Hidden dangers and preventive measures of electric welding operation site

Welding operations belong to special operations. They have strict training and qualification assessment system for the operation qualifications of operators. Although some skills have been acquired through training at the time of forensic renewal, there are still many welders who have a weak sense of safety in welding operations and often have unsafe acts that violate the “Safety Operation Procedures”. Because most welders’ professional knowledge of electrical technology and limited knowledge of safe electricity use, there are many hidden accidents on the site of electric welding operations. For example, the outer shell of the welding machine is not grounded or grounded is unreliable, the exposed terminal posts are not insulated according to the regulations, and the bare lead connector conductors are exposed. Do not perform insulation treatment according to regulations, soak the lead in the water.
From this, it can be seen that eliminating potential accidents at the site of electric welding operations is a job skill that each welder should master. Not only to ensure their own personal safety during the operation, but also to ensure the personal safety of others, welders in the welding operation must do the following preventive measures.

First, the use of qualified welding tools

The welding tools should be checked carefully before operation. The inspection items are as follows:
1. The welding machine insulation performance is good;
2. Whether the insulation layer of the power cord and the welder lead wire is damaged and aged, and the wire is exposed;
3. The first and second side of the welding machine has no loosening and severe burn.
4. Whether the welding clamp and the special welding gloves are damaged or not may be used.

Second, the wiring program

1. Select a well-insulated lead wire to be reliably connected to the welding handle wire (wire holder pin). The joint should be tightened to make it in good contact and prevent overheating. Use insulated tape to wrap the exposed conductors in several layers to make it in good insulation.

2. Lay out the lead wire to the welder and connect it to the secondary terminal of the welder. Compress the screws to make them firmly in contact. It is forbidden to use the winding method. When laying out the lead wire, avoid welding the joint, especially the joint, from the place where there is water, and if necessary, run overhead. When passing the wire through a metal railing or escalator, hang it with a fine wire with good insulation.

3. Reliable earthing of the welder metal shell. That is, one end of a wire is connected to the grounding net, and the other end is connected to the Screw marked with a grounding mark on the casing of the welder and tightened to make it reliably grounded to prevent electric shock caused by energization of the casing.

The principle of protection against electric shock is as follows:

Cases where the enclosure is not grounded: When the insulation of the welding machine is damaged, the shell of the welding machine will be charged with voltage. If someone touches the casing of the welding machine at this time, the human body and the earth and the neutral point of the power supply work ground (three-phase four-wire system neutral point Generally it is earthed.) As shown in the dotted line with the arrow in the figure above, the current will cause an electric shock accident through the human body.

Case grounding: Damaged insulation of the welding machine When the shell of the welding machine is energized, the shell of the welding machine is directly connected to earth through the shell grounding line to form a short circuit (dotted line without an arrow in the figure above). This short-circuit current will make the protection device of the power supply (Automatic switch, fuse or fuse) action to disconnect the power of the welder. Before the power is cut off, even if someone touches the shell of the welder, since the resistance of the earth wire of the shell is almost zero, almost no current passes through the human body, and it can also protect the personal safety.

4. Connect the power cord to the primary side terminal of the welder and press the screw firmly to ensure good contact. Do not connect using the winding method.

5. Wrap the joints of the power cables and welding handles and the damaged parts of the insulation wires with insulating tape. Those with serious aging of the wire insulation must not be used. The exposed terminals should be covered to prevent electric shock accidents.

6. Check whether the fuse with a fuse or the circuit breaker with a fuse is in the open position. Connect the power cable to the fuse of the power switch or the underside of the fuse. Live wiring is strictly prohibited.

7. Carefully check the connected power cord, lead wire, and shell ground wire, and then turn on the power switch after confirming that it is correct. Insulation gloves should be worn when the switch is closed and the other hand must not touch the welder.

3. When entering metal containers, downholes, trenches, etc., it is forbidden to bring in the welding transformer and the lighting transformer for lighting to prevent the electric shock caused by a voltage.

Fourth, during the operation, especially when changing the welding rod must wear electric insulation gloves.

Fifth, in wet environments should wear insulating shoes or standing on a dry wood. Work clothes, work shoes and gloves should be kept dry to ensure that insulation performance will not be reduced.

Six, remove the power cord, eliminate the welder fault, move the welder and the welder leave the scene remember to disconnect the power switch.

7. When the lighting of the welding work site is insufficient, the running lights should be used, 220V lighting lamps are forbidden, and the running light voltage used in the humid environment or metal containers shall not exceed 12V.

VIII. When it is necessary to conduct electric welding operations in the open air in rain and snow days, measures must be taken to prevent rain and snow (such as rain canopies, etc.) to prevent the rain from soaking welders, wires, and welding handles, resulting in electric leakage accidents.