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Knowledge Sharing Of Smart Meters


Why do some din-rail meters have a very small zero terminal?

The suspended meter has two interfaces, one in and one out, regardless of the live wire or the neutral wire. According to the current of the meter, the diameter of the connected wire is different.

1:live wire in

2:live wire out

3:neutral wire in

4:neutral wire out

Note: Ports 20 and 21 are pulse outputs, used for production calibration, without wiring


However, some din-rail meters have a large set of live wire inlets, while the neutral wire has only a small terminal.

The first thing I want to tell you is that this is not a design issue. Why? Will it affect the measurement?

Let me tell you the answer.

Because the meter measurement needs to be connected to the voltage and current, the current can be sampled as long as a live wire is connected, yet the voltage is sampled between netural wire and live wire.

We know that the wire diameter affects the maximum current , thus the live wire must be connected with the whole line, and the netural wire is only used to sample the voltage, so it does not need to be very thick. It not only facilitates installation, but also has no impact on the metering, which is no different from the ordinary suspended meter.

It should be noted that when encountering this kind of din-rail meter, if there are two wiring screws on the neutral terminal and only N is marked on the wiring diagram, it does not mean that one input and one output, you can connect any one. Be sure to check the wiring diagram when wiring and follow the instructions because there is no ability to pass large current between these two screws.