According to the national standard GB / T15283-94 and the international standard IEC521-1988, the electric energy meter is marked with two current values, such as 10⒇A. The 10A marked here is the basic current, and the symbol is the current value that determines the relevant characteristics of the instrument. This current value is also called the calibration current. The ⒇A marked in brackets is the rated maximum current symbol, which is the maximum current value that the meter can meet the accuracy specified by the standard. The current through the energy meter can be as high as 2 to 8 times the basic current, and less than 2 times the meter only the basic current value. In other words, if the energy meter installed by a user is only marked with a current value, such as 5A, this is only the basic current value, not the maximum current allowed. For this kind of energy meter, it can generally be overloaded to 120% without problems, and it can meet the accurate measurement of the energy meter. On the other hand, due to the large resistance of the rotating mechanism of the induction energy meter, the starting current cannot be lower than 0.5% of the basic current (the energy meter with accuracy level) according to the standard. If it is less than 0.5%, it may not start. In China, the power supply line voltage of the family residence is 220V and the frequency is 50Hz. The rated voltage and applicable frequency of the selected energy meter should be consistent with the line voltage and frequency, and should also be 220V, 50Hz. When choosing an energy meter, the selection of the current value is the most important and the most complicated. One is the starting current, which is the minimum current that can turn the turntable continuously; The second is the multiple of the maximum rated current relative to the basic current. In addition, there are differences in performance between old-fashioned watches and new-style watches. The old electric energy meter still in use in the old house has a relatively large starting current, generally (5% to 10%); the maximum rated current is small, generally ≤2, and only one current value is marked on the dial surface of the dial, and is generally called Rated current. Therefore, it is pointed out in the old electrician's manual that the current of the load circuit should be greater than 10% of the rated current, less than 120% or less than 125%. According to the energy meter produced by the national standard GB / T15283-94 and the international standard IEC521-1988, the starting current of the energy meter used in the newly built house is small, which is 0.5% for the level meter; the maximum rated current is large, and the general maximum rated current is ( 2 ～ 4), some can reach (6 ～ 8). There are two current values ​​marked on the dial surface of the new energy meter dial, such as 5 (20A). On the one hand, when choosing this energy meter, it should be noted that the minimum current of the load cannot be lower than the starting current, that is 0.5% × ≥5A = 0.025A; On the other hand, the ammeter value for long-term use cannot be higher than the maximum rated current value of 20A. When choosing an energy meter, you should consider the increasing number of electrical appliances entering the home. You must leave a surplus, and it must be reasonably appropriate, because the larger the multiple, the higher the price of the meter. The current value 10 before the brackets is called the calibration current, which is used to calculate the load base current value. The current 20 in the brackets is called the rated maximum current, which is the maximum current that can make the energy meter work normally for a long time, and the error and temperature rise fully meet the specified requirements. value. According to the requirements of the regulations, the direct current energy meter's calibration current should be determined according to the rated maximum current and overload multiples. Among them, the rated maximum current should be determined according to the approved customer reported load capacity; overload multiples, for normal operation If the actual load current of the energy meter in the system reaches more than 30% of the maximum rated current, it should be taken twice; if the actual load current is less than 30%, it should be taken 4 times. Zhejiang Tepsung Electric Meter Co.,Ltd . is a manufacturer and supplier of single-phase, three-phase electric meters, electric energy meters and digital kWh meter . We have established a mature and professional team in the design, production and sales of electric meters. It is a professional digital energy meter manufacturer and digital energy meter supplier in China. Order for one hundred: https://www.yhddb.com/