Three-phase watt-hour meter 30( 100)A is: the stable working current of three-phase electricity is less than 30 amps, and the maximum short-time working current is 100 amps.
It is incorrect to read 100A 30 times.
There are four terminals on the single-phase watt-hour meter, one for the live wire and the other for the zero wire.
There are eight terminals on the three-phase watt-hour meter, a phase line in and out, b phase line in and out, c phase line in and out, and zero line in and out.
Extended data:
Instruments used for measuring electric energy, also known as watt-hour meter, pyrometer and watt-hour meter, refer to instruments for measuring various electric quantities.
When using the electric energy meter, it should be noted that under the conditions of low voltage (below 500 volts) and small current (tens of amperes), the electric energy meter can be directly connected to the circuit for measurement. In the case of high voltage or high current, the watt-hour meter cannot be directly connected to the line, and it needs to be used with voltage transformer or current transformer.
Classification of commonly used electric energy meters:
1, watt-hour meters can be divided into DC watt-hour meters and AC watt-hour meters according to the circuits they use. Ac watt-hour meters can be divided into single-phase watt-hour meters, three-phase three-wire watt-hour meters and three-phase four-wire watt-hour meters according to their phase lines.
2. According to its working principle, watt-hour meters can be divided into electromechanical watt-hour meters and electronic watt-hour meters (also known as static watt-hour meters and solid-state watt-hour meters). Electromechanical watt-hour meter is a common electric energy metering instrument in AC circuit, among which inductive watt-hour meter is the most commonly used. Electronic watt-hour meters can be divided into full electronic watt-hour meters and electromechanical watt-hour meters.
3. According to its structure, watt-hour meters can be divided into integral watt-hour meters and split watt-hour meters.
4. Watt-hour meters can be divided into active watt-hour meters, reactive watt-hour meters, maximum demand watt-hour meters, standard watt-hour meters, multi-rate time-sharing watt-hour meters, prepaid watt-hour meters, loss watt-hour meters and multifunctional watt-hour meters according to their uses.
5. According to its accuracy grade, electric energy meters 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 (0.0 1, 0.02, 0.05, 0. 1, 0.2).
Working principle of electric energy meter:
When the electric energy meter is connected to the circuit under test, alternating current flows in the current coil and the voltage coil, and these two alternating currents generate alternating magnetic flux in their iron cores respectively; The alternating magnetic flux passes through the aluminum disk and induces eddy current in the aluminum disk; The eddy current is forced in the magnetic field, which makes the aluminum disk gain torque (active torque) and rotate.
The greater the power consumed by the load, the greater the current flowing through the current coil, the greater the eddy current induced in the aluminum disk, and the greater the torque that makes the aluminum disk rotate. That is, the torque is proportional to the power consumed by the load. The greater the power, the greater the torque, and the faster the aluminum disk rotates. When the aluminum disk rotates, it is acted by the braking torque generated by the permanent magnet, which is opposite to the driving torque;
The braking torque is proportional to the rotating speed of aluminum plate, and the faster the rotating speed of aluminum plate, the greater the braking torque. When the active torque and braking torque reach a temporary balance, the aluminum disk will rotate at a uniform speed. The electric energy consumed by the load is proportional to the number of revolutions of the aluminum disk. When the aluminum plate rotates, it drives the counter to display the consumed electric energy. This is the simple process of watt-hour meter working.
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