How to connect two-phase meters?

Generally, there are two kinds of wiring: 1 and 3 incoming wires, and 2 and 4 outgoing wires; The other is to press 1 and 2 to connect, and press 3 and 4 to connect. In any case, the phase wire (live wire) must be connected to the terminal of the current coil of the electric meter. Due to the special wiring of some instruments, the specific wiring method needs to refer to the wiring diagram on the terminal cover plate.

Extended data

Working principle of electric meter

1. When the ammeter 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 get 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.

2. That is to say, the torque is directly 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.

3. When the active torque and braking torque reach a temporary balance, the aluminum plate 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.

Working characteristics of electric meter

1, power consumption. Because smart meters are designed with electronic components, the power consumption of each meter is generally only about 0.6 ~ 0.7 W. For multi-user centralized smart meters, the average power to each household is even smaller. Generally, the power consumption of each induction meter is about1.7w..

2. accuracy. As far as the error range of the electric meter is concerned, the measurement error of the 2.0-class electronic watt-hour meter is 2% within the range of 5% ~ 400% of the calibrated current, and the accuracy grade is 1.0, which is even smaller. The error range of induction watt-hour meter is 0.86% ~ 5.7%, and due to the insurmountable defect of mechanical wear, induction watt-hour meter goes slower and slower, and the final error is getting bigger and bigger. State Grid conducted a spot check on induction meters, and the results showed that more than 50% of induction meters exceeded the allowable range after five years of use.

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