The electric energy meter is a meter for measuring electric energy, and is also called an electric meter, a fire meter, a kilowatt hour meter, and a meter for measuring various electric quantities.
When using the energy meter, be aware that at low voltages (not exceeding 500 volts) and small currents (tens of amps), the energy meter can be directly connected to the circuit for measurement. In the case of high voltage or high current, the energy meter cannot be directly connected to the line, and it needs to be used with a voltage transformer or a current transformer.
The energy meter is divided into two categories: inductive and electronic. Take the induction system electric energy meter as an example to describe its structure. The inductive energy meter uses the principle of electromagnetic induction to transform the voltage, current and phase into a giant magnetic force, which drives the aluminum disc to rotate. The shaft (worm) of the disc drives the drum of the gear drive meter to rotate. The rotation process is The process of accumulating the amount of time.
1. Drive components: voltage components and current components
2, rotating components: aluminum plate and shaft (worm)
3. Brake components: permanent magnets
4, the meter: gears, wheels, counters
Third, the working principle of the electric energy meter
When an alternating current flows through the voltage coil and the current coil, eddy currents are induced on the aluminum disk. The eddy current interacts with the alternating magnetic flux to generate an electromagnetic force, thereby pushing the aluminum disk to rotate, and the aluminum disk interacts with the brake magnet when rotating to generate a braking force (damping force). The number of revolutions of the aluminum disk is proportional to the amount of electrical energy measured.
The "mountain" shaped magnet of the voltage coil produces three eddy currents that interact with the alternating magnetic flux to generate electromagnetic force to drive the aluminum disk to rotate.
Fourth, the classification of commonly used electric energy meters(1) The electric energy meter can be divided into a direct current electric energy meter and an alternating current electric energy meter according to the circuit used. The AC energy meter can be divided into a single-phase electric energy meter, a three-phase three-wire electric energy meter and a three-phase four-wire electric energy meter according to the phase line.
(2) The electric energy meter can be divided into an electromechanical electric energy meter and an electronic electric energy meter (also called a static electric energy meter and a solid electric energy meter) according to the working principle thereof. The electromechanical electric energy meter is used for the AC circuit as an ordinary electric energy measuring instrument, and the most commonly used one is an inductive electric energy meter. Electronic energy meters can be divided into all-electronic energy meters and electromechanical energy meters.
(3) The electric energy meter can be divided into an integral electric energy meter and a split electric energy meter according to its structure.
(4) The electric energy meter can be divided into active energy meter, reactive energy meter, maximum demand meter, standard electric energy meter, multi-rate time-sharing electric energy meter, pre-paid electric energy meter, loss electric energy meter and multi-function electric energy meter according to its use. Wait.
(5) The electric energy meter can be divided into ordinary installed electric energy meters (0.2, 0.5, 1.0, 2.0, 3.0) and portable precision electric energy meters (0.01, 0.02, 0.05, 0.1, 0.2) according to its accuracy level.
1. What is the damping torque?
In order to make the aluminum disk rotate at a constant speed at a constant speed to reflect the electric energy correctly, it is necessary to add a torque equal to the rotating torque and the opposite direction to the aluminum disk. This torque is called the damping torque. It is usually obtained by permanent magnets.
2, the basic characteristics of damping
The damping force or the damping torque is always generated in the opposite direction to the movement of the movable member when the movable member moves, and its magnitude is proportional to the moving speed of the movable member.
3. Judging method
The aluminum disk is rotated counterclockwise in the n direction under the action of the driving torque.
1) Use the right-hand rule (Lenz's law) to find the direction of the eddy current through the aluminum disk a→b
2) Use the left hand rule to find the electromagnetic force F (downward) of the aluminum disk;
3) It can be seen that the F magnetic field force is opposite to the n direction, and the torque generated by F is called the damping torque (braking torque).
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