The ground wire is a safety component of the motor product, and its main role is to connect the motor shell with the ground to protect personal safety and prevent the motor from failure caused by static electricity.
GB/T 755 and GB/T 14711 have special provisions for the grounding of the motor, except that the motor has additional insulation, or is installed in an installation with additional insulation, or has a rated AC voltage of less than 50V, DC voltage of less than 120V, or is used for SELV circuits, all shall have special grounding protection devices.
The color, diameter, fixing of the grounding wire of the motor, the electric corrosion prevention, rust prevention and application compatibility of the conductor and fixing parts; For a motor with a rated power of less than 100kW, there is a ground point, when the rated power of the motor exceeds 100kW, the motor should add a ground device on the basis of the original, a ground point is directly set in the motor junction box, and the additional ground point is mostly set on the foot board of the motor frame.
Grounding resistance is a key element to ensure the grounding reliability of the motor, to no more than 0.1 ohms is appropriate, for small motor ground and the ground can be directly connected, and for the installation of large motors or large equipment, there will be a special grounding system to ensure its grounding reliability.
First of all, the grounding wire should also have an insulating layer to prevent the misconduction of the grounding current; Second, the grounding wire should be able to withstand the immersion of conventional liquids such as water without deterioration, which is also one of the basic requirements for the grounding wire conductor; Third, under the condition that the grounding wire is connected to the ground or the grounding system reliably, the grounding performance of the motor can be improved by water immersion, in particular, if the grounding wire is soaked directly in water instead of grounding, it is obviously not possible.
For the grounding protection of the motor, detailed instructions and requirements are carried out in the professional standards, but in the quality supervision and sampling process of the motor, it is always possible to find some unqualified cases of disposal, especially the connection and fixing of the grounding wire and the motor, followed by the diameter of the grounding wire does not meet the requirements.
Post time: Jun-17-2024
