How are the neutral and live wires in low voltage circuits connected?

The neutral and live wires in a low-voltage circuit are connected together by electrical equipment.

The live wire comes from one of the three phase wires of the transformer's secondary winding, and the neutral wire comes from the neutral point where the transformer's secondary winding has been grounded; The live wire has a voltage of 220V to the ground, which is the source of power, and the ground wire has no voltage to the ground, which is the foundation of safety.

If it is a line in, a line out, plus a number of groups of electrical equipment in the middle, it can be directly connected into a ring type, and it can also be energized, but the electrical equipment we use is using its power, power = current voltage, after series connection, the sum of the voltages of each electrical equipment is 220V, and the voltage on each electrical equipment will be very low, and the electrical equipment is required to work at the rated voltage, otherwise it will not reach the rated output, or it will not work at all, such as connecting the lamp and the refrigerator together, The electric light will be lit up a little bit due to low voltage, and the refrigerator motor will not be able to operate for a long time due to low voltage, or it will not be able to start to cool at all. It can be seen that it is not possible to connect in series, only the parallel connection of electrical equipment can ensure that the voltage added to the electrical equipment is the rated voltage, and the equipment can operate normally and output normally.

If it is connected directly, it will be short-circuited, and the current will be very large and the wire will be burned.

Must be connected by a load.

The live wire in the low-voltage circuit, both phase line L, AC voltage to ground 220V.

The neutral line in the low-voltage circuit is the center line n of the power supply system, and the voltage to the ground is 0V.

In a low-voltage circuit, a load is connected between the neutral and live wires (e.g., a light bulb, both on).

Yellow. Green. Red. They represent L3 (Firewire).

Blue or black represents the zero line.

The yellow and green colors represent the ground line.

The voltage between yellow and green is 380V

Yellow-red phase voltage 380V

Green-red voltage 380V

Yellow-black voltage 220V

Green-black voltage 220V

Red-black voltage 220V

If it is connected into a global type, it will be short-circuited.

Both the live wire and the neutral wire are from a 3-phase generator or transformer, the live wire is one of the phase wires, and the neutral wire is the neutral ground wire of the generator or transformer, 220 to ground

Because the live wire (phase wire) at the power supply end (transformer) is a wire drawn from the transformer coil, and the neutral wire is also a line drawn from the transformer, but in the transformer circuit of the three-phase four-wire is a central point (neutral wire) of the winding coil of the three-phase wire, then the voltage of the neutral wire and any other phase wire should be 220V (China's voltage standard) under normal conditions; Because, in the power supply system, the neutral line of the transformer is grounded, so from"phenomenon"From the perspective of electrical theory, the potential of the ground wire and the neutral wire is equal (the same), and both should be"Zero potential".Therefore, in terms of measurement, the voltage of the live wire to the neutral wire and the ground wire should be the voltage value of the one-phase wire being measured--- that is, the voltage is 220V; The reason why it is divided into neutral wire and ground wire is because the neutral wire is a line that provides a current channel for the circuit when it is working normally, and the ground wire is a line designed for the safety of electrical equipment"Abnormal current"A line of the channel is set up as a protection line together with the control equipment (such as automatic air switch, etc.), and the line is strictly speaking without any value of current passing through the line when the equipment is normal, that is, the current is zero. Therefore, in terms of measurement, these two lines are connected, but the nature of the work (function) is different.

There are two wires in the lighting circuit, one is called the live wire, and the other is called the neutral wire. The difference between the live wire and the neutral wire is that they have different voltages to the ground: the voltage of the live wire to the ground is 220v; The voltage of the neutral line to the ground is equal to zero (which itself is connected to the earth).

So when one part of the person hits the line of fire and the other part is standing on the ground, and the voltage between these two parts of the person is equal to 220V, there is a risk of electric shock. On the contrary, even if a person uses his hand to grasp the zero line, if the person is standing on the ground, because the voltage of the zero line to the ground is equal to zero, the voltage between the various parts of the human body is equal to zero, and the person is not in danger of electric shock.

After a single-phase power supply circuit is loaded, its live wire has current and voltage, while the neutral line has current and no voltage, and the voltage is consumed on electrical appliances. So as the saying goes: there is no electricity on the zero line.

Since the neutral line is directly grounded and has a potential with the earth, there is no voltage between the neutral line and the earth, so even if people touch the neutral line, they will not be electrocuted, which makes people think that the neutral line has no electricity.

The live wire and the neutral wire form a loop, the load works normally, and the ground wire plays a protective role, once there is a leakage of electrical appliances or artificial electric shock, the current will flow into the earth through the ground wire, and the leakage current value of the leakage protection will be tripped. Therefore, from a safety point of view, the ground wire cannot be used as a neutral line, and if the ground wire is really used as a neutral line, the leakage will trip immediately.

The voltage of the live wire and neutral wire is not the same as the voltage of the live wire and ground wire.

The voltage between the ground wire and the live wire is the same as the voltage between the neutral wire and the live wire, both of which are 220V. The ground and neutral wires should be voltage-free (0V).

When it is found that there is more than 5 volts of alternating current on the grounding wire-neutral line, it can be basically ascertained that the ground wire is not grounded or the grounding is poor, or the leakage of some grounded equipment is too serious.

If the ground wire is in good contact with the earth, the voltage between the ground wire and the live wire is the same as the voltage between the neutral wire and the live wire. Both are 220V, and the ground wire and neutral wire should be without electricity (0V).

If it is found that there is more than 5 volts of alternating current on the ground wire-neutral line, it can be basically determined that the ground wire is not grounded or the grounding is poor, or the leakage of some grounded equipment is too serious. Three-phase loads have a serious imbalance, that is, there is a large difference in the current in the three phases, and the current in one phase is larger than that in the other two.

When the three phases are of the same current, the current in the neutral line is 0. Now the three-phase currents are not equal, and there is an unbalanced current in the neutral line. The neutral line is grounded at the power supply transformer, and the current in the neutral line flows through the neutral line, and there will be some voltage drop, compared to the ground wire at the user, there will be a voltage of a few tenths of a volt.

The voltage between the live wire and the neutral line is 220V because the three-phase voltage (live wire) output by the distribution transformer is 220V to the neutral wire (neutral line) of the transformer. These are determined by the system voltage and transformer structure.

The voltage between the ground wire and the neutral wire is 0V, and the system requires that the neutral point of the distribution transformer must be reliably grounded (that is, connected to the grounding device), and the ground wire is required to be drawn out close to the grounding device. Although the ground wire is close to the grounding device and the neutral wire is close to the neutral point of the transformer, they are both connected to the grounding device, which is actually a point, so the voltage between them is zero.

The voltage between the ground wire and the live wire is 220V, understand the above two points, this point is naturally understood, because the neutral wire and the ground wire are one point at the transformer grounding ground, then the neutral wire to the live wire is 220V, of course, my ground wire to the live wire is also 220V.

Because the voltage in our country is 220V.

If you go to Japan, the voltage is 110v