The anti-theft principle of smart meters can be divided into the following two categories: First, when users steal electricity through smart meters, the meters can still measure or measure faster. At present, most commercial anti-theft meters are of this type. Second, when users steal electricity through the energy meter, the energy meter will immediately cut off the power, and the power supply will be automatically restored immediately after the theft stops.

1. The ordinary energy meter counter is changed to a bidirectional counter with a reversing mechanism. When the user changes the polarity of the current and voltage coils, the electrical appliance is stolen (the principle is to change the phase of the current and voltage), or reverses the aluminum disk of the energy meter in other ways, the counter maintains the positive count of the energy meter through the reversing mechanism, and the counter cannot count down through the above method. Therefore, the anti-theft energy meter has the function of anti-reversal and anti-line phase reversal.
2. After the voltage coil hook in the junction box of the ordinary energy meter is removed, the energy meter will not rotate due to the loss of power in the voltage coil of the energy meter, but the user can continue to use electricity. A voltage hook is added to the meter cover to prevent theft. The hook on the junction box has been removed, and there is still a hook on the electric energy meter that cannot be removed, so users cannot steal electricity in this way (the power supply department found many electricity thieves in the commercial census by removing the voltage hook.).
3. The current coil assembly adds a reverse winding auxiliary current coil from the original single-winding main current coil. The forward and reverse winding main and auxiliary current coils are installed in series in the meter. The main coil of the anti-theft meter is more than that of the ordinary meter, but the number of turns of the reverse winding auxiliary current coil is increased.

In this way, after the main current coil and the auxiliary current coil are connected in series, since the reverse winding part of the auxiliary coil just offsets the forward winding part of the main coil, it is also equal to the original winding turns of the general meter.

Assuming that the current coil of the smart meter is 8 turns for the ordinary meter and the auxiliary current coil of the anti-theft electric energy meter is 4 turns (reverse winding part), the main current coil should be 8+4=12 turns. After the main and auxiliary current coils are connected in series, since the 4-turn reverse winding offsets the 4-turn positive winding, in fact, there are still only 8 turns of positive winding, which is the same as the number of turns of the current coil of the general meter.

The functional principle of the second anti-theft watt-hour meter: The utility model adds a controller to the energy meter, and the controller consists of a transformer, a relay and an electronic circuit

The phase line and the neutral line of the main circuit pass through the coil of the zero-sequence current transformer. During normal working hours, the currents on the two lines are equal and opposite. The induction signals in the transformer are offset from each other, and the output signal is 0. When the user steals electricity by various means, the currents of the incoming and outgoing lines are different, and the currents of the two lines are not equal, exceeding a certain value, this function is also applicable to dry leakage protection. Therefore, regardless of leakage or theft, the energy meter will be immediately powered off. (After the above-mentioned theft means and leakage are eliminated, the power supply should be automatically restored immediately.

Nowadays, smart meters are becoming more and more advanced. Many companies have developed various communication and network technologies to adapt to smart meters. Now smart meters have become the mainstream of the meter market.