The electric energy meter is an instrument used to calculate the electricity consumption. Its unit is "KW·h" (kilowatt·hour), which is the "degree" of how many kilowatt-hours of electricity we often say. The normal power is 1kW of electrical equipment to work. The electricity used for 1h is 1KW·h (kilowatt·hour), that is, 1 kWh of electricity is used.
Common electric energy meters are divided into single-phase electric energy meters, three-phase four-wire active energy meters, three-phase three-wire active energy meters and reactive energy meters. There are two types of electric energy meters currently on the market: mechanical and electronic.
Mechanical energy meters have the advantages of high overload and low price, but are easily affected by factors such as temperature, voltage, frequency, etc.; electronic energy meters use integrated circuits to process the collected electrical pulse signals, with high precision, good linearity, and work The advantages of wide voltage and so on.
Therefore, electronic energy meters are gradually replacing mechanical energy meters. In the future, electronic energy meters should be preferred when choosing electric energy meters.
Appearance and technical parameters of single-phase electricity meter
The appearance of the electric energy meter has parameters such as rated voltage, rated current, calibrated current (rated maximum current), power frequency, accuracy level, and electric energy meter constant.
The nameplate of the single-phase electric energy meter is marked with the following parameters: 220V, 5(20)A, 50Hz, 3200imp/KW·h, indicating that the working power supply voltage of this meter is 220V, the calibration current is 5A (rated maximum current 20A), and the power supply The frequency is 50Hz, and the electric pulse indicator light flashes 3200 times for every one degree of rated voltage.
5 (20)A The current value "5" before the current bracket is called the calibration current, which is used to calculate the load base current value. The smaller the calibration current, the smaller the starting current of the meter and the more sensitive the meter. The starting current of the meter is 0.5% of the rated current. If the rated current is 5A, the meter will start counting as long as the current in the circuit is higher than 0.025A, and the meter will not count if it is lower than this value. The current "20" in parentheses is called the rated maximum current, which refers to the maximum current allowed by the electric energy meter when it works within the error range for a long time. The electric energy meter can work within the rated maximum current, but it should not exceed this current for long-term use.
The pulse constant of the electric energy meter is 3200imp/KW·h. When the electricity is used, the pulse indicator of the electric energy meter will flash. When the pulse indicator flashes 3200 times, the counter unit digit value will be increased by one, indicating that 1KW·h (degree) has been used. Electricity.
Sometimes if you see the watch at home flashing quickly, it means that the power consumption is relatively large. When the pulse indicator is still flashing when there is no device in use at home, you need to check whether the power has been stolen.
Single-phase meter wiring method
Single-phase meters are also divided into direct-type and mutual-inductance types. Generally, single-phase meters or direct-type meters are very commonly used. For example, our daily household electricity meters are all direct-type single-phase meters. There are also special cases where the current exceeds the energy meter. The range requires the purchase of a transformer-type electric energy meter.