Electronic watt-hour meter has a history of 10 years since it rose in China in the 1990s. However, due to the backwardness in technology and application, its market share is not high at present. Based on this, the intelligent watt-hour meter is a kind of watt-hour meter with more practical functions, which has a series of advantages and functions and is incomparable to the traditional inductive watt-hour meter. 1 The smart meter is a high-tech product developed in recent years based on the electronic watt-hour meter in structure, principle and characteristics, and its composition and working principle are quite different from the traditional inductive watt-hour meter. Inductive instrument is mainly composed of aluminum plate, current and voltage liner, permanent magnet and other elements. Its working principle is mainly to measure through the interaction between current coil and moving disk in induced eddy current. The electronic intelligent watt-hour meter is mainly composed of electronic components. Its working principle is to sample the voltage and current in real time according to the customer's requirements, and then use the special watt-hour meter ic to process and convert the sampled voltage and current signals into electric energy, which is output in direct proportion to the pulse. Finally, the electric pulse is processed, controlled, displayed and output by the single chip microcomputer. We usually call the number of pulses passed by the A/D converter when the smart meter measures electric energy as the pulse constant. For smart meters, this is a more important constant less than 1, because the number of pulses passed by the A/D converter per unit time will directly determine the metering accuracy of the meter. Most smart meters adopt the design principle of A/D converter, but some manufacturers produce multi-user centralized smart meters with multiple households sharing an A/D converter, so that the electric energy can only be measured by time-sharing queuing, which will lead to the decrease of the metering accuracy of the meter. Pay attention to (1) power in the design and selection: because smart meters are designed with electronic components, each power of aAs is only 016W. The power consumption of each induction meter is about 1 17w. (2) Accuracy: the error range of the table, the measurement error of 2 10 watt-hour meter is+2% in the range of 5% ~ 400% of the calibrated current, while the accuracy level commonly used at present is 1 10, and the error is small. The error range of induction watt-hour meter is from+186% to -5 17%, but due to the insurmountable defect of mechanical wear, the induction watt-hour meter is getting slower and slower, and the final error is getting bigger and bigger. State Grid has conducted spot checks on induction meters, and the results show that more than 50% of induction meters will have errors beyond the allowable range after five years of use. (3) Overload frequency range overload multiple: smart meters can reach 6 to 8 times, with a wide range. At present, more and more users choose the 8to 10 ratio table, and some can even reach the ratio of 20 in a wide range. The working frequency is wide, within the range of 40 Hz ~1000 Hz. However, the overload times of the induction meter are only 4 times, and the working frequency range is only 45~ 55HZ. (4) Because of the electronic technology, the smart meter can be networked with the computer through the phase communication protocol, and the hardware can be controlled and managed through software programming. Therefore, the smart meter not only has the characteristics of small size, but also has the functions of remote control (remote meter reading, remote power cut), multi-rate, malignant load identification, electricity theft prevention, prepayment, etc., and its parameters can be modified through control software to meet different control function requirements, which are difficult or impossible to realize in traditional induction meters. 2 Function application of smart meters According to the design of some engineering examples, different characteristics, different engineering electrical characteristics and different use places, how to reasonably choose smart meters with different functional characteristics is discussed. Share it.