What is the work of grounding and protective grounding

Working grounding refers to a point of the power system (such as the neutral point) directly to the earth, or by the arc-canceling coil, resistance, etc. and the earth metal connection, such as transformers, transformers neutral point grounding. Protective grounding, is to prevent the metal casing of electrical devices, power distribution equipment frame and line towers and other electrically endangered personal and equipment safety and grounding.

The so-called protective grounding is not charged under normal circumstances, but in the insulating material is damaged or other circumstances may be charged electrical metal parts (that is, with the charged part of the metal structure of the insulation part) with a wire and the grounding of a reliable connection to a protective wiring. Grounding protection is generally used for distribution transformer neutral point is not directly grounded (three-phase three-wire system) of the power supply system to ensure that when the electrical equipment due to insulation damage and leakage of the ground voltage does not exceed the safety range.