What is the function of the current transformer on the neutral line

The main function of the current transformer on the neutral line is to detect the current in the actual operation of the neutral line circuit. This current transformer works in the same way as the normal current transformers that people use but with the accuracy. The error requirements are particularly high, and the measurement error does not exceed ±1. The general electrical market does not sell them at all. This is a means for the grid to monitor large and medium-sized enterprises and power users in real time to adapt to smart grids and smart terminal equipment.

Due to the large load of large and medium-sized users, the "neutral line current transformer" is installed on the neutral busbar of the low-voltage distribution board to detect the current flowing through the neutral line of the three-phase load and then send the collected current signal to the dedicated Energy metering chip for data analysis and statistics. At the same time, the voltage is also sent to the energy metering chip at the same time. The data processing is performed by the microprocessor, and the carrier communication is fed back to the server of the power supply company in time. The following is a structural diagram of the working principle of the intelligent anti-theft metering of the power supply company.

The smart metering device uses a microprocessor and a chip dedicated to energy metering. It has the characteristics of complete functions and high measurement accuracy. For single-phase 220V power users, the current smart energy meter has installed a "neutral line current transformer" in its internal structure. In order to improve the technical protection ability of the smart energy meter, when the power supply is connected to the phase line, it can detect the current flowing through the neutral circuit of the energy meter. In addition, the grid clearly stipulates in the technical specifications that all smart meters must have the function of measuring and recording the neutral current transformer.

In electrical engineering, it should be pointed out that for single-phase loads (ie, phase and neutral), the incoming phase current and outgoing neutral current are the same. According to this principle, the current mutual inductance can be connected in series in the neutral wire of the smart meter. The device is used for current sampling, which is then sent to a microprocessor for data comparison and analysis. By comparing the current imbalance between the phase line and the neutral line, the usage status or working status of the smart meter can be distinguished. The load switch in the meter can be tripped remotely if necessary.

Do not underestimate the role of this neutral current transformer. In the current smart energy meter, through the self-test of the energy meter, if the current of the phase line and the neutral line is seriously unbalanced, and through the internal preset settings of the energy meter, it can be judged whether the single-phase user has violated the rules, and an alarm will be sent to the user Alarm signal or automatic control to stop the power supply in the energy meter.