Power transformers are one of the main equipment in power plants and substations. The function of transformer is many, not only can increase the voltage to send power to the electricity area, but also can reduce the voltage to all levels of voltage, to meet the needs of electricity. In short, the step-up and step-down must be completed by the transformer. In the process of transmitting electric energy in the power system, voltage and power losses are bound to occur. When transmitting the same power, voltage loss is inversely proportional to voltage, and power loss is inversely proportional to the square of voltage. The transformer is used to increase the voltage and reduce the transmission loss. The transformer is composed of two or more coil windings wound on the same core. The windings are connected by alternating magnetic field and work according to the principle of electromagnetic induction. The transformer installation location should be considered to facilitate operation, maintenance and transportation, and a safe and reliable place should be selected. The rated capacity of the transformer must be reasonably selected when using the transformer. When the transformer runs without load, large reactive power is needed. This reactive power is supplied by the power supply system. If the capacity of the transformer is too large, not only the initial investment is increased, but also the transformer is in no-load or light-load operation for a long time, so that the proportion of no-load loss increases, the power factor is reduced, the network loss increases, so that the operation is neither economical nor reasonable. Transformer capacity selection is too small, will make the transformer long-term overload, easy to damage the equipment. Therefore, the rated capacity of the transformer should be selected according to the needs of the electricity load, and should not be too large or too small.

"Vacuum circuit breaker" because its arc extinguisher medium and the contact gap after arc extinguisher insulation medium are high vacuum; It has the advantages of small size, light weight, suitable for frequent operation, arc extinguision without maintenance, and is widely used in distribution network. Vacuum circuit breaker is 3 ~ 10kV, 50Hz three-phase AC system in the indoor distribution device, can be used as the protection and control of electrical equipment in industrial and mining enterprises, power plants, substations.Especially suitable for the requirements of no oil, less maintenance and frequent operation of the use of places. The circuit breaker can be configured in the middle cabinet, double cabinet and fixed cabinet as the control and protection of high voltage electrical equipment.