High voltage grounding, capacitive current, how is ground capacitance current generated

For the neutral point non-grounding system, such as the 6-35kv system used in most parts of China, when a high-voltage line is disconnected and falls to the ground for various reasons, the phase voltage of this line at this time is close to 0, the specific value depends on the grounding situation, the current at the grounding point is the grounding capacitor current, at this time, the gate of the superior substation will not trip, and the regulations can continue to run for 2 hours.

For the neutral point direct grounding system, such as the 380V 220V system and the 110KV system used in most parts of China, when a high-voltage line is disconnected and falls to the ground for various reasons, the phase voltage of the line at this time is close to 0, and the current at the grounding point is the single-phase short-circuit current, at this time, the gate of the superior substation will trip immediately, and the trip time is determined by the time setting value of the protection device.

I'm a technician at the power plant:

The voltage of the earth is 0, so when the high-voltage line falls to the ground, the voltage of this phase is close to 0.

Because the resistance is very small, the current on this line will become very large, and in the event of such a single-phase grounding accident, the gate in the substation will be in a very short period of time (in this short period of time to determine whether it is instantaneous grounding is generally.

The so-called capacitive current is that the wire has a voltage relative to the ground at high altitude, and there is a very small leakage current to the ground.

The grounding is as follows:Capacitor grounding is generally a filter, such as electrolytic capacitors can filter low frequencies, and ceramic capacitors can filter high frequencies. The principle is the direct characteristics of the capacitor, the higher the signal frequency, the smaller the impedance, the larger the capacitor capacity, the smaller the impedance, and the DC signal is disconnected.

If a capacitor is connected to the positive and negative poles of the DC power supply, it is equivalent to a short circuit for the AC signal, so the fluctuating signal will be consumed through this capacitor, so the voltage will be more stable.

Introduction:

The two shirts talk about a conductor close to each other, and a layer of non-conductive or cherry blossom insulating medium is sandwiched in between, which constitutes a capacitor. When a voltage is added between the two plates of a capacitor, the capacitor stores an electric charge. The capacitance of a capacitor.

Numerically equal to the amount of charge on a conductive electrode plate.

The ratio of the voltage between the two plates. The basic unit of capacitance of a capacitor is the farad.

f)。in the circuit diagram.

The letter C is usually used to denote capacitive elements.

Hello, capacitor grounding is generally a filter, such as electrolytic capacitors.

Low frequencies can be filtered, and ceramic capacitors can filter high frequencies. The Zheng principle is the on-current-resistion and straight-up characteristics of the capacitor, and the capacitor is on the AC signal path.

The higher the signal frequency, the smaller the impedance, and the larger the capacitance capacity, the smaller the impedance, while the DC signal is disconnected.

In order to ensure that the potential of the grounding terminal is 0, in the actual problem, this is done to ensure that the electrical appliances and people are not harmed. Capacitor grounding doesn't necessarily complicate the problem, because when a capacitor is grounded, there is not necessarily a change in charge, which is important to understand. A live capacitor, grounded at one end, has no effect on the amount of electricity on the plates.

The purchase of capacitors should go to the original capacitor factory like Zhixu JEC, and the quality is ***!

The electric grounding capacitance current refers to the failure of the ground grounding device, when the electrical grounding capacitor exists, a part of the leakage current will flow into the ground as the current of the ground capacitor that hits the ground. This current is generated because there is capacitive coupling between the two ends of the electric ground capacitor, and in the case of failure, the ground voltage is slightly higher, which will form a ground capacitance current flowing into the ground.

Single-phase grounding capacitance current refers to the capacitive current flowing into the fault point due to the existence of the relative ground capacitance of the grid in the grid insulated by the neutral point of the transformer.

In the high-voltage power grid where the neutral point is not grounded, the hazards of single-phase grounding capacitor current are mainly reflected in: 1Arc grounding overvoltage hazards. When the capacitor current is too large, the grounding point arc cannot be extinguished by itself.

2. Cause thermal damage to the grounding point and increase the voltage of the grounding grid. The single-phase grounding capacitor current is too large, so that the grounding point heating effect increases, causing thermal damage to cables and other equipment, and the current flows into the ground due to the grounding resistance, so that the voltage of the entire grounding network increases, endangering personal safety.

3. AC stray current hazards. After the capacitive current flows into the earth, a stray current is formed in the earth, which may produce sparks, ignite gas**, etc., which may cause the early discharge of the lightning delay seepage jujube pipe, and corrode the water pipe code and air pipe.

4. Gas coal dust caused by grounding arc**.

Summary. 1.Balanced wiring:

If a capacitor is connected in a balanced wiring arrangement, then it will produce the same impedance to the circuit. In this case, when the electrical interrupter is turned on, the current in the capacitor increases instantaneously. 2.

Unilateral Turn-On: In single-sided turn-on, only one polarized wire is connected to the power supply. In this case, the current in the capacitor gradually increases until it reaches a maximum, and then gradually decreases at the same rate until it reaches zero.

3.Ground connection: If the capacitor is mounted using the ground connection method, one polarized wire is placed on the ground loop and the other is boarded or predetermined at a predetermined point.

In this way, the current in the capacitor changes with the change in power factor. In summary, the capacitance current is related to the connection method and the grounding method. Correct selection of connection and grounding methods can improve the safety and stability of the circuit.

1.Balanced wiring: If a capacitor is connected in balanced wiring, it will produce the same impedance to the circuit.

In this case, when the electrical interrupter slag collapses and is turned on, the current in the capacitor will increase instantaneously. 2.Unilateral on:

In a one-sided switch-on, only one polarized wire is connected to the power supply. In this case, the current in the capacitor gradually increases until it reaches a maximum, and then gradually decreases at the same rate until it reaches zero. 3.

Ground connection: If the capacitor is installed using the ground connection method, one polarized wire is placed on the ground loop, and the other is boarded or predetermined at a predetermined point. In this way, the current in the capacitor changes with the change in power factor.

In summary, the capacitance current is related to the connection method and the grounding method. Correct selection of connection and grounding methods can improve the safety and stability of the circuit.

Can you elaborate on that a little bit more?

1.Balanced wiring: In this way, the capacitors will produce the same impedance, but in different directions.

This means that the current in the capacitor always remains the same size and direction during charging or discharging. In this case, there is little chance of instantaneous plexus changes in the current in the capacitor, so the safety of the circuit is relatively high. 2.

Unilateral turn-on: In this way, only one power supply polarity is connected to the capacitor, and the other polarity is not. During discharging and charging, the current in the capacitor gradually increases or decreases.

This can lead to rapid changes in the voltage in the capacitor, which can have an impact on the circuit permeation. 3.Ground Method:

In this way, one power supply is polarized into the capacitor and the other is connected to ground via a ground loop. In this case, the current in the capacitor changes with the change in power factor. This approach can have an impact on the circuit, as different devices have different power factors.

In short, the correct connection and grounding methods can effectively ensure the safety and stability of the circuit, and at the same time, it can also avoid other problems caused by current changes in the capacitor.

It is stipulated in the technical regulations for power design that an arc suppression coil should be installed when the single-phase grounding fault current of the power network of 3 10kV is greater than 30A. The function of the arc suppression coil is to provide an inductor current to compensate the grounding capacitance current, reduce the grounding current, and reduce the recovery voltage speed at both ends of the fault phase grounding arc when a single-phase grounding fault occurs, so as to achieve the purpose of extinguishing the arc.

Overcompensation means that the inductance current of the arc suppression coil is greater than the capacitance current of the system to the ground, and the residual current at the grounding point is inductive.