Electric meter is an abbreviation of electric energy meter, which is a meter used to measure electric energy.
First, the identification of energy meters.
The identification and differentiation of electricity meters are based on national current standards GB / T15283-94 and international standards IEC521-1988. Energy meters are marked with two current values, such as 10 (20) A. The 10A marked here is the basic current, which is the current value that determines the relevant characteristics of the instrument. This current value is also called the calibration current. The 20A marked in parentheses is the rated maximum current, which is the maximum current value that the meter can meet the accuracy specified by the standard.
Second, the basic understanding of energy meter accuracy.
The current through the energy meter can be as high as 2 to 8 times the basic current, and less than 2 times the basic current value on the meter. 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 allowed current. This kind of energy meter 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 system electric energy meter, the starting current cannot be lower than 0.5% of the basic current according to the standard (electricity meter with accuracy level). It may fail to start at 0.5% or less.
In China, the voltage of the domestic residential power supply line is 220V and the frequency is 50Hz. The rated voltage and applicable frequency of the selected energy meter should be consistent with this line voltage and frequency, and should also be 220V, 50Hz.
Third, the choice of energy meter: When choosing an energy meter, the choice of current value is the most important and the most complicated.
One is the starting current, which is the minimum current that enables the turntable to continuously rotate; the other is the multiple of the maximum rated current relative to the basic current. In addition, there are differences in performance between old-fashioned and new-style watches. The old electric energy meters that are still used in old houses have relatively large starting currents, generally (5% to 10%); the maximum rated current is small, generally ≤ 2, and only one current value is marked on the dial surface, and it 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%, less than 120% or less than 125% of the rated current when in use. According to the national standard GB / T15283-94 and the international standard IEC521-1988, the starting current of the energy meter used in newly built houses is small, which is 0.5% for the meter; the maximum rated current is large, and the maximum current It is (2 ~ 4), and some can reach (6 ~ 8).
Zhejiang Chint Instrument & Meter Co., Ltd
Wenzhou Production Base: Wenzhou Bridge Industrial Zone, Yueqing, Zhejiang, PR.China
Headquarter: No.560, Yueming Road, Binjiang District, Hangzhou, Zhejiang, China