Dry-type transformer characteristics Dry-type transformer technical parameters
1. Development
The “2013-2017 China Dry-type Transformer Industry Market Demand Forecast and Investment Strategic Planning Analysis Report” [1] shows that my country has become the country with the largest production and sales of dry-type transformers in the world. . In the past, various foreign high and low voltage electrical products occupied some important domestic markets. Only dry-type transformers have been almost never imported from abroad since the end of the 20th century. In key domestic projects and major projects, it is difficult to find foreign dry-type transformers. traces.
At present, the pace of urban and rural power grid construction is accelerating, and my country’s power generation and electricity consumption are increasing day by day. Generally speaking, for every 1kW of additional power generation, the total capacity of the transformer needs to be increased by 11kVA; among which, Satons distribution transformers account for approximately 1/3-1/2 of the total transformer capacity. It is estimated that dry-type distribution transformers account for approximately 1/5-1/4 of all distribution transformers. Driven by investment in power grid construction, the transformer industry is booming and output will maintain a growth rate of around 20% after 2010. According to historical experience and changes in transformer voltage grade structure, the proportion of distribution transformers is around 40%. Calculated based on the 40% ratio, my country’s new dry-type transformer output this year will reach about 200 million KVA.
In the past 20 years, with the development of the world economy, dry transformers have achieved rapid development all over the world. Especially in distribution transformers, dry transformers account for an increasing proportion. According to statistics , in developed countries such as Europe and the United States, it has accounted for 40 to 50% of distribution transformers. In our country, it accounts for about 50%. From the perspective of output, my country’s dry-type transformer output has increased significantly since the second urban power grid transformation conference in 1989. Since the 1990s, it has increased at a rate of about 20% every year. In 1999, the total output The output has approached 10,000 MVA (this value has greatly exceeded the forecast 10 years ago of 4,500 MVA), and the total output in 2002 reached 20,000 MVA, and in 2004 it reached 32,000 MVA. This kind of growth rate is unprecedented in the world.
It can be seen from the above data that our country has become one of the countries with the largest sales of dry conversion in the world, and it is already at the world’s leading level in terms of factory scale, product capacity, voltage, etc.
2. Structure type
Structural performance
⑴Solid insulation encapsulated winding
⑵ Unencapsulated winding
Among the two windings, the higher voltage is the high-voltage winding and the lower voltage is the low-voltage winding
From the relative positions of the high and low voltage windings Look, high voltage can be divided into concentric overlapping types
Concentric windings are simple, easy to manufacture, all adopt this structure.
Overlapping type, mainly used for special transformers.
Structural Features
1. Safe, fireproof, non-polluting, can be run directly in the load center;
2. Adopt domestic Advanced technology, high mechanical strength, strong short-circuit resistance, small partial discharge, good thermal stability, high reliability, long service life;
3. Low loss, low noise, obvious energy saving effect, maintenance-free ;
4. Good heat dissipation performance, strong overload capacity, and can increase capacity operation when forced air cooling;
5. Good moisture-proof performance, suitable for operation in high humidity and other harsh environments ;
6. Dry-type transformers can be equipped with complete temperature detection and protection systems. It adopts an intelligent signal temperature control system that can automatically detect and display the respective operating temperatures of the three-phase windings. It can automatically start and stop the fan, and has alarm, trip and other function settings;
7. Small size and weight Light, takes up less space, and has low installation costs.
Iron core
Dry type isolation transformer
Using high-quality cold-rolled grain-oriented silicon steel sheets, the core silicon steel sheets adopt 45-degree fully oblique joints to allow magnetic flux to pass along the joint direction of the silicon steel sheets.
Winding form
⑴ Winding;
⑵ Epoxy resin plus quartz sand filling and casting;
⑶ Glass fiber reinforced epoxy resin Pouring (i.e. thin insulation structure);
⑷Multi-strand glass filaments impregnated with epoxy resin winding type (3 is generally used because it can effectively prevent the poured resin from cracking and improve the reliability of the equipment).
High voltage winding
Generally adopts multi-layer cylindrical or multi-layer segmented structure.
Dry-type transformer
Low voltage Winding
Generally adopts layered or foil structure.
3. Form
⒈Open type: It is a commonly used form. Its body is in direct contact with the atmosphere and is suitable for relatively dry and clean environments. Indoors, (when the ambient temperature is 20 degrees, the relative humidity should not exceed 85%), there are generally two cooling methods: air self-cooling and air cooling.
⒉ Closed type: The device is in a closed shell and is not in direct contact with the atmosphere (due to poor sealing and heat dissipation conditions, it is mainly used in mining and is explosion-proof).
⒊Pouring type: use epoxy treeGrease or other resin casting is used as the main insulation. It has a simple structure and small volume, and is suitable for smaller capacity transformers.
4. Characteristic structure
Temperature control system
Safe operation of dry-type transformer and its The service life of the transformer depends largely on the safety and reliability of the transformer winding insulation.
Cooling methods
Dry-type transformer cooling methods are divided into natural air cooling (AN) and forced air cooling (AF). When naturally air-cooled, the transformer can operate continuously for a long time at rated capacity. When forced air cooling is used, the output capacity of the transformer can be increased by 50%. It is suitable for intermittent overload operation or emergency overload operation; because the load loss and impedance voltage increase greatly during overload, it is in a non-economic operating state, so it should not be placed in long-term continuous overload operation.
5. Technical parameters
1. Frequency of use: 50 / 60HZ;
2. No-load current: < 4 % ;
3. Withstand voltage strength: 2000V/min without breakdown; Test instrument: YZ1802 withstand voltage tester (20mA);
4. Insulation grade: F grade (special grade Can be customized);
5. Insulation resistance: ≥2M ohm Testing instrument: ZC25B-4 type megohmmeter <1000 V);
6. Connection method: Y/Y, △/Y0, Yo/△, auto-coupling type (optional);
7. Coil allowable temperature rise: I00K;
8. Heat dissipation method: natural air cooling or temperature control Automatic heat dissipation;
9. Noise coefficient: ≤30dB.
6. Future development direction
(1) Energy saving and low noise: low loss silicon steel sheets, stepped core seams, foil winding structure , in-depth noise research, environmental protection requirements, the introduction and development of new materials, new processes, new technologies such as computer optimization design, will make future dry-type transformers more energy-saving and quieter. However, we believe that it is not advisable to simply rely on material investment to reduce iron loss or copper loss.
(2) High reliability: The operational reliability of electrical products, especially transformers, is particularly important. Conduct a large amount of basic research on electromagnetic field theory and its calculation, wave process, pouring process, hot spot temperature rise, partial discharge mechanism, quality assurance system, reliability engineering, etc., and actively conduct reliability certification to further improve the reliability of dry-type transformers. will be people’s unremitting pursuit.
(3) Environmental protection characteristic certification: Based on the European standard HD464, carry out the weather resistance (C0, C1, C2), environment resistance (E0, E1, E2), resistance to dry-type transformers.Research and certification of fire (F0, F1, F2) characteristics.
(4) Large capacity: Distribution transformer capacity is usually below 2,500KVA. As urban electricity loads continue to increase, urban network regional substations are increasingly embedded in load centers such as urban central areas, residential areas, large and medium-sized factories and mines, and 35KV large-capacity dry-type power transformers for regional power supply will be widely used. Shunte has produced nearly ten 35KV 16,000/24,000KVA ultra-large capacity dry transformers.
(5) Multi-functional combination and intelligence: from a single transformer with power transformation function to a transformer with forced air cooling, protective shell, power metering, computer interface, closed busbar, various low-voltage sides Develop towards multi-functional combined transformers such as outlet lines; introduce TTU intelligent interfaces with functions such as data processing, status control, status display, etc., thus making the transformer a multi-functional and intelligent electrical equipment that is in optimal operating condition at all times.
(6) Multi-field development: from mainly distribution transformers to power plant excitation transformers, factory transformers, rail transit traction rectifier transformers, high-current electric furnace transformers, nuclear power plants, ships, and oil production platforms. and other special transformers and multi-purpose and multi-field development. In recent years, Shunte Electric has developed and mass-produced these special products in many fields.
(7) Multiple materials and multiple varieties: In my country, epoxy resin vacuum cast dry-type transformers occupy the dominant market.
7. Working environment
1.0 – 40 (℃), relative humidity < 80%;
2. Altitude: No more than 2500 meters;
3. Avoid rain, moisture, high temperature, high heat or direct sunlight. The distance between the cooling vents and surrounding objects should be no less than 40cm;
4. Prevent working in places with a lot of corrosive liquids, gases, dust, conductive fibers or metal chips;
5. Prevent working in places with vibration or electromagnetic interference;
6. Avoid long-term inverted storage and transportation, and do not subject to strong impact.
Parameter table
Wiring method
1. Short-circuit the “input” and “output” terminals of the transformer and use a megger to test the insulation resistance between it and the ground wire. When measured with a 1000V megger, the resistance is greater than 2M ohms.
2. The cross-section wiring of the transformer input and output power cords should meet the requirements of their current values; it is appropriate to configure them according to the current density of 2-2.5A/min2.
3. The input and output three-phase power lines should be connected to phase A, phase B, and phase C respectively according to the colors of yellow, green, and red busbars on the transformer wiring board. The neutral line should be connected to the neutral neutral line of the transformer. Phase connection, the ground wire, the transformer shell and the center point of the transformer are connected.The ground wire and neutral wire we usually talk about are drawn from the neutral point of the transformer. (If the transformer has a cabinet, it should be connected to the ground wire mark on the cabinet correspondingly).
Check the input and output lines to make sure they are correct.
4. Turn on the power without load first, and observe and test that the input and output voltages meet the requirements. At the same time, observe whether there are abnormal noises, sparks, odors or other abnormal phenomena inside the machine. If there is any abnormality, please disconnect the input power immediately.
5. After the no-load test is completed and normal, the load can be connected.
8. Selection
Temperature control system
The safe operation and service life of dry-type transformers largely depend on For the safety and reliability of transformer winding insulation. When the winding temperature exceeds the insulation withstand temperature, causing insulation damage, it is one of the main reasons why the transformer cannot work normally. Therefore, monitoring the operating temperature of the transformer and its alarm control are very important.
⑴Fan automatic control: The temperature signal is measured through the Pt100 thermistor temperature measuring resistor embedded in the hottest part of the low-voltage winding. As the load of the transformer increases, the operating temperature rises. When the winding temperature reaches 110°C, the system automatically starts the fan for cooling; when the winding temperature drops to 90°C, the system automatically stops the fan.
⑵ Over-temperature alarm and tripping: The winding or core temperature signal is collected through the PTC non-linear thermistor temperature measuring resistor embedded in the low-voltage winding. When the temperature of the transformer winding continues to rise, if it reaches 155°C, the system will output an over-temperature alarm signal; if the temperature continues to rise to 170°C, the transformer can no longer continue to operate, and an over-temperature trip signal must be sent to the secondary protection circuit to cause the transformer to Trip quickly.
⑶ Temperature display system: The temperature change value is measured through the Pt100 thermistor embedded in the low-voltage winding, and the temperature of each phase winding is directly displayed (three-phase inspection and maximum value display, and history can be recorded Maximum temperature), the maximum temperature can be output as 4~20mA analog quantity. If it needs to be transmitted to a remote computer (distance up to 1200m), a computer interface can be added. One transmitter can monitor up to 31 transformers at the same time. The over-temperature alarm and trip of the system can also be activated by the Pt100 thermal sensing resistor signal, further improving the reliability of the temperature control protection system.
Protection methods
Based on the characteristics of the use environment and protection requirements, different shells can be selected for dry-type transformers.
IP20 protective shell is usually used to prevent solid foreign objects with a diameter greater than 12mm and small animals such as rats, snakes, cats, finches, etc. from entering, causing short circuits and power outages and other vicious faults, and provides a safety barrier for live parts. If the transformer needs to be installed outdoors, an IP23 protective enclosure can be used. In addition to the above-mentioned IP20 protection function, it can also prevent water dripping within an angle of 60° from the vertical line. However, the IP23 casing will reduce the cooling capacity of the transformer, so attention should be paid to the reduction in its operating capacity when selecting it.
Overload capacity
The overload capacity of a dry-type transformer is related to the ambient temperature, the load condition before overload (initial load), the insulation heat dissipation condition of the transformer and the heating time constant, etc., if necessary , you can obtain the overload curve of the dry transformer from the manufacturer.
How to make use of its overload capacity? The author puts forward two points for reference:
⑴ When choosing to calculate the transformer capacity, it can be appropriately reduced: fully consider the short-term impact overload of some steel rolling, welding and other equipment Possibility – try to make use of the strong overload capacity of dry-type transformers to reduce the transformer capacity; for some places with uneven loads, such as residential areas, cultural and entertainment facilities, air conditioning and daytime lighting that mainly provide night lighting, etc. Main shopping malls, etc., can make full use of its overload capacity and appropriately reduce the transformer capacity so that its main operating time is at full load or short-term overload.
Application status
Dry-type transformers do not have oil, so there are no problems such as fire, explosion, pollution, etc., so there are no requirements for electrical specifications, regulations, etc. Dry-type transformers are placed in separate rooms. The loss and noise have been reduced to a new level, creating conditions for the transformer and the low-voltage panel to be placed in the same power distribution room.
China’s annual output of resin insulated dry-type transformers has reached 10,000MVA, becoming one of the countries with the largest production and sales of dry-type transformers in the world. Dry-type transformers are now widely used in almost all electrical applications such as power stations, factories, and hospitals. With the promotion and application of the low-noise (noise of distribution transformers below 2500kVA has been controlled within 50dB) and energy-saving (no-load loss reduced by up to 25%) SC(B)9 series, the performance indicators and manufacturing of dry-type transformers in China have The technology has reached the world’s advanced level.
9. Check
⒈ Whether there are abnormal sounds and vibrations.
⒉ Whether there is any discoloration caused by local overheating, harmful gas corrosion, etc. that may cause creepage traces and carbonization on the insulation surface.
⒊Is the air cooling device of the transformer operating normally?
⒋The high and low voltage joints should be free of overheating. The cable heads should be free of leakage and creepage.
⒌The temperature rise of the winding should be based on the grade of insulation material used in the transformer, and the temperature rise should not exceed the specified value.
⒍The supporting porcelain bottle should have no cracks or traces of discharge.
⒎ Check whether the winding pressing piece is loose.
⒏Indoor ventilation and iron core air ducts should be free of dust and debris, and the iron core should be free of rust or corrosion.
10. National standards
· GB 1094.3-2003 Power transformer Part 3: Insulation level, insulation test and external insulation air gap
· GB 1094.5- 2003 Power transformer Part 5: Ability to withstand short circuit
· GB 13223-2003 Air pollutant emission standards for thermal power plants
· GB 156-2003 Standard voltage
· GB 19212.1-2003 Safety of power transformers, power supply units and similar products Part 1: General requirements and tests
· GB/T 10760.1-2003 Generators for off-grid wind turbines Part 1: Technical conditions
· GB/T 10760.2-2003 Generators for off-grid wind turbines Part 2: Test methods
· GB/T 1094.10-2003 Power transformer Part 10: Sound level determination
· GB/T 12325-2003 Power quality supply voltage tolerance
· GB/T 14099.1- 2004 Gas turbine procurement Part 1: General principles and definitions
· GB/T 14099.2-2004 Gas turbine procurement Part 2: Standard reference conditions and ratings
· GB/T 15146.11-2004 Nuclear criticality safety of fissile materials outside the reactor Nuclear criticality safety based on restriction and control of moderator
· GB/T 17625.6-2003 Electromagnetic compatibility limits for equipment with a rated current greater than 16A in low-voltage power supply systems Harmonic electricity generated
· GB/T 17680.10-2003 Nuclear power plant emergency planning and preparation guidelines for emergency field radiation monitoring, sampling and analysis of nuclear power plant operating units
· GB/T 17680.6-2003 Nuclear power plant emergency plan and preparedness guidelines on-site emergency response functions and organizational structure
· GB/T 17680.7-2003 Nuclear power plant emergency plan and preparedness guidelines on-site emergency facility functions and characteristics
· GB/T 17680.8-2003 Nuclear Power Plant Emergency Plan and Preparedness Guidelines On-site Emergency Planning and Execution Procedures
· GB/T 17680.9-2003 Nuclear Power Plant Emergency Plan and Preparedness Guidelines On-site Emergency Response Capabilities Maintenance
· GB/T 18039.3-2003 Compatibility level of low-frequency conduction disturbance and signal transmission in public low-voltage power supply systems in electromagnetic compatibility environment
· GB/T 18039.5-2003 Electromagnetic compatibility environment for public use Electromagnetic environment for low-frequency conduction disturbance and signal transmission in power supply system
· GB/T 18451.2-2003 Wind turbine power characteristics test
· GB/T 19068.1-2003 Off-grid wind power generation Unit Part 1: Technical conditions
· GB/T 19068.2-2003 Off-grid wind turbine unit Part 2: Test methods
· GB/T 19068.3-2003 Off-grid wind turbines Part 3: Wind tunnel test methods
· GB/T 19069-2003 Technical conditions for wind turbine controllers
· GB/T 19070-2003 Test methods for wind turbine controllers
· GB/T 19071.1-2003 Wind turbine asynchronous generators Part 1: Technical conditions
· GB/T 19071.2-2003 Wind turbine asynchronous generator Part 2: Test methods
·GB/T 19072-2003 Wind turbine tower
·GB/T 19073-2003 Wind turbine gearbox
· GB/T 19115.1-2003 Off-grid household wind and solar hybrid power generation system Part 1: Technical conditions
· GB/T 19115.2-2003 Off-grid household wind and solar hybrid power generation system Power generation system Part 2: Test methods
·GB/T 19184-2003 Cavitation corrosion assessment of pelton turbines
·GB/T 19519-2004 Nominal voltage higher than 1000V Composite insulators for AC overhead lines – definition, test methods and
· GB/T 19568-2004 Wind turbine assembly and installation specifications
· GB/T 2694-2003 Transmission line towers Manufacturing technical conditions
· GB/T 2893.1-2004 Graphical symbols safety colors and safety signs Part 1: Safety signs in workplaces and public areas
· GB/T 2900.33- 2004 Electrical Terminology Power Electronics Technology
· GB/T 2900.36-2003 Electrical Terminology Electric Traction
· GB/T 2900.49-2004 Electrical Terminology Power System Protection
· GB/T 4585-2004 Artificial contamination test of high-voltage insulation for AC systems
· GB/T 7267-2003 Basic size series of secondary circuit control, protection screens and cabinets of power systems
· GB/T 8564-2003 Technical Specifications for Installation of Hydrogenerator Sets
· GB/T 8732-2004 Steel for Steam Turbine Blades
· JB/T 10317-2002 Single Phase Technical parameters and requirements of oil-immersed distribution transformers
11. Product selection
Product definition
Distribution transformers provide power supply and distribution systems for industrial and mining enterprises and civil buildingsOne of the important equipment in the power grid, it reduces the 10⑹kV or 35kV network voltage to the 230/400V bus voltage used by users. This type of product is suitable for AC 50 (60) Hz, three-phase maximum rated capacity 2500kVA (single-phase maximum rated capacity 833kVA, single-phase transformers are generally not recommended).
Selection points
Select a transformer according to the nature of the load:
1) There are a large number of primary or For secondary loads, two or more transformers should be installed. When any one of the transformers is disconnected, the capacity of the remaining transformers can meet the power consumption of the primary and secondary loads. The primary and secondary loads should be concentrated as much as possible and should not be too scattered.
2) When the seasonal load capacity is large, a dedicated transformer should be installed. Such as the load of air conditioning refrigerators and electric heating loads in large civil S4270D27-29 27 2005.7.29,3:24 AM buildings.
3) When the centralized load is large, a special transformer should be installed. Such as large heating equipment, large X-ray machines, arc furnaces, etc.
4) When the lighting load is large or the use of a shared transformer for power and lighting seriously affects the lighting quality and bulb life, a dedicated lighting transformer can be installed. Normally, power and lighting share a transformer.
Select a transformer according to the use environment:
1) Under normal medium conditions, oil-immersed transformers or dry-type transformers can be used, such as industrial and mining enterprises, Agricultural independent or attached substations, community independent substations, etc. Available transformers include S8, S9, S10, SC (B) 9, SC (B) 10, etc.
2) In multi-story or high-rise main buildings, non-combustible or flame-retardant transformers should be used, such as SC (B) 9, SC (B) 10, SCZ (B) 9, SCZ (B) 10 etc.
3) In places where dust or corrosive gas seriously affects the safe operation of the transformer, closed or sealed transformers should be selected, such as B S 9, S9 -, S10-, SH12-M, etc.
4) High and low power distribution devices without flammable oil and non-oil-immersed distribution transformers can be installed in the same room. At this time, the transformer should have an IP2X protective shell for safety.
Select a transformer based on the power load:
1) The capacity of the distribution transformer should be calculated based on the facility capacity of various electrical equipment. Load (generally excluding fire protection load), the compensated apparent capacity is the basis for selecting the capacity and number of transformers. Generally, the load factor of the transformer is about 85%. This method is relatively simple and can be used to estimate capacity.
2) In GB/T17468-1998 “Guidelines for Selection of Power Transformers”, the recommended capacity of distribution transformersWhen selecting the capacity, its capacity should be determined based on GB/T17211-1998 “Load Guidelines for Dry-type Power Transformers” and the calculated load. The above two guidelines provide computer programs and normal cycle load diagrams to determine distribution transformer sizing.
Installation points
Distribution transformers are important components of substations. Dry-type transformers without casings are installed directly on the ground, with protective barriers around them; The shell dry-type transformer is installed directly on the floor. For its installation, please refer to the National Building Standard Design Atlas. 03D201-4 10/0.4kV transformer room layout and installation of common equipment components in the substation.
12. Differences
Frequency converter: Through its adjustment, the required power frequency (50hz, 60hz, etc.) can be achieved to meet our needs. Special needs for electricity. Transformer: Generally called a “step-down transformer”, it is commonly found near communities or factories. Its function is to reduce ultra-high voltage to the normal power voltage for our residents to meet people’s daily electricity consumption.
13. The future
With the promotion and application of dry-type transformers, their manufacturing technology has also made great progress. It can be predicted that the future dry-type transformers Further development will be achieved in the following aspects:
⑴ Energy saving and low noise: With the in-depth research on new low-consumption silicon steel sheets, foil winding structures, stepped core joints, environmental protection requirements, and noise, As well as the introduction of new materials, new processes, and new technologies such as computer optimized design, future dry-type transformers will be more energy-saving and quieter.
⑵ High reliability: Improving product quality and reliability will be people’s unremitting pursuit.
⑶Environmental protection characteristic certification: Based on the European standard HD464, carry out the weather resistance (C0, C1, C2), environment resistance (E0, E1, E2) and fire resistance (F0, F1, F2) Research and certification of characteristics.
⑷Large capacity: From dry-type transformers, mainly 50-2500kVA distribution transformers, to 10000-20000kVA/35kV power transformers. As urban power loads continue to increase, urban network regional substations Going deeper and deeper into load centers such as urban centers, residential areas, large factories and mines, 35kV large-capacity residential center power supply power transformers will be widely used. ⑸ Multi-functional combination: From a single transformer to a multi-functional combined transformer with air cooling, protective shell, temperature computer interface, zero sequence transformer, power metering, closed busbar and side outlet.
It can be predicted that the distribution transformers in the 21st century will be resin-insulated dry-type transformers with superior performance, low noise and energy saving.
14. Protection device
Dry-type transformer microcomputer protection device is an economical protection that integrates measurement, control, protection and communication; For distribution network terminalsThe high-voltage power distribution room is tailor-made, with three-stage non-directional current protection as the core, and is equipped with monitoring and collection functions of power grid parameters, which can eliminate the need for traditional ammeters, voltmeters, power meters, frequency meters, watt-hour meters, etc., and The measurement data and protection information can be remotely transmitted to the host computer through the communication port, which facilitates the realization of distribution network automation; the device integrates a backup power automatic switching function in the device according to the characteristics of the distribution network power supply, which can flexibly realize incoming line backup and bus backup. cast function.
The dry-type transformer microcomputer protection device adopts internationally advanced DSP and surface mount technology and flexible field bus (CAN) technology to meet the requirements of different voltage levels in the substation and realize the coordination and digitalization of the substation. style and intelligence. This series of products can complete substation protection, measurement, control, regulation, signaling, fault recording, electricity collection, small current grounding line selection, low-cycle load shedding and other functions, making the product’s technical requirements, functions, and internal wiring more standardized. . The product adopts distributed protection measurement and control devices, which can be grouped together in a centralized manner or installed dispersedly. The configuration can also be changed at will according to user needs to meet the requirements of different solutions.
15. Class H dry-type transformer
SG (B) 10 non-encapsulated Class H dry-type transformer is an insulation system based on insulating paper
. Excellent electrical and mechanical properties are maintained throughout the transformer’s service life. The insulating paper is not easy to age, is resistant to shrinkage and compression, and has extremely strong elasticity, which ensures that the coils of the transformer will remain structurally tight even after several years of use, and can withstand the pressure of short circuits.
Main structure
1. The iron core is a step-by-step 45° full bevel joint
2. The insulation between turns, between layers, between sections and the insulation cylinder are all composed of insulating paper or molded parts
3. The low-voltage coil is of foil type
4. The high-voltage coil is continuous type
5. The device body adopts special isolation and noise reduction measures
High-voltage coil
High-voltage line The coil adopts a continuous structure with high mechanical strength and good heat dissipation conditions. The coil is wound on a molded insulating cylinder.
Insulating paper-wrapped flat copper wire is used as the conductor, and insulating material insulating paper is used between layers. The coil is subjected to VPI vacuum pressure Impregnated into a solid whole, it avoids the shortcomings of multi-layer cylindrical coils such as high interlayer voltage, poor heat dissipation, easy thermal breakdown, and low mechanical strength, thereby improving the reliability of product operation; it has excellent moisture-proof performance and is more durable Withstand thermal shock, never crack, partial discharge <5Pc, easy to decompose and recycle after life, protecting the environment.
Low-voltage coil
The low-voltage coil is a foil-wound structure, and the coil is High quality copperIt is made of foil and H-class insulation material, and the insulation system is made of
insulating material paper between layers. The coil is impregnated with VPI vacuum pressure to form a solid whole. Product structure features:
1. Coil machinery High strength and strong short circuit resistance.
2. The coil has strong resistance to thermal shock and improves product life.
3. The coil has strong “moisture-proof, dust-proof, and salt-spray proof” capabilities.
Iron core
The core material is made of 0.2mm thick high quality and high magnetic permeability The silicon steel sheets are fully overlapped at 45°, and the iron core adopts a non-punching,
draw plate structure; the surface is coated with insulating paint, which is moisture-proof, rust-proof, low loss and low noise. The operating noise is about 16db lower than the national standard, reaching the national first-class residential area noise requirements.
VPI
Vacuum pressure impregnation technology
①Preheating: Preheat the coil to 135-150 ℃, keep it for several hours, take out the coil and reduce the surface temperature;
②Vacuum: Open the lid of the impregnation tank, put the coil in, then close the lid to vacuum;
③Dip: Open the release valve of the impregnation tank, put the impregnation paint to more than 50mm from the top of the coil, and close the switching valve;
④ Vacuum: Apply vacuum again and maintain it for about 30 minutes;
⑤ Pressurize : Close the vacuum valve of the dipping tank; open the pressure valve of the dipping tank and increase the pressure to 6 Pa;
⑥Drip drying: Take out the coil and wait until the paint on the coil is completely dry;
⑦Drying: Put the coil into the drying room, adjust the temperature to 135-150℃, and dry continuously for 8-10 hours;
⑧Cooling: After the coil is dried, take out the coil and cool it to room temperature. The process ends.
Performance Features
High Safety
SG10 transformer does not contain flammable resin during use. It does not support combustion, is flame retardant, will not explode or release toxic gases, will not cause harm to the environment, other equipment and the human body, and is not sensitive to humidity, dust, and pollution; there will be no partial discharge and no possibility of “cracking” during operation. .
High reliability
High and low voltage coils are made of NOMEX insulation materials and have been impregnated with H-class solvent-free impregnating paint multiple times by VPI vacuum pressurization equipment. , and baked and cured at high temperatures multiple times. The product is Class H (180℃), and the main insulation material is Class C (220℃). It has strong overload capacity and good short-circuit resistance. With good ventilation, 20% overload operation is allowed.
Energy saving and environmental protection
After the product life ends,Steel, iron and other materials are easy to recycle;
All NOMEX paper used will not release toxic substances when burned;
Other insulation materials can be degraded and do not pollute the environment;
The product has low loss and energy saving;
Low noise and flexible design.
Development Prospects
H-class dry-type transformers are currently mainly used in the United States, accounting for about 2/3~3/ of the entire dry-type transformer market. 4. In Europe, Japan and other countries, epoxy casting is still the main method.
So far, H-class dry-type transformers occupy a very small share in my country’s dry-type transformer market, and there are only a few influential manufacturers among them. Since the vast majority of dry-type transformer manufacturers in my country use imported epoxy cast structures, and this type of product has long been accepted by the majority of users, the cost and selling price are constantly decreasing. Therefore, in my country, the situation in which epoxy cast-type manufacturers dominate the market of cast-type transformers is expected to be unlikely to change for a considerable period of time.
There are still some manufacturers that originally produced oil-immersed transformers planning to manufacture dry-type transformers. Based on considerations such as reducing initial investment and innovation, some manufacturers are planning to develop H-class products.
The future development prospects of H-class products in my country are still mainly determined by the quality and price of the products. It is undeniable that users’ demand for overload capabilities, and users’ acceptance and recognition of such products, will affect their development prospects.
In the new century, with the improvement of national environmental protection requirements for fire safety, degradation of waste materials after the end of transformer operating life, and the direction of specific national environmental protection policies in the future, H-class Dry-type transformers will use their advantages in environmental protection to form strong competitiveness in future market competition. Therefore, on the one hand, they are favored by manufacturers, and on the other hand, they also give users more choices. I believe that in the near future In the future, it will become more and more popular among users and even occupy part of the market of traditional dry-type transformers. Transformers with this technology are the future development trend of China and will have very broad development prospects in the future.
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