33kV Cast Resin Dry Type Transformer 1000kVA–5000kVA Three Phase
The 33kV Cast Resin Dry Type Transformer 1000kVA–5000kVA Three Phase is a high-capacity, oil-free power solution engineered for demanding indoor medium- and high-voltage distribution networks. This robust three-phase cast resin transformer utilizes premium low-loss grain-oriented silicon steel cores and high-conductivity copper windings (aluminum optional) fully encapsulated in high-grade epoxy resin under vacuum pressure, delivering exceptional energy efficiency (typically 98.5–99.5%), significantly reduced no-load and load losses, and superior partial discharge performance (<10pC). Fully compliant with IEC 60076-11, IEEE/ANSI, and relevant energy efficiency standards, this transformer steps down 33kV primary (with ±2×2.5% to ±10% off-circuit taps standard) to secondary voltages such as 0.4kV, 0.69kV, 6.6kV, or 11kV (Dyn11 vector group typical).
- Primary Voltage Ratings 33 kV (33000 V) delta or grounded wye
- Secondary Voltage Ratings 0.4 kV (400/230 V), 6.6 kV, 11 kV 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 7500kVA
- Certificate IEC 60076-11, IEC 60076-1, IEC 60076-3, UL 1561
- Cooling Method OA/OF
- Opeartion Step Down & Step Up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
33kV Cast Resin Dry Type Transformer 1000kVA–5000kVA Three Phase
Technical Specifications
Accessories
| Rated Power | 1000 - 5000 kVA | |
| Rating Primary Voltage | 33kV | |
| Secondary Voltage | 480/277V 400/230V 380/220V Customized |
|
| Frequency | 50/60Hz | |
| Vector Group | Dyn11,Yyn0,Dyn5 | |
| 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 | |
|
Insulation system |
Class F (155°C) or Class H (180°C) rise |
|
|
Impedance |
6.0–8.0% (±7.5%) |
|
| HV Bushing |
| LV Bushing |
| Tap changer connector |
| Lifting hook for complete transformer |
| Name plate |
Customization Optional
33kV Cast Resin Dry Type Transformer 1000kVA–5000kVA Three Phase
The 33kV cast resin dry type transformer series (1000kVA–5000kVA) supports extensive customization to precisely match high-voltage grid codes, project voltage needs, load profiles, acoustic limits, and environmental conditions. Primary voltage is centered on 33 kV (33000 V) in delta or grounded wye configuration, while secondary voltage can be configured as 0.4 kV (400/230 V), 6.6 kV, 11 kV, 22 kV, or any custom medium/low-voltage output. Vector groups include Dyn11 (standard), Dyn1, Yyn0, or special configurations for phase shift and harmonic mitigation. Full copper windings are standard for maximum efficiency, lowest hot-spot temperatures, and superior short-circuit strength; aluminum windings are available for cost-sensitive applications. Insulation system options are Class F (155°C) or Class H (180°C) using high-quality cast-resin (epoxy) encapsulation for excellent resistance to moisture, dust, chemicals, and thermal cycling.
Enclosure choices include IP23 ventilated (indoor standard), IP54/IP55 totally enclosed (dust-tight/semi-outdoor), or forced-air cooled (AF) for 133–150% overload capacity in high-ambient or confined spaces. Temperature rise can be specified as 100°C or 120°C. 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, VFDs), seismic bracing, ultra-low-noise execution (<60 dB with special core clamping and fan design), and custom finishes for corrosive or cleanroom environments. All variants are fully validated to IEC 60076-11, CE marking, local efficiency standards, and client specifications.
Packing and Shipping
33kV Cast Resin Dry Type Transformer 1000kVA–5000kVA Three Phase
Packaging the large 33kV Cast Resin Dry Type Transformer (1000–5000kVA) is engineered for ultimate protection of resin windings, core, and accessories during heavy-lift transport. The unit is rigidly anchored to an extra-heavy reinforced wooden skid with steel cross-bracing, multiple anti-vibration isolators, and high-strength lifting trunnions. Terminals, bushings, sensors, and fragile components receive custom-molded foam cradles and rigid protective covers. The complete assembly is wrapped in thick multi-layer moisture-proof film, anti-static sheeting, and reinforced edge/corner guards. A purpose-built, ISPM 15-compliant heavy-duty wooden crate or open steel frame fully encloses the transformer, incorporating internal supports, active desiccant systems, humidity indicator cards, and multi-axis electronic shock & tilt recorders to document handling and preserve dry-type integrity.
Shipping is tailored for secure, global delivery of this high-capacity cast resin unit. Ocean freight in dedicated 40ft open-top, flat-rack, or break-bulk vessels with custom cradles and certified multi-point lashing provides economical transport (typically 30–75 days to international ports). Air charter services expedite critical components or urgent replacements in 8–20 days. Overland transport utilizes specialized low-loader trailers with hydraulic suspension, police escorts, and pre-approved heavy-haul routes for domestic/regional movements.
Comprehensive export documentation—including commercial invoices, detailed dimensional/weight manifests, origin certificates, test reports, and IEC compliance declarations—is prepared in advance for rapid customs clearance. Sustainable logistics practices incorporate reusable skids, optimised container loading, and carbon-offset options where available. Clients benefit from secure tracking portals with real-time satellite positioning, ETA forecasts, and dedicated logistics engineer support.
Post-arrival services include optional heavy-lift crane, SPMT, or hydraulic jacking offloading coordination, immediate condition assessment, insulation verification, and packaging recycling/disposal to accelerate commissioning. Multi-unit factory-direct orders leverage consolidated shipments and phased delivery scheduling. This end-to-end heavy-equipment logistics ensures the 33kV transformer arrives pristine and installation-ready, leading searches for "secure high-capacity dry type transformer shipping."
Shipping is tailored for secure, global delivery of this high-capacity cast resin unit. Ocean freight in dedicated 40ft open-top, flat-rack, or break-bulk vessels with custom cradles and certified multi-point lashing provides economical transport (typically 30–75 days to international ports). Air charter services expedite critical components or urgent replacements in 8–20 days. Overland transport utilizes specialized low-loader trailers with hydraulic suspension, police escorts, and pre-approved heavy-haul routes for domestic/regional movements.
Comprehensive export documentation—including commercial invoices, detailed dimensional/weight manifests, origin certificates, test reports, and IEC compliance declarations—is prepared in advance for rapid customs clearance. Sustainable logistics practices incorporate reusable skids, optimised container loading, and carbon-offset options where available. Clients benefit from secure tracking portals with real-time satellite positioning, ETA forecasts, and dedicated logistics engineer support.
Post-arrival services include optional heavy-lift crane, SPMT, or hydraulic jacking offloading coordination, immediate condition assessment, insulation verification, and packaging recycling/disposal to accelerate commissioning. Multi-unit factory-direct orders leverage consolidated shipments and phased delivery scheduling. This end-to-end heavy-equipment logistics ensures the 33kV transformer arrives pristine and installation-ready, leading searches for "secure high-capacity dry type transformer shipping."
32
32 years of industry experience
Manufacturer Test
33kV Cast Resin Dry Type Transformer 1000kVA–5000kVA Three Phase
Progress Test
Progress tests for the 33kV cast resin dry type transformer (1000–5000kVA) are conducted at every critical 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. Cast resin encapsulation progress 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
Factory acceptance testing (FAT) for the 33kV cast resin dry type transformer strictly follows IEC 60076-11, IEEE C57.12.91, and UL 1561 protocols to confirm full compliance before shipment. Routine visual and mechanical inspections verify enclosure finish, weld quality (if applicable), nameplate data accuracy, accessory mounting, and terminal tightness. Winding resistance is measured across all tap positions at reference temperature to confirm conductor uniformity and match calculated loss values. Turns ratio (TTR) testing is performed on every tap to ensure ratio accuracy within 0.5% and correct vector group alignment. Polarity and phase relation checks confirm proper connection. Insulation resistance (megger at 2500–5000 V) evaluates winding-to-winding and winding-to-ground paths for multi-gigohm readings. Applied potential withstand test applies one-minute power-frequency voltage to HV and LV separately per insulation class without breakdown or excessive corona. Induced voltage test at double frequency stresses inter-turn and layer insulation with sensitive partial discharge monitoring to confirm corona-free operation.
Routine Test - DC Insulation Resistance Test
Purpose of Testing
The purpose of DC insulation resistance testing is to measure the insulation resistance of a device by applying a DC voltage, thereby evaluating the health of the insulation material and the voltage withstand capability of the electrical device. This test helps detect potential insulation aging, moisture or damage, preventing electrical failures in the device.
Testing Equipment
Insulation resistance tester (e.g. Megger, Fluke, Hioki, Klein Tools, etc.)
Voltage source (usually 500V, 1000V, 2500V, or customized according to customer requirements)
Temperature and humidity meter (used to record the ambient temperature and humidity during the test to ensure that the test conditions meet the standard requirements.)
Voltage source (usually 500V, 1000V, 2500V, or customized according to customer requirements)
Temperature and humidity meter (used to record the ambient temperature and humidity during the test to ensure that the test conditions meet the standard requirements.)
Pre-Test Preparation
Make sure the device is properly grounded and fully discharged to prevent residual charge in the device from affecting the test results.
Perform the test under suitable environmental conditions. It is recommended to have a relative humidity below 75%, no rain, and a temperature range of 20-30°C to avoid moisture or temperature fluctuations affecting the test results.
Perform the test under suitable environmental conditions. It is recommended to have a relative humidity below 75%, no rain, and a temperature range of 20-30°C to avoid moisture or temperature fluctuations affecting the test results.
Test Progress
Connect the Test Instrument:
Connect an insulation resistance tester to the high voltage terminal of the device under test and to ground.
Apply Test Voltage:
Select an appropriate test voltage based on the rated voltage of the equipment .
Connect an insulation resistance tester to the high voltage terminal of the device under test and to ground.
Apply Test Voltage:
Select an appropriate test voltage based on the rated voltage of the equipment .
Measure and Record
Start the test and record the following parameters:
Insulation resistance value (MΩ)
Applied voltage
Ambient temperature and humidity during testing
Insulation resistance value (MΩ)
Applied voltage
Ambient temperature and humidity during testing
Temperature Correction
The measured insulation resistance values are corrected to a reference temperature (usually 20°C) for accurate evaluation.
Repeat Testing (if necessary)
Measure different windings (high voltage, medium voltage, low voltage) or each bushing separately, and conduct comparative analysis to ensure the insulation status of all parts.
Evaluation Criteria (Reference)
nsulation resistance ≥ 1000 MΩ (excellent)
500 MΩ ≤ Insulation resistance < 1000 MΩ (good)
100 MΩ ≤ Insulation resistance < 500 MΩ
Insulation resistance < 100 MΩ
500 MΩ ≤ Insulation resistance < 1000 MΩ (good)
100 MΩ ≤ Insulation resistance < 500 MΩ
Insulation resistance < 100 MΩ
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 large commercial office buildings, shopping malls, hotels, high-rise residential towers, schools, and hospitals for safe indoor step-down from 22 kV medium-voltage to 400/230 V low-voltage distribution. Ideal for fire-sensitive, noise-restricted, or space-constrained locations where oil-filled transformers are prohibited by building codes, insurance requirements, or environmental regulations.
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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