DAELIM Transformer


Prompt preparation of bids

• Optimized, consistent end-to-end project management

• Noticeably shorter production and delivery times

• Very high delivery reliability

• Fast, standardized documentation

• Just-in-time delivery

Power Transformer

Daelim’s power transforemrs are accordling to ANSI/EEE,IEC,CSA,AS as well as NEMA standards, The power ratings are up to 270 MVA and for volumes up o the highest insulation classof 900 kV. There are a large number of project cases in North and South America, such as: 230kv power transformer in the United States, 115kv power transformer in Mexico, 66kv power transformer in Canada, 69kv, 110kv power transformer in Ecuador, etc. The local service team can provide installation, maintenance, after-sales guidance and other services for your transformer. Quick solution to your problem.

Power Transformer manufacturer

Power Transformer manufacturer

Daelim Transformer, a UL, cUL, and CSA certified power transformer manufacturer, adheres to global standards such as ANSI/IEEE/IEC/CSA/AS and NEMA. They offer transformers with ratings up to 270 MVA and insulation levels up to 800 kV. Daelim excels in providing innovative electrical transformer solutions, prioritizing safety and sustainability while meeting rigorous standards.

Each transformer is uniquely designed, considering factors like voltage, power rating, climate, and network topology. These solutions prioritize efficiency, eco-friendliness, high short-circuit strength, overload capacity, high-temperature operation, reliable startup during outages, and cost-effective maintenance. Their applications span renewable energy, urban substations, utilities, and industrial sectors.

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Daelim Transformer

At Daelim Transformer:

  • Swift and efficient bid preparation
  • Streamlined, end-to-end project management optimized for consistency
  • Markedly reduced production and delivery lead times
  • Exceptional delivery reliability
  • Expedited, standardized documentation
  • Punctual, just-in-time delivery

Daelim Transformer stands as a trusted partner, offering innovative and efficient power transformer solutions tailored to meet unique demands.

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Daelim Transformer
Power Transformer Desing Capability

Power Transformer Desing Capability


Equipment : 3F/2F/1F Multi-winding Transformer / Autotransformer


Design: Sealed-tank system /Inert-gas pressure system or conservator-tank system without diaphragm; On load or no load voltage tap changer


Insulation: Mineral Oil Inhibited I Not Inhibited I Vegetable oil

Primary voltage: Up to 230kV, up to 900 kV BIL

Capacity:  Up to 270 MVA           Frequency: 50/60 HZ

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    Power Transformer Operating Condition

    Suitable for indoor and outdoor application.

    Ambient temperature: - 50℃-40℃

    Relative humidity: ambient air relative humidity should be below 93%,

    Altitude: ≤1000m

    Max wind speed:≤35 m/s

    Earthquake acceleration: horizontal acceleration ≤0.3g

    Vertical acceleration ≤0.15g

    Special conditions: customized products are available.

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    Power Transformer Operating Condition

    Daelim Transformer Overseas Projiect Cases

    66 kV 12 MVA Power Transformer

    66 kV 12 MVA Power Transformer

    Location: British Columbia, Canada            

    Quantity: 3 units            Standards: IEEE & CSA                                     

    Special applications: Need to step down 66kV to 12.47kV, then connect to 4 units 3mva pad mounted transformer to supply power for crypto mining machines.

    Accessories: Some of the accessories need to be explosion-proof, and customer have special requirements for gauges and valves.

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    230 kV 10 MVA Power Transformer

    230 kV 10 MVA Power Transformer

    Location: Nevada, USA

    Quantity: 1 unit               Standard: IEEE

    The primary voltage is 230 kV, while the secondary voltage is 24.94 kV. This 230 kV transformer is capable of providing power ratings of 10 MVA, 12.5 MVA, and 15 MVA under various cooling methods.

    It is designed with a KNAN/KNAF/KNAF configuration, and it utilizes vegetable oil as the insulating liquid.

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    66 kV 15 MVA Power Transformer

    66 kV 15 MVA Power Transformer

    Location: Australia           Application: Solar Farm

    Standards: AS & IEC         Power rating: 12.5 MVA/15 MVA

    Primary voltage: 66 kV     Secondary voltage: 33000Y/19052V

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    69 kV 10 MVA Power Transformer

    69 kV 10 MVA Power Transformer

    Location: Quebec, Canada        Application: 69 kV Substation

    Standards: IEEE & CSA              Power rating: 10000/13300kVA

    Primary voltage: 69 kV              Secondary voltage: 4.16 kV

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    138 kV 40 MVA Power Transformer

    138 kV 40 MVA Power Transformer

    Location: Guayaquil,  Ecuador           Application: Substation

    Standards: IEEE                                  Power rating: 40 MVA

    High Voltage: 138 kV                         Low voltage: 34.5 kV         

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    115 kV 20 MVA Power Transformer

    115 kV 20 MVA Power Transformer

    Location: NUEVO LEÓN Mexico           Application: Substation

    Standards: IEEE                                    Power rating: 20 MVA

    High Voltage: 115 kV                          Low voltage: 13.8 kV       

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    Daelim Power Transformer

    Optional Accessories

    Optional Accessories

    Junction Box                 Fiber-optic temperature measurements

    Neutral Terminals            Other Moving Facilities (Wheels)

    Rapid Rise Relay             Nitrogen gas fluid preservation system

    Electrostatic shield           Special / low sound level         Schrader Valve 

    Special environment          Special paint for marine ambient       Gas Test Valve

    Line Dissolved Gas Monitor       Bushing Mounted Current Transformers        

    Fire Prevention System (SERGl)     On-line monitoring system

    High ambient designs available            High elevation designs available




    Optional Accessories

    Optional Accessories

    Insulating oil: Natural ester( FR3 Enviro Temp, RAPO etc)     Fans

    Cooling: ONAN/ONAF, KNAN, KNAN/KNAF                   Frequency: 50 Hertz

    Average winding rise: 55°C or 55/65°C                    Future fan wiring and control

    Automatic pressure relief device                         Galvanized or stainless-steel radiators

    Accessories with additional contacts                Controls Cabinet: NEMA 3R, 4, 4X

    Customizable Colors                                  Harmonic allowances up to k-20

    Station Class                                    Seismic designs: Zones 1-4

    HV lightning arresters: Distribution Class, Intermediate Class

    Power Transformer Standard Features

    Capacity range: Through 60 MVA (ONAN), with high-voltage ratings through 230 kV (900 kV BIL)

    Service Location: Outdoor    Coils: Cylindrical construction;

    Core: Regular grain-oriented; mitered cruciform with step-lap construction

    all copper windings; custom tempered per design requirements; circular windings with rectangular or continuously-transposed conductor; helical low-voltage windings; continuous disc medium-voltage windings; shielded disc high-voltage windings Radiators: Detachable panel type with shut-off valves, mild steel

    Insulating oil: Mineral oil type I & type Il             Tank Cover: Welded, Bolted

    Manholes: On cover or tank                                 Tank Base: Flat bottom or Skid under base

    Tank Material: Mid Steel                                       Frequency: 60 Hertz

    Winding Tem rise: 55C

    HV Taps: DETC, ETC in the tank or out

    - Above rated volts: 2 x 2-1/2% offload taps of full capacity

    - Below rated volts: 2 x 2-1/2% offload taps of full capacity

    Valve: Drain and Filter Valves, w/Sampler Lifting, Moving, and Jacking Facilities

    Pressure relief valve                                    Magnetic oi-level indicator

    Dial-type oil temperature indicator            Dial-type winding temperature indicator

    Dial-type sudden pressure relay                 Pressure vacuum gauge

    Paint: Exterior polyurethane enamel, ANSI 70 gray color; interior polyurethane enamel, white color

    HV bushing: IEEE segment 1-4, on the top cover or in the Air Terminal Chamber.

    Porcelain Condenser, Solid Bulk.Solid Dielectric, Quick link

    LV bushing: IEEE segment 1-4, Cover mounted or in Air Terminal Chamber Porcelain Condenser, Solid Bulk. Solid Dielectric, Quick link 

    Diagrammatic nameplate, engraved stainless steel

    Transformer lifting lugs                            Tank grounding pads

    Routine Tests

    Routine tests, also known as factory tests, are essential for ensuring the quality of every transformer. These tests include:

    • Dielectric tests
    • Measurement of Voltage Ratio and Vector Group
    • Measurement of Winding Resistance
    • Separate-Source Power-Frequency Voltage Withstand Test
    • Measurement of Bushing Capacitance and Dielectric Dissipation Factor
    • Induced Voltage Withstand Test
    • Measurement of No-load Losses and No-load Current
    • Measurement of Impedance Voltage and Load Losses
    • Sealed Test
    • Measurement of the winding frequency spectrum response curve
    • Current transformer test
    • On-Load Tap Changer (OLTC) tests
    • Measurement
    • Oil test
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    Routine Tests

    Type Tests & Special Tests

    Type Tests

    Type tests verify if a transformer meets specified standards and whether products of the same type or series meet these standards. Type test items include:

    • Temperature rise test
    • Lightning impulse test

    Special Tests

    Special tests are conducted as mutually agreed upon by the manufacturer and the user. Special test items encompass:

    • Transient voltage transfer characteristics measurement
    • Three-phase transformer zero-sequence impedance measurement
    • Short-circuit test
    • Sound level measurement
    • Measurement of harmonic currents during no-load
    • Measurement of power consumption by fans and oil pumps
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    Type Tests & Special Tests
    Core Assembly & Coil Winding

    Core Assembly & Coil Winding

    Core Assembly:

    The iron core consists of cold-rolled, granular-oriented silicon steel sheets known for their low loss and high magnetic conductivity. These sheets are structured in multiple steps with a complete tilt to minimize both loss and noise. Fixed clamps are applied to the iron core to enhance mechanical strength and reduce leakage losses. The addition of a PET banding structure further reduces noise and ensures the core column's stability.

    Coil Winding:

    For the high-voltage (HV) winding, the adoption of an entanglement or inner-screened continuous design with a phase insulation structure guarantees robust insulating strength. The medium voltage (MV) and low voltage (LV) windings use high-strength conductors or conductor transposition and incorporate forced cooling to reduce temperature rise and enhance short-circuit resilience. The specific winding construction—whether interleaved, shielded disc, helical, disc, or layer—is selected based on voltage and impulse ratings.

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    Active Parts Assembly & Oil Tank

    Active Parts Assembly:

    The assembly process for active parts involves cold pressing to ensure cleanliness and enhance the reliability of leads. Whole assembled phase insulation is utilized to expedite assembly and guarantee the precise dimension and shape of the insulation structure. High-voltage (HV) leads are fortified with specially molded insulation parts for protection, significantly improving insulating strength and reducing the risk of partial discharges.

    Oil Tank:

    The oil tank undergoes a three-dimensional finite element strength analysis and employs a Pro-E mold to strengthen its mechanical integrity. Welding methods incorporate automatic submerged arc welding, accompanied by ultrasonic fluorescence leakage testing to ensure a leak-free performance. Stringent quality control is maintained throughout the surface coating process.

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    Active Parts Assembly & Oil Tank
    Service & Support

    Service & Support

    Daelim Transformer collaborates with clients to understand their specific transformer requirements and tailors solutions accordingly. Once the exact needs are determined, the company's engineers swiftly recommend the appropriate solutions.

    The engineering team has the expertise to meet various performance requirements. This includes enhancing short-circuit strength, upgrading kVA ratings, adjusting voltages, reducing losses, modernizing LTC (Load Tap Changer), reducing sound levels, and modifying the transformer tank.

    For technical inquiries, Daelim Transformer's engineering team responds promptly to address questions from both clients and end-users.

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    Service & Support

    Factory-to-Onsite Logistics Support:

    The company provides logistical support for safe transportation, utilizing both ships and trucks. Impact recorders are employed to measure and store three-axis impact data, identifying any unusually severe impacts that could potentially damage the transformer during transportation.

    On-Site Technical Assistance:

    On-site technical support is available, covering assembly, oil treatment, testing, and commissioning (energization), and is conducted by an experienced engineer.


    Factory specialists offer training on transformer operation and maintenance to ensure clients can effectively manage their equipment.


    Daelim Transformer's technicians are capable of performing various repairs, such as replacing gaskets, broken bushings, and accessories. They can also purify or replace the oil, conduct sanding, priming, and repainting as needed. After repairs are completed, the unit undergoes comprehensive testing to ensure proper functionality.

    Service & Support
    Package and Transportation

    Package and Transportation

    Power transformers are typically high-voltage transformers known for their substantial size and weight. Daelim Transformer often disassembles various components of the transformer for transportation. The primary transformer unit is typically arranged for transport within an open-top container, while the disassembled components are securely packaged in wooden crates and transported using separate 20 ft/40 ft containers.

    Throughout the packaging process, Daelim Transformer pays meticulous attention to numerous details. For example, the control box on the transformer unit is individually encased in a wooden crate to safeguard against potential impacts during transit. Moreover, a protective rain and sun cover is placed above the open-top container to ensure that the transformer unit remains shielded from rain, moisture, and corrosion during transportation.

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