When choosing an energy meter, the selection of the current value is the most important and the most complicated.
One is the starting current, that 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 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, generally the maximum rated current For (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, ie 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 electric energy meter, one should consider the increasing number of electrical appliances entering the home. It is necessary to leave a margin, 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.
Residents generally double the meter allocation to meet the needs of residents’ natural increase in electricity consumption in a certain period of time. If they apply for 10a, they will be allocated a meter with a maximum rated current of 20a. Considering that the household electricity load varies greatly with seasonality, in order to measure accurately Choose 4 times table that is 5⒇a.
The above means that the maximum allowable current of the 5⑽a table is twice that of the 10⒇a and 5⒇a. The maximum allowable current of the 5⒇a table and the 10⒇a table is the same, but the measurement of the 5⒇a table is more accurate at light load.
1. 1.5 is the calibrated current of the watt-hour meter, 6A is the rated maximum current of the meter, and 6/1.5=4 is a multiple of the meter, which means that your meter is 4 times the meter.
2. The regulations stipulate that “the watt-hour meter connected through the current transformer should not exceed 30% of the rated secondary current of the current transformer, and its rated maximum current should be about 120% of the rated secondary current of the current transformer” ?TA secondary current has been standardized to 5A, then 30% of it is 1.5 A, and its rated maximum current value is 6A.
This is the origin of 1.5 and 6A.
3. The regulations stipulate that "in order to improve the accuracy of low-load measurement, an energy meter with an overload of 4 times or more should be selected." Therefore, the difference between 2 times and 4 times lies in the accuracy of low-load measurement. What does the nameplate current 5⑽a, 10⒇a, 5⒇a of the energy meter mean? What's the difference?
4. The general service life of the electric meter is 6 years. According to national regulations, the electric meter should be inspected, adjusted, and replaced every six years to ensure the safety of electricity.
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