33kV Three-Phase Oil-Immersed Step-Up Power Transformer
The 33kV Three-Phase Oil-Immersed Step-Up Power Transformer is engineered for reliable voltage elevation in medium- and high-voltage distribution networks. Designed with high-grade silicon-steel cores, copper windings, and an efficient oil-immersed cooling system, this transformer delivers stable power transmission with low losses and strong short-circuit endurance. Its robust insulation, sealed tank structure, and advanced protection devices ensure long-term performance in demanding industrial and substation environments. Widely used in renewable energy plants, utility networks, industrial facilities, and rural power upgrades, the 33kV step-up transformer provides secure, efficient, and continuous operation. It supports both on-load and off-load tap changers, offering precise voltage regulation and adaptability to varying grid conditions, making it a dependable choice for modern power distribution systems.
- Primary Voltage Ratings 35kV, 34.5kV, 33kV, 46kV or others
- Secondary Voltage Ratings 13.8kV 6kV 10kV or others
- H.V. Tap Range ±8×1.25% or others
- Type Oil-immersed power transformer
- BIL 33kV
- Standards IEEE, ANSI, NEMA, IEC, CE
- Application utility substations, industrial power systems, renewable energy projects
- Power Rating 1600 kVA 200kVA 250kVA 500kVA
- Certificate UL, CESI, IEEE
- Cooling Method ONAN/ONAF
- Oil Mineral Oil or FR3
- Opeartion Step Down & Step Up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
33kV Three-Phase Oil-Immersed Step-Up Power Transformer
Technical Specifications
Accessories
| Rated Power | 1600 kVA 200kVA 250kVA 500kVA | |
| Rating Primary Voltage | 33 kV | |
| Secondary Voltage |
6.6kV 10kV 13.8kV 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 | |
| Color | ANSI 70 Light gray/Munsell 7GY3.29/1.5 or customized, etc | |
| Tank material | Mild Steel, 304 Stainless Steel | |
| HV Bushing |
| LV Bushing |
| Tap changer |
| Oil level gauge |
| Oil temperature indicator |
| Pressure relief device |
| Pressure vacuum gauge |
| Lifting hook for complete transformer |
| Name plate |
| Radiators |
| Oil upper filtering valve |
| Oil drain valve with 3/8" sampler |
Customization Optional
33kV Three-Phase Oil-Immersed Step-Up Power Transformer
The 33kV Three-Phase Oil-Immersed Step-Up Power Transformer supports extensive customization to accommodate diverse grid standards and project requirements. Clients may select custom voltage ratios, rated capacities, impedance values, vector groups, and tapping ranges. Both on-load and off-load tap changers are available for precise voltage regulation under varying load conditions. Enhanced insulation classes, low-loss core materials, and high-conductivity copper windings can be specified to meet efficiency and durability requirements.
Additional options include advanced monitoring systems, such as temperature controllers, online oil monitoring, and gas relay alarms, enabling real-time supervision. The tank configuration can also be customized, offering sealed, conservator-type, corrugated-wall, or radiators tailored to climate and installation environments. Anti-corrosion coatings, high-altitude designs, and reinforced short-circuit resistance further support deployment across industrial, utility, and renewable energy substations. These flexible configurations ensure that each 33kV step-up transformer aligns precisely with the client’s performance, safety, and operational expectations.
Packing and Shipping
33kV Three-Phase Oil-Immersed Step-Up Power Transformer
The 33kV Three-Phase Oil-Immersed Step-Up Power Transformer is packed and shipped following stringent international standards to ensure maximum safety and product integrity. Before packing, the transformer undergoes final cleaning, vacuum oil treatment, sealing, and accessory protection. All valves, bushings, radiators, and exposed components are fitted with protective caps and moisture-proof coverings. Detachable accessories, including conservators, radiators, tap changers, and sensors, are individually wrapped with shock-resistant materials and packed in reinforced wooden crates.
The main transformer body is mounted on a heavy-duty steel or timber pallet, secured using high-strength bolts, straps, and anti-slip blocks to prevent movement during transportation. Vibration-damping pads, rigid corner protectors, and steel reinforcement frames are used based on transformer size and weight. A complete set of technical documents—including test reports, manuals, packing lists, and wiring diagrams—is enclosed in a waterproof document bag.
Shipping arrangements are customized based on destination, weight, and transportation mode. The transformer can be transported via sea, land, or rail using flat racks, open-top containers, or specialized heavy-haul trailers. All lifting points are clearly marked, and forklift channels or lifting lugs ensure safe loading and unloading. Compliance with IEC, ISO, and international logistics standards guarantees safe arrival at the project site, allowing the 33kV oil-immersed step-up transformer to be installed and commissioned efficiently.
The main transformer body is mounted on a heavy-duty steel or timber pallet, secured using high-strength bolts, straps, and anti-slip blocks to prevent movement during transportation. Vibration-damping pads, rigid corner protectors, and steel reinforcement frames are used based on transformer size and weight. A complete set of technical documents—including test reports, manuals, packing lists, and wiring diagrams—is enclosed in a waterproof document bag.
Shipping arrangements are customized based on destination, weight, and transportation mode. The transformer can be transported via sea, land, or rail using flat racks, open-top containers, or specialized heavy-haul trailers. All lifting points are clearly marked, and forklift channels or lifting lugs ensure safe loading and unloading. Compliance with IEC, ISO, and international logistics standards guarantees safe arrival at the project site, allowing the 33kV oil-immersed step-up transformer to be installed and commissioned efficiently.
32
32 years of industry experience
Manufacturer Test
33kV Three-Phase Oil-Immersed Step-Up Power Transformer
Progress Test
During production, the 33kV Three-Phase Oil-Immersed Step-Up Power Transformer undergoes staged Progress Tests to ensure continuous quality control. Key inspections include raw material verification, core lamination accuracy, winding tension and alignment checks, and insulation strength assessment. Intermediate electrical tests such as DC resistance measurement, turns ratio testing, insulation resistance evaluation, and partial discharge screening identify early deviations. Mechanical inspections confirm structural integrity, while oil processing tests verify moisture removal and dielectric strength. This progressive testing system ensures each transformer component meets technical standards, guaranteeing stable performance before entering final quality assessment.
Design Tests
All transformer will be test after finished the production, test items as below:
♦ Insulation Power Factor
♦ Ratio, Polarity, and Phase Relation
♦ 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)
♦ Polarity, 1-Ph / Phase Relation, 3-Ph (Rated Voltage)
♦ Excitation & No-Load Loss (Rated Voltage)
♦ Applied Voltage
♦ Induced Voltage
♦ Lightning Impulse
♦ Insulation Resistance (Rated Voltage)
♦ Temperature Rise
♦ Dielectric Withstand (Hipot)
Transformer Factory Acceptance Test
Before shipment, the 33kV Three-Phase Oil-Immersed Step-Up Power Transformer undergoes a comprehensive Factory Acceptance Test (FAT) in compliance with IEC 60076. Mandatory tests include winding resistance measurement, voltage ratio and vector group verification, no-load and load loss measurement, insulation resistance, induced overvoltage, and applied high-voltage withstand tests. Partial discharge tests and dielectric assessments confirm insulation performance, while mechanical inspections validate structural integrity and accessory functionality. Oil quality analysis, protection device checks, and terminal inspections further ensure operational readiness. The FAT guarantees that the 33kV step-up transformer meets all performance, efficiency, and safety requirements prior to delivery.
Routine Test - Applied Voltage
Purpose of Testing
The purpose of testing the applied voltage is to verify the insulation strength of the transformer by applying a voltage higher than its normal operating level, ensuring it can withstand potential electrical stresses. This test helps identify any weaknesses or defects in the insulation system before the transformer is put into service.
Testing Equipment
Test equipment: High voltage tester (e.g. TTR, Hipot, etc.)
Voltage source: usually 1 kV, 5 kV, 10 kV, or customized according to customer needs
Temperature and humidity meter: used to record environmental conditions
Voltage source: usually 1 kV, 5 kV, 10 kV, or customized according to customer needs
Temperature and humidity meter: used to record environmental conditions
Pre-Test Preparation
Disconnect the device from the power supply and make sure it is properly grounded and discharged.
Check the connection terminals and wiring to ensure that they are not loose or contaminated.
Test under suitable environmental conditions: relative humidity below 75% and no rain (recommended temperature: 20-30°C).
Check the connection terminals and wiring to ensure that they are not loose or contaminated.
Test under suitable environmental conditions: relative humidity below 75% and no rain (recommended temperature: 20-30°C).
Test Progress
Connect the Test Instrument:
Properly connect the test equipment to the bushings or terminals of the device under test and ensure that all connection points are properly grounded.
Selecting the test voltage:
Select the appropriate applied voltage based on the rated voltage of the equipment.
Properly connect the test equipment to the bushings or terminals of the device under test and ensure that all connection points are properly grounded.
Selecting the test voltage:
Select the appropriate applied voltage based on the rated voltage of the equipment.
Measure and Record
Start the test and record the following parameters:
Measuring leakage current
Applied voltage
Current stability
Any possible voltage fluctuations
Measuring leakage current
Applied voltage
Current stability
Any possible voltage fluctuations
Temperature Correction
If necessary, the measured data is temperature corrected to ensure that it corresponds to standard temperature conditions (usually 20°C).
Repeat Testing (if necessary)
Multiple tests were conducted on different windings (high voltage, medium voltage, low voltage) and bushings, and comparative analysis was performed.
Evaluation Criteria (Reference)
The test was normal and the equipment performed well (qualified)
The current value exceeded the allowable range and the equipment needs to be inspected or maintained (pending repair)
There was a serious fault or instability and the equipment could not continue to operate (unqualified)
The current value exceeded the allowable range and the equipment needs to be inspected or maintained (pending repair)
There was a serious fault or instability and the equipment could not continue to operate (unqualified)
Observing electrical behavior
Observe the electrical behavior of the device under test to ensure that there are no abnormal currents, arcing, noise, or electrical faults.
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
It efficiently elevates medium-voltage power for long-distance transmission, supporting wind farms, solar plants, manufacturing facilities, and mining operations. Its stable performance and strong insulation design make it suitable for harsh environments, ensuring reliable and continuous power delivery for various distribution networks.
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
Product Packaging
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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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