Electric energy meters, commonly known as electric meters, are metering devices used by power grid companies to measure electrical energy and are the gateway for power companies to settle electricity bills with users.
Electricity consumption is also called electric energy and electric energy, which also conforms to the physical formula: W=P·t=U·I·tW=electric energy (unit is Joule J); P=electric power (unit is Watt); U=voltage value ( The unit is volt V); I = current value (unit is ampere A); t = time (unit is second t); the principle of electric energy meter measurement is the product of voltage value, current value and time.
Because 1 kilowatt hour (3600VAt) of electric energy is specified as one kilowatt hour, the electric energy meter is also called an watt-hour meter or a kilowatt-hour meter. With the advent of the second technological revolution, mankind has entered the electrical age. Electric energy is a new type of energy, and its metering device, electric energy meter, has also emerged.
The development of electric energy meters has gone through the following stages:
1. Induction type electric energy meter
In 1880, the American invention king Edison made the world's first DC electric energy meter using the principle of electrolysis in the laboratory.
In 1889, German physicist Boutel developed an induction watt-hour meter without a separate current core.
In 1890, an induction watt-hour meter with a current iron core appeared, but the braking element was a copper ring, and the torque was generated by an AC electromagnet.
At the end of the 19th century and the beginning of the 20th century, permanent magnets replaced electromagnets, aluminum discs replaced copper discs, and induction watt-hour meters were formally produced.
The induction type electric energy meter is commonly known as a mechanical meter, which measures electric energy by driving the aluminum plate to rotate by electromagnetic torque. The working principle of the induction watt-hour meter is that when alternating current passes through the current and voltage components of the watt-hour meter, eddy currents are induced on the aluminum plate. These eddy currents interact with the alternating magnetic flux to generate electromagnetic force, which causes the aluminum plate to rotate. At the same time, the brake electromagnet also interacts with the rotating aluminum disk to generate a braking torque. When the rotating torque is balanced with the braking torque, the aluminum disk rotates at a stable speed. The number of revolutions of the aluminum plate is proportional to the magnitude of the measured electrical energy, so that the electrical energy consumed can be measured.
2. Induction pulse electric energy meter
The induction pulse electric energy meter still uses the measuring mechanism of the induction electric energy meter as the component, and converts the electric energy into a pulse signal through the photoelectric sensor, and then uses the electronic circuit to process the pulse signal, thereby realizing the measurement of the electric energy. Because this kind of electric energy meter adopts inductive system measuring element with pulse generating device, it is also called electromechanical pulse type electric energy meter.
In the 1970s, induction pulse electric energy meters have been widely popularized in some industrialized countries.
3. Fully electronic watt-hour meter
With the development of power electronic technology and new components, electronic watt-hour meters came into being.
With the development of science and technology and the advancement of technology, electronic watt-hour meters with long life, high reliability and strong anti-interference have appeared. Its functions are beginning to diversify, and it can measure parameters such as active electric energy, reactive electric energy, voltage, current, apparent power, power factor, and voltage loss time.
The principle of electronic watt-hour meters: use voltage divider resistors or voltage transformers to turn voltage signals into small signals that can be used for electronic measurement, and use shunts or current transformers to turn current signals into small signals that can be used for electronic measurement. The electric energy measurement chip of the company performs analog or digital multiplication of the converted voltage and current signals, accumulates the electric energy, and then outputs a pulse signal whose frequency is proportional to the electric energy; the pulse signal drives the stepping motor to drive the mechanical counter to display, or send Digital display is performed after microcomputer processing.
According to the measurement structure, electronic electric energy meters are divided into single-phase energy meters, three-phase four-wire energy meters, and three-phase three-wire energy meters. According to their uses, they are divided into active, reactive, and standard energy meters, multi-function energy meters, maximum demand meters, Multi-rate meter, prepaid rate electric energy meter. Recently, the electric energy meter is connected with mobile phones and other devices, which is called the Internet of Things electric energy meter.