100kVA Oil Immersed Transformer
NPC ELECTRIC 100kva Oil Immersed Transformer boasts a robust design that utilizes high-quality materials to ensure long-lasting performance. Its oil-immersed cooling system provides effective heat dissipation, maintaining optimal operating temperatures even under heavy loads. This transformer is designed to handle a maximum power capacity of 100kVA, making it suitable for a wide range of applications, including commercial, industrial, and residential settings. One of the standout features of the SGOB 100kva Oil Immersed Transformer is its advanced insulation system, which enhances its short-circuit resistance and overall safety.
- 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
- Application Industrial Power Distribution, Commercial Buildings
- Power Rating 100kVA
- 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
100kVA Oil Immersed Transformer
Technical Specifications
Accessories
| Rated Power | 100 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 | 155 kg | |
| Total Weight | 605 kg | |
| Outline Dimensions（L×W×H）in. | 890 × 520 × 81140（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
100kVA Oil Immersed Transformer
The 100kVA oil immersed transformer offers extensive customization to precisely suit utility, commercial, and industrial project needs. Primary voltages range from 2.4kV to 34.5kV (common: 34.5kV, 24.94kV, 13.8kV, 13.2kV, 12.47kV, 4.16kV) in delta or grounded wye configurations with BIL up to 200kV. Secondary voltages include 600Y/347V, 480Y/277V, 208Y/120V, 240/120V, or custom outputs with vector groups Dyn11, Dyn1, Yyn0, etc.
Winding materials are available in high-conductivity copper for maximum efficiency and thermal endurance or aluminum for cost-effective performance. Impedance is adjustable between 4.0–7.0% (±7.5% tolerance) for optimal fault current limiting and system coordination. Cooling is standard ONAN; forced-air (ONAF) options enable 33–50% increased capacity for high-ambient or overload duty. Insulating fluid choices include conventional non-PCB mineral oil or FR3 natural ester fluid (fire point >300°C, fully biodegradable, extended insulation life).
Protection and switching configurations include radial or loop-feed, dead-front or live-front bushings, load-break elbow-operated switches, bayonet expulsion fuses + partial-range current-limiting fuses, external or internal arresters (normal/heavy duty), and visible break options. Accessories can be tailored with oil temperature/pressure gauges, liquid level indicators, sudden pressure relay, nitrogen blanket system, FR3-compatible gauges, wildlife guards, and digital monitoring (temperature, oil condition, SCADA-ready).
Enclosure options feature ANSI 70 gray, Munsell green, or custom powder-coated finishes with stainless steel hardware for coastal/high-pollution areas, seismic IBC/OSHPD bracing, high-altitude derating, low-sound designs (<52 dB), and K-factor ratings for harmonic-rich loads (data centers, EV charging). Special designs support solar/wind inverter duty, rectifier loads, or dual-voltage primaries. Every customization is fully engineered and validated to exceed IEEE, ANSI, IEC, DOE 2016/2029 efficiency, and client specifications while minimizing total ownership cost
Packing and Shipping
100kVA Oil Immersed Transformer
The 100kVA oil immersed transformer is packaged with utmost care to ensure safe worldwide transport and immediate field installation. The core-coil assembly is vacuum-dried and oil-filled under controlled conditions before final tank sealing to eliminate moisture and ensure dielectric strength. All bushings, arresters, switches, and gauges are factory-installed where possible; sensitive items are protected with wooden covers and foam padding.
The transformer is mounted on a reinforced steel or wooden skid base suitable for forklift/crane handling, wrapped in VCI corrosion-inhibiting film and heavy polyethylene sheeting with desiccant packs inserted. Oil is shipped fully filled with nitrogen blanket or partially drained with sealed drums provided separately to reduce weight and comply with hazmat regulations (typical filled weight 2800–4000 kg / 6200–8800 lbs).
Export packaging uses ISPM-15 certified heat-treated wooden crating reinforced with steel strapping and corner protectors, clearly marked with weight, center of gravity, lifting points, dimensions (approx. 2.4–3.0m L × 2.2–2.6m W × 2.4–2.9m H), and handling instructions (“Fragile – High Voltage Equipment”). Tamper-evident seals secure all access doors; weatherproof covers protect HV/LV compartments and bushings.
Domestic transport utilizes flatbed or lowboy trailers with secure blocking and tie-downs; oversize permits arranged when required. International shipping options include 20ft/40ft open-top containers or flat-rack with professional lashing (chains, turnbuckles, timber dunnage) to prevent movement during ocean transit. Air freight is available for urgent spare parts. Real-time GPS tracking and full cargo value insurance provide complete visibility and protection.
Upon delivery, detailed instructions cover safe unloading (via tank lifting lugs), positioning, oil top-off if required, grounding, accessory connections, and pre-energization checks. Comprehensive documentation — commercial invoice, packing list, certificate of origin, certified test reports, material certificates — ensures smooth customs clearance. Third-party pre-shipment inspection or customer witnessing can be arranged. Our logistics team guarantees regulatory compliance, minimal delays, and transformer arrival in perfect condition ready for immediate installation and commissioning.
The transformer is mounted on a reinforced steel or wooden skid base suitable for forklift/crane handling, wrapped in VCI corrosion-inhibiting film and heavy polyethylene sheeting with desiccant packs inserted. Oil is shipped fully filled with nitrogen blanket or partially drained with sealed drums provided separately to reduce weight and comply with hazmat regulations (typical filled weight 2800–4000 kg / 6200–8800 lbs).
Export packaging uses ISPM-15 certified heat-treated wooden crating reinforced with steel strapping and corner protectors, clearly marked with weight, center of gravity, lifting points, dimensions (approx. 2.4–3.0m L × 2.2–2.6m W × 2.4–2.9m H), and handling instructions (“Fragile – High Voltage Equipment”). Tamper-evident seals secure all access doors; weatherproof covers protect HV/LV compartments and bushings.
Domestic transport utilizes flatbed or lowboy trailers with secure blocking and tie-downs; oversize permits arranged when required. International shipping options include 20ft/40ft open-top containers or flat-rack with professional lashing (chains, turnbuckles, timber dunnage) to prevent movement during ocean transit. Air freight is available for urgent spare parts. Real-time GPS tracking and full cargo value insurance provide complete visibility and protection.
Upon delivery, detailed instructions cover safe unloading (via tank lifting lugs), positioning, oil top-off if required, grounding, accessory connections, and pre-energization checks. Comprehensive documentation — commercial invoice, packing list, certificate of origin, certified test reports, material certificates — ensures smooth customs clearance. Third-party pre-shipment inspection or customer witnessing can be arranged. Our logistics team guarantees regulatory compliance, minimal delays, and transformer arrival in perfect condition ready for immediate installation and commissioning.
32
32 years of industry experience
Manufacturer Test
100kVA Oil Immersed Transformer
Progress Test
NPC Electric manufactures three-phase oil-immersed transformers the strict quality control. The Progress Test of a 100kVA three-phase oil-immersed transformer is a series of intermediate tests performed during the transformer production process to ensure that the design requirements are met at each stage of manufacturing and to detect potential problems early. These tests are usually carried out in stages to ensure that the transformer gradually meets the quality standards during the production process. Mainly include: Winding inspection: Resistance measurement is performed after the initial winding is completed to ensure that there are no short circuits or open circuits and to verify the quality of the winding. Insulation performance test: After the winding is completed, the transformer is subjected to preliminary insulation testing to ensure that the insulation material and design meet safety requirements and avoid any short circuits or electrical leakage during the production process.
Design Tests
All transformers will be tested after finishing the production, test items as follows:
♦ 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
♦ 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
The Factory Acceptance Test (FAT) of the 100kVA three-phase oil-immersed transformer is the final verification before the transformer leaves the factory, and its purpose is to ensure that the transformer fully complies with the design specifications and quality standards. This test is carried out after the transformer is assembled and usually includes the following steps: Load loss and no-load loss test: Test the energy loss of the transformer under no-load and full-load conditions to ensure that the energy efficiency meets the standards and reduce energy waste. Short-circuit impedance test: Test the electrical performance of the transformer under short-circuit conditions to ensure that the transformer can safely withstand short-circuit conditions and has sufficient short-circuit resistance. Winding resistance test: Check the winding resistance to ensure that the winding is not damaged, short-circuited, or out of specification. Insulation resistance test: Test the various insulation parts of the transformer to ensure that there are no leaks or faults, especially the insulation of the windings and grounding system.
Routine Test - Impulse Tests
Purpose of Testing
The purpose of Impulse Tests is to verify the insulation strength of electrical equipment when it is subjected to lightning strikes or switching overvoltages. By applying high-energy impulse voltages, it is possible to detect potential defects in the insulation system.
Testing Equipment
Impulse voltage generator (e.g. Haefely, Hipotronics, Tettex, etc.)
Voltage divider (used to measure impulse voltage waveform, resistor divider or capacitor divider)
Oscilloscope (used to record impulse waveform, common brands such as Tektronix, Keysight)
Voltage divider (used to measure impulse voltage waveform, resistor divider or capacitor divider)
Oscilloscope (used to record impulse waveform, common brands such as Tektronix, Keysight)
Pre-Test Preparation
Please test under suitable environmental conditions: relative humidity less than 65%, no rain or condensation (recommended temperature: 15-30°C).
Calibrate and check the impulse voltage generator, measurement system, and control system to ensure that the instruments and equipment are in good condition and meet the test standards.
Calibrate and check the impulse voltage generator, measurement system, and control system to ensure that the instruments and equipment are in good condition and meet the test standards.
Test Progress
Connect the Test Instrument:
Connect the impulse voltage generator correctly to each winding terminal (high voltage terminal, ground terminal) of the device under test, and ensure that all test instruments are well grounded.
Apply Test Voltage:
Select the appropriate impulse voltage waveform and amplitude according to the rated voltage of the equipment
Connect the impulse voltage generator correctly to each winding terminal (high voltage terminal, ground terminal) of the device under test, and ensure that all test instruments are well grounded.
Apply Test Voltage:
Select the appropriate impulse voltage waveform and amplitude according to the rated voltage of the equipment
Measure and Record
Collect and record the impact waveform, including:
Front Time
Time to Half-Value
Peak Voltage
Distortion
Ambient temperature and humidity (especially when the test environment needs to be corrected)
Front Time
Time to Half-Value
Peak Voltage
Distortion
Ambient temperature and humidity (especially when the test environment needs to be corrected)
Waveform Correction
Check whether the impulse voltage waveform meets the specification requirements (wave head time 1.2μs ±30%, half-peak time 50μs ±20%).
If the waveform deviation is too large, adjust the impulse generator parameters and reapply the test.
If the waveform deviation is too large, adjust the impulse generator parameters and reapply the test.
Repeat Testing (if necessary)
Impact tests are performed for different phases and windings (HV/MV/LV).
In special cases, inter-winding impact, voltage-to-ground impact or coil corner impact are performed (according to the test plan).
In special cases, inter-winding impact, voltage-to-ground impact or coil corner impact are performed (according to the test plan).
Evaluation Criteria (Reference)
No internal insulation breakdown or flashover (detected by observing waveform continuity and audibly).
Waveforms are stable and meet standard specifications.
Waveform variations between repeated tests are minimal (usually good waveform overlap with no noticeable abnormal excursions).
Waveforms are stable and meet standard specifications.
Waveform variations between repeated tests are minimal (usually good waveform overlap with no noticeable abnormal excursions).
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
Ideal for medium to large commercial buildings, office complexes, retail centers, schools, hospitals, and light-to-medium manufacturing facilities requiring reliable step-down from medium-voltage utility feed to 480V or 208V. Also suits suburban/urban distribution networks with underground or overhead feeds, delivering safe, low-maintenance power in moderate to high-traffic locations.
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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