Padmount Transformers

Safe & Reliable, compact structure, convenient maintenance

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Safe and Efficient Energy Solutions

At Daqo Power Systems, we are constantly striving to introduce new innovations to the transformer industry, bringing you the highest quality, most reliable transformers. Daqo Power Systems Transformer Products are ISO 9001 compliant, emphasizing process improvement in all phases of design, manufacture,and testing.

With transformer sizes ranging from 45 kVA to 12 MVA and high voltages ranging from 2400V to 46 kV, Daqo Power Systems has you covered. From fabrication of the tanks and cabinets to winding of the cores and coils, Daqo Power Systems does it all. Daqo Power Systems transformers are available with electrical grade mineral oil or EnvirotempTM FR3TM fluid, a less-flammable and bio-degradable fluid. Electrical codes recognize the advantages of using EnvirotempTM FR3TM fluid both indoors and outdoors for fire sensitive applications. The bio-based fluid meets Occupational Safety and Health Administration (OSHA) and Section 450.23 NEC Requirements.

Padmount Transformers
Terminal Power Supply Options

Industry-Leading Lead Times

1 Weeks RFQ Lead Times

2 - 4 Weeks Drawing Approval

6 - 8 Weeks Delivery

Padmount Transformers

At Daqo Power Systems, we are constantly striving to introduce new innovations to the transformer industry, bringing you the highest quality, most reliable transformers. Daqo Power Systems Transformer Products are ISO 9001 compliant, emphasizing process improvement in all phases of design, manufacture,and testing.

With transformer sizes ranging from 45 kVA to 12 MVA and high voltages ranging from 2400V to 46 kV, Daqo Power Systems has you covered. From fabrication of the tanks and cabinets to winding of the cores and coils, Daqo Power Systems does it all. Daqo Power Systems transformers are available with electrical grade mineral oil or EnvirotempTM FR3TM fluid, a less-flammable and bio-degradable fluid. Electrical codes recognize the advantages of using EnvirotempTM FR3TM fluid both indoors and outdoors for fire sensitive applications. The bio-based fluid meets Occupational Safety and Health Administration (OSHA) and Section 450.23 NEC Requirements.

Padmount Transformers Features

  • Delta -Wye: Low voltage neutral shall be a fully insulated X0 bushing with removable ground strap.
  • Grounded Wye-Wye: High voltage neutral shall be internally tied to the low voltage neutral and brought out as the H0X0 bushing in the secondary compartment with a removable ground strap.
  • Delta-Delta: Transformer shall be provided without a neutral bushing.
  • Wye-Wye: High voltage neutral shall be brought out as the H0 bushing in the primary compartment and the low voltage neutral shall be brought as the X0- bushing in the secondary compartment.
  • Wye-Delta: High voltage neutral shall be brought out as the H0 bushing in the primary compartment. No ground strap shall be provided (line to line rated fusing is required).
  • 200 A bushing wells (15, 25, and 35 kV)
  • 200 A, 35 kV Large Interface
  • 600A (15, 25, and 35 kv) Integral bushings (dead-front)
  • Electrical-grade wet-process porcelain bushings (live-front)
  • Bolted cover for tank access (45-1750 kVA)
  • Welded cover with hand hole (2000-12.000 kVA)
  • Three-point latching door for security
  • Removable sill for easy installation
  • Lifting lugs (4)
  • Stainless steel cabinet hinges and mounting studs
  • Steel divider between HV and LV compartment
  • 20" Deep cabinet (45-1000 kVA)
  • 24"Deep cabinet (1500-7500 kVA)
  • 30" Deep cabinet (34.5/19.92 kV)
  • Pentahead captive bolt
  • Stainless steel 1-hole ground pads (45-500 kVA)
  • Stainless steel 2-hole ground pads (750-10,000 kVA)
  • Parking Stands
  • One-inch upper filling plug
  • One-inch drain plug (45-500 kVA)
  • One-inch combination drain valve with sampling device in low voltage compartment (750-12,000 kVA)
  • Automatic pressure relief valve
  • Laser-scribed anodized aluminum nameplate

Our Transformers Advantages

The three-legged, step-lap mitered core construction is manufactured using a high-quality cutting machine. For maximum efficiency,cores are precisely stacked, virtually eliminating gaps in the corner joints.

Five-legged wound core or shell-type triplex designs are used for wye-wye connected transformers, and other special transformer designs.

Cores are manufactured with precision cut, burr-free, grain-oriented silicon steel. Many grades of core steel are available for optimizing core loss efficiency.

Pad-mounted transformers feature a quasi-elliptical coil configuration with wire-wound, high-voltage primaries and sheet-wound secondaries.The design minimizes axial stress developed by short circuits and provides for magnetic balancing of tap connections.

Coils are wound using the highest quality winding machines providing exacting tension control and conductor placement for superior short-circuit strength and maximum efficiency.

Extra mechanical strength is provided by diamond pattern, epoxycoated paper insulation, used throughout the coil, with additional epoxy at heavy stress points.The diamond pattern distribution of the epoxy and carefully arranged ducts, provide a network of passages through which cooling fluid can freely circulate.

Coil assemblies are heat-cured under calculated hydraulic pressure to ensure performance against short-circuit forces.

Pad-mounted transformer core and coil assemblies are braced with heavy steel ends to prevent the rectangular coil from distorting under short-circuit conditions. Plates are clamped in place using presses, and welded or bolted to form a solid core and coil assembly. Core and coil assemblies exceed ANSI®and IEEE®requirements for short-circuit performance. Due to the rigidity of the design,impedance shift after short-circuit is comparable to that of circular wound assemblies.

Transformer tanks are designed for high strength and ease of handling, installation, and maintenance.Tanks are welded using precision-cut, hot rolled, pickled and oiled steel.They are sealed to protect the insulating fluid and other internal components.

Transformer tanks are pressure-tested to withstand 7 psig without permanent distortion and 15 psig without rupture.

Transformers are dried and filled with filtered insulating fluid under vacuum,while secondary windings are energized. Coils are heated to drive out moisture, ensuring maximum penetration of fluid into the coil insulation system.

Transformers from Daqo Power Systems are available with electrical-grade mineral insulating oil or EnvirotempTM  FR3TMfluid. The highly refined fluids are tested and degassed to assure a chemically inert product with minimal acid ions. Special additives minimize oxygen absorption and inhibit oxidation.To ensure high dielectric strength, the fluid is re-tested for dryness and dielectric strength, refiltered, heated, dried, and stored under vacuum before being added to the completed transformer.

Daqo Power Systems transformers filled with EnvirotempTM FR3TM fluid enjoy unique fire safety, environmental.electrical, and chemical advantages, including insulation life extending properties.A bio-based, sustainable, natural ester dielectric coolant,EnvirotempTM FR3TM fluid quickly and thoroughly biodegrades in the environment and is non-toxic per acute aquatic and oral toxicity tests.

Building for Environmental and Economic Sustainability (BEES)total life cycle assessment software, utilized by the US Dept. of Commerce, reports its overall environmental performance impact score at 1/4th that reported for mineral oil. EnvirotempTMFR3TMfluid has also earned the EPA Environmental Technology Verification of transformer materials.

With a fire point of 360°C, EnvirotempTM FR3TM fluid is FM Approvede® and Underwriters Laboratories (UL®) Classified “Less-Flammable” per NEC® Article 450-23, fitting the definition of a Listed Product per NEC®.

Daqo’s EnvirotranTM transformer series complies with the requirements of NEC 2008, Section 450.23 – Low Combustible Liquid-Filled Transformers, for both indoor and outdoor installations.

Core

The three-legged, step-lap mitered core construction is manufactured using a high-quality cutting machine. For maximum efficiency,cores are precisely stacked, virtually eliminating gaps in the corner joints.

Five-legged wound core or shell-type triplex designs are used for wye-wye connected transformers, and other special transformer designs.

Cores are manufactured with precision cut, burr-free, grain-oriented silicon steel. Many grades of core steel are available for optimizing core loss efficiency.

Coils

Pad-mounted transformers feature a quasi-elliptical coil configuration with wire-wound, high-voltage primaries and sheet-wound secondaries.The design minimizes axial stress developed by short circuits and provides for magnetic balancing of tap connections.

Coils are wound using the highest quality winding machines providing exacting tension control and conductor placement for superior short-circuit strength and maximum efficiency.

Extra mechanical strength is provided by diamond pattern, epoxycoated paper insulation, used throughout the coil, with additional epoxy at heavy stress points.The diamond pattern distribution of the epoxy and carefully arranged ducts, provide a network of passages through which cooling fluid can freely circulate.

Coil assemblies are heat-cured under calculated hydraulic pressure to ensure performance against short-circuit forces.

Assemblies

Pad-mounted transformer core and coil assemblies are braced with heavy steel ends to prevent the rectangular coil from distorting under short-circuit conditions. Plates are clamped in place using presses, and welded or bolted to form a solid core and coil assembly. Core and coil assemblies exceed ANSI®and IEEE®requirements for short-circuit performance. Due to the rigidity of the design,impedance shift after short-circuit is comparable to that of circular wound assemblies.

Tanks

Transformer tanks are designed for high strength and ease of handling, installation, and maintenance.Tanks are welded using precision-cut, hot rolled, pickled and oiled steel.They are sealed to protect the insulating fluid and other internal components.

Transformer tanks are pressure-tested to withstand 7 psig without permanent distortion and 15 psig without rupture.

Vacuum processing

Transformers are dried and filled with filtered insulating fluid under vacuum,while secondary windings are energized. Coils are heated to drive out moisture, ensuring maximum penetration of fluid into the coil insulation system.

Insulating fluid

Transformers from Daqo Power Systems are available with electrical-grade mineral insulating oil or EnvirotempTM FR3TMfluid.The highly refined fluids are tested and degassed to assure a chemically inert product with minimal acid ions. Special additives minimize oxygen absorption and inhibit oxidation.To ensure high dielectric strength, the fluid is re-tested for dryness and dielectric strength, refiltered, heated, dried, and stored under vacuum before being added to the completed transformer.

Daqo Power Systems transformers filled with EnvirotempTM FR3TM fluid enjoy unique fire safety, environmental.electrical, and chemical advantages, including insulation life extending properties.A bio-based, sustainable, natural ester dielectric coolant,EnvirotempTM FR3TM fluid quickly and thoroughly biodegrades in the environment and is non-toxic per acute aquatic and oral toxicity tests.

Building for Environmental and Economic Sustainability (BEES)total life cycle assessment software, utilized by the US Dept. of Commerce, reports its overall environmental performance impact score at 1/4th that reported for mineral oil. EnvirotempTMFR3TMfluid has also earned the EPA Environmental Technology Verification of transformer materials.

With a fire point of 360°C, EnvirotempTM FR3TM fluid is FM Approvede® and Underwriters Laboratories (UL®) Classified "Less-Flammable" per NEC® Article 450-23, fitting the definition of a Listed Product per NEC®.

EnvirotranTM transformer

Daqo’s EnvirotranTM transformer series complies with the requirements of NEC 2008, Section 450.23 – Low Combustible Liquid-Filled Transformers, for both indoor and outdoor installations.

Core

The three-legged, step-lap mitered core construction is manufactured using a high-quality cutting machine. For maximum efficiency,cores are precisely stacked, virtually eliminating gaps in the corner joints.

Five-legged wound core or shell-type triplex designs are used for wye-wye connected transformers, and other special transformer designs.

Cores are manufactured with precision cut, burr-free, grain-oriented silicon steel. Many grades of core steel are available for optimizing core loss efficiency.

Coils

Pad-mounted transformers feature a quasi-elliptical coil configuration with wire-wound, high-voltage primaries and sheet-wound secondaries.The design minimizes axial stress developed by short circuits and provides for magnetic balancing of tap connections.

Coils are wound using the highest quality winding machines providing exacting tension control and conductor placement for superior short-circuit strength and maximum efficiency.

Extra mechanical strength is provided by diamond pattern, epoxycoated paper insulation, used throughout the coil, with additional epoxy at heavy stress points.The diamond pattern distribution of the epoxy and carefully arranged ducts, provide a network of passages through which cooling fluid can freely circulate.

Coil assemblies are heat-cured under calculated hydraulic pressure to ensure performance against short-circuit forces.

Assemblies

Pad-mounted transformer core and coil assemblies are braced with heavy steel ends to prevent the rectangular coil from distorting under short-circuit conditions. Plates are clamped in place using presses, and welded or bolted to form a solid core and coil assembly. Core and coil assemblies exceed ANSI®and IEEE®requirements for short-circuit performance. Due to the rigidity of the design,impedance shift after short-circuit is comparable to that of circular wound assemblies.

Tanks

Transformer tanks are designed for high strength and ease of handling, installation, and maintenance.Tanks are welded using precision-cut, hot rolled, pickled and oiled steel.They are sealed to protect the insulating fluid and other internal components.

Transformer tanks are pressure-tested to withstand 7 psig without permanent distortion and 15 psig without rupture.

Vacuum processing

Transformers are dried and filled with filtered insulating fluid under vacuum,while secondary windings are energized. Coils are heated to drive out moisture, ensuring maximum penetration of fluid into the coil insulation system.

Insulating fluid

Transformers from Daqo Power Systems are available with electrical-grade mineral insulating oil or EnvirotempTM FR3TMfluid.The highly refined fluids are tested and degassed to assure a chemically inert product with minimal acid ions. Special additives minimize oxygen absorption and inhibit oxidation.To ensure high dielectric strength, the fluid is re-tested for dryness and dielectric strength, refiltered, heated, dried, and stored under vacuum before being added to the completed transformer.

Daqo Power Systems transformers filled with EnvirotempTM FR3TM fluid enjoy unique fire safety, environmental.electrical, and chemical advantages, including insulation life extending properties.A bio-based, sustainable, natural ester dielectric coolant,EnvirotempTM FR3TM fluid quickly and thoroughly biodegrades in the environment and is non-toxic per acute aquatic and oral toxicity tests.

Building for Environmental and Economic Sustainability (BEES)total life cycle assessment software, utilized by the US Dept. of Commerce, reports its overall environmental performance impact score at 1/4th that reported for mineral oil. EnvirotempTMFR3TMfluid has also earned the EPA Environmental Technology Verification of transformer materials.

With a fire point of 360°C, EnvirotempTM FR3TM fluid is FM Approvede® and Underwriters Laboratories (UL®) Classified "Less-Flammable" per NEC® Article 450-23, fitting the definition of a Listed Product per NEC®.

EnvirotranTM FM Approved special protection transformer

Daqo’s EnvirotranTM transformer series complies with the requirements of NEC 2008, Section 450.23 – Low Combustible Liquid-Filled Transformers, for both indoor and outdoor installations.

Special application transformers

Data Center transformer

With focus rapidly shifting from simply maximizing uptime and supporting demand to improving energy utilization, the data center industry is continually looking for methods to increase its energy efficiency and reliability. Utilizing cutting edge technology, Daqo Power Systems Hardened Data Center (HDC) transformers are the solution. Designed with special attention given to surge protection, HDC liquid-filled transformers provide superior performance under the harshest electrical environments. Contrary to traditional dry-type units, HDC transformers provide unsurpassed reliability, overloadability, operational life, efficiency, thermal loading and installed footprint. These Daqo Power Systems units have reliably served more than 100 MW of critical data center capacity for a total of more than 2,000,000 hours without any reported downtime caused by a thermal or short-circuit coil failure.

The top priority in data center operations is uninterrupted service. Envirotran HDC transformers from Daqo Power Systems, having substantially higher levels of insulation, are less susceptible to voltage surges. Daqo Power Systems has experienced zero failures due to switching transients. The ANSI® and IEEE® standard impulse withstand ratings are higher for liquid-filled transformers, making them less susceptible to insulation failure. The Envirotran HDC transformer provides ultimate protection by increasing the BIL rating one level higher than standard liquid-filled transformer ratings. The cooling system of liquid-filled transformers provides better protection from severe overloads—overloads that can lead to significant loss of life or failure.

Data center design typically includes multiple layers of redundancy, ensuring maximum uptime for the critical IT load. When best in class transformer manufacturing lead times are typically weeks, not days, an unexpected transformer failure will adversely affect the facility’s reliability and profitability. Therefore, the ability to determine the electrical and mechanical health of a transformer can reduce the probability of costly, unplanned downtime. Routine diagnostic tests, including key fluid properties and dissolved gas analysis (DGA), can help determine the health of a liquid-filled transformer. Although sampling is not required for safe operation, it will provide the user with valuable information, leading to scheduled repair or replacement, and minimizing the duration and expense of an outage. With a dry-type transformer, there is no reliable way to measure the health or likelihood of an impending failure.

Solar transformer

As a result of the increasing number of states that are adopting aggressive Renewable & Alternative Energy Portfolio Standards,the solar energy market is growing—nearly doubling year over year. Daqo Power Systems,a key innovator and supplier in this expanding market,is proud to offer Envirotran transformers specifically designed for Solar Photovoltaic medium-voltage applications. Daqo Power Systems is working with top solar photovoltaic developers, integrators and inverter manufacturers to evolve the industry and change the way we distribute power.

In accordance with this progressive stance, every Daqo Power Systems Envirotran Solar transformer is filled with non-toxic, biodegradable EnvirotempTM FR3TM dielectric fluid,made from renewable seed oils. On top of its biodegradability EnvirotempTM FR3TM fluid substantially extends the life of the transformer insulation, saving valuable resources. What better way to distribute green power than to use a green transformer. In fact, delaying conversion to Envirotran transformers places the burden of today's environmental issues onto tomorrow's generations.Daqo Power Systems can help you create a customized transformer, based on site specific characteristics including:temperature profile, site altitude, solar profile and required system life. Some of the benefits gained from this custom rating include:

  • Reduction in core losses
  • Improved payback on investment
  • Reduction in footprint
  • Improved fire safety
  • Reduced environmental impact

For the solar photovoltaic industry, Daqo Power Systems is offering standard step up transformers and dual secondary designs, including 4-winding, 3-winding (Low-High-Low) and 3-winding (Low-Low-High) designs.

DOE efficiency

The United States Department of Energy (DOE) has mandated efficiency values for most liquid type, medium voltage transformers. As a result, all applicable Daqo Power Systems transformers are designed to meet or exceed the standard efficiency values per DOE 2010; Final Ruling, 10 CFR Part 431.

Underwriters Laboratories® (UL®) Listed and Labeled/ Classified

The Envirotran transformer from Daqo Power Systems can be specified as UL® Listed & Labeled, and/or UL® Classified. Underwriters Laboratories (UL®) listing is a verification of the design and construction of the transformer to the ANSI® and IEEE® standards. UL® listing generally is the most efficient, cost-effective solution for complying with relevant state and local electrical codes. UL® Combination Classification/Listing is another way in which to comply with Section 450.23, 2008 NEC® requirements. This combines the UL® listed transformer with a UL® Classified Less-Flammable Liquid and complies with the use restrictions found within the liquid Classification.

Product Scope Data Sheet

TypeThree Phase，50 or 60 Hz，65℃ Rise (55℃，55/65℃)，65/75℃，75℃
Fluid TypeMineral oil or Envirotemp™ FR3™ fluid
Coil Configuration2-winding or 4-winding or 3-winding (Low-High-Low), 3-winding (Low-Low-High)
Size45 – 12,000 kVA
Primary Voltage2,400 – 46,000 V
Secondary Voltage208Y/120 V to 14,400 V
Specialty DesignsInverter/Rectifier Bridge
K-Factor (up to K-19)
UL® Listed & Labeled and Classified
Factory Mutual (FM) Approved®
Solar/Wind Designs
Differential Protection
Seismic Applications (including OSHPD)
Hardened Data Center

DOE Efficiency & Audible Sound Levels Data Sheet
Volume（kvA）DOE EfficiencySound（dB）
750.990354
112.50.991155
1500.991655
2250.992355
3000.992755
5000.993556
7500.99457
10000.994358
12500.994559
15000.994860
20000.995161
25000.995362
3000Customized63
3001-4000Customized64
4000-5001Customized65
5001-6000Customized66
6001-7500Customized67
7501-12000Customized68
Insulation Test Levels Data Sheet
KV ClassInduced Test 180 or 400 Hz 7200 CyclekV BILApplied Test 60 Hz (kV)
Distribution
1.2TWICE RATED VOLTAGE3010
2.54515
56019
8.77526
159534
25(grd Y Only)12540
2515050
34.5(grd Y Only)12540
34.515070
4620095

Enclosure Options

Choose from a variety of enclosure options to meet your specific system needs. Our enclosures are designed to meet all CSA and UL 50 requirements.

Quality Certifications

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