This electric shock phenomenon is called single-phase electric shock. For the high-voltage charged body, although the human body is not in direct contact, but because of the safety distance, the high voltage discharges to the human body, causing electric shock caused by single-phase grounding, and also belongs to single-phase electric shock.

3 two-phase electric shock

The human body simultaneously contacts the two-phase conductor in the charging device or the line, or in the high-voltage system, the human body simultaneously approaches the two-phase charged conductor of different phases, and the arc discharge occurs, and the current flows from the one-phase conductor through the human body to the other phase conductor to form a Closed loop, this type of electric shock is called two-phase electric shock. When two phases of electric shock occur, the voltage applied to the human body is equal to the line voltage. This type of electric shock is the most dangerous.

4 step voltage electric shock

When a ground fault occurs in an electrical device, the ground current flows to the ground through the grounding body. When a potential distribution is formed on the ground, if a person walks around the grounding short-circuit point, the potential difference between the two legs is the step voltage. Human body electric shock caused by striding voltage is called strid voltage electric shock.

5, electric shock accident rescue

(1) On-site first aid principle:

1. Rapid: The rescuer should quickly move the electric shock to a safe place for rescue.

2, local: to fight for time, on the spot (safe place) to rescue electric shockers on the spot.

3. Accurate: The rescue method and the rescue action should be correct.

4. Insistence: First aid must be adhered to the end until the medical staff determines that the electric shock has died and can stop the rescue.

(2) On-site first aid measures:

1. Turn off the power immediately, or use a non-conducting object such as a dry wooden stick, bamboo stick or dry cloth to get the injured person out of the power supply as soon as possible. First-aiders should not directly contact the injured person to prevent electric shock and affect the rescue work.

2. When the injured person leaves the power supply, they should immediately check the general condition of the injured person, especially the breathing and heartbeat. When the breathing and heartbeat are stopped, they should be rescued immediately.

3. If the respiratory heartbeat is stopped, the chest should be pressed at the same time as artificial respiration to establish breathing and circulation. The rescue must be carried out until the medical staff arrives.

Transfer from: Electrical Building Network

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