What is working grounding and what is the difference between working grounding and protective ground

The grounding carried out in order to guarantee the reliable operation of electrical equipment in normal and accident situations is called working grounding, such as direct grounding and indirect grounding of neutral points and repeated grounding of the neutral line.

Lightning protection grounding, etc. are all working grounding.

Working grounding refers to the power system.

A certain point (such as a neutral point) is directly connected to the ground, or connected with the earth metal through an arc suppression coil, resistance, etc., such as a transformer and transformer are grounded at the neutral point.

Wait. Compared with the working grounding to ensure the normal operation of electrical equipment, in order to ensure personal safety and avoid human electric shock accidents, the way of connecting the metal shell of electrical equipment with the grounding device is called protective grounding.

When the human body touches the electrical equipment whose shell has been electrified, it is due to the contact resistance of the grounding body.

Much less than the resistance of the human body.

Most of the current enters the earth through the grounding body, and only a small part flows through the human body, so as not to cause harm to human life.

Grounding is divided into protective grounding and working grounding.

Protective grounding generally refers to the metal shell of electrical equipment, due to insulation damage may be electrified, in order to prevent this voltage from endangering personal safety of the grounding, called protective grounding, as shown in Figure 2, this grounding, generally used in the neutral point non-grounding system.

Working grounding means that under normal or accident conditions, in order to ensure the reliable operation of electrical equipment, it must be directly or through special devices such as arc suppression coils, reactances, resistances, breakdown fuses and ground at a certain point in the power system (such as the neutral point of a generator or transformer, a point of a lightning arrester to prevent overvoltage) and the ground. The decoupling circuit is also a working ground.

Work grounding. Working earthing is the grounding of a circuit or equipment to meet the operational requirements, such as the grounding of the low-voltage neutral point of a transformer.

Communication work grounding.

A point in the power system is connected to the earth directly or through special equipment.

Working grounding mainly refers to the neutral point or neutral (N-line) grounding of the transformer. The n wire must be insulated with copper core. In the power distribution, there are auxiliary equipotential terminals, which are generally in the cabinet.

It must be noted that the terminal block must not be exposed; It cannot be mixed with other grounding systems, such as DC grounding, shielding grounding, anti-static grounding, etc.; It cannot be connected with PE wire.

In the power system, all the grounding required for operation can be called working grounding.

In the power system, all live operation must be grounded, which is called working grounding, which is the ground wire that I usually say.

Grounding: working grounding, lightning protection grounding and protective grounding.

Distinguishes the ground wire of the circuit from the ground of the ground.

Work grounding withProtective groundingThe differences are as follows:

1. The definitions are different.

In order to ensure the reliable operation of electrical equipment under normal or fault conditions, the power system will be used.

A point in the ground is called a working ground.

Grounding the exposed conductive part of the equipment with a voltage to ground that may be at risk in the event of a fault is called protective grounding.

2. The role is different.

Working grounding: It can maintain the non-fault relative ground voltage unchanged; It can ensure the accuracy of relatively low finger spine voltage measurement in a primary system; When lightning strikes, the lightning current is discharged to the ground drainage.

Protective grounding: In order to ensure personal safety, avoid or reduce the hazard of accidents, electrical engineering.

Protective grounding is often used.

3. The scope of application is different.

Working grounding: The neutral point of the power supply (generator or transformer) is directly (or through the arc suppression coil) grounding, voltage transformer.

The neutral point of the primary side coil is grounded.

Grounding of lightning protection equipment.

Protective Grounding: A metal enclosure on electrical equipment that is insulated from a dotted part.

Protective grounding: grounding of the metal shell of communication equipment and other abnormal live parts.

Working grounding: In the AC DC power supply or power distribution panel (note that it is inside the power supply), the positive pole of the output DC 48V main terminal block is grounded; For 24 systems, it is DC 24V negative ground.

The concept of working grounding is not for the power line connection of the 48V positive (or 24 negative pole) of DC electrical communication equipment, and the connection of the 48V positive (or 24 negative pole) of DC electrical communication equipment to the power supply equipment should belong to the concept of power line connection and should not belong to the ground wire.

Connecting the Sphere. Shield grounding is a kind of working grounding; The zero line of the electrical shell is the protective grounding; More than two times the neutral line is grounded repeatedly.

Working grounding: Working grounding refers to the direct connection of a certain point of the power system (such as the neutral point) to the ground, or the connection with the earth metal through arc suppression coils, resistors, etc., such as the neutral point grounding of transformers and transformers.

Protective grounding: Grounding to prevent the metal shell of electrical installations, the frame of power distribution devices and line towers from being electrified and endangering people and the safety of the equipment. The so-called protective grounding is a protective wiring method that reliably connects the metal part of the electrical appliance (that is, the metal structure part insulated from the live part) that is not charged under normal circumstances and may be charged after the insulation material is damaged or under other circumstances.

The basic principle of grounding protection is to limit the leakage current of the leakage equipment to the ground, so that it does not exceed a certain safety range, and once it exceeds a certain setting value, the protector can automatically cut off the power supply; The principle of zero connection protection is to use the short-circuit current to promote the rapid action of the protection device on the line with the help of the zero connection line, so that when the equipment hits the shell after the insulation is damaged to form a single-phase metal short circuit.

The essence is to use the ground as a current loop to fix the cable grounding potential at the allowable ground potential under the conditions of normal and accident and internal overvoltage and lightning overvoltage of the cable system. The grounding potential is not only related to the waveform and amplitude of the current carried by the grounding section, but also related to the geometric size of the grounding body, geodetic resistivity and other parameters.

Protective grounding is the grounding carried out to prevent the metal shell of the electrical installation, the frame of the power distribution device and the line tower from being charged to endanger the safety of people and equipment.

Working grounding refers to the direct connection of a certain point of the power system (such as the neutral point) to the ground, or the connection with the earth metal through arc suppression coils, resistors, etc., such as the neutral point grounding of transformers and transformers.

The simplest: the working grounding is also into the ground, which is required by the equipment, and may flow through a large grounding current, and the working grounding potential may also be slightly higher, and the noise level on the ground line may be very high.

Comparatively high. Protective grounding

It is also into the ground, but basically will not access strong electrical equipment, but mainly for personal protection and set up, the ground wire current flowing over the protective grounding is generally very small, the ground wire level is very low, and it is safe enough.

In general, a distance of at least 5 meters should be left between the protective ground and the working ground.

In addition, it can also be subdivided into strong electric ground, weak electric ground, lightning protection ground, although they are all ground wires, but the first rolling points must be separated by appropriate distances, different types of grounding points do not share the ground wire, and the entry points are separated by more than 5 meters.

For modern buildings, there are many backfill layers around the perimeter, the thickness can reach 5-6 meters, in this case it is recommended to use geological drilling, drill a hole tens of meters deep, with a diameter of about 100-200mm, and then hot-dip galvanized steel pipe.

Welding and burying the surplus section by section can be very reliable to achieve a grounding resistance of less than 1.

1. Earthing refers to the neutral point of the power system and the electrical device, the exposed conductive part of the electrical equipment and the external conductive part of the device are connected to the earth through the conductor. It can be divided into working grounding, lightning protection grounding and protective grounding. The working grounding is set by the operation needs of the power system (such as neutral grounding), so under normal circumstances, there will be a long-term flow of current over the grounding electrode, but it is only an unbalanced current of a few amperes to tens of amperes.

In the event of a grounding fault in the system, there will be thousands of amperes of working current flowing through the grounding electrode, but the current will be cut off by the relay protection device, even if it is a backup protection, the action is generally within 1s. Lightning protection grounding is a grounding designed to eliminate the dangerous effects of overvoltage, such as the grounding of lightning rods, lightning wires and lightning arresters. The lightning protection grounding will only flow under the action of lightning impact, and the lightning current amplitude flowing through the lightning protection grounding electrode can reach tens to hundreds of thousands of amperes, but the duration is very short.

Protective grounding is to prevent equipment from endangering personal safety due to insulation damage and electrification, such as metal shells, reinforced concrete poles and metal towers of power equipment. Protective grounding will only flow through the equipment if the insulation is damaged, and its value can vary over a wide range. When the current flows through the above three types of grounding electrodes, the potential of the grounding electrodes will increase, which will affect the safety of people and equipment.

For this purpose, it is necessary to limit the potential increase of the grounding electrode or to take appropriate safety measures to ensure the safety of equipment and personnel.

2. The ground wire is a wire connected to the earth, the shell or the wire with zero reference potential in the electrical system or electronic equipment. On general electrical appliances, the ground wire is connected to the shell to prevent electric shock accidents caused by the internal insulation damage to the shell. Ground wire is short for grounding device.

Ground wire is further divided into working grounding and safety grounding. In order to prevent people from electrocution accidents when using electronic equipment such as home appliances and offices, the protective grounding is a kind of safety grounding guard. A ground wire is a wire in an electrical system or electronic device that is connected to the ground, to the enclosure, or to a wire with a reference potential of zero.

On general electrical appliances, the ground wire is connected to the shell to prevent electric shock accidents caused by the internal insulation damage to the shell. The symbol for the ground wire is pe; It can be divided into two types: power supply ground wire and circuit ground wire. According to the current standard in China, when the third circuit in GB2681 is marked according to the color of the wire, it should generally be the phase wire - phase A yellow, phase B green, and phase C red.

Neutral wire - light blue, the ground wire is yellow and green, if it is a three-pin socket, the left is the neutral wire, the middle (top) is the ground wire, and the right is the live wire.

Working grounding and protection are two concepts in the power system.

Working grounding refers to connecting the neutral point of a force system (e.g., the neutral point of a transformer) to the ground through a grounding electrode to provide a working environment in the circuit. It is used to supply the current circuits required for power distribution and electrical installations, as well as for low voltage excursion and system stability in the system.

Grounding protection refers to the adoption of measures in the electrical system to make the fault current flow into the ground through the grounding electrode, so as to play a role in the safety of the body and the safety of the equipment. Typically, the housing of electrical equipment or a conductive device component is connected to a grounding electrode to ensure that the faulty current can be dispersed throughout the ground flow surface in the event of a fault.

Therefore, the grounding master is to provide electrical energy and the current circuit of the equipment operation, while the protective grounding is mainly to protect the safety of people and the safety of equipment. Both are important grounding measures in the power system, but the purpose and use scenario are slightly the same.

1. Caution is different.

In order to ensure the reliable operation of electrical equipment under normal or fault conditions, grounding a certain point in the power system is called working grounding.

Grounding the exposed conductive portion of a device that may present a dangerous voltage to ground in the event of a fault is called protective grounding.

2. The role is different.

Working grounding: It can maintain the non-fault relative ground voltage unchanged; It can ensure the accuracy of relatively low voltage measurement in the primary system; When lightning strikes, the ground is pure and filial piety is discharged.

Protective grounding: In order to ensure personal safety and avoid or reduce the hazard of accidents, protective grounding is often used in electrical engineering.

3. The scope of application is different.

Working grounding: the neutral point of the power supply (generator or transformer) is directly grounded (or through the arc suppression coil), the neutral point of the primary side coil of the voltage transformer is grounded, and the lightning protection equipment is grounded.

Protective Grounding: A metal enclosure on electrical equipment that is insulated from a dotted part.

Working grounding refers to the direct connection of a certain point of the power system (such as the noisy point in the middle) to the earth, or to connect with the earth's Jinsun subordinates through the lack of arc suppression coil and resistance, such as the neutral point grounding of transformers and transformers. [1] Chinese name: working grounding, foreign name: working earthing, reducing human body contact voltage, other types of signals, ground, analog ground, etc., applications, anti-electric shock protection, etc.