What should be paid attention to the safe use
Hand-held power tools play a very important role in our production operations and are widely used in our production operations. For example, we often use: impact drill, angle grinder, electric screwdriver, electric drill, hand-held edge banding machine and so on. These tools have greatly improved our work efficiency. But in the process of use, it may cause harm to us for various reasons. One of the common production safety accidents is the electric shock caused by using these tools. What should we do about electric shock caused by using electric tools? Can we effectively prevent such accidents? ■ First choice we first understand the classification of power tools Hand-held power tools can be classified into 3 categories according to electrical protection. Class I equipment: the common type electric tools whose rated voltage exceeds 50V. A type of power tool not only relies on basic insulation for protection against electric shock, but also contains an additional safety precaution. The method is to connect the accessible conductive parts with the protective conductors already installed in the fixed line, so that the accessible conductive parts will not become a charged body in the event of damage to the basic insulation. For tools equipped with non-reconnectable power plugs, the grounding terminal in the tool must be connected to the core wire in the flexible cable or cord for protective grounding. Ⅱ Class II equipment: that is, electric tools whose insulation structure is all double-insulation structure, whose rated voltage exceeds 50V. The double insulation structure is a form of double insulation or reinforced insulation or a combination of both. In addition to the basic insulation, the double insulation also has an independent additional insulation. Equipment with double insulation or reinforced insulation has a 'back' sign on the nameplate. Ⅲ Three types of equipment: safety voltage tools whose rated voltage does not exceed 50V. The protection against electric shock depends on the power supply from the safety voltage and inside the tool, no voltage higher than the safety voltage will be generated. The electric shock protection of the three types of tools adopts reliable basic insulation, the power supply is insulated to ground and the so-called 'triple protection' of ultra-low voltage below 50V is selected, so that the tools have higher safety performance in use. Both type 2 and type 3 tools can protect the electrical safety and reliability during use, and no protective grounding or zero connection is allowed. ■ Select the correct power tool for different usage environments In general places, in order to ensure safety, category II tools should be selected. If category 1 is selected, in addition to proper grounding or zero connection, additional protective measures should be taken: use of insulated appliances (gloves, shoes, pads, tables) Leakage protector; safety isolation transformer. In humid places or metal framed work places with good electrical conductivity, tools of category II or III must be used. If Class I is selected, a leakage protector with a leakage operating current of less than 30mA and an operating time of less than 0.1 seconds must be installed. In narrow places with good electrical conductivity, such as boilers, metal containers, pipes, etc., category III tools should be used. If category II is selected, a leakage protector with a leakage operating current of less than 15mA and an operating time of less than 0.1 seconds must be installed. And a safety transformer is installed, and the leakage protector must be placed outside, while someone is monitoring outside. ■ Precautions for safe use The tool shell cannot be ruptured, and the mechanical protection device is complete and reliable. After the switch, lead, plug, shell grounding protection device, etc. are intact, connect the power supply and check that the shell is not live before use. If the insulation is damaged, the flexible cable or cord sheath is damaged, the zero connection is protected or the ground wire is dropped, the plug and socket are cracked, or the mechanical damage to the safety is damaged, etc., repair should be done immediately. The insulation resistance of the power tool must be measured after long-term unused and overhaul of the power tool; When you need to move tools or stop working during use, when people leave or suddenly lose power, you must turn off the power switch or unplug the power plug. Wear protective equipment such as protective masks and protective glasses when using power tools. The flexible cable or cord of the tool should not be too long. The power switch should be set in an obvious place and there is no debris around to facilitate the operation.