What is the function of the primary grounding switch of the coupling capacitor of the high frequency

A coupling capacitor is a capacitor that is used to transmit signals in a power network. It is mainly used in power frequency high-voltage and ultra-high-voltage AC transmission lines to achieve the purposes of carrier, communication, measurement, control, protection and extraction of electric energy. The function of the coupling capacitor is to make the strong and weak current systems coupled and isolated through the capacitor, provide a high-frequency signal path, prevent the power frequency current from entering the weak current system, and ensure personal safety.

In addition to the above functions, the coupling capacitor with voltage extraction device can also extract the power frequency voltage for protection and reclosing, and play the role of a voltage transformer.

The grounding switch is actually a mechanical switch in the grounding part of the circuit, which can carry the current under abnormal conditions (such as short-circuit current) for a certain period of time, but it is not required to carry the current under normal circuit conditions.

The above answers are too abstract, let me put it bluntly for you, for example, you listen**, you want to amplify the audio signal, in order to drive the speaker to vibrate and make a loud enough sound, two levels of circuit cooperation are required, one is the pre-stage circuit, the output audio signal, the other is the amplification circuit, and the audio is amplified after receiving it. The audio signal is an alternating current, and amplification is to amplify the voltage and current intensity of this alternating current.

However, there may be a DC component in the audio signal of the pre-amp circuit, so a capacitor in parallel between the two stages can play the function of allowing alternating current (audio signal) to pass through and block direct current, so that the audio signal is transmitted from the pre-amp to the amplification circuit.

Coupling is the transmission of the signal from the previous stage to the next stage, because it is done through capacitors, so it is called capacitive coupling.

The filtering effect of capacitance is the same as this principle, but the filtering is to eliminate the AC as a useless component and directly short-circuit the ground wire, while the capacitive coupling is to transmit it to the next level as a useful component.

Capacitive coupling is to filter out the DC component, because the principle of capacitance determines that it is equivalent to an open circuit for DC power, and it cannot be passed, so it blocks DC. After the capacitive filtering blocks the DC, there is still a line for the blocked DC to go to the next component that needs to use DC.

Got it clear, right?

It is to transmit the AC signal from the previous level to the next level. There are also direct coupling and transformer coupling methods. The direct coupling efficiency is the highest, and the signal is not distorted, but the adjustment of the front and rear two operating points is more complex and implicated in each other.

In order to make the working point of the latter stage not affected by the previous stage, it is necessary to separate the previous stage and the latter stage in the DC aspect, and at the same time, the AC signal can be smoothly transmitted from the previous stage to the latter stage, and the method that can complete this task is to use capacitor transmission or transformer transmission to achieve. They can transmit AC signals and block DC, so that the working points of the front and rear stages are not implicated in each other. However, the difference is that when transmitting with capacitors, the phase of the signal is delayed, and when transmitting with a transformer, the high-frequency component of the signal is lost.

In general, capacitors are commonly used as coupling elements for small signal transmission, and transformers are commonly used as coupling components for large signal or strong signal transmission.

The role of the coupling capacitor is to transmit the AC signal from the previous stage to the next stage. In order not to leave the work point of the latter level unaffected by the previous stage, it is necessary to separate the former and the latter stage in the DC aspect. At the same time, it can make the AC signal smoothly transmitted from the previous stage to the next stage, and the capacitor can transmit the AC signal and block the DC, so that the working points of the front and rear stages are not implicated in each other.

The high-frequency weak current signals (such as dispatching signals, high-frequency protection signals, etc.) used in communication in the power system use the high-voltage line as the carrier channel, and the role of the coupling capacitor is to provide a path for the high-frequency weak current and block the high-voltage power frequency current at the same time, so as to isolate the strong current and the weak current system. We all know that the capacitive reactance of a capacitor is inversely proportional to the frequency, and it has a low impedance for high-frequency signals and a high impedance for power-frequency signals, which is the basic principle of its operation.

In fact, to put it more simply, when the front circuit needs to be used with the back circuit, add a capacitor in the middle, then this capacitor is a coupling capacitor!

I hope that's right.

Agree with what was said upstairs, simply put, "transmit AC signals and block DC contacts".

Strictly speaking, the grounding point of the coupling vessel is actually a grounding switch connected in parallel on the high voltage side of the combined filter, and there is also a discharge gap. The grounding point of the combined filter is the common grounding point of the high and low voltage windings.

The former is used to protect the safety of personnel and equipment when combined with filter maintenance or channel equipment maintenance.

The latter is a technical requirement for the protection channel. The former falls under the category of high-voltage equipment, because the coupling capacitor is directly connected to the line. The latter is a secondary circuit.

In engineering, the former needs to connect the grounding flat iron of the primary equipment.

The latter should be grounded separately according to the requirements of countermeasures, and through a 50mm2 copper wire to a place 3m away from the point where Zheng Yi erected a grounding gap. (Countermeasures are not necessarily accurate.) ）

The disconnection and connection of the coupling capacitor will affect the normal operation of the high-frequency protection channel of the line. When the line is operating normally, disconnecting the coupling capacitor will cause an interruption for the protection that works in the sending mode, and the failure of the receiver at the opposite end to receive the latch may cause tripping. For the Baozu sales guard that works according to the start-up signaling mode at the time of failure, when the coupling capacitor is connected, the key file may also emit an abnormal shock, causing protection malfunction.

For this reason, when the capacitor is connected to the coupling capacitor with power, it should be grounded and the high-frequency protection should be deactivated. In order to play a role in safety protection, the grounding gate knife should also be closed (many are drop-off fuse spikes), and the disconnected coupling capacitor should be discharged to the ground immediately to prevent the staff from being electrocuted.

Binding filter The binding device is connected between the low-voltage end of the coupling capacitor and the high-frequency cable connecting the power line carrier; Or, in the case of bridges, directly or via an additional device, it is connected to another bonding device.

The binding device is coupled to one or more phase wires of power lines by coupling capacitors. Phase-to-ground coupling and phase-to-phase coupling are the most common coupling methods.

The binding device consists of the following basic elements:

a.Grounding switch: to meet the needs of maintenance and other needs, will be combined with the primary terminal of the equipment direct and effective grounding, to ensure the safety of equipment and personnel.

b.Surge arrester: Limits transient overvoltages from power lines.

c.Discharge coil: Ground the power frequency current from the coupling capacitor.

d.Tuning components (including matching variants): together with coupling capacitors, they form high-pass, band-pass filters, or other networks to improve the transmission efficiency of carrier signals.

Mechanical structure: The two parts of the equipment are combined with the discharge coil and the tuning element (including the matching transformer) in a shell, and the grounding knife switch is outside the shell. Under normal use conditions, the combined equipment should be able to withstand sunlight, rain, fog, hail, snow and ice.

Circuit type: high-pass, band-pass filter or other network.

Specifications The combined equipment can be divided according to the design serial number, coupling capacitor capacitance, and nominal power.

a.Coupling Capacitor Series:

3300，3500，4500，5000，7500，10000，15000 pf。

25， ，600， ，w。

Product nomenclature and model compilation regulations.

The model of the combined equipment is composed of the Chinese pinyin letters that characterize the structural characteristics of the combined equipment and the numbers that characterize the scope of application of the combined equipment, and generally includes three parts. In general, Part 1 represents the type and design type of the combined device, Part 2 represents the nominal power, and Part 3 represents the capacitance of the coupling capacitor. Sections 1 and 3 need to be separated by a hyphen.

Purpose: 1) Combine filters'The upper end of the > filter is connected to the high-voltage transmission line through a coupling capacitor, and the lower end is connected to the high-frequency cable to form a bandpass filter'> filters. It can not only further isolate the high-voltage and high-frequency equipment, and suppress the interference of other frequency signals, but also match the input impedance of the high-frequency path with the input impedance of the high-frequency cable, so as to facilitate the transmission of high-frequency signals.

2) By combining filters'The > filter can also reliably ground the high-voltage power frequency current leaked through the coupling capacitor to ensure the safety of high-frequency equipment.

Hello! Shielding from homogeneous or near-wave-like interference.

If it helps you, hope.

Shielding from homogeneous or near-wave-like interference.

The disconnection and connection of the coupling capacitor will affect the normal operation of the high-frequency protection signal channel of the line. When the line is operating normally, for the protection of long-term signal transmission, disconnecting the coupling capacitor will cause signal interruption, and the opposite transmitter may cause tripping if it does not receive the blocking signal. In the case of protection that operates in the start-and-send mode at fault, an abnormal impulse signal may be emitted when the coupling capacitor is connected, causing the protection to malfunction.

For this reason, when the capacitor is connected to the coupling capacitor, its family sales number should be grounded, and the high-frequency protection should be deactivated. In order to play a role in safety protection, the grounding knife should also be closed (many of the key gears are drop-out fuses), and the disconnected coupling capacitor should be discharged to the ground immediately to prevent the staff from being electrocuted.

Coupling is bai refers to the energy from a medium (e.g. du a gold zhi

genus wires, optical fibers) propagation to another.

The process of DAO medium.

Difference: Edition. 1. The functional rights are different.

In electronics, coupling refers to the transfer of energy from one part of a circuit to another.

Filtering is the operation of filtering out the frequency of a specific band in the signal, which is an important measure to suppress and prevent interference, and filtering is divided into classical filtering and modern filtering.

2. The working principle is different.

With conductive coupling, energy is propagated from a voltage source to a load. Capacitors allow the AC and DC parts of a circuit to be coupled by allowing the AC component to pass through and block the DC component. The transformer can also act as a coupling medium, and a proper impedance match can be achieved by configuring the appropriate impedance at both ends.

Filtering is the operation of filtering out a specific band frequency in a signal, and is an important measure to suppress and prevent interference. It is a probability theory and method that estimates another random process related to it based on the results of observing the results of a random process.

3. The characteristics are different.

If a set of modules all access the same common data environment, the coupling between them is called public coupling. A common data environment can be a global data structure, a shared communication area, a common footprint for memory, and so on.

The term filtering originates from the theory of communication, which is a technique for extracting useful signals from received signals that contain interference. A "received signal" corresponds to a stochastic process to be observed, and a "useful signal" corresponds to a stochastic process to be estimated.

Capacitive coupling is one of the ways in which signals are transmitted in a circuit, which is different from filtering.

In the circuit, it is often necessary to transmit the signal of this level to the next level of the circuit, and this transmission is called coupling. Depending on the components used, there are various coupling methods, such as inductive coupling, capacitive coupling, photoelectric coupling, and DC coupling. The way in which this signal transmission is achieved with capacitors is called capacitive coupling.

The amplifier is a common electrical appliance, the preamplifier amplifies the weak audio signal of the microphone, and needs to transmit it to the power amplifier stage, and the output is enough power to push the speaker to make sound. A capacitor is often used to connect between the pre-amp and the power amplifier, and according to the characteristics of the capacitor "AC and DC isolated", the useful audio signal (AC) is transmitted to the power amplification stage. DC will be isolated, so there is no direct current transmission between the two stages, and the working state of each other will not be affected.

This is what capacitive coupling means.

Capacitors are often used in filter circuits, although they all use the characteristics of capacitors "through AC, DC block", but there are differences, which are manifested in:

1. The role is different. Coupling is to transmit the useful AC components to the next level, while filtering is to remove the harmful AC components.

2. The capacity is different. Coupling often uses a capacity of 10 microfarads or less, while filtering often uses capacities of hundreds or thousands of microfarads.

3. The pressure resistance is different. The withstand voltage of coupling capacitors is generally low, while the withstand voltage of filter capacitors is generally relatively high.

4. The volume is different. The coupling capacitor is relatively small, while the filter capacitor is much larger due to its large capacitance.

Of course, these differences are general and not absolute, for example, sometimes the filter circuit uses a small capacitance capacitor to filter out high-frequency harmful components.

Capacitive coupling: Also known as electric field coupling or electrostatic coupling, it is a type of coupling that occurs due to the presence of distributed capacitance.

Round mode. Filter capacitors are used in power supply rectifier circuits to filter out AC components. Makes the DC output smoother. Decoupling capacitors are used in amplifier circuits where AC is not required to eliminate self-excitation and make the amplifier work stably.

The voltage transformer is used to monitor whether the line is live, and the line is closed and automatically reclosed at the same time to verify that the line is no voltage, there is pressure, and the line side voltage transformer provides the basis for line voltage sampling.

The coupling capacitor is used in conjunction with the wave blocker to reuse a certain phase wire of the high-voltage line as a communication channel, and can also be used as a relay protection high-frequency protection channel. With the development of optical fiber communication technology, this means of communication will gradually fade out of the historical stage.