A large number of large copper plates should be buried inside the well that is well grounded, and then copper bars or copper meshes should be used in conjunction with the interior to achieve good results (other metals are acceptable but susceptible to corrosion)
The grounding system of the computer room is an important means to prevent the interference of parasitic capacitive coupling, to protect the safety of equipment and people, and to ensure the stable and reliable operation of the computer system.
The grounding system of an electronic computer is the simplest, most economical, and most effective one in terms of anti-jamming design. If grounding is properly combined with shielding, the noise problem can be better resolved.
Thus, a computer system in order to ensure safe, reliable, and stable operation, to ensure the equipment, personal safety, for the different requirements of different types of computers, should be designed in the form of an appropriate earthing system.
According to the requirements of the computer grounding system in the "Computer Technology Requirements" of the national standard, the requirements for the computer grounding system are specified. The computing stations generally have the following types:
DC ground of the computer system; resistance value is not more than 1Ω.
Exchange work place; resistance value is not more than 4Ω.
Safety ground; resistance value is not more than 4Ω.
Anti-static grounding; resistance value does not hit 4Ω.
Lightning protection ground; resistance value does not hit 10Ω.
The so-called ground, i.e. to a point in the circuit or a wire with a metal case together with the earth, a ground current is easy to flow as the target, and therefore the lower the resistance to ground, ground current to flow more easily. In addition, the grounding of the electronic computer system is also desired to minimize potential fluctuations that cause noise. Therefore, the lower the grounding resistance, the better.
When dealing with computer grounding, the following two points should be noted:
Signal circuits and power circuits, high voltage circuits and low voltage circuits should not use common ground loops;
The grounding of sensitive circuits should be isolated or shielded separately to prevent backflow and electrostatic induction from causing interference.
The following description of several ground lines and implementation methods are as follows:
The role of exchange work place
In the computer system, there are a large number of electrical equipment using 380V/220V AC power supply, such as the computer's external equipment, transformers, fans and maintenance equipment on the air-conditioning equipment cabinet, according to national regulations to carry out work grounding, that is to neutral grounding Also known as secondary grounding. Its role is to ensure personal safety and equipment safety.
In the computer system, there are many AC devices, but the secondary grounding problem of AC devices is often not paid attention to by people. For this reason, people and equipment are often caused some unnecessary harm.
specific measure:
Connect the neutral point outside the computer in series with the insulated wire to the center line of the power distribution cabinet and ground it with a grounding strap. Other AC equipment, such as air conditioners, new fans, frequency stabilization equipment and other neutral points are each independently grounded according to the electrical specifications.
Safe place
All the equipment housings in the equipment room and the housings of the electric motors, air conditioners and other equipment are properly grounded, which is called safety protection. When the insulation is punctured due to the large amount of stray impedance between the chassis and the ground, the voltage on the chassis is substantially equal to the voltage of the AC power supply (220V). When the human body touches the casing, and the insulation of the human body is not good, there will be a considerable amount of current through the human body into the earth. This is very dangerous. If the chassis grounding situation is completely different. When the insulation is broken down, the ground short-circuit current flows into the ground along the two ground paths and the human body. Because the grounding resistance is very small, it is far less than the human body resistance. Large values ​​of current flow into the ground through the grounding resistor, thereby protecting personal safety.
Implementing measures:
The safe protection place in the computer room is to connect the cabinets of all cabinets with several insulated conductors in series, and then use a grounding busbar (multi-strand braided wire connected to the earth).
Other equipment in the computer room, such as air conditioners.
The DC ground of the computer system is also called logical ground.
In order for the computer to work properly, all the electronics of the machine must operate at a stable base potential, which is the zero potential reference point. When designing a DC ground, care should be taken to eliminate the noise voltage generated when each circuit current flows through a common ground impedance. We do not suspend the DC ground, or use the method of DC ground connection, that is, the digital circuit in the electronic computer is connected to the earth and the resistance is determined according to the requirements of Party A.
In a system that uses DC to ground, it should also have a good safety protection system. Moreover, the DC ground and the casing safety ground are separated in many computer systems, ie are insulated from each other in the engine room. This provides a low-resistance path to ground release for high-frequency interference and also provides a low-resistance path for venting of the chassis (electrostatic).
DC ground connection and selection:
Series grounding: Multi-point grounding, the so-called series grounding, is to connect the DC ground of each device in the computing system in series to the copper ground that is the DC ground. It should be noted that the direct wire used here is a multi-strand braided or copper tape and should be insulated from the housing.
Connected to the ground: single point grounding computer system with a plurality of shielded cords connected to the copper block ground wire, copper pads under the insulating material.
Lightning protection ground
Lightning is a natural discharge phenomenon in the atmosphere. Lightning strikes discharge very quickly and lightning currents change drastically. Lightning current increases rapidly when thunderclouds begin to discharge, and currents can reach 200-300 kiloamperes during lightning. The destruction of lightning can basically be divided into three categories. The first type is the effect of direct lightning, ie lightning strikes directly on buildings or equipment. Cause damage. The second type is a secondary effect of lightning, commonly referred to as lightning, that the role of electrostatic and magnetic effects generated by lightning current effect generated in: With the lightning current with a drastic change in the electromagnetic field generated by a lightning current. On the other hand, static charge sensing induces high voltages (up to hundreds of thousands of volts) on metal objects or on electrical circuits, which can seriously endanger the safety of equipment and personnel. The third category is that lightning currents carry high voltages along the electrical lines and pipeline lines to the interior of buildings, creating a so-called potential introduction, which of course is very dangerous.
Lightning protection device
In general, lightning protection devices can be divided into three basic parts.
Lightning receptor
A lightning receptor is also called a lightning protection device. It is a metal conductor that receives lightning currents. It is also known as a lightning rod, a lightning conductor, or a lightning protection net.
Downstream
The down conductor is the conductor that connects the lightning rod (net) and the grounding device. It is usually laid on the roof and the wall. Its role is to direct the lightning current from the lightning protection device to the grounding device.
Grounding device - The grounding pile should pay attention to that, for the safety of equipment and human body, there should be an interval of more than 15m between the lightning protection ground and the DC ground and the safe protection ground.
Several kinds of grounding system relations
If the DC component systems still, the security protected, and the exchange of lightning protection, and access to each different piles, the biggest advantage of this scheme is that interference to other equipment can be prevented and stable operation of the computer, but the construction of complex Costly and difficult to find a suitable occasion.
Now we adopt a scheme in which the DC ground and the lightning protection ground are each independently grounded, and the safety protection ground and the exchange work ground share a ground pile. That is, all the AC power equipment in the computer room are connected together with the midline terminal of the power distribution cabinet; the casings (shelves) of the equipments are connected together with insulated wires, and they are also connected to the neutral terminal of the power distribution cabinet. On the bus, lead the busbar to the ground of the engine room.
The grounding system of the computer room is an important means to prevent the interference of parasitic capacitive coupling, to protect the safety of equipment and people, and to ensure the stable and reliable operation of the computer system.
The grounding system of an electronic computer is the simplest, most economical, and most effective one in terms of anti-jamming design. If grounding is properly combined with shielding, the noise problem can be better resolved.
Thus, a computer system in order to ensure safe, reliable, and stable operation, to ensure the equipment, personal safety, for the different requirements of different types of computers, should be designed in the form of an appropriate earthing system.
According to the requirements of the computer grounding system in the "Computer Technology Requirements" of the national standard, the requirements for the computer grounding system are specified. The computing stations generally have the following types:
DC ground of the computer system; resistance value is not more than 1Ω.
Exchange work place; resistance value is not more than 4Ω.
Safety ground; resistance value is not more than 4Ω.
Anti-static grounding; resistance value does not hit 4Ω.
Lightning protection ground; resistance value does not hit 10Ω.
The so-called ground, i.e. to a point in the circuit or a wire with a metal case together with the earth, a ground current is easy to flow as the target, and therefore the lower the resistance to ground, ground current to flow more easily. In addition, the grounding of the electronic computer system is also desired to minimize potential fluctuations that cause noise. Therefore, the lower the grounding resistance, the better.
When dealing with computer grounding, the following two points should be noted:
Signal circuits and power circuits, high voltage circuits and low voltage circuits should not use common ground loops;
The grounding of sensitive circuits should be isolated or shielded separately to prevent backflow and electrostatic induction from causing interference.
The following description of several ground lines and implementation methods are as follows:
The role of exchange work place
In the computer system, there are a large number of electrical equipment using 380V/220V AC power supply, such as the computer's external equipment, transformers, fans and maintenance equipment on the air-conditioning equipment cabinet, according to national regulations to carry out work grounding, that is to neutral grounding Also known as secondary grounding. Its role is to ensure personal safety and equipment safety.
In the computer system, there are many AC devices, but the secondary grounding problem of AC devices is often not paid attention to by people. For this reason, people and equipment are often caused some unnecessary harm.
specific measure:
Connect the neutral point outside the computer in series with the insulated wire to the center line of the power distribution cabinet and ground it with a grounding strap. Other AC equipment, such as air conditioners, new fans, frequency stabilization equipment and other neutral points are each independently grounded according to the electrical specifications.
Safe place
All the equipment housings in the equipment room and the housings of the electric motors, air conditioners and other equipment are properly grounded, which is called safety protection. When the insulation is punctured due to the large amount of stray impedance between the chassis and the ground, the voltage on the chassis is substantially equal to the voltage of the AC power supply (220V). When the human body touches the casing, and the insulation of the human body is not good, there will be a considerable amount of current through the human body into the earth. This is very dangerous. If the chassis grounding situation is completely different. When the insulation is broken down, the ground short-circuit current flows into the ground along the two ground paths and the human body. Because the grounding resistance is very small, it is far less than the human body resistance. Large values ​​of current flow into the ground through the grounding resistor, thereby protecting personal safety.
Implementing measures:
The safe protection place in the computer room is to connect the cabinets of all cabinets with several insulated conductors in series, and then use a grounding busbar (multi-strand braided wire connected to the earth).
Other equipment in the computer room, such as air conditioners.
The DC ground of the computer system is also called logical ground.
In order for the computer to work properly, all the electronics of the machine must operate at a stable base potential, which is the zero potential reference point. When designing a DC ground, care should be taken to eliminate the noise voltage generated when each circuit current flows through a common ground impedance. We do not suspend the DC ground, or use the method of DC ground connection, that is, the digital circuit in the electronic computer is connected to the earth and the resistance is determined according to the requirements of Party A.
In a system that uses DC to ground, it should also have a good safety protection system. Moreover, the DC ground and the casing safety ground are separated in many computer systems, ie are insulated from each other in the engine room. This provides a low-resistance path to ground release for high-frequency interference and also provides a low-resistance path for venting of the chassis (electrostatic).
DC ground connection and selection:
Series grounding: Multi-point grounding, the so-called series grounding, is to connect the DC ground of each device in the computing system in series to the copper ground that is the DC ground. It should be noted that the direct wire used here is a multi-strand braided or copper tape and should be insulated from the housing.
Connected to the ground: single point grounding computer system with a plurality of shielded cords connected to the copper block ground wire, copper pads under the insulating material.
Lightning protection ground
Lightning is a natural discharge phenomenon in the atmosphere. Lightning strikes discharge very quickly and lightning currents change drastically. Lightning current increases rapidly when thunderclouds begin to discharge, and currents can reach 200-300 kiloamperes during lightning. The destruction of lightning can basically be divided into three categories. The first type is the effect of direct lightning, ie lightning strikes directly on buildings or equipment. Cause damage. The second type is a secondary effect of lightning, commonly referred to as lightning, that the role of electrostatic and magnetic effects generated by lightning current effect generated in: With the lightning current with a drastic change in the electromagnetic field generated by a lightning current. On the other hand, static charge sensing induces high voltages (up to hundreds of thousands of volts) on metal objects or on electrical circuits, which can seriously endanger the safety of equipment and personnel. The third category is that lightning currents carry high voltages along the electrical lines and pipeline lines to the interior of buildings, creating a so-called potential introduction, which of course is very dangerous.
Lightning protection device
In general, lightning protection devices can be divided into three basic parts.
Lightning receptor
A lightning receptor is also called a lightning protection device. It is a metal conductor that receives lightning currents. It is also known as a lightning rod, a lightning conductor, or a lightning protection net.
Downstream
The down conductor is the conductor that connects the lightning rod (net) and the grounding device. It is usually laid on the roof and the wall. Its role is to direct the lightning current from the lightning protection device to the grounding device.
Grounding device - The grounding pile should pay attention to that, for the safety of equipment and human body, there should be an interval of more than 15m between the lightning protection ground and the DC ground and the safe protection ground.
Several kinds of grounding system relations
If the DC component systems still, the security protected, and the exchange of lightning protection, and access to each different piles, the biggest advantage of this scheme is that interference to other equipment can be prevented and stable operation of the computer, but the construction of complex Costly and difficult to find a suitable occasion.
Now we adopt a scheme in which the DC ground and the lightning protection ground are each independently grounded, and the safety protection ground and the exchange work ground share a ground pile. That is, all the AC power equipment in the computer room are connected together with the midline terminal of the power distribution cabinet; the casings (shelves) of the equipments are connected together with insulated wires, and they are also connected to the neutral terminal of the power distribution cabinet. On the bus, lead the busbar to the ground of the engine room.
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