75kVA Dry Type Transformer | High Efficiency Indoor Power Transformer
The 75kVA Dry Type Transformer is a compact, three-phase, high-efficiency indoor power transformer engineered for safe, reliable voltage transformation in commercial, institutional, and light industrial environments. Utilizing advanced cast-resin or vacuum pressure impregnated (VPI) insulation technology, it eliminates oil-related fire hazards, maintenance requirements, and environmental risks while delivering exceptional performance in confined spaces, high-rise buildings, hospitals, schools, data centers, office complexes, and renewable energy tie-in applications.
- Primary Voltage Ratings 480V, 600V, 4160V, 12470V or custom
- Secondary Voltage Ratings 208Y/120V, 480Y/277V, 600Y/347V or custom
- H.V. Tap Range ± 2×2.5% HV taps or others
- Type Dry type transformer
- BIL 30/95kV
- Standards IEEE, ANSI, NEMA,IEC,GB
- Application office buildings, transportation facilities
- Power Rating 75kVA
- Certificate UL ,CESI
- Cooling Method OA/OF
- Opeartion Step Down & Step Up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
75kVA Dry Type Transformer | High Efficiency Indoor Power Transformer
Technical Specifications
Accessories
| Rated Power | 75 kVA | |
| Rating Primary Voltage | 2.4-35kV | |
| Secondary Voltage | 480/277V 400/230V 380/220V Customized |
|
| Frequency | 50/60Hz | |
| Vector Group | Dyn11 (most common), Dyn1, Yyn0 or others | |
| Winding Material | Aluminum/Copper | |
| Efficiency | As IEEE,Doe 2016,CAS Std or Customized | |
| Impedance Voltage | Nominal 2% or Customized 1.1-5.75% | |
| Altitude | ≤1,000m or Customized | |
| Enclosure material | 304 Stainless Steel | |
|
Cooling |
Natural air (AN); forced air (AF) optional for overload |
|
| HV Bushing |
| LV Bushing |
| Tap changer connector |
| Lifting hook for complete transformer |
| Name plate |
Customization Optional
75kVA Dry Type Transformer | High Efficiency Indoor Power Transformer
The 75kVA three-phase dry type transformer supports comprehensive customization to meet precise installation, voltage, load, safety, and environmental requirements. Primary voltage ranges from 208V to 15kV (common: 480V delta, 600V delta, 4160V, 12470V), while secondary voltage can be configured as 208Y/120V, 480Y/277V, 600Y/347V, or any custom low-voltage output. Vector groups include Dyn11 (standard), Dyn1, Yyn0, or special configurations for phase shift and harmonic mitigation. Winding material is selectable as high-conductivity copper (preferred for lower temperature rise and higher efficiency) or aluminum (cost-optimized).
Insulation system options are Class F (155°C) or Class H (180°C) using vacuum pressure impregnated (VPI) or cast-resin (epoxy) encapsulation for superior resistance to moisture, dust, chemicals, and thermal cycling.
Enclosure choices include NEMA 1 ventilated (indoor standard), NEMA 3R weather-resistant (outdoor), totally enclosed non-ventilated (TENV), or forced-air cooled (AF) for 133–150% overload in high-ambient or space-constrained areas. Temperature rise can be specified as 80°C, 115°C, 150°C, or dual-rated. Additional features include forced-air cooling packages with fan controls, digital temperature monitoring with alarm/trip relays, surge arresters, electrostatic shielding for noise-sensitive locations, K-factor rating (K-4 to K-13) for harmonic-rich loads (data centers, EV charging, variable frequency drives), seismic bracing, low-noise fans (<48 dB), IP54/IP55 protection, and special finishes for corrosive or cleanroom environments. All variants are engineered to exceed IEEE C57.12.01, IEC 60076-11, UL 1561, and DOE 2016/2029 efficiency standards.
Packing and Shipping
75kVA Dry Type Transformer | High Efficiency Indoor Power Transformer
The 75kVA three-phase dry type transformer is packaged with maximum protection to ensure safe domestic and international transport. The core-coil assembly is fully encapsulated (cast resin or VPI) and rigidly secured inside the enclosure to prevent movement during transit. All terminals, taps, temperature sensors, fans (if equipped), and accessories are factory-installed and protected with caps or padding to avoid damage to bushings and connections.
The transformer is mounted on a reinforced wooden pallet or steel skid designed for forklift and crane handling, wrapped in multi-layer stretch film and moisture-barrier material. Desiccant packs are included to control humidity, critical for cast-resin units that must remain dry before energization. The entire unit is then placed in a sturdy export-grade wooden crate (ISPM-15 heat-treated) with foam corner protectors, wooden bracing, and steel strapping for stability. Clear markings include gross/net weight, center of gravity, lift points, dimensions (approx. 1.8–2.4m L × 1.2–1.6m W × 1.8–2.2m H), and handling instructions (“Fragile – Electrical Equipment – No Tipping”).
Domestic shipping uses enclosed trailers or flatbeds with secure blocking and tie-downs to minimize vibration. International shipments typically utilize 20ft/40ft containers (palletized and shrink-wrapped) or flat-rack loading, with professional lashing using chains and timber dunnage for sea and road stability. Real-time GPS tracking and full-value cargo insurance are standard for high-value units. Upon arrival, detailed handling and installation manuals are provided, covering lifting procedures (via integrated lifting eyes), foundation placement with ventilation clearances, electrical connections, grounding, and pre-energization checks (insulation resistance, turns ratio, temperature sensor calibration).
The transformer is mounted on a reinforced wooden pallet or steel skid designed for forklift and crane handling, wrapped in multi-layer stretch film and moisture-barrier material. Desiccant packs are included to control humidity, critical for cast-resin units that must remain dry before energization. The entire unit is then placed in a sturdy export-grade wooden crate (ISPM-15 heat-treated) with foam corner protectors, wooden bracing, and steel strapping for stability. Clear markings include gross/net weight, center of gravity, lift points, dimensions (approx. 1.8–2.4m L × 1.2–1.6m W × 1.8–2.2m H), and handling instructions (“Fragile – Electrical Equipment – No Tipping”).
Domestic shipping uses enclosed trailers or flatbeds with secure blocking and tie-downs to minimize vibration. International shipments typically utilize 20ft/40ft containers (palletized and shrink-wrapped) or flat-rack loading, with professional lashing using chains and timber dunnage for sea and road stability. Real-time GPS tracking and full-value cargo insurance are standard for high-value units. Upon arrival, detailed handling and installation manuals are provided, covering lifting procedures (via integrated lifting eyes), foundation placement with ventilation clearances, electrical connections, grounding, and pre-energization checks (insulation resistance, turns ratio, temperature sensor calibration).
32
32 years of industry experience
Manufacturer Test
75kVA Dry Type Transformer | High Efficiency Indoor Power Transformer
Progress Test
Progress tests for the 75kVA three-phase dry type transformer are conducted at every key manufacturing stage to ensure material quality and specification conformance. Core lamination stacking is inspected for precise alignment, clamp pressure uniformity, and inter-lamination insulation integrity to minimize no-load losses and audible noise. Winding fabrication progress verifies exact turn counts using automated counters, consistent conductor tension, correct transposition, and adequate insulation thickness between layers for balanced impedance and thermal distribution. After core-coil assembly, preliminary DC resistance, turns ratio, polarity, and inductance measurements are taken to confirm correct phasing, no shorted turns, and electrical symmetry before encapsulation. Core-coil encapsulation progress (cast resin or VPI) monitors resin mixing ratios, vacuum pressure levels, curing temperature profiles, and partial discharge testing during cure to ensure void-free insulation. Enclosure assembly checks verify fit-up, ventilation openings (if ventilated), grounding continuity, and surface preparation for paint adhesion. These incremental checks enable early identification and correction of nonconformities, ensuring the finished transformer meets efficiency, dielectric, and reliability targets.
Design Tests
All transformer will be test after finished the production, test items as below:
♦ Insulation Power Factor
♦ Winding Resistance
♦ Impulse Tests
♦ On load Loss Test
♦ No Load Loss Test
♦ Leak Test
♦ DC Insulation Resistance Test
♦ Transformer Turns Ratio/TTR (All Tap Voltages)
♦ Impedance Voltage & Load Loss (Rated Voltage)
♦ Excitation & No-Load Loss (Rated Voltage)
♦ Applied Voltage
♦ Insulation Resistance (Rated Voltage)
♦ Temperature Rise
Transformer Factory Acceptance Test
Induced voltage test at double frequency stresses inter-turn and layer insulation with sensitive partial discharge monitoring to confirm corona-free operation. No-load loss and excitation current are measured at rated voltage to validate core performance against DOE efficiency targets. Impedance/load loss at rated current is determined to verify percentage impedance, copper losses, and regulation characteristics. Temperature rise test (optional witnessed heat run) confirms compliance with class rise limits under rated load. Sound level measurement verifies compliance with specified dB limits. Functional verification operates tap changer through all positions, checks temperature sensors, fan controls (if AF), and alarms. Certified test reports with traceable calibration data and customer witness provisions (if requested) document all results, confirming the transformer exceeds efficiency, dielectric strength, safety, and performance requirements for reliable dry-type service.
Routine Test - On load Loss Test
Purpose of Testing
The purpose of On-load Loss Test is to measure the active power loss of the transformer under rated voltage and rated load, evaluate its energy efficiency level and design compliance, and provide a basis for energy consumption calculation and performance optimization during operation.
Testing Equipment
Power transformer test system (e.g. OMICRON, ISA, Tettex, Vanguard, etc.)
Voltage source and current source (usually rated voltage, or adjusted according to the test standard, such as 10 KV, 20 KV, 35 KV, etc.)
Temperature and humidity meter (used to record ambient temperature and humidity for correction of test data)
Voltage source and current source (usually rated voltage, or adjusted according to the test standard, such as 10 KV, 20 KV, 35 KV, etc.)
Temperature and humidity meter (used to record ambient temperature and humidity for correction of test data)
Pre-Test Preparation
Disconnect the transformer high voltage, low voltage and neutral power supply to ensure that the equipment is properly grounded and safely discharged.
The test environment should be dry and rainless, with a relative humidity of less than 75% and a recommended temperature range of 20–30°C.
The test environment should be dry and rainless, with a relative humidity of less than 75% and a recommended temperature range of 20–30°C.
Test Progress
Connect the Test Instrument:
Connect the test equipment to the appropriate terminals of the device under test and ensure that all wiring is correct and the device is well grounded.
Apply Test Voltage:
Apply the specified test voltage at the rated frequency and adjust the low voltage side to maintain the rated current (or specified current).
Connect the test equipment to the appropriate terminals of the device under test and ensure that all wiring is correct and the device is well grounded.
Apply Test Voltage:
Apply the specified test voltage at the rated frequency and adjust the low voltage side to maintain the rated current (or specified current).
Measure and Record
Start the test and record the following parameters:
On-Load Loss Power
Input Power and Output Power
Current
Voltage
Temperature (temperature rise or winding temperature)
Ambient temperature and humidity during the test
On-Load Loss Power
Input Power and Output Power
Current
Voltage
Temperature (temperature rise or winding temperature)
Ambient temperature and humidity during the test
Temperature Correction
The measured loss data is corrected based on a reference temperature (usually 20°C) to ensure the accuracy of the results.
Repeat Testing (if necessary)
Test different tap positions (Tap Changer) and record and compare the load loss data of each tap point.
Evaluation Criteria (Reference)
Evaluate the test results based on the equipment type and manufacturer requirements. If the load losses are low and the efficiency is high, it is considered "normal".
Test standard
IEEE C57.12.01 & IEEE C57.12.91 (Dry-Type)
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
Widely deployed in commercial office buildings, retail centers, schools, hospitals, and high-rise residential towers for safe indoor step-down from medium-voltage (480V/600V) to low-voltage (208Y/120V or 480Y/277V) distribution. Perfect for fire-sensitive or space-constrained locations where oil-filled transformers are restricted by building codes or insurance requirements.
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
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What is a Transformer?A transformer is an electrical device used to change the voltage of alternating current (AC). It works on the principle of electromagnetic induction, converting high-voltage current into low-voltage current or low-voltage current into high-voltage current. Transformers are widely used in power transmission, distribution systems, and various electronic devices.
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What are the main uses of a transformer?The main use of a transformer is voltage conversion. Transformers are used in power transmission systems to help transfer electricity from power plants to consumers. In addition, transformers are also used in electronic devices such as chargers, televisions, power adapters, etc., to adjust the voltage to meet the requirements of different devices.
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Do you have UL listed?Yes, our transformer has UL listed. We have exported to America many pad mounted transformer,substation transformer and HV.
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