What does it mean to use electrical short circuits, ask for details, and add points if you understan

In the event of a short circuit, current passes through another circuit with a much smaller resistance, such as a wire, and does not pass through the consumer being shorted. There is no current passing through the electrical appliances, how can the electrical appliances burn out, no. In the event of a short circuit, if there are no other electrical appliances on the circuit, it means that the positive and negative poles of the power supply are connected together, and the power supply will burn out.

Well, I'll add one more.

1. After the wire short-circuits the electrical appliance, the current passing through the short-circuited electrical appliance is zero, and the current on the wire used for short-circuit is very large (the short circuit is equivalent to using the advantage of its own small resistance to "snatch" the current of the thing with large resistance).

2. Since there is no current passing through the electrical appliances, the electrical appliances will not burn out. Your idea is that you think that the electrical appliances are burned out and become wires, right, when there is a short circuit, the current goes the other way, and if you don't use the electrical appliances, it is equivalent to changing to a better way, and the electrical appliances are out of power! Doesn't work!

3. After the short circuit, the current passing through the wire used for the short circuit (that is, the new way the current goes) is too large, because the resistance of the wire is very small.

Short circuit is the short connection of the two input terminals of the electrical appliance to form the same potential, resulting in the electrical appliance being unable to work. At the same time, due to the small resistance of the line at the power supply end, according to I=U R, the line will form a large current, which will burn out the insurance, the line, the power supply, and cause a disaster in serious cases.

To put it simply: a short circuit is the positive and negative poles of the power supply, which are directly connected together without passing through the electrical appliances. This is called a short circuit.

When the line is short-circuited, because it does not pass through the electrical appliances, the amount of current in the line is too large, which will burn out the power supply. When there is an electrical appliance, the current is shared and the power supply does not burn out!

This question is indeed impractical. But let's break it up. 1.Electrical appliances require voltage to work. If the wires are connected to both ends of the appliance. The voltage at both ends of the appliance is equal to the voltage at both ends of the wire is zero. So doesn't work.

But that's the way it turned out in practice. The power supply will be automatically disconnected for short circuits. The other appliance won't work either.

A short circuit in the power supply refers to the handoverDC short circuit, electrical short circuit refers to AC short circuit.

In a circuit, the current does not flow through the electrical appliance, but is directly connected to the two poles of the power supply, and the power supply is short-circuited (short circuit). According to Ohm's law i=u r, we know that since the resistance of the wire is small, the current on the circuit will be very large when the power supply is short-circuited.

Such a large current, the battery or other power sources cannot withstand it, which will cause damage to the power supply; What's more, because the current is too high, the temperature of the wire will rise, and in severe cases, it may cause a fire.

1. Definitions

In the operation of the power system, there is an abnormal connection (i.e., short circuit) between phases or between phases and ground (or neutral wires), and a very large current flows sometimes.

The current value is much greater than the rated current and depends on the electrical distance from the power supply at the short-circuit point. A short circuit is a low-resistance short circuit between the conductive parts of different potentials, which is equivalent to a closed circuit directly connected by the wire without passing through the load. (Usually this is a serious fault that should be avoided as much as possible, which can cause the circuit to burn out and fire due to excessive current.)

2. Basic type

Power short circuit: that is, the current does not pass through any electrical appliances, but flows directly from the positive electrode to the negative electrode through the wire. It is particularly easy to burn out the power supply.

Electrical short circuit: also called partial circuit short circuit. That is, a wire is connected to both ends of the electrical appliance (the ammeter is connected in parallel, and the closed switch is connected in parallel), and the electrical appliance is short-circuited, which is easy to burn other electrical appliances.

Short-circuit capacity:

Short-circuit capacity is a characteristic quantity that reflects the electrical performance of a certain power supply point in the power system. The short-circuit capacity is for a certain power supply point of the power system, reflecting some important performance of the point, such as the load capacity and voltage stability of the point, the strength of the connection between the point and the power supply of the power system, the level of short-circuit current when the point is short-circuited, etc. Secondly, the short-circuit capacity is also related to the capacity of the entire system.

As the capacity of the power system expands, so does the level of the system's short-circuit capacity. In the rated capacity of high-voltage switchgear, the short-circuit capacity has been changed to a short-circuit current value, such as the rated breaking current.

Power short circuit refers to a direct short circuit at the positive and negative poles of the power supply output, and the current flows through the short circuit, so that it cannot supply power to external electrical appliances and there is no voltage output. In this case, the power supply may be burned out, or it may be that the power supply is done well and has short-circuit protection without burning out.

Short circuit of electrical appliances refers to the short circuit of the electrical appliances themselves, which can be a direct short circuit, that is, the pins of the electrical input are short-circuited externally, and when measuring both ends of the electrical appliances, the resistance is zero, or it may be an internal short circuit, that is, the electrical resistance of the electrical appliances is very small or zero when measured with a multimeter. In this case, the power supply will output voltage, and the current will flow through the short-circuit part of the electrical appliance. If the electrical appliance is not well welded and the pin is shorted, the power supply will not flow through the inside of the electrical appliance, and the electrical appliance will not be damaged, but the pin that flows through the short-circuit current will be ablated to different degrees due to the different magnitude of the short-circuit current.

If there is a short circuit inside, the appliance may be damaged due to the flow of high current.

The short-circuit location is different in both cases.

The circuit includes power supply U, switch K, and electrical appliance L.

Figure 1 shows the normal use circuit;

Figure 2 shows that the power supply is short-circuited, which will cause the pre-protection circuit to trip (such as the neighbor's power supply is also cut off);

Figure 3 shows a short circuit in the electrical appliance, which only causes the switch K in the room to trip (does not affect the power supply of the neighbor's house).

When the power supply is short-circuited, the output of the power supply is short-circuited, and the current will form a loop from the power supply to the short circuit, so that the protection on the power supply will be disconnected. When the electrical appliance is short-circuited, there is nothing wrong with the electrical appliance, but it is not connected to the power supply, but the power supply is equivalent to the short circuit of the wire.

The short circuit of the power supply is to directly short the positive and negative poles of the power supply, because the resistance tends to 0, a huge current will be generated instantly, and the power supply will be burned out.

Electrical short circuit is to short the two ends of the electrical appliance, because there is resistance in the electrical appliance, all the current passes through the short circuit, the electrical appliance does not work, and the electrical appliance will not be damaged.

Power Short Circuit: Connect the two poles of the power supply directly1. Definitions.

A short circuit with an electrical appliance is to connect the two ends of the electrical appliance with a wire.

2. Features. 1) When the electrical appliance is short-circuited, most of the current passes through the wire, and only a very small current passes through the electrical appliance. In this case, it can be approximated that no current is passing through the consumer.

2) Because the current through the electrical appliance is too small, the electrical appliance cannot work. When analyzing the circuit connection form, the electrical appliances that have been short-circuited can be removed, and the circuit can be organized into a simple and intuitive "equivalent circuit".

3. Application. 1) Practical application.

In household circuits, when using electrical appliances with metal housings, short circuits are used to ensure that the ground wire is safely connected. The grounding wire is connected in parallel with the human body, and both are connected to the earth, and the grounding wire short-circuits the human body (which can be considered as an electrical appliance with greater resistance). When the metal shell of the electrical appliance is electrified, if the person touches the shell, only a very small current passes through the human body, ensuring personal safety.

The electrical appliance itself has impedance, so that the current of the power supply is limited to a reasonable range, and the short circuit is that the impedance of the electrical appliance becomes smaller (such as less than 1 ohm), so that the impedance of the two poles of the power supply is very small, and the current is very large, causing the accident of heating and fire.

A short circuit is a conductor with zero resistance such as a wire to connect the electrical appliances or the power supply, and the electrical appliances are used without current and voltage, so that the power supply is burned out or the output voltage is zero.

The so-called short circuit of a certain component means that the two ends of the element are directly connected to the two ends of a wire with negligible resistance (the resistance value is very small, considered to be equal to 0), and the current in the circuit (almost) passes through this wire, and the current in the element is (almost) 0.

It can be seen that the electrical appliance is short-circuited, that is, its two ends are connected to both ends of a wire with negligible resistance, and all the current passes through the wire, and there is no current in the electrical appliance.

Example: As shown in the figure below, when the switch S is closed, the lamp L is short-circuited.

The short circuit of the electrical appliance is that the two ends of the electrical appliance are connected with wires, and the current flows directly through the wires without passing through the electrical appliances.

A short circuit in an electrical appliance means that the live wire and the neutral wire collide inside the appliance or the internal resistance of the appliance becomes much smaller than normal.

A short circuit in a physical appliance refers to a situation in which the resistance value of electricity used in the electrical appliance is much smaller than the resistance value of the ground due to some reason.

It means that the two ends of the electrical appliance are directly connected by the wire, because the resistance of the wire is very small (approximately zero), so the current passes through the wire, and there is no current passing through the electrical appliance, so it is called a short circuit.

There is a kind of short circuit that is not caused by the short circuit of the electrical appliance, and the live wire and the neutral wire are directly connected at the front end of the electrical appliance or with low resistance. Some are caused by the burn-through of electrical appliances, a diode or other devices. The second type is what you call bad electrical appliances.

The short circuit of the electrical appliance means that the current does not flow through the electrical appliance and directly constitutes a loop, resulting in the electrical appliance not working normally, and the current in the cutting circuit is very large, which will cause the danger of burning the safety or burning the power supply. The picture upstairs is very clear, so I won't pass it on.

It is to use the wire to directly connect the two ends of the electrical appliance directly, which is a short circuit of the electrical appliance;

A short circuit in an electrical appliance is an internal damage to the electrical appliance that causes the internal resistance to decrease and the current to increase.

The two ends of the power supply are connected directly with wires.

Take a look at the attachment, there are pictures and descriptions in it.

It's not called a short circuit here. It's called shorting.

Once the current flows through the upper L, it does not pass through the lower L. Because the current is also lazy, the upper L is what it has to pass through, but when it comes to the lower L, because the lower L has resistance (resistance), it will be lazy directly from the upper ammeter.

The resistance of the ammeter is almost zero, so it is equivalent to a wire connection node) flows back to the power supply, so the l below will not light up.

The current selects the circuit with the lowest resistance, and that's how it works.

In this way, if the appliance is short-circuited, it means that the current does not pass through it. Your teacher said that the current will choose the one with the lowest resistance, right? If it is connected in parallel with the ammeter wire, the resistance of the ammeter wire is 0, and all the current flows through there.

So the electrical appliances are short-circuited.