Electricity meter is used to calculate the electricity consumption of the meter. its unit is “KW·h” (KW·h), that is, we often say how many degrees of electricity “degree”, the normal power of 1kW electrical equipment working 1H electricity consumption is 1kW ·h (KW·h), that is, used 1 degree of electricity.
Common electricity meters are divided into single-phase electricity meters, three-phase four-wire active electricity meters, three-phase three-wire active electricity meters and reactive electricity meters. At present, the electricity meter that is used on the market has mechanical type and electronic type two kinds.
Mechanical watt-hour meters have the advantages of high overload and low price, but are easily affected by temperature, voltage, frequency and other factors. The electronic watt-hour meter uses integrated circuit to process the collected electrical pulse signal, which has the advantages of high precision, good linearity and wide working voltage.
Therefore, electronic watt-hour meters are gradually replacing mechanical watt-hour meters. In the future, electronic watt-hour meters should be preferred.
Mechanical electricity meter
Electronic electricity meter
Appearance and technical parameters of single-phase ammeter
The appearance of the watt-hour meter includes rated voltage, rated current, calibration current (rated maximum current), power supply frequency, accuracy grade, watt-hour meter constant and other parameters.
Appearance and technical parameters of electricity meter
For example, the nameplate of A single-phase watt-hour meter is marked with the following parameters: 220V, 5(20)A, 50Hz, 3200IMP /KW· H, which means that the operating power supply voltage of the meter is 220V, the calibration current is 5A (rated maximum current is 20A), the power frequency is 50Hz, and the electric pulse indicator lights 3200 times for each degree of rated voltage.
The current value “5” before the brackets is called the calibration current, which is used to calculate the load base current value. The smaller the calibration current is, the smaller the starting current of the meter will be and the more sensitive the meter will be. The starting current of the meter is 0.5% of the calibrated current. If the calibrated current is A meter of 5A, the meter will start counting as long as the current in the circuit is higher than 0.025A, while the meter will not count if it is lower than this value. The current “20” in the brackets is called the rated maximum current, which refers to the maximum current allowed to pass the watt-hour meter when it works within the error range for a long time. The watt-hour meter can work within the rated maximum current, but it should not be used over this current for a long time.
The pulse constant of the electricity meter is 3200IMP /KW·h. When the electricity is used, the pulse indicator light of the electricity meter will flicker. When the pulse indicator light flickers for 3200 times, the counter digit value will be advanced, indicating that 1KW· H (h) electricity has been used.
Sometimes, if you see the home table flash quickly indicates that the power consumption is relatively large, when there is no equipment in the home when the pulse indicator is still blinking, you need to check whether it is stolen power.
Wiring method for single-phase ammeter
Single-phase ammeters are also divided into straight type and mutual inductance type. Generally, single-phase ammeters or straight type are very common. For example, our daily household electricity meters are straight type single-phase meters.
So how to wire a single-phase meter? In fact, there is a wiring diagram on the top of the cover of each electric meter, (especially for the connection of the transformer type electric energy meter, check the wiring diagram).
Connection method 1: direct connection
(1) Inlet of port 1 and outlet of port 2.
(2) Inlet line No.3, outlet line No.4.
Connection method 2: transformer connection
(1) Port 1 and port 2 are connected to port K1 and K2 of the transformer.
(2) No. 3 inlet line, No. 4 inlet line zero line.
The choice of electricity meter capacity is neither the larger the better, nor the smaller the better, should be matched with the power consumption. The capacity choice is too large or too small will cause the measurement is not accurate, especially the power meter capacity is small, the power meter is also easy to burn. So the current capacity to calculate the useful electrical appliances add up to the maximum current, it is recommended to choose a slightly larger capacity of the watt-hour meter.