Circuit return end, grounding, earth, equipotential body, electrostatic field, loop, electric energy

0. Several important electronic understanding portals:

A.Understanding electricity from the concept of electric field or potential, and from the perspective of potential energy and energy

B.The latter potential of the electric field is a reference value, that is, to have a reference point. It is better to have a zero fire in the AC, or a VCC Gnd in the DC

C.Loop. Only the loop has current, and only the loop can consume energy.The mains electric shock is caused by power supply-man-Earth-zero line forming a loop, and the current is too large. Of course, instantaneous discharge is another situation.

D.The earth is regarded as a conductor, but it has a characteristic that it can absorb any amount of charge. Therefore, without forming a loop, the electric charge connected to the earth will be absorbed by the Earth to form an equipotential, and the potential is relative. Therefore, it is customary to define the Earth as a 0 V potential.The role of the earth is protection, the absorption of excess charge, and the definition of 0 V.

E.When an open circuit is used, the electric field, potential, equipotential body, and static electricity are used for analysis. When there is a loop, we use Ohm's law to analyze it with an electric field!

F.An important analysis method is: the analysis of Ohm's law when there is a loop, and also includes (transient and stable State difference analysis); when there is no loop, according to the electric field potential, analyze the idea of static electricity balance and other potential bodies.

1. current flow, or electric field work, must have a loop, so that the current continues to pass. If there is no path, like a power supply, directly connected to a resistor, that is, at most at the moment of the connection, there is a change in the electric field around the resistor, this change is instantly balanced, the resistance end at this time, from the field or energy point of view, the voltage is the same as that of the power supply.

2. The current return end is to form a loop. At this time, the power supply negative pole may not be zero for the potential of the Earth, but it can be grounded to protect the device or person.

3. Both the earth and the human body can be regarded as high resistance. Single Point measurement means that the earth resistance is greater than the human body, but the mains supply is grounded at multiple points. Therefore, the area of the conductor increases, resulting in the earth resistance being smaller than the human body.

4. The location in the DC Circuit generally refers to the potential reference point of the circuit (0 V), which is also the return end of the circuit.

5. When the alternating current (AC) and the FireWire are grounded, the leakage protection will take effect. If there is no leakage protection circuit, there will be a current return to the ground pole of the power distribution room, but the current is not large (related to geological conditions); in the near-line grounding danger, prone to cross-step voltage electric shock.

6. if the transformer Neutral Line is not connected to the earth, although the power supply line is not directly connected to the Earth, there is a capacitive effect. If the human body is connected to the Earth, it is equivalent to charging the capacitor, still electric shock. this is if the device shell is connected to the earth, protecting people and becomingGround Protection.

If the transformer Neutral Line is connected to the Earth, when there is leakage, people will be exposed to the earth, forming a loop, people will be electric shock, at this time, if the device shell is connected to the zero line, leakage, forming a short circuit, at this time, it will trip and won't make people electric shock.Zero protection.

7. the Earth can absorb any charge, and the neutral end of the transformer of the Power Distribution Center is grounded. If the fireline of the user end leaks through the device casing, the Neutral Line of the device--substation forms a circuit, the current is transmitted in the earth. At this time, if a person contacts the device, nothing will happen. Because at this time, the grounding wire and the ground are short, the human body resistance is large, will not be electric shock.

8. After grounding, the potential of the grounding point is zero. The metal is an equipotential body. As long as one point is zero, all links are zero. Otherwise, the charge flow occurs until zero.

9. one end of the power supply is connected to the conductor, and the other end of the conductor is disconnected. At this time, the other end of the conductor has the same potential as the power supply. This is because after a short Charge flow, the power supply and the charge of the conductor are balanced and become the Equipotential body.

10. without forming a loop, there will be a process of charge balance between the connected conductors. The earth is special and can absorb any amount of charge, so the current of the charged object will be absorbed by the earth.

11. Several Questions:

 

A. DC Circuit Board (most commonly used PCB) refers to the return end of the circuit, that is, the negative pole of the power supply. Is it also the 0 V potential reference point in the board?
The ground in the circuit board is the circuit return end. The negative pole of the corresponding power supply is the 0 V potential reference point. This should be basically correct.
B. is the logical "Ground" side of a DC Circuit Board (same as 1) connected to the Earth affecting the circuit?
In general, the place where the DC board is located is the place where the electrons are generated, that is, the negative charge. This place is connected to the Earth, because the negative pole has the electrostatic field, and the negative charge has the tendency to move to the earth. However, at this time, if there is a return path, the function of the Loop Electric Field may be greater than the electrostatic field, resulting in negative charges will not be absorbed by the earth. If there is no loop, there will basically be no extra negative charge. If there is a loop, static electricity will be balanced and absorbed by the earth.
C. For a DC Circuit Board (same as 1), the non-logical "Ground" end is any non-location, connected to the earth, does it affect the circuit? Is there a current flowing into the earth?
The principle and result are the same as those in step 2.
D. Normally used power supplies, such as computer adapters, are directly connected to the earth as the positive pole. Is there a current flowing out? Does it last forever?
The principle is similar to 2 and 3. There should be no extra charge in the case of no loop, and there is no current in the case of no loop formed on the earth.
E. Is there no current flowing into the earth when the transformer of the power station is connected to the Earth in the midline? Will it not waste energy?
The principle is similar to 2 and 3.
F. After the transformer of the power distribution station is assigned to the user, after the user's load goes through, all the energy consumed by the user's load?
The current of the inflow branch is because there is voltage at both ends. The current reaches the negative pole from the positive pole. The electric energy has been done, and the negative potential can be 0.