In agricultural production, often use hand-held mobile tools, such as electric scissors, submersible pumps, threshers and so on. However, due to various reasons, may cause leakage of these electrical equipment, this manual tool once the leakage will immediately touch the human body. In order to take preventive measures, in the conditional circumstances, can be used three-phase power transformer isolation to solve this problem. It works as shown in Figure 1. The three-phase isolation transformer has a primary and secondary coils which electrically connect the secondary side through the magnetic circuit without directly contacting the central point grounding system on the primary power supply side and thus have good electrical isolation to earth.
    When the electrical equipment shell leakage, regardless of which side of the secondary coil to the electrical shell access, will not cause personal electric shock. The transformer primary and secondary are equipped with fuse insurance, the transformer core and metal shell are reliable connections to the ground, play a role in shielding, with anti-jamming performance, used for instruments, electric hand tools, safe power supply is very reliable. Transformer voltage can be selected according to need, general specifications are single-phase 220 / 220V, 220 / 36V, 380 / 220V. Three-phase 380 / 380V, 380 / 220V, 380 / 36V. Pay special attention to the use of electrical appliances with the total capacity is less than the safety isolation transformer capacity. The current production of safety isolation transformer capacity of 0.1-15KVA.
    In rural households then three safety socket, the electrical outlet should be connected to the ground end of the three-phase four-wire zero line, in order to achieve the purpose of protection to zero. It can be used for the protection of household appliances, such as washing machines, refrigerators and so on. Because these appliances work in a humid environment, the metal shell prone to leakage. But the application of this method requires the right end of the socket directly connected to the home front of the zero line.
    Based on the frequent occurrence of this situation, technical personnel are also on the exchange of voltage regulator safety and intelligent research, to ensure future medical assistance in the process to ensure the safety of patients.