In the food processing industry, because the equipment is in a harsh environment such as humidity and high temperature, the correct electrical installation of the mechanical equipment plays a great role in ensuring the safe operation of production. In electromechanical equipment, how to prevent electric shock and protect personal safety is always an important issue. There are many forms of electric shock, which can be roughly divided into direct contact and indirect contact. Direct electric shock refers to the electric shock that occurs when the human body directly contacts a charged body. In addition to isolation and reinforced insulation, it is generally difficult to perform other protections, especially for two-phase electric shocks. The indirect electrical contact refers to the failure of the shell due to insulation damage, which makes the originally uncharged objects charged. If the human body touches these objects, the electric shock is caused. Generally speaking, the most important measure of electric shock protection is grounding protection. The most important technical measure of indirect electrical protection is grounding protection, and the core principle of grounding protection is to cut off the power supply of the faulty equipment in time after the equipment encounters a shell fault, so as to avoid further indirect electrical contact.In the actual installation work of electromechanical equipment, many people think that the "grounding" is directly connected to the earth. Therefore, in various occasions, the owner is required to provide an independent grounding body. I don't know how many hidden dangers such indiscriminate"grounding protection"leaves? In addition, my country's electrical standard-setters have also changed the term"grounding protection"to"grounding protection", causing many people to misunderstandAnd confusion? For grounding protection, not only should we have an understanding of the grounding protection form of the power distribution system, but also three concepts should be clarified, namely zero connection protection, grounding protection and repeated grounding. According to the regulations of (B90892), there are 3 types of protective grounding in power distribution system: IN, TT and TT.(1) IN type a system where the neutral point of a transformer is directly grounded and the shell of the electrical equipment is connected to the neutral point. (2) The neutral point of the T-type transformer is also directly grounded but the enclosure of the electrical equipment uses an independent grounding body for grounding protection. (3) π type→that is, the system whose neutral point is not grounded
