1 Introduction The high quality of power supply equipment is the basis and guarantee for uninterrupted, high-quality power supply for communication power systems. Although we are constantly improving the testing standards and testing methods and implementing the network access and selection system for communication power equipment, we will inevitably generate some misunderstandings or be confused by some misleading. To this end, we have summarized some experiences on the basis of comprehensive analysis and scientific judgments, and discussed with peers engaged in the research, production, and use of power supply equipment.
2 Output capability and efficiency are the most important technical indicators for evaluating the quality of power supply products. The so-called conventional indicators refer to such factors as accuracy, distortion, balance, conversion time, and dynamic response. At present, many power supply products have reached the standard of the product. High indicators, but too high indicators are not necessarily required for actual use. The level of a certain performance index cannot be used as a criterion for determining the quality of a product. The most important indicator for determining the pros and cons of a product is reliability, and improving reliability is an eternal theme of power products. It is meaningless to leave the reliability in terms of advancement and usability. The reliability index is generally based on the reliability design and a large number of statistical data for comprehensive assessment, it is difficult to detect proofreading in a short time, but we can assess its reliability by detecting output capacity and efficiency. In a product of the same specification, its strong output means that it is not operating at full capacity under normal use conditions, but also has reserves of energy and fewer failures; high efficiency means low temperature rise. Products that meet this requirement can generally be considered highly reliable. The following will be combined with specific equipment to be reviewed.
(1) The centralized monitoring and management system of the centralized monitoring and management system shall be further improved and put into operation. The emphasis in this system shall be on the DC system, especially on the main battery (basic power system - 48 V) The intelligent management of the start-up battery and UPS backup battery of the generator set must not be set for the three remote control points that can be set. The remote signaling point should not be set up again, but the setting of the alarm point must be strengthened. Put practicality first.
When designing and implementing a monitoring system, if the three remote points are repeatedly set, it will inevitably result in a high project cost and a complicated system, thereby reducing the reliability of the system.
(2) Lightning protection problems Lightning devices can easily cause fires and explosions, especially in the fields of electric power and communications. All-round lightning protection shall adopt the principles of comprehensive management, overall defense, multiple protection, and layered defense. In particular, strict control over the lightning strike point, safe guidance of lightning current into the ground, improvement of low resistance ground network, elimination of ground loops, current surge protection, and signal And data line transient protection and other effective lightning protection measures.
Since lightning generation is affected by many factors such as the surrounding environment, no matter what kind of manufacturer's lightning protection device, over-voltage protection device, over-current arrester, over-voltage surge suppressor, etc., must be combined with good grounding. The system can effectively play a role in coordination.
(3) AC Uninterruptible Power System (UPS)
The reliability of UPS is the basic premise of the availability of information systems. The development of information systems is fully computerized. In the future, the AC load will become larger and larger, and the importance will be higher and higher. Therefore, improving the reliability of UPS power supply systems is a major issue. Focus. Good quality UPS equipment should have the following basic functions:
1) It can be put into operation under various complicated grid environments, and it can still operate normally under a wide range of grid voltage variation;
2) No additional interference with the power supply network will occur during operation.
3) Its output electrical performance indicators should be comprehensive, high-quality, capable of continuous full-load operation;
4) UPS itself should be highly efficient;
5) Highly intelligent automatic management function.
If you see the promotional materials of a certain UPS equipment manufacturer, do not be confused by high-performance indicators such as how high the output voltage accuracy is and how small the distortion of the output waveform is, you should also look at other indicators such as output capacity.
(4) The weak link of the oil turbine generator set is that the prime mover oil turbine generator set is the key equipment for improving the availability of AC power supply, which was once a major problem for unattended operation. Because of the low ignition point and poor stability of gasoline-powered gasoline generators, the use of ignition bursts should be avoided. The generator is the most classic and mature technology in China and even in the world. Generally speaking, its eight steady performance and transient performance indicators have reached the relatively high technical level stipulated by the standard. Some of the world's air-conditioner manufacturers have purchased engines for the production of engines and purchased engines for the production of original engines. Some of the plant's prime movers and engines have been purchased from outside. China's assembly technology is not worse than foreign countries, far higher than some countries in the surrounding countries. Although the quality of domestically produced prime movers is constantly improving, there is still a certain gap compared with developed countries, and proper import is necessary.
For the unit, do not superstition foreign original imported units, generators do not emphasize the use of foreign, it is important to pay attention to some indicators determined by the quality of the prime mover, such as overload capacity of 10% of the rated capacity of 1 h can reach, can Add 100% of the rated load at a time, whether the consumption of fuel per hour is relatively low.
(5) Rectifier equipment For rectifier equipment, we must choose products with strong output and high efficiency. Since electronic devices are mostly faulty in the momentary process of switching on and off, it is advisable to increase the number of switching machines in an appropriate manner during the acceptance of the device.
(6) Battery Accumulator is the last line of defense for DC uninterrupted power supply, and is the top priority in technical maintenance. The life expectancy of valve-regulated sealed lead-acid batteries is the theoretical value of 25°C ambient temperature, float voltage not exceeding 2.25 V per unit and long-term floating state. To choose a good valve-regulated sealed lead-acid battery, from the perspective of the production of batteries, due to the different places of use and discharge, so the battery requirements are not the same.
• For batteries used in access networks, batteries suitable for low-current, long-time deep discharge should be selected.
• For UPS batteries, choose a battery that is suitable for high-current, short-time deep discharge.
• The batteries used in the solar power supply system should be selected to be suitable for long-time deep discharge, fast recharge, high charge/discharge efficiency, and no regular charge/discharge, and large and small batteries for the charging current.
According to these characteristics, manufacturers should make special designs in the aspects of alloy composition, active material formulation, plate thickness, structure, and on-off valve pressure of the battery. There are currently no batteries that can meet the above requirements.
For large-capacity main batteries, some people think that the use of internal parallel integrated battery is better than external parallel connection, which is a misunderstanding. When large-capacity batteries are needed, it is advisable to use a parallel connection outside the cells in terms of improving reliability, increasing maintainability, avoiding circulation, etc.; when selecting the main battery, it is necessary to conduct a full-scale inspection according to the standard and perform tests. The results of a comprehensive analysis, evaluation, the most important thing is based on the actual operating conditions, choose the preferred use.
Others believe that valve-regulated sealed lead-acid batteries are better than acid-proof and explosion-proof batteries, which is not comprehensive. The valve-regulated sealed lead-acid battery is free from acid mist under normal use, so it is suitable for use in special occasions such as decentralized power supply, vehicle-mounted power supply, military and field. In the fixed communication station, when the battery room is conditionally set, the use of an acid-proof flameproof battery still has certain merits.
(7) On-line detection of the capacity of valve-regulated sealed lead-acid batteries Online rapid and accurate detection of the capacity of VRLA batteries is still a major challenge. Now there are two most effective methods. One is to find the backward battery in a set of batteries (the backward battery can only be correctly judged in the discharged state, the battery voltage drops the fastest is the backward battery), and then to a The backward battery alone discharges on-line, and the worst battery capacity represents the effective capacity of the battery. After the battery is discharged, the battery can be fully charged and then put into normal operation. This traditional, classic, and mature operation method has little effect on the change of the system power supply voltage. The diagnosis of the health of the battery is the most accurate, but it is required. It takes a long time and is not suitable for fast sampling determination in remote monitoring. The second method is to use the discharge curve comparison method to compare the discharge curve of each basic constant load with the original discharge curve of the full-capacity state of the battery and discharge for a few minutes. The discharge curve is closer to the original curve, indicating that the battery is The better the effective capacity, the faster the discharge curve drops than the original curve, indicating that the effective capacity of the battery pack will be lost faster. Using this method, it is necessary to have the original discharge curves of batteries of different manufacturers, different models, and different discharge rates stored in the computer as a benchmark for comparison. The difficulty of this method is the lack of the original discharge curve, and the dispersion of different battery curves is greater.
How to understand the capacity of valve-regulated sealed lead-acid batteries has caused widespread concern among many battery researchers and manufacturers in the world. At present, a new rapid method has emerged in the world. The battery is judged by measuring the conductance or resistance of a battery. The capacity. This method also has reference value for judging whether the battery is good or bad.
Conductance is the ability to conduct current. Failures of valve-regulated sealed lead-acid batteries, such as corrosion and growth of grids, poor contact, decreased availability of active materials, and loss of water, are all manifested in the increase in the internal resistance of the battery, and the conductance is reduced. Therefore, conductance or resistance Levels provide effective information that reflects battery failure and usage.
· MTTB current internal resistance measuring meter Test method: Use AC power generation device to inject a low-frequency 60 Hz AC signal into the battery pack. Measure the alternating current through the battery and the AC voltage across each battery to calculate the Vac/Iac resistance value.
· CCT-20 conductance test device test method: Apply an AC 20 ~ 30 Hz signal and measure the injection current on the battery cell or component, then calculate the I / U, and display this value as the measured conductance.
In short, both test methods inject a test signal into the battery, measuring the AC voltage across the battery and the current through the battery. If there is a certain amount of ripple voltage on the battery, in this case, it is necessary to use an off-line test or use a variety of devices to eliminate the ripple.
The increase in the internal resistance of the battery causes an increase in the internal pressure drop, which inevitably reduces the effective capacity. Due to the amount of effective substances and the amount and density of the electrolyte, the storage capacity of the battery is characterized. Therefore, the increase in electrochemical resistance has a more significant effect on the capacity. All the resistances in the battery have an effect on the capacity, but their influence is different. This means that the internal resistance of the battery is closely related to the capacity, but it is not linear.
In general, all kinds of electronic equipment, power equipment, and electrochemical equipment must focus on detection of output capabilities and efficiency. In general, products with strong output and high efficiency are products of good quality.
3 How to correctly evaluate the quality of power supply products. • To properly evaluate product quality, we must first establish a good inspection standard. We must set out the technical performance indicators of products from the perspective of actual use. However, it is by no means the higher the index, the better. The indicators may cause the overall reliability to decrease and the costs increase. In the detection of product reliability must be strictly controlled, to do full load and overload output capacity testing 10% of the rated load. The high temperature test of electronic products and the low temperature test of batteries should be improved. Products tested should be sampled and not sent for inspection. Sampling requirements must be strictly enforced. In the process of implementation, it is necessary to continuously summarize the operation of the equipment on the Internet, and timely revise the standards according to technological progress and operational needs. Take a positive attitude towards new technologies and new products.
· To create a good sales atmosphere for companies with sound quality assurance systems, and to make good products stable in mass production. In order to improve transparency, companies are advised to publicize their system review on the Internet.
· Make manufacturers and distributors have reasonable profits. Low-priced products are generally not good products. High-priced products are not necessarily good products, but good products are the majority.
· The power supply technical support unit must fulfill its duties and timely explain the misunderstanding and misleading of the relevant product quality.
• Be cautious in notifying the accident caused by the quality of the product within a certain range.
2 Output capability and efficiency are the most important technical indicators for evaluating the quality of power supply products. The so-called conventional indicators refer to such factors as accuracy, distortion, balance, conversion time, and dynamic response. At present, many power supply products have reached the standard of the product. High indicators, but too high indicators are not necessarily required for actual use. The level of a certain performance index cannot be used as a criterion for determining the quality of a product. The most important indicator for determining the pros and cons of a product is reliability, and improving reliability is an eternal theme of power products. It is meaningless to leave the reliability in terms of advancement and usability. The reliability index is generally based on the reliability design and a large number of statistical data for comprehensive assessment, it is difficult to detect proofreading in a short time, but we can assess its reliability by detecting output capacity and efficiency. In a product of the same specification, its strong output means that it is not operating at full capacity under normal use conditions, but also has reserves of energy and fewer failures; high efficiency means low temperature rise. Products that meet this requirement can generally be considered highly reliable. The following will be combined with specific equipment to be reviewed.
(1) The centralized monitoring and management system of the centralized monitoring and management system shall be further improved and put into operation. The emphasis in this system shall be on the DC system, especially on the main battery (basic power system - 48 V) The intelligent management of the start-up battery and UPS backup battery of the generator set must not be set for the three remote control points that can be set. The remote signaling point should not be set up again, but the setting of the alarm point must be strengthened. Put practicality first.
When designing and implementing a monitoring system, if the three remote points are repeatedly set, it will inevitably result in a high project cost and a complicated system, thereby reducing the reliability of the system.
(2) Lightning protection problems Lightning devices can easily cause fires and explosions, especially in the fields of electric power and communications. All-round lightning protection shall adopt the principles of comprehensive management, overall defense, multiple protection, and layered defense. In particular, strict control over the lightning strike point, safe guidance of lightning current into the ground, improvement of low resistance ground network, elimination of ground loops, current surge protection, and signal And data line transient protection and other effective lightning protection measures.
Since lightning generation is affected by many factors such as the surrounding environment, no matter what kind of manufacturer's lightning protection device, over-voltage protection device, over-current arrester, over-voltage surge suppressor, etc., must be combined with good grounding. The system can effectively play a role in coordination.
(3) AC Uninterruptible Power System (UPS)
The reliability of UPS is the basic premise of the availability of information systems. The development of information systems is fully computerized. In the future, the AC load will become larger and larger, and the importance will be higher and higher. Therefore, improving the reliability of UPS power supply systems is a major issue. Focus. Good quality UPS equipment should have the following basic functions:
1) It can be put into operation under various complicated grid environments, and it can still operate normally under a wide range of grid voltage variation;
2) No additional interference with the power supply network will occur during operation.
3) Its output electrical performance indicators should be comprehensive, high-quality, capable of continuous full-load operation;
4) UPS itself should be highly efficient;
5) Highly intelligent automatic management function.
If you see the promotional materials of a certain UPS equipment manufacturer, do not be confused by high-performance indicators such as how high the output voltage accuracy is and how small the distortion of the output waveform is, you should also look at other indicators such as output capacity.
(4) The weak link of the oil turbine generator set is that the prime mover oil turbine generator set is the key equipment for improving the availability of AC power supply, which was once a major problem for unattended operation. Because of the low ignition point and poor stability of gasoline-powered gasoline generators, the use of ignition bursts should be avoided. The generator is the most classic and mature technology in China and even in the world. Generally speaking, its eight steady performance and transient performance indicators have reached the relatively high technical level stipulated by the standard. Some of the world's air-conditioner manufacturers have purchased engines for the production of engines and purchased engines for the production of original engines. Some of the plant's prime movers and engines have been purchased from outside. China's assembly technology is not worse than foreign countries, far higher than some countries in the surrounding countries. Although the quality of domestically produced prime movers is constantly improving, there is still a certain gap compared with developed countries, and proper import is necessary.
For the unit, do not superstition foreign original imported units, generators do not emphasize the use of foreign, it is important to pay attention to some indicators determined by the quality of the prime mover, such as overload capacity of 10% of the rated capacity of 1 h can reach, can Add 100% of the rated load at a time, whether the consumption of fuel per hour is relatively low.
(5) Rectifier equipment For rectifier equipment, we must choose products with strong output and high efficiency. Since electronic devices are mostly faulty in the momentary process of switching on and off, it is advisable to increase the number of switching machines in an appropriate manner during the acceptance of the device.
(6) Battery Accumulator is the last line of defense for DC uninterrupted power supply, and is the top priority in technical maintenance. The life expectancy of valve-regulated sealed lead-acid batteries is the theoretical value of 25°C ambient temperature, float voltage not exceeding 2.25 V per unit and long-term floating state. To choose a good valve-regulated sealed lead-acid battery, from the perspective of the production of batteries, due to the different places of use and discharge, so the battery requirements are not the same.
• For batteries used in access networks, batteries suitable for low-current, long-time deep discharge should be selected.
• For UPS batteries, choose a battery that is suitable for high-current, short-time deep discharge.
• The batteries used in the solar power supply system should be selected to be suitable for long-time deep discharge, fast recharge, high charge/discharge efficiency, and no regular charge/discharge, and large and small batteries for the charging current.
According to these characteristics, manufacturers should make special designs in the aspects of alloy composition, active material formulation, plate thickness, structure, and on-off valve pressure of the battery. There are currently no batteries that can meet the above requirements.
For large-capacity main batteries, some people think that the use of internal parallel integrated battery is better than external parallel connection, which is a misunderstanding. When large-capacity batteries are needed, it is advisable to use a parallel connection outside the cells in terms of improving reliability, increasing maintainability, avoiding circulation, etc.; when selecting the main battery, it is necessary to conduct a full-scale inspection according to the standard and perform tests. The results of a comprehensive analysis, evaluation, the most important thing is based on the actual operating conditions, choose the preferred use.
Others believe that valve-regulated sealed lead-acid batteries are better than acid-proof and explosion-proof batteries, which is not comprehensive. The valve-regulated sealed lead-acid battery is free from acid mist under normal use, so it is suitable for use in special occasions such as decentralized power supply, vehicle-mounted power supply, military and field. In the fixed communication station, when the battery room is conditionally set, the use of an acid-proof flameproof battery still has certain merits.
(7) On-line detection of the capacity of valve-regulated sealed lead-acid batteries Online rapid and accurate detection of the capacity of VRLA batteries is still a major challenge. Now there are two most effective methods. One is to find the backward battery in a set of batteries (the backward battery can only be correctly judged in the discharged state, the battery voltage drops the fastest is the backward battery), and then to a The backward battery alone discharges on-line, and the worst battery capacity represents the effective capacity of the battery. After the battery is discharged, the battery can be fully charged and then put into normal operation. This traditional, classic, and mature operation method has little effect on the change of the system power supply voltage. The diagnosis of the health of the battery is the most accurate, but it is required. It takes a long time and is not suitable for fast sampling determination in remote monitoring. The second method is to use the discharge curve comparison method to compare the discharge curve of each basic constant load with the original discharge curve of the full-capacity state of the battery and discharge for a few minutes. The discharge curve is closer to the original curve, indicating that the battery is The better the effective capacity, the faster the discharge curve drops than the original curve, indicating that the effective capacity of the battery pack will be lost faster. Using this method, it is necessary to have the original discharge curves of batteries of different manufacturers, different models, and different discharge rates stored in the computer as a benchmark for comparison. The difficulty of this method is the lack of the original discharge curve, and the dispersion of different battery curves is greater.
How to understand the capacity of valve-regulated sealed lead-acid batteries has caused widespread concern among many battery researchers and manufacturers in the world. At present, a new rapid method has emerged in the world. The battery is judged by measuring the conductance or resistance of a battery. The capacity. This method also has reference value for judging whether the battery is good or bad.
Conductance is the ability to conduct current. Failures of valve-regulated sealed lead-acid batteries, such as corrosion and growth of grids, poor contact, decreased availability of active materials, and loss of water, are all manifested in the increase in the internal resistance of the battery, and the conductance is reduced. Therefore, conductance or resistance Levels provide effective information that reflects battery failure and usage.
· MTTB current internal resistance measuring meter Test method: Use AC power generation device to inject a low-frequency 60 Hz AC signal into the battery pack. Measure the alternating current through the battery and the AC voltage across each battery to calculate the Vac/Iac resistance value.
· CCT-20 conductance test device test method: Apply an AC 20 ~ 30 Hz signal and measure the injection current on the battery cell or component, then calculate the I / U, and display this value as the measured conductance.
In short, both test methods inject a test signal into the battery, measuring the AC voltage across the battery and the current through the battery. If there is a certain amount of ripple voltage on the battery, in this case, it is necessary to use an off-line test or use a variety of devices to eliminate the ripple.
The increase in the internal resistance of the battery causes an increase in the internal pressure drop, which inevitably reduces the effective capacity. Due to the amount of effective substances and the amount and density of the electrolyte, the storage capacity of the battery is characterized. Therefore, the increase in electrochemical resistance has a more significant effect on the capacity. All the resistances in the battery have an effect on the capacity, but their influence is different. This means that the internal resistance of the battery is closely related to the capacity, but it is not linear.
In general, all kinds of electronic equipment, power equipment, and electrochemical equipment must focus on detection of output capabilities and efficiency. In general, products with strong output and high efficiency are products of good quality.
3 How to correctly evaluate the quality of power supply products. • To properly evaluate product quality, we must first establish a good inspection standard. We must set out the technical performance indicators of products from the perspective of actual use. However, it is by no means the higher the index, the better. The indicators may cause the overall reliability to decrease and the costs increase. In the detection of product reliability must be strictly controlled, to do full load and overload output capacity testing 10% of the rated load. The high temperature test of electronic products and the low temperature test of batteries should be improved. Products tested should be sampled and not sent for inspection. Sampling requirements must be strictly enforced. In the process of implementation, it is necessary to continuously summarize the operation of the equipment on the Internet, and timely revise the standards according to technological progress and operational needs. Take a positive attitude towards new technologies and new products.
· To create a good sales atmosphere for companies with sound quality assurance systems, and to make good products stable in mass production. In order to improve transparency, companies are advised to publicize their system review on the Internet.
· Make manufacturers and distributors have reasonable profits. Low-priced products are generally not good products. High-priced products are not necessarily good products, but good products are the majority.
· The power supply technical support unit must fulfill its duties and timely explain the misunderstanding and misleading of the relevant product quality.
• Be cautious in notifying the accident caused by the quality of the product within a certain range.