What is a surge? Is it harmful? How to suppress it? A surge is an instantaneous peak that exceeds the stable value, which includes surge voltage and surge current. There are many reasons for surges to occur. Possible causes of surges are: heavy equipment, short circuits, power switching, or large engines. Products containing surge blocking devices can effectively absorb large bursts of energy to protect connected equipment from damage. The most common is the voltage transients and surges encountered during the use of Electronic products, resulting in damage to electronic products. The reason for the damage is the semiconductor devices (including diodes, transistors, thyristors and integrated circuits) in electronic products. ) is burned out or broken down. This article describes the solutions for suppressing surges~
It is estimated that 75% of failures in electronic products are caused by transients and surges. Voltage transients and surges are everywhere. Power grids, lightning strikes, blasting, and even people walking on carpets will generate tens of thousands of volts of static induced voltage. These are the invisible deadly killers of electronic products. Therefore, in order to improve the reliability of electronic products and the safety of the human body, it is necessary to take protective measures against voltage transients and surges.
Method 1: Ground the whole machine and the system. The ground (common end) of the whole machine and the system should be separated from the earth. The whole machine and each subsystem in the system should have an independent public end, and data needs to be transmitted between the subsystems. Or signal, the ground should be used as the reference level, and the ground wire (surface) must be able to flow a large current, such as several hundred amperes.
Method 2: Use voltage transient and surge protection devices in the whole machine and key parts of the system (such as computer monitors, etc.), so that voltage transients and surges are bypassed to the subsystem ground and the earth through the protection device, thereby The transient voltage and surge amplitude entering the whole machine and system are greatly reduced.
Method 3: Use a combination of several voltage transient and surge protection devices for important and expensive complete machines and systems to form a multi-level protection circuit.
The surge protector provides a simple, economical and reliable protection method for the power surge protection of electronic equipment. Through the anti-surge component (MOV), the surge energy is quickly introduced into the lightning induction and operating overvoltage. Earth, protecting equipment from damage.
Protection against surges
(1) Parallel surge protector is connected in parallel to the power supply line
Under normal circumstances, the varistor in the lightning protection module is in a high resistance state. When the power grid is struck by lightning or an instantaneous surge overvoltage occurs during switching operations, the lightning arrester responds within nanoseconds, and the varistor is in a low resistance state, quickly limiting the overvoltage to a very low amplitude. When there is a long-term continuous pulse or continuous overvoltage in the line, the performance of the varistor deteriorates and heats up to a certain extent, causing the thermal tripping mechanism to trip, avoiding fire and protecting the equipment.
(2) The series filtering surge protector is connected in series to the power supply line
Provide safe and clean power supply for valuable electronic equipment. In addition to huge energy, lightning waves also have extremely steep voltage and current rise rates. The parallel-type surge protector can only suppress the amplitude of the lightning wave, but cannot change its sharply rising leading edge. The series filter type power surge protector is connected in series on the power supply line. In the case of overvoltage, MOV1 and MOV2 respond within nanoscale time to clamp the overvoltage; at the same time, the LC filter reduces the steep voltage and current boost rate of the lightning wave by nearly 1000 times, and the residual voltage is reduced by 5 times, thereby Protect sensitive user devices.
(3) Install pressure-sensitive amplitude limiting components between phases and lines of power lines to limit surge overvoltage
The first method has a better protection effect on electrical equipment with a high level of withstand voltage such as lighting, elevators, air conditioners, and motors. But for modern electronic equipment with high integration and compact structure, the actual protection effect is not so satisfactory. The reasons are as follows: Taking the induction lightning strike protection of single-phase 220V AC power supply as an example, the common method is to install a suitable pressure-sensitive element between the zero and ground wires to absorb and limit the peak voltage generated by the induction lightning strike. The lightning protection effect of the power line depends entirely on the selection of the parameters of the varistor and the reliability of the varistor.
The selection of the varistor limit value is based on the peak value of 310V of the mains plus 20% of the power grid fluctuation, 10% of the device dispersion error and 15% of the reliability caused by long-term work such as heat, moisture, and component aging. Factor compensation, the general value is 470V ~ 510V. Various spikes such as induced lightning strikes are limited to 470V. For voltages below 470V, the varistor does not operate.
The power frequency withstand voltage of ordinary low-voltage electrical equipment (machine tools, elevators, lighting, air conditioners, etc.) is generally 1500V AC, and the instantaneous withstand voltage peak value can reach more than 2500V, so the voltage of 470V is very safe. However, the working voltage of modern electronic equipment composed of large-scale integrated circuits is generally between ±5V and ±15V, and the maximum withstand voltage value generally does not exceed 50V, so the high-frequency peak voltage less than 470V superimposed on the mains will be sent directly. If it enters the load, through the space coupling capacitance, the interlayer and interpole capacitances of the transformer are disproportionately transmitted to the switching power supply or the integrated circuit chip, which can cause failure.
Although high-frequency switching power supplies and electronic equipment have corresponding anti-spike interference measures, due to cost and volume constraints, coupled with large changes in the intensity and spectrum of spike interference such as induced lightning strikes, the protection effect is not ideal. This is still the effect obtained when the pressure-sensitive limiting element is ideal. In fact, due to the influence of the residual voltage of the pressure-sensitive element and the lead inductance, under a strong inductive lightning strike, the actual peak value of the limiting voltage may rise to 800V ～1000V or more, and the post-level electronic equipment is threatened.
(4) To strengthen the protection effect of electronic equipment, an ultra-isolation transformer (also known as isolation method) is connected in series between the power supply and the load to isolate high-frequency spike interference, and at the same time, it can facilitate the secondary equipotential connection
The isolation method mainly uses an isolation transformer with a shielding layer. Since the common mode interference is a relatively earth interference, it is mainly transmitted through the coupling capacitance between the transformer windings. If a shielding layer is inserted between the primary and secondary, and it is well grounded, the interference voltage can be shunted through the shielding layer, thereby reducing the interference voltage at the output end.
Theoretically, the transformer with shielding layer can make the attenuation reach about 60dB. However, the quality of the isolation effect often depends on the process of the shielding layer. It is best to choose a 0.2 mm thick copper plate, and add a shielding layer to the primary side and the secondary side. Usually, the shield of the primary side is connected to the shield of the secondary side through a capacitor, and then connected to the ground of the secondary side. The shielding layer of the primary side can also be connected to the ground wire of the primary side, and the shielding layer of the secondary side can be connected to the ground wire of the side. And the cross-sectional area of the ground lead should also be larger. Using an isolation transformer with a shielding layer is a good method, but it is larger in size.
This method is too single in function of the transformer, relatively large in size and weight, inconvenient to install, and has poor protection against medium and low frequency peaks and surges, so the market is limited and there are not many manufacturers. Therefore, it is generally not necessary for non-special occasions.
(5) Absorption method
The absorption method mainly uses absorbing devices to absorb the surge peak interference voltage. The wave absorbing devices all have a common feature, that is, high impedance below the threshold voltage, and once the threshold voltage is exceeded, the impedance will drop sharply, so it has a certain inhibitory effect on the peak voltage. Such absorbing devices mainly include varistors, gas discharge tubes, TVS tubes, solid discharge tubes, etc. Different wave absorbing devices also have their own limitations in suppressing the spike voltage. If the current absorption capacity of the varistor is not large enough, the response speed of the gas amplifying tube is slow. The above are some of the surge suppression methods, I hope to help you.
What is a surge? Is it harmful? How to suppress it? A surge is an instantaneous peak that exceeds the stable value, which includes surge voltage and surge current. There are many reasons for surges to occur. Possible causes of surges are: heavy equipment, short circuits, power switching, or large engines. Products containing surge blocking devices can effectively absorb large bursts of energy to protect connected equipment from damage. The most common is the voltage transients and surges encountered during the use of Electronic products, resulting in damage to electronic products. The reason for the damage is the semiconductor devices (including diodes, transistors, thyristors and integrated circuits) in electronic products. ) is burned out or broken down. This article describes the solutions for suppressing surges~
It is estimated that 75% of failures in electronic products are caused by transients and surges. Voltage transients and surges are everywhere. Power grids, lightning strikes, blasting, and even people walking on carpets will generate tens of thousands of volts of static induced voltage. These are the invisible deadly killers of electronic products. Therefore, in order to improve the reliability of electronic products and the safety of the human body, it is necessary to take protective measures against voltage transients and surges.
Method 1: Ground the whole machine and the system. The ground (common end) of the whole machine and the system should be separated from the earth. The whole machine and each subsystem in the system should have an independent public end, and data needs to be transmitted between the subsystems. Or signal, the ground should be used as the reference level, and the ground wire (surface) must be able to flow a large current, such as several hundred amperes.
Method 2: Use voltage transient and surge protection devices in the whole machine and key parts of the system (such as computer monitors, etc.), so that voltage transients and surges are bypassed to the subsystem ground and the earth through the protection device, thereby The transient voltage and surge amplitude entering the whole machine and system are greatly reduced.
Method 3: Use a combination of several voltage transient and surge protection devices for important and expensive complete machines and systems to form a multi-level protection circuit.
The surge protector provides a simple, economical and reliable protection method for the power surge protection of electronic equipment. Through the anti-surge component (MOV), the surge energy is quickly introduced into the lightning induction and operating overvoltage. Earth, protecting equipment from damage.
Protection against surges
(1) Parallel surge protector is connected in parallel to the power supply line
Under normal circumstances, the varistor in the lightning protection module is in a high resistance state. When the power grid is struck by lightning or an instantaneous surge overvoltage occurs during switching operations, the lightning arrester responds within nanoseconds, and the varistor is in a low resistance state, quickly limiting the overvoltage to a very low amplitude. When there is a long-term continuous pulse or continuous overvoltage in the line, the performance of the varistor deteriorates and heats up to a certain extent, causing the thermal tripping mechanism to trip, avoiding fire and protecting the equipment.
(2) The series filtering surge protector is connected in series to the power supply line
Provide safe and clean power supply for valuable electronic equipment. In addition to huge energy, lightning waves also have extremely steep voltage and current rise rates. The parallel-type surge protector can only suppress the amplitude of the lightning wave, but cannot change its sharply rising leading edge. The series filter type power surge protector is connected in series on the power supply line. In the case of overvoltage, MOV1 and MOV2 respond within nanoscale time to clamp the overvoltage; at the same time, the LC filter reduces the steep voltage and current boost rate of the lightning wave by nearly 1000 times, and the residual voltage is reduced by 5 times, thereby Protect sensitive user devices.
(3) Install pressure-sensitive amplitude limiting components between phases and lines of power lines to limit surge overvoltage
The first method has a better protection effect on electrical equipment with a high level of withstand voltage such as lighting, elevators, air conditioners, and motors. But for modern electronic equipment with high integration and compact structure, the actual protection effect is not so satisfactory. The reasons are as follows: Taking the induction lightning strike protection of single-phase 220V AC power supply as an example, the common method is to install a suitable pressure-sensitive element between the zero and ground wires to absorb and limit the peak voltage generated by the induction lightning strike. The lightning protection effect of the power line depends entirely on the selection of the parameters of the varistor and the reliability of the varistor.
The selection of the varistor limit value is based on the peak value of 310V of the mains plus 20% of the power grid fluctuation, 10% of the device dispersion error and 15% of the reliability caused by long-term work such as heat, moisture, and component aging. Factor compensation, the general value is 470V ~ 510V. Various spikes such as induced lightning strikes are limited to 470V. For voltages below 470V, the varistor does not operate.
The power frequency withstand voltage of ordinary low-voltage electrical equipment (machine tools, elevators, lighting, air conditioners, etc.) is generally 1500V AC, and the instantaneous withstand voltage peak value can reach more than 2500V, so the voltage of 470V is very safe. However, the working voltage of modern electronic equipment composed of large-scale integrated circuits is generally between ±5V and ±15V, and the maximum withstand voltage value generally does not exceed 50V, so the high-frequency peak voltage less than 470V superimposed on the mains will be sent directly. If it enters the load, through the space coupling capacitance, the interlayer and interpole capacitances of the transformer are disproportionately transmitted to the switching power supply or the integrated circuit chip, which can cause failure.
Although high-frequency switching power supplies and electronic equipment have corresponding anti-spike interference measures, due to cost and volume constraints, coupled with large changes in the intensity and spectrum of spike interference such as induced lightning strikes, the protection effect is not ideal. This is still the effect obtained when the pressure-sensitive limiting element is ideal. In fact, due to the influence of the residual voltage of the pressure-sensitive element and the lead inductance, under a strong inductive lightning strike, the actual peak value of the limiting voltage may rise to 800V ～1000V or more, and the post-level electronic equipment is threatened.
(4) To strengthen the protection effect of electronic equipment, an ultra-isolation transformer (also known as isolation method) is connected in series between the power supply and the load to isolate high-frequency spike interference, and at the same time, it can facilitate the secondary equipotential connection
The isolation method mainly uses an isolation transformer with a shielding layer. Since the common mode interference is a relatively earth interference, it is mainly transmitted through the coupling capacitance between the transformer windings. If a shielding layer is inserted between the primary and secondary, and it is well grounded, the interference voltage can be shunted through the shielding layer, thereby reducing the interference voltage at the output end.
Theoretically, the transformer with shielding layer can make the attenuation reach about 60dB. However, the quality of the isolation effect often depends on the process of the shielding layer. It is best to choose a 0.2 mm thick copper plate, and add a shielding layer to the primary side and the secondary side. Usually, the shield of the primary side is connected to the shield of the secondary side through a capacitor, and then connected to the ground of the secondary side. The shielding layer of the primary side can also be connected to the ground wire of the primary side, and the shielding layer of the secondary side can be connected to the ground wire of the side. And the cross-sectional area of the ground lead should also be larger. Using an isolation transformer with a shielding layer is a good method, but it is larger in size.
This method is too single in function of the transformer, relatively large in size and weight, inconvenient to install, and has poor protection against medium and low frequency peaks and surges, so the market is limited and there are not many manufacturers. Therefore, it is generally not necessary for non-special occasions.
(5) Absorption method
The absorption method mainly uses absorbing devices to absorb the surge peak interference voltage. The wave absorbing devices all have a common feature, that is, high impedance below the threshold voltage, and once the threshold voltage is exceeded, the impedance will drop sharply, so it has a certain inhibitory effect on the peak voltage. Such absorbing devices mainly include varistors, gas discharge tubes, TVS tubes, solid discharge tubes, etc. Different wave absorbing devices also have their own limitations in suppressing the spike voltage. If the current absorption capacity of the varistor is not large enough, the response speed of the gas amplifying tube is slow. The above are some of the surge suppression methods, I hope to help you.
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