Views: 16 Author: Site Editor Publish Time: 2023-04-11 Origin: Site
Power tools held or suspended by hand, such as electric drills commonly used in construction, curve saw, oblique cut saw, welding pliers, hand-held grinding machine, etc
1. Classification of Handheld power tools:
Class I tools: electric shock protection not only relies on basic insulation, double insulation or strengthened insulation, but also includes an additional safety measure, that is, connecting the easily accessible conductive parts with the protective grounding wire of the fixed wiring in the facility, so that the easily accessible conductive parts can not become a live body when the basic insulation is damaged. Tools for double insulation and / or reinforced insulation with ground terminals or ground contacts are also considered as class I tools.
Class tools: Electric shock protection depends not only on basic insulation, but also on additional safety measures provided, such as double insulation or reinforced insulation, without protective grounding measures and not relying on installation conditions.
Class tools: shock protection depends on the safe ultra-low voltage power supply, the tool does not produce a voltage higher than the safe ultra-low voltage.
2. Application division of handheld power tools:
1, the general workplace, can be used as a kind of tools;
2, in the wet workplace or metal framework and other conductive good workplace, should use class or class tools;
3, in the boiler, metal container, pipeline and other working places, should use tools or installed in the electrical line rated residual action current not more than 30 mA residual current action protector tools.
3. Risk analysis of handheld power tools:
1. The quality of the handheld power tools is unqualified.
2. The protective cover, cover, handle and other hand-held power tools are not firmly connected.
3. The power cord of the handheld power tools is too long, and there are joints in the middle and insulation damage, etc.
4, the rotation of the block phenomenon or switch action slow.
5. Connect N in plug and socket with PE at will; PE line, N line and phase line are misconnected or loose or fall off; the rating parameters of connector do not match the tools used.
6. The insulation resistance is not tested regularly, and the resistance value does not meet the requirements.
7. When using class I tools, no residual current action protection device is configured.
8. When such tools are used in narrow places or limited space or humid environment, no residual current action protection device is configured.
4. Measures for the hand-held power tool:
1. The handheld power tools shall have the national compulsory certification mark, product qualification certificate and operation instruction manual, and shall be used under the prescribed conditions.
2. The protective cover, cover and handle of the tool are firmly connected, and have enough strength, with no damage, cracks and deformation in appearance.
3. The length of the power line is less than 6m, no joint is allowed in the middle, and there is no damage, no aging, not through the channel.
4. The rotating part is flexible without block; the switch is flexible without defect and rupture.
5. It is strictly prohibited to connect N in the plug and socket with PE; PE line, N line and phase line are well connected or loose or fall off. The connector rated parameters matched the tools used and had no burn, no rupture and serious damage.
6. Regular inspection of insulation resistance at least twice a year, timely detection in rainy season or when tools are damaged, and detection shall be conducted by professional electricians. The insulation resistance value shall comply with the relevant requirements of GB3787.
7. When class I tools are used, the residual current action protection device is configured. The PE line connection is standard and reliable. The action current of the residual current protection device shall not be greater than 30 mA, and the action time shall not be greater than 0.1s.
8. When using tools in narrow places or limited space or humid environment, the residual current action protection device shall be configured. The action current of the residual current action protection device shall not be greater than 15 mA, and the action time shall not be greater than 0.1s.
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