Electric energy metering devices include various types of energy meters, such as transformer ratio testers and current transformer ratio testers. The production of electricity is different from the production of other products. Its characteristic is that the three departments of power generation, supply, and use are connected into a system that cannot be interrupted and completed at the same time, and they are closely related to each other. How they sell each other and how they calculate economically requires a measuring instrument to measure and calculate the quantity of electricity between the three departments. This device is an energy metering device, without which, in the process of power generation, supply Electricity cannot be sold or traded in three aspects, so the position of electricity metering devices in power generation, supply, and consumption is very important. A large number of energy metering devices are installed in various stages of power generation, supply, and consumption in the power system. Used to measure power generation, plant consumption, power supply, sales, etc. To provide a basis for formulating production plans, conducting reasonable economic accounting, and calculating electricity consumption. In various work such as industrial, agricultural production, and commercial operation, in order to strengthen business management, vigorously save energy, assess the power consumption of unit products, establish power consumption quotas, and improve economic efficiency, electric energy metering devices are essential measuring instruments. With the continuous improvement of people's lives and the increasing consumption of electricity, kilowatt hour meters have gradually become indispensable electrical instruments for thousands of households. In short, wherever there is electricity, kilowatt hour meters are indispensable