4hw.org: when living at home, it's hard to avoid dealing with electricity. There are some small things about electricity that you can solve by yourself without asking others for help. Let's learn a basic common sense about electricity, the difference between zero line and bottom line! Let's have a look with Xiaobian!
Zero line of first live line ground wire
In order to make alternating current have a very convenient power conversion function, usually industrial power, three sinusoidal alternating current. The current phase (reflecting the direction of the current) is 120 degrees different from each other. Generally, we call each such wire as phase line (live line). Generally, the power transmission is in the way of three-phase four wire. The three heads of three-phase electricity are called phase line, and the three tails of three-phase electricity are connected together, which is called neutral line or zero line. The reason why it is called zero line is that there is no current passing through the neutral line at the time of three-phase balance, and then it is directly or indirectly connected to the earth, and the earth voltage is also close to zero. The ground wire is a reliable line connecting the equipment or the shell of the electric appliance to the ground, which is a good scheme to prevent electric shock accidents. The live wire is also called the phase line, which together with the zero line forms the power supply circuit. In the low-voltage power grid, three-phase four wire system is used for power transmission, among which three phase lines and one zero line are used. In order to ensure the safety of electricity use, the user area is changed to use three-phase five wire system for power supply. The fifth wire is the ground wire. One end of the wire is buried in the ground with a metal conductor near the user area, and the other end is connected with the ground wire contact of each user to play the role of ground protection.
Color of two live wires, zero wires and ground wires
According to the current standard of China, the third circuit in gb2681 should be marked by the color of conductor, which should be phase a yellow, phase B green and phase C red. Zero line - light blue. The ground wire is yellow and green. If it is a three-phase socket, the left side is the zero line, the middle (upper) is the ground wire, and the right side is the live wire
Three kinds of electricity are divided into power electricity and household electricity
Power consumption is commonly known as 380V power, which is mostly used in factories. This kind of electricity is mostly three-phase four wire. Three live wires in four wires, one zero wire. Live wire refers to any phase in three-phase four wire power grid a B C, and the zero wire refers to the wire with no voltage and current to the ground. After three live wires pass through electric equipment such as motors and other electrical equipment, they form a circuit through the zero wire, so that the equipment can work normally The line is grounded in the power plant. Generally, red, yellow and blue colors are used to represent three live lines in three-phase circuit, and black is used for zero line.
Household electricity refers to the 220 volt electricity, also known as single-phase electricity, which has two wires, one live wire and one zero wire. The live wire can work normally after passing through the zero wire to form a circuit after passing through the electrical appliances such as light bulbs. The zero wire here is also grounded in the power plant. In the single-phase lighting circuit, generally yellow indicates the live wire, blue indicates the zero wire, and yellow green indicates the ground wire. In some places, red indicates live wire, black indicates zero wire, and yellow green indicates ground wire. Generally, red is the live line, blue is the zero line and black is the ground line
Although the zero line of power and household electricity is grounded in the power plant, we usually say that the ground line and zero line are not the same concept. Look at the three hole power socket in our home. If it is a normal construction, one hole is the live line, one hole is the zero line, and one hole is the ground line. The ground line here is grounded after the whole building is assembled. This is the common ground line. Most household appliances require the ground line, It is to be connected with this ground wire
The live wire is live, and the ground wire and zero wire are not. There is a live wire and a zero wire in the socket with two jacks for household use. The live wire can be measured with the electric pen. The neutral wire is not live. Only the socket with three jacks has the ground wire. The ground wire should be connected to the shell of the appliance to prevent electric leakage from causing electric shock.
In addition, the wiring position of each hole in the household socket is specified. If the socket is disassembled, it can be seen that the point marked with L is the ground wire, the point marked with n is the neutral wire, and the ground wire has a special grounding symbol. People who don't understand should never connect (especially the position of the ground wire) randomly, otherwise it may cause serious consequences.
The ground wire is the equipotential body as the potential reference point of the circuit. This definition is not in line with the actual situation. The actual potential on the ground is not constant. If you use an instrument to measure the potential between the points on the ground wire, you will find that the potential of each point on the ground wire may vary greatly. It is these potential differences that cause the abnormal operation of the circuit. The definition of circuit as an equipotential body is only people's expectation for the ground potential. Henry gave a more realistic definition of the ground wire, which he defined as the low impedance path of the signal flow back to the source. This definition highlights the flow of current in the earth wire. According to this definition, it is easy to understand the cause of potential difference in the ground wire. Because the impedance of the ground wire will never be zero, when a current passes through a limited impedance, a voltage drop will occur. Therefore, we should think of the potential on the ground as the wave in the sea, one after another.
At present, most of the power sockets we use are single-phase three wire socket or single-phase two wire socket. In the single-phase three wire socket, the middle is the ground wire, also used for positioning. In addition, the two ends are respectively connected with the live wire and the zero wire. The wiring sequence is left zero and right fire, that is, the left is the zero wire, and the right is the live wire. All household appliances with metal shell adopt the single-phase three wire power plug. The three plugs are arranged in a triple shape, and the longest and thickest copper plug on the top is the ground wire. The two below the ground wire are the live wire (L livewire) and the zero wire (n naught wire). The order is left zero and right fire (when the back of the plug is facing itself).
The ground wire is short circuited to the ground through a deeply buried electrode. The transmission of municipal power is in the form of three-phase, and there is a neutral line. When the three-phase is balanced, the current of the neutral line is zero, commonly known as the zero line. Another feature of the zero line is that it is short circuited with the ground wire in the total distribution input of the system, and the voltage difference is close to zero. Three phase lines and zero lines of three-phase electricity have 220 voltage, which will produce electric shock to people, commonly known as live line.
4. Why is electric shock?
Some people mistakenly think that the zero line is the ground wire, which connects the ground wire and the zero line of household appliances together. Then the live line forms a circuit with the zero line and the shell of household appliances at the same time, which makes the shell electrified, especially when the zero line has been disconnected due to the fault and the power socket is not well grounded
Zero line: in household electricity, the zero line usually refers to the line from the transformer grounding body. Its grounding resistance has strict regulations, which must be less than or equal to 0.5 ohm, so as to ensure the normal use of electrical equipment;
Live wire: it is relative to the zero line. Generally, the household electricity is only one phase of three-phase electricity, and its line voltage is 220 V, which makes the household appliances work through the zero line circuit;
Ground wire: the wire we connect to household appliances is usually the ground wire for safety and elimination of static electricity. There is no strict requirement for its grounding resistance, which is usually relatively large. When there is no current passing through the ground voltage, it is zero. It is impossible for the equipment to work normally when it is used as the zero wire of appliances;
Neutral line: the line connecting the metal shell of the electrical equipment with the ground wire of the power supply (generator and transformer). It requires the fuse or air switch in the line supplying the electrical equipment. When the electrical equipment collides with the shell, the circuit can be disconnected in the shortest time, so as to protect the safety of the equipment and life;
The socket in the home is not a three-phase socket but a three wire socket. The middle of the socket is a ground wire, and the two sides are used to connect the zero wire and the live wire. Although there are also provisions on the electrician's Manual for left zero and right fire, our requirements in real life are not so strict.
Two wires in the lighting circuit, one is called the live wire and the other is called the zero wire. The difference between the live wire and the neutral wire lies in their different voltage to the ground: the live wire to the ground voltage is 220V, and the zero wire to the ground voltage is 0. Generally, the three hole socket is not a three-phase socket, the middle is the ground wire, the two sides are the live wire and the neutral wire, the right side is the live wire (L), the left side is the zero wire (n)
The difference between the live line and the neutral line lies in their different voltage to the ground: the live line to the ground voltage is 220V, and the zero line to the ground voltage is 0.
The neutral line is the line from the neutral point of the generator or power transformer. If it is not grounded, it is called the neutral line. If it is well grounded (the earth is zero potential), then the neutral line is also called the zero line. Although the zero line and ground line of civil power are all led out from the same point, their respective functions are separate and cannot be mixed. For example, the zero line and the live line are the electric circuit lines. They are edge to the shell of the electric appliance. The current flowing in the line is the same size, so the wire diameter is the same thickness. And the ground wire is connected with the shell of the electric appliance. When the electric appliance has a fault, there is current flow in it. Generally, there is no current, so the wire diameter is much smaller. Zero line and live line are electric circuits, so it is absolutely not allowed to connect the zero line to the shell, which will cause electric shock.
Difference between five live lines and zero line
The live line and the zero line are both live lines,. Zero line is not charged because the other end of the power supply (zero line) is grounded. When we contact the zero line on the ground, because there is no potential difference, no current will be formed. The zero line and the live line are originally from the power supply, the positive direction of the current is from one out, through the external equipment, from the other end into a loop. The difference between the zero line and the live line is that one of the two terminals of the power supply is grounded
Difference between six zero line and ground line
1. Zero line and ground line are different concepts, not the same thing.
2. The potential of ground wire to ground is zero. The nearest point of the electrical appliance used is grounded.
3. The ground potential of the zero line is not necessarily zero. The nearest ground point of the neutral line is at the substation or the power supply transformer.
4. When does the zero line sometimes electrify people? When your electric furnace doesn't heat up, don't think it's out of power, it won't electrify people, wrong! There may be such a possibility, where the N line is very yuan away from your electric appliance, it's disconnected. When you measure it with a voltmeter, you will find that the LN line of the electric appliance is the voltage of the mains!
5. The ground wire won't electrify people, unless it's in a bad situation, the designer doesn't understand it, or the product is messed up!
6. If you have zero line and ground line in your circuit, you will find a high voltage withstand capacitor in the middle of them.