What is protection to zero? -Solutions - Huaqiang Electronic Network
In the low-voltage circuit of the three-phase four-wire 380/220V with neutral grounding, in order to ensure personal safety, the metal casing of the electric equipment such as the motor is directly connected with the neutral line of the power supply ground. This grounding method is called connection. Zero protection. After the motor is protected and connected to zero, when the insulation of the motor is charged and the motor casing is charged, because the grounding neutral resistance is small, the short-circuit current relative to the neutral (ground) is large, which will make the circuit protection device, such as a fuse. Electrical protection devices such as automatic air protection switches act quickly to cut off the power supply for the purpose of protecting personal safety. In addition, it should be noted that in the low-voltage three-phase four-wire power distribution network where the neutral point is directly grounded, the protection grounding is simply used, and personal safety cannot be guaranteed. Because the human body touches the live motor casing, it is in a position parallel to the protective ground. Therefore, there is a certain safety current that passes through the human body, which is fatal. Therefore, in the direct neutral grounding system of the power supply, the grounding protection is not safe enough, and zero-connection protection should be adopted.
Flexible membraneswitch is a typical form of membraneswitch. This kind of film switch is called flexible, because the film switch mask layer, isolation layer, circuit layer are all composed of a variety of flexible films of different properties. The circuit layer of flexible membraneswitch adopts PET with good electrical performance as the carrier of switch circuit graphics. This layer is also divided into handle shrapnel, upper and lower circuits. Because of the influence of the properties of polyester film, the film switch has good insulation, heat resistance, flexural resistance and high resilience. The graphics of the switch circuit, including the connection of the switch and its lead line are printed with low resistance, low temperature curing conductive coating. Therefore, the composition of the whole Membrane Switch, with a certain flexibility, not only suitable for use on the plane body, but also with the curved body. The lead wire of flexible membraneswitch is integrated with the switch body itself. When making the connection of group switch, it is assembled in a certain place of the film, and extends outward according to the position specified in the design and the standard line distance, as a soft, flexible and sealed lead wire connected with the back circuit of the whole machine.
Flexible Membrane Switch,Robot Membrane Keypad,Hmst Membrane Keypad,Manipulator Membrane Keypad
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