With the domestic urban renewal, commercial infrastructure upgrading as well as photovoltaic, wind power new energy project scale development, the modern power distribution system comprehensively towards the underground layout, landscape appearance, high security, low operation and maintenance costs of the direction of iteration. Pad-mounted transformer by virtue of fully enclosed protection, without fencing, suitable for underground cable, safe and stable, convenient operation and maintenance and other core advantages, accurately fill the small pole transformer and large substation transformer between the market gap, become the core of the modern low-density power distribution scenarios of the main equipment, widely used in residential, commercial, municipal, light industry, new energy and other types of scenarios.
What is a Pad-mounted transformer?
Pad-mounted transformer is an integrated power distribution equipment specially developed for underground cable distribution system, the whole fixed installation in the outdoor concrete foundation platform, with locking fully enclosed steel cabinet, is suitable for modern cities, municipal engineering and small and medium-sized industrial projects of the core low-voltage power distribution equipment. Different from the traditional open power distribution equipment, it focuses on the design concept of Pad-mounted, fully enclosed protection, no exposed charged structure, perfectly adapted to the modern underground pipeline network power distribution system.
Pad-mounted transformer adopts the whole grounded closed structure, the core, winding, switch and all other electrically charged core components are completely sealed inside the cabinet, eliminating from the root of the risk of electric shock, short circuit, accidental contact brought about by the exposed electrically charged body. At the same time using the bottom hidden into the standardized process, the site without exposed cables, the overall neat and tidy, without the need to set up additional protective fences, can be directly deployed in the community, shopping areas, roads around the periphery and other public activities.
Key components of Pad-mounted transformers
Pad-mounted transformer can realize the core advantages of high safety, low failure, long life, easy operation and maintenance, can not be separated from the modularization, refinement, high protection structure design.
Cabinet shell
Pad-mounted transformer cabinet is made of thickened weather-resistant steel, with strong overall rigidity and excellent impact resistance, which can resist external collision and man-made damage. Surface spraying special anti-corrosion coating, after high temperature curing treatment, with rain, dust, corrosion, oxidation, anti-ultraviolet multiple performance.
Iron core and winding
As the core of the transformer, the iron core is made of high permeability cold rolled silicon steel sheet. The material has very low magnetic loss and high magnetic conductivity efficiency, which can effectively reduce the no-load loss of the equipment, improve the overall energy efficiency, and reduce the long-term operating energy costs.
The windings support the flexible selection of two mainstream materials, pure copper and aluminum alloy, to meet the needs of different budgets and working conditions.
Heat dissipation cooling system
Market mainstream floor-standing transformer adopts mature natural oil circulation self-cooling (OA) design, relying on the natural convection of insulating oil to complete the heat exchange, no need to install fans, pumps and other external cooling equipment. The overall structure is simple, no running noise, very low failure rate, daily maintenance-free.
Casing structure
All the equipment adopts the industry’s cutting-edge closed dead zone casing design, completely abandoning the traditional bare casing structure, without any exposed electrified parts, eliminating the risk of electric shock and short circuit from the root.
The casing is reserved with standard insulated operating rod adaptable interface, supporting industry common hot rod electrified operation and maintenance work. Staff can complete maintenance, debugging and troubleshooting without power supply, which not only protects the personal safety of operation and maintenance personnel, but also significantly improves the continuity of power supply and reduces the loss of power outage.
Multiple protection system
The Pad-mounted transformer is equipped with integrated multiple safety protection system, which provides all-round protection for the equipment and the back-end power grid and power equipment. Equipment standard with pressure release device, intelligent fault indicator, high voltage arrester, overload short circuit protection components.
5 advantages of Pad-mounted transformer
Compared with traditional pole-mounted transformers and large station transformers, the comprehensive advantages of Pad-mounted transformers are very prominent, and they perfectly fit the construction standards of “safety, aesthetics, energy saving, low operation and maintenance, and high reliability” of modern power engineering. Its five core values, but also all kinds of projects is the key reason for priority selection.
Occupies a very small area
Pad-mounted transformer compact structure, small footprint, conventional size of only 1.5m × 2m. equipment without poles, no additional protection fence, with underground cable wiring, completely solve the problem of messy overhead lines.
The appearance of the whole machine is low and hidden, can be arranged in the green belt, road corners and other locations, does not occupy the core space, does not damage the cityscape, highly suitable for high-end urban areas, business districts, scenic spots and other environmental value of the scene requires a high degree.
Multiple physical protection
The equipment adopts locking fully enclosed steel cabinet, completely isolating the internal electrified structure, eliminating personnel accidental contact, vandalism and other security risks, which is very suitable for crowded public areas.
The standard one-piece oil storage structure can effectively prevent the leakage of insulating oil to pollute water and soil, in line with the EPA environmental protection regulations. Equipped with multiple protection devices such as short-circuit, overload, lightning protection, etc., it can quickly cut off faults and significantly reduce the risk of electrical fires, making public power distribution safer.
Halve the workload of operation and maintenance
According to IEEE C57.12.00 industry standard, the Pad-mounted transformer adopts a fully sealed tank and moisture-proof insulation structure, which effectively isolates moisture, dust and impurities, greatly reducing internal aging and the probability of failure.
Compared with open pole-mounted transformers, its daily operation and maintenance workload is reduced by more than 50%, no need for frequent overhaul, cleaning and replacement of parts, long-term labor and maintenance costs are lower, and the whole life cycle cost performance is better.
Significantly reduce the risk of power outages
Pad-mounted transformers natively support loop power supply architecture, which can realize redundant configuration of the power grid and build a highly reliable power distribution network. This is the core advantage that traditional pole-mounted transformers do not have, and it is also the core of the municipal, commercial and new energy key projects just need.
When a single device fails, a single line is overhauled or a sudden failure occurs, the grid intelligent switch can automatically switch power supply circuits and quickly transfer the electricity load. The entire switching process does not require manual intervention, which can minimize the scope of power outages, shorten the duration of power outages, and effectively protect the uninterrupted power supply of hospitals, commercial centers, municipal facilities, data rooms and other key scenarios.
High degree of customization
Pad-mounted transformer parameters can be configured flexibly and customized according to the project load characteristics, site environment and usage requirements, which is suitable for most of the power distribution scenarios. The single-phase 25-500kVA model is specially adapted to the small load scenarios such as residential houses and stores along the street, and the three-phase 75-5000kVA model can meet the centralized large-load power supply needs of industry and commerce.
At the same time, it supports a number of customized upgrades, including low-noise design (operating noise ≤ 65dB), grid harmonic management, DOE2023 energy-efficient upgrades, corrosion-resistant enhanced protection, plateau adaptive transformation, etc., which can be targeted to solve the pain points of special conditions of electricity, adaptability and practicality is very strong.
Which projects are suitable for the selection of Pad-mounted transformers?
With the comprehensive advantages of safety, beauty, stability, low operation and maintenance, customizable, Pad-mounted transformers have a wide range of application scenarios, basically covering the modern civil, commercial, light industry, new energy, municipal power distribution projects in all fields, the core adaptable scenarios are as follows:
Urban and rural residential community transformation
At present, the domestic city new district, the old district renovation project, the general implementation of underground cable power distribution mode, eliminating the traditional overhead lines. Pad-mounted transformers are perfectly adapted to the needs of community power distribution by virtue of no risk of exposure, high safety coefficient, and hidden and beautiful appearance. The equipment can be flexibly deployed in the community green belt, corner open space and other unused areas, without occupying the owners’ activity space.
Urban business district
Shopping malls, office buildings, commercial streets, urban complexes and other commercial scenarios, with concentrated electrical loads, large flow of people, the characteristics of the equipment running around the clock, the security of the power distribution equipment, stability, continuity requirements are extremely high.
Pad-mounted transformer is fully enclosed without exposure, anti-vandalism, anti-interference, convenient operation and maintenance, which can support the stable operation of commercial equipment 24 hours a day. At the same time, the appearance of the equipment is neat and low-profile, will not affect the overall commercial landscape of the business district, is the standard distribution equipment for urban commercial infrastructure.
Industrial sites
Light industrial processing plant, warehousing park, small manufacturing plant and other small and medium-sized industrial scenarios, the power load is medium and stable, just match the optimal capacity range of Pad-mounted transformer 50-5000kVA.
The equipment is anti-vibration, anti-dust, continuous high-temperature operation, can be adapted to the complex working conditions of industrial factories, long-term stable output of electricity, to protect the production line, warehousing equipment, ventilation and lighting system of normal operation. At the same time, the low operation and maintenance characteristics can effectively reduce the downtime of industrial production equipment maintenance time.
Photovoltaic, wind power new energy projects
Distributed photovoltaic power stations, onshore wind power projects have clear requirements for power distribution equipment, need to meet the modular deployment, low visual interference, underground wiring adaptable, outdoor weather resistance and other conditions.
Pad-mounted transformers have compact structure, flexible deployment, high protection level, and can withstand the harsh environment of outdoor open air, big temperature difference between day and night, and wind and rain exposure for a long time. At the same time to adapt to the new energy power station underground wiring mode, does not destroy the overall layout of the power station, can efficiently complete the power boosting, voltage stabilization, grid-connected power distribution work, is the core of the new energy project supporting equipment.
Municipal public and campus infrastructure projects
Schools, hospitals, government buildings, city parks, public venues and other municipal public facilities, crowded, high social concern, equipment safety, noise control, stability has strict standards. Pad-mounted transformer without exposed live parts, low operating noise, low probability of failure, high protection level, will not be teachers and students, patients, the public security threats and noise interference.
Pad-mounted transformer specifications: common kVA capacity
Pad-mounted transformer capacity covers a wide range, from small civil loads to large industrial and commercial loads can be adapted.
75kVA floor-type transformer: belongs to the small standard model, mainly adapted to small residential areas, clusters of stores along the street, community facilities, light municipal supporting projects and other low-load scenarios. Stable power supply, very low energy consumption, cost-effective, fully meet the basic daily power needs.
150kVA floor-type transformer: Suitable for medium-sized residential areas, townships and townships centralized residential areas, small commercial store clusters and other medium small load scenarios. Equipment load capacity is moderate, low energy loss, can run stably for a long time, suitable for ordinary people’s livelihood power distribution projects.
300kVA Pad-mounted transformer: a popular model in the market, suitable for small processing plants, medium-sized commercial streets, communities and other scenes. The capacity of the perfect balance between power supply capacity and energy consumption level, the overall cost-effective, is the preferred model for the transition between civilian and light industrial scenes.
500kVA floor-type transformer: the main medium load industrial and commercial scenarios, suitable for large commercial complexes, chain stores, light industrial parks, centralized office parks. Can be stable to carry a long time continuous power load, power supply redundancy is sufficient, suitable for centralized, large-scale power needs.
750kVA floor-type transformer: high load special model, suitable for medium-sized industrial plants, high-density commercial areas, large-scale comprehensive community and other high-load power consumption scenarios. Equipment overload resistance is strong, can cope with peak load fluctuations, to ensure that the power supply does not trip, no pressure drop.
1000kVA Pad-mounted transformer: a large main model, suitable for large industrial workshops, mega commercial complexes, centralized new energy grid-connected projects and other high power demand scenarios. The equipment has strong power supply capacity and high stability, which can meet the high-intensity, uninterrupted scale of power demand.
How to choose the pad-mounted transformer?
Pad-mounted transformer selection directly determines the project power supply stability, equipment life and overall investment costs. Many projects have insufficient power supply, high energy consumption, frequent failures, later expansion difficulties and other issues, the core reason is that the selection of non-standardized, unreasonable parameter matching.
Accounting for electricity load
The core of selection is to calculate the average load and peak load of the project, combined with the simultaneous coefficient to calculate the appropriate capacity. It is recommended to reserve 20%-30% capacity margin to meet the later load expansion. Small capacity is easy to overload tripping, burn equipment; large capacity is high no-load loss, waste of investment. Single-phase models are suitable for small loads such as houses and stores, while three-phase models are suitable for centralized loads such as businesses, factories and large communities.
Matching voltage level and wiring configuration
The voltage of the high voltage side should be strictly matched with the local grid standard, commonly used 12.47kV, 13.8kV, 34.5kV and other specifications, and at the same time, the BIL withstand voltage level should be verified, so as to enhance the ability of lightning protection and resistance to the fluctuation of the grid. On the low voltage side, standard voltages such as 120/240V, 208Y/120V, 480Y/277V can be selected as required. The equipment is equipped with ±2.5%/±5% tapping regulator switch as standard, which can adapt to the fluctuation of power grid and ensure the stability of output voltage.
Selection of power supply structure (radial/loop)
For non-core loads such as ordinary houses, light factories, street stores, etc., radial power supply can be selected, which is simple in structure and cost-effective. For important loads such as hospitals, data centers, new energy power stations, and large business districts, it is recommended to use redundant loop power supply, which can automatically switch circuits in case of failure, avoiding large-scale power outages and ensuring the continuity of power supply.
Confirmation of heat dissipation and energy efficiency standards
Standard ONAN oil-immersed self-cooling design is adopted in regular residential and commercial scenarios, which is quiet, maintenance-free and cost-effective. For high-temperature environments and 24-hour uninterrupted high-load working conditions, the forced cooling structure can be upgraded to improve overload resistance. DOE2023 energy-efficient models are preferred for long-term operation projects, reducing no-load and load losses and significantly saving long-term electricity costs.
Verification of certification standards and core configuration
Compliance equipment must meet international electrical standards such as ANSI, IEEE, UL, CSA, etc., and come standard with current limiting fuse, lightning arrester, grounding protection and fault indicator to form a complete safety protection system. Key long-term project priority selection of copper winding, stability, durability is stronger; ordinary civil short-term projects can choose aluminum winding, balancing the procurement cost and the use of performance.
Pad-mounted transformer installation and operation and maintenance
High-quality equipment quality needs standardized installation and operation and maintenance support, standardized construction and maintenance can maximize the performance of the equipment, greatly extend the service life of the equipment, reduce the probability of failure, to ensure the long-term stable operation of the power distribution system.
Standardized installation core requirements
Pad-mounted transformers must be installed on a level, solid, load-bearing prefabricated concrete platform, to ensure that the foundation level without tilt, no settlement. The platform should be reserved for standard drainage slope and drainage channel, to ensure that there is no water in rainy days, to avoid long-term equipment soaking and moisture.
During the installation process, standardized grounding construction should be strictly implemented to ensure that the grounding resistance meets the industry norms, effectively channeling the lightning current and static electricity, and avoiding the risk of electric shock and equipment breakdown. Underground cable wiring needs to be regular and orderly, sealed tightly, in strict accordance with the equipment wiring specification construction, to eliminate false connection, leakage, sealing problems. At the same time in accordance with the norms reserved for equipment maintenance safety spacing, to facilitate the later operation and maintenance operations.
Daily Inspection Core Program
Daily inspection is a key means to detect faults and avoid hidden dangers of the equipment in advance, which needs to be carried out on a regular basis. Inspectors need to regularly check the equipment tank oil level is standard, there is no oil leakage, to ensure that the amount of insulation oil is sufficient.
At the same time, check the cabinet sealing status, shell anticorrosion coating intact, to see whether the cabinet water, dust, rust, deformation and other issues. Regularly test the insulation performance of the equipment, terminal temperature, operation sound, check the abnormal temperature rise, abnormal noise, leakage and other hidden faults, so as to achieve early detection of hidden problems, early treatment.
Preventive regular maintenance specification
In addition to daily inspections, quarterly and annual preventive maintenance mechanisms need to be established to reduce the equipment failure rate from the source. Regularly clean and remove dust from the cabinet interior, ventilation structure, and terminals to avoid excessive accumulation of dust leading to insulation degradation and short-circuit failure.
Carry out professional electrical performance testing, including insulation resistance testing, ratio testing, protective device action testing, etc., to confirm that the performance parameters of the equipment are up to standard. Replace aging, worn-out and degraded accessories, such as tap changers, bushings, sealing tape, etc., in a timely manner to prevent minor faults from turning into major equipment failures.
Adjustment of environment suitability operation and maintenance
According to the temperature, humidity and climate change of the operating environment of the equipment, the frequency of operation and maintenance is dynamically adjusted and the maintenance program. During the summer high temperature period, focus on checking the equipment cooling performance, to avoid high temperature overload; rainy season and flood season focus on checking the waterproof sealing, foundation drainage, grounding system, to prevent water and moisture.
Coastal, dust, corrosion and other special conditions of the region, the need to encrypt the frequency of inspection, increase the anti-corrosion, dust removal, sealing inspection program, targeted to adapt to harsh environments, to protect the equipment throughout the year stable operation.
Frequently Asked Questions
In order to solve the project selection, installation, operation and maintenance of common questions, organize the industry’s high-frequency consulting questions, combined with professional standards and uniform answers to help users quickly answer questions and solve puzzles.
Q1：What is the normal service life of pad-mounted transformer?
In the standardized installation, regular operation and maintenance, under the premise of normal working conditions, the standard service life of floor-mounted transformers can reach more than 30 years. The structural design of fully sealed anticorrosive cabinet, inert insulating oil, and high-quality core winding significantly reduces the aging speed of the equipment, which is far better than the traditional pole-mounted transformer.
Q2：How to accurately determine how large capacity of floor-mounted transformer is needed for the project?
Need to count the project average load, peak load, combined with the load coefficient of the same time to calculate the basic capacity, and then reserve 20% -30% expansion margin. Small livelihood scenarios use 75-150kVA, medium-sized commercial light industrial use 300-500kVA, large industrial and commercial use 750-1000kVA and above specifications. Complex projects are recommended by professional electrical engineers to issue load measurement program.
Q3：Can pad-mounted transformers be used in photovoltaic and wind power new energy projects?
Completely suitable. Pad-mounted transformer outdoor weather resistance, flexible deployment, adaptable to underground wiring, visual interference is small, perfectly suited to the construction needs of the new energy power plant, can efficiently complete the power stabilization, boosting, grid-connected distribution work, is the mainstream of distributed new energy projects supporting equipment.
Q4：How often do floor-mounted transformers need to be maintained?
Conventional scenarios suggest a monthly simple inspection, a quarterly special inspection, and an annual comprehensive in-depth maintenance. Compared with the traditional transformer, its operation and maintenance workload is reduced by 50%, no frequent replacement, frequent maintenance needs, long-term operation and maintenance costs are extremely low.
Conclusion
Under the industry trend of grid intelligence, urban infrastructure landscaping, and new energy power distribution, floor-mounted transformers have become the core equipment of modern power distribution system by virtue of their comprehensive advantages of safety and reliability, beautiful and hidden, easy operation and maintenance, strong adaptability, and outstanding cost performance.
Jinma Electric, as a leading transformer manufacturer in China, we continue to provide stable, safe and efficient power distribution support for all kinds of power projects. Contact us for professional transformer solutions.
