Tantalum Tubes,Tantalum Dish,Tantalum Rods,Tantalum Sheet Baoji Yongshengtai Titanium Industry Co., Ltd. , https://www.bjystititanium.com
SPD general installation requirements
SPD general installation requirements
Selection of SPDs in Low-Voltage Systems, Installation Locations and the Protections Provided For stationary SPDs, routine installation should follow the following steps:
1) Determine the discharge current path
2) Conductors that mark the extra voltage drop at the device terminal,
Explanation: Residual pressure of Type I and Type II SPDs, or more generally limit voltages.
3) To avoid unnecessary induction loops, the PE conductor of each device should be marked
Note: Two SPDs are required if a single grounding is not possible
4) Establish equipotential bonding between the device and the SPD.
5) To carry out multi-level SPD energy coordination
In order to limit the inductive coupling between the protected portion after installation and the unprotected device portion, certain measurements are required. The mutual inductance can be reduced by the separation of the sensing source and the sacrificial circuit, the selection of the loop angle, and the limitation of the closed loop area.
When the current-carrying component wire is part of a closed loop, the loop and induced voltage are reduced due to the proximity of the wire to the circuit.
In general, it is better to separate the protected conductor from the unprotected conductor, and it should be separated from the grounding conductor. At the same time, in order to avoid transient orthogonal coupling between the power cable and the communication cable, necessary measurements should be made.
Oscillation effect related to guard distance
When SPD1 is used to protect the equipment or is installed on the switchboard of the input port but cannot provide sufficient protection for certain equipment, the SPD2 should be installed as close as possible to the equipment to be protected. If the distance is too far, an oscillating voltage that is 2 times higher than or even higher may be generated on the terminal device. Although SPD protection is used for the device, the oscillating voltage still causes the device to be damaged. The reasonable distance (also known as the guard distance) is related to the type of SPD, the type of system, the steepness and waveform of incoming surge sources, and the connected load. Especially if the device is equivalent to a high-impedance load or there is a divergence inside the device, voltage multiplication may occur. To explain this phenomenon, Figure (4) gives an example of voltage multiplication in this type of situation.
It is generally believed that there will be no oscillation when the distance is less than 10 meters. Figure 4 shows that even if the distance is 10 meters, voltage multiplication may occur, but only if the load is pure capacitance. Sometimes the device has internal protection components (such as varistors) and oscillations are significantly reduced even at long distances. At this point, attention should be paid to the coordination between the SPD and the device's internal protection components.
Explanation: In general, it is not sufficient to install an SPD only near the protected equipment. Due to electromagnetic compatibility reasons (to avoid electromagnetic interference caused by surge voltage, it is good to shunt at the entrance) and to protect the equipment (to avoid flashover between wires), it is better to install SPD at the entrance of the equipment. If the device is not within the protection scope of the SPD installed at the entrance, it is necessary to install an SPD near the device, and matching should also be considered at this time.
Explanation: This phenomenon can be explained by oscillations and traveling waves that are related to the surge frequency and the length of the wire.
Effect of the length of the connecting line
For better overvoltage protection, the SPD's connection leads should be as short as possible. If the wire is too long will cause the SPD voltage drop, in order to provide effective protection it is necessary to reduce the protection level of the SPD installed here. The residual voltage transferred to the device is the sum of the voltage induced on the SPD and on the wire. The two voltages do not necessarily peak at the same time. For practical purposes, they can be added together under normal circumstances. Figure (5) shows how the induction of the connection leads to an increase in the residual pressure of the SPD.
It is generally assumed that the line inductance is 1 μH/m. When the pulse steepness is 1 kA/μs, the induced voltage drop on the wire is close to 1 kV/m, and if the di/dt steepness is greater, the induced voltage value will increase. When possible, when the influence of this inductive reactance is considered to be significantly reduced due to the separation of the loop, Figure 6(6) is the best choice for option c); when option c) cannot be used, option d) is used. , Avoid using scheme a) as much as possible.
Note: If the return line and the incoming line are magnetically coupled by compact wiring, the inductive reactance will be reduced.
When the surge voltage at the entrance to the building is low, install an SPD near the entrance. However, in some special cases, such as the installation of very sensitive equipment (electronic equipment, computers) or the equipment to be protected is too far away from the SPD installed at the entrance, and is caused by lightning discharge and internal interference sources within the building. In the case of electromagnetic fields, it is necessary to install additional SPDs near the protected equipment or inside the equipment.
When the power system and signal network lines enter the protection zone, they should be close to each other and connected to the same metal object to achieve equipotential bonding, which is particularly important for buildings with non-shielded metal (such as wood, masonry structures).
Consider the withstand voltage level of most protected electronic sensitive devices in the system. For the SPD installed at the nearest location of the equipment, the UP value must be at least 20% lower than the equipment's pressure resistance value. Assuming that the SPD installed at the incoming line is within the protection range, if the SPD of the incoming line is multiplied by an overvoltage factor and is lower than UP2, then only the SPD at the incoming line can be used. (See Figure 7)
Note: The user should pay attention to the anti-interference of equipment according to IEC6l000-4-5 standard, using a hybrid wave generator for testing. In this case, the immunity of low-impedance equipment is not only defined by the withstand voltage UW, but part of the inrush current is diverted through the equipment and a reasonable coordination needs to be designed.
When some high-energy switching surges (switching overvoltages) may occur inside the building, additional SPDs need to be installed at this time.
SPD should have features and additional requirements
1. The basic function of SPD
For a low-voltage system under normal operating conditions, the installed SPD should not have a significant impact on the operating characteristics of the system and system equipment.
For low voltage systems with surges and other abnormal operating conditions, the SPD should respond to surges in a timely manner. The SPD can limit transient overvoltages and share the characteristics of surge currents, and reduce the overvoltage to the requirements of IEC60664-1. The class location equipment is below the shock overvoltage rating.
For a low-voltage system that has undergone an abnormal state, that is, SPD that returns to normal after a surge, its high-impedance characteristic should be restored, and measures must be taken to prevent or suppress the freewheeling on the power line.
2. Additional requirements for using SPD
1) Protect direct contact. The SPD should be installed in such a way that it is installed in an inaccessible area or protected from direct contact (such as installing isolation equipment).
2) The safety of SPD failure events. When the surge voltage exceeds the designed maximum capacity and discharge current capacity, the SPD may fail or be damaged. The failure modes of SPD can be broadly divided into open circuit and short circuit.
In open circuit mode, the protected device will no longer be protected. At this time, it is difficult to find that the SPD has failed because it hardly affects the system itself. In order to ensure that the failed SPD can be replaced before the next surge arrives, the SPD must be required to indicate the failure.
In short-circuit mode, the system is severely affected by the failure of the SPD. The short circuit current flows from the power distribution system to the failed SPD. Because the failed SPD is usually not completely short-circuited and has a certain impedance, thermal energy is generated before the open circuit causes combustion. In this case, the protected system does not have a suitable device to disengage from the failed SPD. At this time, the SPD in the short-circuit failure mode is required to install an appropriate disengagement device. (breaker)
SPD selection steps
described as follows:
A: Uc, UT, and Ic
The value of Uc in different power supply systems has been described herein. UT is the short-term overvoltage value that SPD can bear. It is theoretically a straight line. However, in actual practice, some values ​​(power frequency, DC overvoltage) may change with time, so that within a certain time interval (usually between 0.05 seconds and 10 seconds), the maximum continuous operating voltage Uc will be exceeded, so the UT value is used. Greater than UTOV should be considered. However, in fact, it is required that an SPD not only has a high tolerance to short-time overvoltage but also can provide a low level of protection. It can only be discarded by comparison, or it can adopt multiple levels of protection.
When the continuous operating voltage Uc is applied, the maximum continuous operating current through the SPD is Ic. In order to avoid unnecessary action of overcurrent protection devices or other protection devices (such as RCD), the choice of Ic value is very useful. The choice of Ic can be determined by using the diversion of the "fifth law."
B. Protection distance
Mainly refers to the SPD installation location. The general SPD shall be installed on the switchboard of the low-voltage power supply system at the entrance of the building and more on the low-voltage side of the transformer (special note: installation of the SPD in the public power distribution system must be approved by the public power distribution system management department such as the power supply bureau). . When the distance between the switchboard and the power equipment is long or the power equipment needs multiple protection, the SPD2 and SPD3 should be as close as possible to the protected equipment and make equipotential bonding at the junction of the lightning protection area.
In general, there are six steps to the selection of the SPD, see figure (8)
Precautions when using and using SPD
1. Different SPDs should be used within different ranges of use. When selecting the power supply SPD, consider the form of power supply system, rated voltage and other factors. The SPD at the junction of LPZ0 and LPZ1
Must be a product that has passed the 10/350us waveform impact test. For the signal SPD should be considered in the selection of SPD compatibility with electronic devices.
2. SPD protection must be multi-level. For example, for the lightning protection of the power supply of the electronic equipment, at least two levels of protection should be adopted: discharge-type SPD and pressure-limiting SPD.
3. For the effective coordination between SPDs at all levels, when the distance between the two-level SPD power line or communication line is not up to the specified requirements, appropriate decoupling measures should be used between the two SPDs.
4. The computer room built in different environments in cities, suburbs, and mountains must be designed with SPD. The SPD must be selected with proper operating voltage.
5. For unattended occasions, a power SPD with a remote contact can be selected; for an attended station, a power SPD with audible and visual alarm can be selected. All power surge protectors have an old
Display.
SPD general installation requirements
Selection of SPDs in Low-Voltage Systems, Installation Locations and the Protections Provided For stationary SPDs, routine installation should follow the following steps:
1) Determine the discharge current path
2) Conductors that mark the extra voltage drop at the device terminal,
Explanation: Residual pressure of Type I and Type II SPDs, or more generally limit voltages.
3) To avoid unnecessary induction loops, the PE conductor of each device should be marked
Note: Two SPDs are required if a single grounding is not possible
4) Establish equipotential bonding between the device and the SPD.
5) To carry out multi-level SPD energy coordination
In order to limit the inductive coupling between the protected portion after installation and the unprotected device portion, certain measurements are required. The mutual inductance can be reduced by the separation of the sensing source and the sacrificial circuit, the choice of the loop angle, and the limitation of the closed loop area.
When the current-carrying component wire is part of a closed loop, the loop and induced voltage are reduced due to the proximity of the wire to the circuit.
In general, it is better to separate the protected conductor from the unprotected conductor, and it should be separated from the grounding conductor. At the same time, in order to avoid transient orthogonal coupling between the power cable and the communication cable, necessary measurements should be made.
Oscillation effect related to guard distance
When SPD1 is used to protect the equipment or is installed on the switchboard of the input port but cannot provide sufficient protection for certain equipment, the SPD2 should be installed as close as possible to the equipment to be protected. If the distance is too far, an oscillating voltage that is 2 times higher than or even higher may be generated on the terminal device. Although SPD protection is used for the device, the oscillating voltage still causes the device to be damaged. The reasonable distance (also known as the guard distance) is related to the type of SPD, the type of system, the steepness and waveform of incoming surge sources, and the connected load. Especially if the device is equivalent to a high-impedance load or there is a divergence inside the device, voltage multiplication may occur. To explain this phenomenon, Figure (4) gives an example of voltage multiplication in this type of situation.
It is generally believed that there will be no oscillation when the distance is less than 10 meters. Figure 4 shows that even if the distance is 10 meters, voltage multiplication may occur, but only if the load is pure capacitance. Sometimes the device has internal protection components (such as varistors) and oscillations are significantly reduced even at long distances. At this point, attention should be paid to the coordination between the SPD and the device's internal protection components.
Explanation: In general, it is not sufficient to install an SPD only near the protected equipment. Due to electromagnetic compatibility reasons (to avoid electromagnetic interference caused by surge voltage, it is good to shunt at the entrance) and to protect the equipment (to avoid flashover between wires), it is better to install SPD at the entrance of the equipment. If the device is not within the protection scope of the SPD installed at the entrance, it is necessary to install an SPD near the device, and matching should also be considered at this time.
Explanation: This phenomenon can be explained by oscillations and traveling waves that are related to the surge frequency and the length of the wire.
Effect of the length of the connecting line
For better overvoltage protection, the SPD's connection leads should be as short as possible. If the wire is too long will cause the SPD voltage drop, in order to provide effective protection it is necessary to reduce the protection level of the SPD installed here. The residual voltage transferred to the device is the sum of the voltage induced on the SPD and on the wire. The two voltages do not necessarily peak at the same time. For practical purposes, they can be added together under normal circumstances. Figure (5) shows how the induction of the connection leads to an increase in the residual pressure of the SPD.
It is generally assumed that the line inductance is 1 μH/m. When the pulse steepness is 1 kA/μs, the induced voltage drop on the wire is close to 1 kV/m, and if the di/dt steepness is greater, the induced voltage value will increase. When possible, when the influence of this inductive reactance is considered to be significantly reduced due to the separation of the loop, Figure 6(6) is the best choice for option c); when option c) cannot be used, option d) is used. , Avoid using scheme a) as much as possible.
Note: If the return line and the incoming line are magnetically coupled by compact wiring, the inductive reactance will be reduced.
When the surge voltage at the entrance to the building is low, install an SPD near the entrance. However, in some special cases, such as the installation of very sensitive equipment (electronic equipment, computers) or the equipment to be protected is too far away from the SPD installed at the entrance, and is caused by lightning discharge and internal interference sources within the building. In the case of electromagnetic fields, it is necessary to install additional SPDs near the protected equipment or inside the equipment.
When the power system and signal network lines enter the protection zone, they should be close to each other and connected to the same metal object to achieve equipotential bonding, which is particularly important for buildings with non-shielded metal (such as wood, masonry structures).
Consider the withstand voltage level of most protected electronic sensitive devices in the system. For the SPD installed at the nearest location of the equipment, the UP value must be at least 20% lower than the equipment's pressure resistance value. Assume that the SPD installed at the incoming line is within the protection range. If the SPD of the incoming line is multiplied by an overvoltage factor and is lower than UP2, then only the SPD at the incoming line can be used. (See Figure 7)
Note: The user should pay attention to the anti-interference of equipment according to IEC6l000-4-5 standard, using a hybrid wave generator for testing. In this case, the immunity of low-impedance equipment is not only defined by the withstand voltage UW, but part of the inrush current is diverted through the equipment and a reasonable coordination needs to be designed.
When some high-energy switching surges (switching overvoltages) may occur inside the building, additional SPDs need to be installed at this time.
SPD should have features and additional requirements
1. The basic function of SPD
For a low-voltage system under normal operating conditions, the installed SPD should not have a significant impact on the operating characteristics of the system and system equipment.
For low voltage systems with surges and other abnormal operating conditions, the SPD should respond to surges in a timely manner. The SPD can limit transient overvoltages and share the characteristics of surge currents, and reduce the overvoltage to the requirements of IEC60664-1. The class location equipment is below the shock overvoltage rating.
For a low-voltage system that has undergone an abnormal state, that is, SPD that returns to normal after a surge, its high-impedance characteristics should be restored, and measures must be taken to prevent or suppress freewheeling on the power line.
2. Additional requirements for using SPD
1) Protect direct contact. The SPD should be installed in such a way that it is installed in an inaccessible area or protected from direct contact (such as installing isolation equipment).
2) The safety of SPD failure events. When the surge voltage exceeds the designed maximum capacity and discharge current capacity, the SPD may fail or be damaged. The failure modes of SPD can be broadly divided into open circuit and short circuit.
In open circuit mode, the protected device will no longer be protected. At this time, it is difficult to find that the SPD has failed because it hardly affects the system itself. In order to ensure that the failed SPD can be replaced before the next surge arrives, the SPD must be required to indicate the failure.
In short-circuit mode, the system is severely affected by the failure of the SPD. The short circuit current flows from the power distribution system to the failed SPD. Because the failed SPD is usually not completely short-circuited and has a certain impedance, thermal energy is generated before the open circuit causes combustion. In this case, the protected system does not have a suitable device to disengage from the failed SPD. At this time, the SPD in the short-circuit failure mode is required to install an appropriate disengagement device. (breaker)
SPD selection steps
described as follows:
A: Uc, UT, and Ic
The value of Uc in different power supply systems has been described herein. UT is the short-term overvoltage value that SPD can bear. It is theoretically a straight line. However, in actual practice, some values ​​(power frequency, DC overvoltage) may change with time, so that within a certain time interval (usually between 0.05 seconds and 10 seconds), the maximum continuous operating voltage Uc will be exceeded, so the UT value is used. Greater than UTOV should be considered. However, in fact, it is required that an SPD not only has a high tolerance to short-time overvoltage but also can provide a low level of protection. It can only be discarded by comparison, or it can adopt multiple levels of protection.
When the continuous operating voltage Uc is applied, the maximum continuous operating current through the SPD is Ic. In order to avoid unnecessary action of overcurrent protection devices or other protection devices (such as RCD), the choice of Ic value is very useful. The choice of Ic can be determined by using the diversion of the "fifth law."
B. Protection distance
Mainly refers to the SPD installation location. The general SPD shall be installed on the switchboard of the low-voltage power supply system at the entrance of the building and more on the low-voltage side of the transformer (special note: installation of the SPD in the public power distribution system must be approved by the public power distribution system management department such as the power supply bureau). . When the distance between the switchboard and the power equipment is long or the power equipment needs multiple protection, the SPD2 and SPD3 should be as close as possible to the protected equipment and make equipotential bonding at the junction of the lightning protection area.
In general, there are six steps to the selection of the SPD, see figure (8)
Precautions when using and using SPD
1. Different SPDs should be used within different ranges of use. When selecting the power supply SPD, consider the form of power supply system, rated voltage and other factors. The SPD at the junction of LPZ0 and LPZ1
Must be a product that has passed the 10/350us waveform impact test. For the signal SPD should be considered in the selection of SPD and electronic equipment compatibility.
2. SPD protection must be multi-level. For example, for the lightning protection of the power supply of the electronic equipment, at least two levels of protection should be adopted: discharge-type SPD and pressure-limiting SPD.
3. For the effective coordination between SPDs at all levels, when the distance between the two-level SPD power line or communication line is not up to the specified requirements, appropriate decoupling measures should be used between the two SPDs.
4. The computer room built in different environments in cities, suburbs, and mountains must be designed with SPD. The SPD must be selected with proper operating voltage.
5. For unattended occasions, a power SPD with a remote contact can be selected; for an attended station, a power SPD with audible and visual alarm can be selected. All power surge protectors have an old
Display.
6. The signal SPD should meet the needs of the signal transmission rate, working level, and network type, and the interface should be compatible with the protected equipment.
7. Since the signal SPD is connected in series in the line, the SPD with smaller insertion loss should be used when it is selected.
8. When selecting an SPD, the designated supplier should be provided with relevant SPD technical parameter data.
9. The correct installation can achieve the desired effect. The installation of the SPD should be strictly based on the installation requirements provided by the factory.
6. The signal SPD should meet the needs of the signal transmission rate, working level, and network type, and the interface should be compatible with the protected equipment.
7. Since the signal SPD is connected in series in the line, the SPD with smaller insertion loss should be used when it is selected.
8. When selecting an SPD, the designated supplier should be provided with relevant SPD technical parameter data.
9. The correct installation can achieve the desired effect. The installation of the SPD should be strictly based on the installation requirements provided by the factory.