How To Choose a Single-Phase Energy Meter Correctly?
With the rapid development of high and new technology, especially electronic information technology, the power consumption of industry, agriculture and commerce has increased, and the development of electric energy meters has become faster and faster. At present, the types, models, and functions of electric meters on the market are complete. There are many manufacturers, and the quality levels are uneven. If the selection is not good, not only the advantages of electric meters cannot be exerted, but also unnecessary losses are brought. Based on the development and current situation of single-phase electric energy meters, this paper makes objective reference suggestions for purchasing electric energy meters.
1.Selection of energy meter specifications:
The common voltage specification of single-phase electric energy meter is 220V, and the current specification is 1.5(6)A, 5(20)A, 5(60)A, 15(60)A, 20(80)A, etc.
There are many specifications of the meter, and the general voltage specification is 220V. The choice of current specification mainly depends on the user's load. Generally, the upper limit of the load current cannot exceed the rated current of the electric energy meter, and the lower limit is not lower than the load current specified within the allowable error range of the electric energy meter. For example: the user's power consumption is about 10KW, the voltage is 220V, and the current is 10000÷220≈46A, that is to say, the current value is about 46A, considering that a certain margin needs to be reserved, you can choose 5 (60), 15 (60) A current specification. You can also choose a smaller current specification, and then connect the current transformer(CT).
2. Selection of electric energy meter current transformer:
The current transformer can convert the primary current with a larger value into a secondary current with a smaller value through a certain transformation ratio, which is used for protection, measurement, and other purposes. For example, a 100/5 current transformer can convert an actual current of 100A into a current of 5A.
The selection of the specifications of the current transformer is mainly for low-voltage users. Low-voltage users may change the power load at will, and the power consumption is not easy to estimate, so the transformer specifications are not easy to fix. Generally, it is calculated based on the known power consumption. For example, for a user with a power consumption of 100KW and a voltage of 220V, the current should be approximately equal to 100000÷220≈455A, that is to say, the value of the current obtained is approximately equal to 455A, but considering that a certain margin needs to be reserved, it is necessary to Select a 500A current transformer, and the secondary output current of the transformer is generally 5A. So choose a 500 to 5 transformer. Regarding the accuracy of the current transformer, it needs to be at least at the same level as the meter.
3. Uses and benefits of meter selection:
We all know that the biggest function of the electric energy meter is to measure the electricity, but the accuracy of the electric meter measurement is not accurate, we do not know. In fact, the inaccuracy of the meter measurement is related to the error of the meter in the production calibration. For example, in the national verification regulation JJG596-1999, the error range of the 100% 1.0 point of the 0.5S level electric energy meter connected through the transformer is ±0.5%. 1.0 is power and 100% is current. That is to say, the small current 0.5S level meter will have a deviation of 0.005 in the measurement of electricity when the current is normal. If the electricity of 1000kwh is used, the electricity measured by the meter may be 1000±5 degrees.
There will be a certain amount of power loss when the meter measures the amount of electricity. Some meters have high measurement sensitivity and can be measured, while others have average measurement sensitivity and cannot be measured. Therefore, if a customer buys an electric meter for their own use and for payment, they can choose an electric meter with a general measurement sensitivity. If the customer buys the meter to collect electricity bills, you can choose a meter with high measurement sensitivity.
