75kVA Oil Immersed Transformer
75kVA oil-immersed transformer is an efficient and reliable power conversion device, which is widely used in power distribution systems in industrial, commercial, and construction sites. The transformer adopts oil-immersed cooling technology, has good heat dissipation performance, and can work continuously and stably under high load conditions. Its internal use of high-quality copper wire windings and silicon steel sheets ensures low loss and efficient power conversion. The 75kVA oil-immersed transformer also has complete protection functions, including overload protection, short-circuit protection, and temperature monitoring, to ensure the safety and stability of the equipment during operation.
- Primary Voltage Ratings 34.5-19.92/13.8-7.957/13.2-7.62/12.47-7.2, 24.94, 26.25, 33 or others
- Secondary Voltage Ratings 480/277V, 400/230V, 380/220V or customized
- H.V. Tap Range ± 2×2.5% HV taps or others
- Type Oil immersed distribution transformer
- BIL 30/95kV
- Standards IEEE, ANSI, NEMA, IEC, GB
- Application Residential Power Distribution, Underground Distribution Systems etc
- Power Rating 75kVA
- Certificate UL, CESI, IEEE
- Cooling Method ONAN, ONAN/ONAF, KNAN, KNAN/KNAF
- Oil Mineral Oil or FR3
- Opeartion Step Down & Step Up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
75kVA Oil Immersed Transformer
Technical Specifications
Accessories
| Technical Specifications | ||
| Rated Power | 75 kVA | |
| Rating Primary Voltage | 2.4 - 34.5kV | |
| 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 | |
| Color | ANSI 70 Light gray/Munsell 7GY3.29/1.5 or customized, etc | |
| Tank material | Mild Steel, 304 Stainless Steel | |
| Insulating Oil Weight | 100 kg | |
| Total Weight | 400 kg | |
| Outline Dimensions（L×W×H）in. | 800 × 700 × 1200（mm) | |
| 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
75kVA Oil Immersed Transformer
NPC ELECTRIC’s three-phase oil-immersed transformers can be fully customized to meet your specific requirements.
The optional specifications of the 75kVA three-phase oil-immersed transformer provide a variety of customized options to meet the needs of different applications and environments. Users can choose different voltage levels and load adjustment options according to specific needs to ensure that the transformer is suitable for various power systems and distribution networks. In addition, the transformer can be equipped with additional load adjustment devices, such as tap switches with load or no load adjustment, to achieve precise voltage adjustment. In order to improve the safety and durability of the equipment, customers can also choose higher-grade insulating oil, which is particularly suitable for use in extreme climates or high-temperature environments.
The optional specifications of the 75kVA three-phase oil-immersed transformer provide a variety of customized options to meet the needs of different applications and environments. Users can choose different voltage levels and load adjustment options according to specific needs to ensure that the transformer is suitable for various power systems and distribution networks. In addition, the transformer can be equipped with additional load adjustment devices, such as tap switches with load or no load adjustment, to achieve precise voltage adjustment. In order to improve the safety and durability of the equipment, customers can also choose higher-grade insulating oil, which is particularly suitable for use in extreme climates or high-temperature environments.
In terms of shell materials, you can choose a more corrosion-resistant coating or stainless steel shell, which is suitable for operation in harsh environments. The transformer can also be equipped with an advanced temperature monitoring system, including temperature sensors, oil level monitoring devices, pressure relief valves, etc., to achieve real-time monitoring of the transformer's operating status and ensure that the equipment remains in optimal condition and safe operation during work. With these optional configurations, the 75kVA three-phase oil-immersed transformer can flexibly meet the needs of different customers and provide more stable and efficient power services.
Packing and Shipping
75kVA Oil Immersed Transformer
NPC ELECTRIC 75kVA Oil Immersed Transformers are designed to be securely packaged for sea freight transport, ensuring safe delivery across long distances.
For this purpose, the packaging and transportation process of the 75kVA three-phase oil-immersed transformer is carefully designed to ensure that the transformer is fully protected during transportation and arrives safely at the destination. First, the transformer will be placed in a sturdy wooden box or wooden pallet for packaging. The packaging materials are treated with anti-corrosion to prevent moisture, corrosion, and external environmental factors. In order to reduce vibration and impact during transportation, the transformer will be wrapped with materials such as shock pads, bubble film, or plastic film, and ensure that the transformer is firmly fixed in the packaging box to avoid any displacement or collision. Considering that the transformer is an oil-immersed design, special attention is paid to the sealing and oil level of the oil tank during packaging to prevent oil leakage during transportation. Logos and warning labels such as "fragile", "moisture-proof", and "keep dry" will be attached to the outside of the package to remind the transport personnel to be cautious during handling. Depending on the destination and conditions of transportation, the transformer is usually delivered by land, sea, or rail transportation to ensure the most appropriate transportation method is selected. If it is an international transportation, relevant customs documents such as commercial invoice, packing list, export license, etc., will be prepared according to the requirements of the destination country to ensure smooth customs clearance and compliance with import regulations. After the transformer arrives at the destination, it will be unloaded, and the integrity of the packaging will be checked to ensure that the equipment is not damaged.
Through this series of carefully planned packaging and transportation measures, it is ensured that the 75kVA three-phase oil-immersed transformer can be delivered to the customer safely and on time, and maintain good performance and reliability during installation and operation.
For this purpose, the packaging and transportation process of the 75kVA three-phase oil-immersed transformer is carefully designed to ensure that the transformer is fully protected during transportation and arrives safely at the destination. First, the transformer will be placed in a sturdy wooden box or wooden pallet for packaging. The packaging materials are treated with anti-corrosion to prevent moisture, corrosion, and external environmental factors. In order to reduce vibration and impact during transportation, the transformer will be wrapped with materials such as shock pads, bubble film, or plastic film, and ensure that the transformer is firmly fixed in the packaging box to avoid any displacement or collision. Considering that the transformer is an oil-immersed design, special attention is paid to the sealing and oil level of the oil tank during packaging to prevent oil leakage during transportation. Logos and warning labels such as "fragile", "moisture-proof", and "keep dry" will be attached to the outside of the package to remind the transport personnel to be cautious during handling. Depending on the destination and conditions of transportation, the transformer is usually delivered by land, sea, or rail transportation to ensure the most appropriate transportation method is selected. If it is an international transportation, relevant customs documents such as commercial invoice, packing list, export license, etc., will be prepared according to the requirements of the destination country to ensure smooth customs clearance and compliance with import regulations. After the transformer arrives at the destination, it will be unloaded, and the integrity of the packaging will be checked to ensure that the equipment is not damaged.
Through this series of carefully planned packaging and transportation measures, it is ensured that the 75kVA three-phase oil-immersed transformer can be delivered to the customer safely and on time, and maintain good performance and reliability during installation and operation.
32
32 years of industry experience
Manufacturer Test
75kVA Oil Immersed Transformer
Progress Test
NPC Electric manufactures three-phase oil-immersed transformers the strict quality control. The progress test of the 75kVA three-phase oil-immersed transformer is an important step to ensure that the transformer meets the design specifications and quality standards during the manufacturing process. The test content includes a series of electrical performance and mechanical safety checks. First, the winding resistance test is carried out to verify whether the resistance value of the winding meets the design requirements. Next, the insulation resistance test is carried out to ensure that all parts of the transformer have good insulation performance to prevent electrical faults. The load loss and no-load loss tests are used to evaluate the energy efficiency of the transformer to ensure that it has low energy losses in normal operation. The short-circuit impedance test examines the electrical characteristics of the transformer under short-circuit conditions to ensure that it has sufficient safety and stability. In addition, the oil insulation strength test is also carried out to check the quality and insulation performance of the oil to ensure that the oil can effectively isolate the current and dissipate heat. The temperature rise test simulates the working state of the transformer under rated load to ensure that the transformer can maintain a reasonable temperature in long-term operation to avoid overheating damage. Finally, the external structure of the transformer is checked, including the tightness of the oil tank, the effectiveness of the cooling system, and the function of the pressure relief device to ensure the safety of the mechanical part.
These comprehensive progress tests ensure the quality and reliability of the 75kVA three-phase oil-immersed transformers to meet customer needs and industry standards.
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
NPC Electric will have tests made for quality control by the manufacturer on every device or representative samples, or on parts or materials as required, to verify during production that the product meets the design specifications.
The Factory Acceptance Test (FAT) of the 75kVA three-phase oil-immersed transformer is an important step to ensure that the transformer meets the design standards and quality requirements. The factory acceptance test usually includes a series of detailed electrical and mechanical performance tests. First, the winding resistance test is carried out to ensure that the winding resistance value meets the design specifications and there are no abnormalities. Next, the insulation resistance test is carried out to verify whether the various parts of the transformer (such as windings, casing, and grounding system) have good insulation performance to ensure that the transformer is safe and reliable during use. The temperature rise test checks whether the temperature of the transformer exceeds the safe range by simulating the load conditions of long-term operation, ensuring that a reasonable temperature can be maintained under normal working conditions. Finally, the factory acceptance test also checks the external structure of the transformer, such as the sealing of the oil tank, the pressure relief device, the effectiveness of the cooling system, and other mechanical components to ensure their reliability and safety. Through these comprehensive tests, it is ensured that all performance of the transformer meets customer requirements and relevant industry standards before leaving the factory.
Routine Test - Induced Voltage
Purpose of Testing
The purpose of the Induced Voltage test is to simulate the electrical stress that the equipment may encounter under actual working conditions by applying an induced voltage, thereby evaluating the tolerance and stability of the equipment's insulation system. This test helps to detect the insulation performance of the equipment under high voltage conditions and ensure its safety and reliability in operation.
Testing Equipment
Induced Voltage Tester (e.g. OMICRON, Megger, HioKI, etc.)
AC voltage source, commonly 2 kV, 5 kV, 10 kV, or customized according to test requirements.
Environmental thermometer and hygrometer, used to record the temperature and humidity of the environment for appropriate test evaluation.
AC voltage source, commonly 2 kV, 5 kV, 10 kV, or customized according to test requirements.
Environmental thermometer and hygrometer, used to record the temperature and humidity of the environment for appropriate test evaluation.
Pre-Test Preparation
Disconnect all relevant power supplies and ensure that the equipment is properly grounded and discharged.
Check the connection wires and terminals to ensure they are secure and free of contamination.
Test under suitable environmental conditions: relative humidity below 75%, no rain (recommended temperature: 20-30°C).
Check the connection wires and terminals to ensure they are secure and free of contamination.
Test under suitable environmental conditions: relative humidity below 75%, no rain (recommended temperature: 20-30°C).
Test Progress
Connect the Test Instrument:
Connect the test equipment to the appropriate terminals or bushings of the device under test, ensuring that the connections are secure and properly grounded.
Apply Test Voltage:
Select the appropriate induction voltage according to the rated voltage and standard of the equipment.
Connect the test equipment to the appropriate terminals or bushings of the device under test, ensuring that the connections are secure and properly grounded.
Apply Test Voltage:
Select the appropriate induction voltage according to the rated voltage and standard of the equipment.
Measure and Record
Start the test and record the following parameters:
Induced Voltage
Applied Current
Voltage peak, stability and waveform (waveform analysis)
Any abnormal current or voltage changes during the measurement process.
Induced Voltage
Applied Current
Voltage peak, stability and waveform (waveform analysis)
Any abnormal current or voltage changes during the measurement process.
Temperature Correction
The measured induced voltage data is corrected to the reference temperature (usually 20°C) to ensure the accuracy of the test results.
Repeat Testing (if necessary)
If necessary, test different windings (HV, MV, LV) and bushings separately and compare the results at different test points.
Evaluation Criteria (Reference)
Inductive voltage ≤ 1% (Excellent): normally and meets safety standards.
1% < Inductive voltage ≤ 3% (Good): still within acceptable range.
Inductive voltage > 3% : faulty or not meet safety requirements and requires further analysis and repair.
1% < Inductive voltage ≤ 3% (Good): still within acceptable range.
Inductive voltage > 3% : faulty or not meet safety requirements and requires further analysis and repair.
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
Residential Power Distribution, Underground Distribution Systems, etc
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
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