Good tools for an easy life.

The power tool company talks about several methods

by:WORKSITE     2021-01-03
①Protection of class Ⅰ things: grounding devices are installed in the things, and all or most parts of the insulation structure have basic insulation. If the insulation is damaged, because the accessible metal parts are connected to the protective grounding (see grounding) or the protective zero conductor installed in the fixed line through the grounding device, they will not become live objects, which can reduce the operator's electric shock.

②Protection of class Ⅱ things: the insulation structure of this kind of things consists of two layers of insulation or reinforced insulation composed of base insulation and additional insulation. When the bottom insulation is damaged, the operator will be separated from the charged body by additional insulation to prevent electric shock. Type II items should not be reconnected to the power plug and grounding is not allowed.

③Protection of class Ⅲ things: this kind of things are powered by a voltage source. The value of the no-load voltage between the voltage conductors or between a conductor and the ground does not exceed 50V; for a three-phase power supply, the value of the no-load voltage between the conductor and the neutral does not exceed 29V. The voltage is generally supplied by a transformer or a converter with windings. It is not allowed to install protective grounding devices on Class III things.

④ Restraint of radio disturbances: Single-phase series motors and DC motors with commutators will cause serious electromagnetic disturbances to televisions and radios. Therefore, when designing electric appliances, consider suppressing the disturbance to radios. It is necessary to select shielding, symmetrical connection of excitation windings, set up electrical filters, and connect the filters into a delta shape. Small inductance coils can also be connected in series on both ends of the motor armature.
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