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<p>Hand-held power tools include hand electric drills, hand grinding wheels, impact electric drills, electric hammers, flashlight silver and other tools. When using a hand-held electric tool, it is necessary to hold the handle and move continuously, and the vibration is large during work, and its internal insulation is easily damaged. </p><p><br></p><p>Therefore, hand-held electric tools are more prone to electric shock hazards than electrical appliances, so there are special requirements in terms of electrical safety.</p><p><br></p><p>1. Classification of hand-held<a href="https://www.worksitetool.com/product.html" rel="noopener noreferrer" target="_blank"> power tools</a></p><p><br></p><p>There are two classification methods for hand-held power tools, namely, classification according to electric shock protection method and classification according to degree of moisture resistance.</p><p><br></p><p>(1) According to the degree of prevention of personal electric shock, hand-held power tools can be divided into three categories.</p><p><br></p><p>Class I power tools (ordinary power tools). In addition to basic insulation, this type of tool has an additional safety measure to prevent electric shock, which is to connect the accessible conductive parts with the protective (grounding) conductor in the installed fixed line. When the basic insulation fails, the metal parts that may be accidentally charged will not cause the risk of electric shock. Both zeroing and grounding can be used as additional safety measures for this type of equipment. Connecting to zero can realize quick disconnection when leakage occurs, and can reduce the voltage to ground that may appear on these metal parts. Class I equipment can also have Class I structural parts with double insulation or reinforced insulation, and Class I structural parts that work under extra-low safety voltage.</p><p><br></p><p>Class I power tool housings are generally all metal.</p><p><br></p><p>Class II power tools (power tools whose insulation structure is all double insulation), whose rated voltage exceeds 50 V. This type of equipment has double insulation and reinforced insulation safety protection measures, but there is no protective grounding or measures that depend on installation conditions.</p><p><br></p><p>According to the shell structure, Class I can be divided into three types: the first is Class I equipment with an insulated enclosure. Except for small objects such as nameplates, screws, and rivets, all metal parts of this equipment are basically connected in an integrated insulating shell. The enclosure constitutes part or all of supplementary insulation or reinforced insulation; the second type is Class I equipment with a metal enclosure. This kind of equipment has a metal shell that is basically connected as a whole, and it is best to use double insulation inside, and reinforced insulation can also be used under special circumstances: the third type is a comprehensive Class I device that combines the above two kinds of shells. Class I equipment can have sub-class structural components that work under extra-low safety voltage. There are two types of power tool housings: metal and non-metal, but the hand-held part is non-metal, and the non-metal part is marked with a "back" symbol.</p><p><br></p><p>Class III electric tools (that is, extra-low voltage electric tools), whose rated voltage does not exceed 50V. In terms of protection against electric shock, such tools rely on extra-low safety voltage power supply to prevent electric shock, and no low-safety voltage and high voltage must be generated inside the tool. The power supply of ultra-low safety voltage must meet the requirements of safety voltage power supply. At the same time, the insulation of Class III power tools must meet the requirements of reinforced insulation.</p><p><br></p><p>The shells of class Ⅲ power tools are all plastic.</p><p><br></p><p>(2) According to the degree of moisture resistance, it can be divided into three categories: ordinary tools, splash-proof tools, and watertight tools.</p>
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