250kVA Single Phase Pad Mounted Transformer
NPC ELECTRIC 250 kVA single phase pad mounted transformer operates safely, reliably, and efficiently and can be installed indoors and outdoors. The industrial transformer has a rated power of 250 kVA, a primary voltage of 27600/16000V single-phase and a secondary voltage of 120/240V single-phase.The transformer has a primary loop feed and dead front primary connections.
- 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 480-240/240-120or customized
- H.V. Tap Range ± 2×2.5% HV taps or others
- Type Loop Feed or Radial Feed
- BIL 30/95kV
- Standards IEEE, CSA, DOE, NEMA
- Application Utility, Residential areas, Commercial hubs
- Power Rating 250kVA
- Certificate UL/cUL, CSA, CESI
- 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
250kVA Single Phase Pad Mounted Transformer
Technical Specifications
Accessories
| Rated Power | 250 kVA |
| Rating Primary Voltage | 11950Delta or Customized |
| Secondary Voltage | 480-240V 240-120V 277V Customized |
| Frequency | 50/60Hz |
| Vector Group | Ii0,Ii6 |
| 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 | 325 kg |
| Total Weight | 1106 kg |
| Outline Dimensions（L×W×H）in. | 1430×1300×1250(mm) |
| Lifting Lug | ELSP Fuse |
| Hinged Door | BAY-O-NET Fuse |
| Parking Bracket | Tap Changer |
| Tank Cover | Oil Level Gauge |
| L.V Bushing (4-Hole ) | Pressure Relief Valve |
| Two/Four Position Load break Switch | Vacuum Pressure Gauge |
| HV Grounding Copper Bar | Terminal Block |
| Temperature Indicator | Door Handle |
| H.V Bushing Well | Ground Strap |
| Grounding Copper Bar | Nameplate |
| 1"'Drain Valve With 3/8" Sampler | Non-PCB decal |
| 1" Upper Fill Valve Filter Press Connection | High Voltage Warning Signs |
Customization Optional
250kVA Single Phase Pad Mounted Transformer
The optional specifications for a 250kVA Single Phase Pad Mounted transformer typically include a range of features to meet various application requirements. These options may include different primary and secondary voltage combinations, such as custom voltage settings to suit specific load demands. The transformer may offer different feed configurations, such as radial or loop feed, as well as options for primary and secondary connections, including dead front or live front setups. Additional customization options could include various enclosure types with different IP (Ingress Protection) ratings for outdoor use, overload protection devices, metering provisions, and options for added cooling systems or remote monitoring. These optional specifications enable the transformer to be tailored for optimal performance, reliability, and safety in diverse installation environments.
Packing and Shipping
250kVA Single Phase Pad Mounted Transformer
The 250kVA single phase pad mounted transformer is meticulously prepared for secure global transport to ensure it arrives in optimal condition. Prior to packing, the unit undergoes thorough final inspections, including oil filling (if shipped filled) or nitrogen blanketing for dry shipments to prevent moisture ingress and oxidation. All external accessories, such as bushings, gauges, valves, and fittings, are protected with impact-resistant covers and securely fastened to avoid vibration damage during transit. The transformer tank and enclosure receive anti-corrosion coatings and temporary protective wraps, while sensitive components like loadbreak bushings are shielded with specialized padding.
Standard packing utilizes heavy-duty wooden crating reinforced with steel bands and internal bracing tailored to the transformer's dimensions and weight (approximately 2200-2500 lbs dry). For international shipments, crates comply with ISPM 15 heat-treated standards to prevent pest issues, often combined with plastic film wrapping and desiccant packs for humidity control. When shipped oil-filled, leak-proof seals and absorbent materials are added around potential seep points, adhering to DOT and international hazardous material regulations for insulating fluids. Domestic deliveries may employ flatbed trucking with secure tie-downs, while export orders favor containerization (20ft or 40ft open-top/high-cube) or RoRo vessels for larger volumes.
Shipping methods prioritize safety, efficiency, and cost-effectiveness based on destination and urgency. For North American routes, reliable trucking partners handle door-to-site delivery with specialized lowboy trailers for heavy equipment. Overseas shipments typically involve multimodal transport—truck to port, ocean freight via secure carriers, then final delivery—coordinated with full tracking and insurance coverage. Lift points and center-of-gravity markings are clearly indicated on the crate for safe handling using cranes or forklifts at all transfer points. Documentation includes packing lists, test reports, installation manuals, and customs declarations to facilitate smooth clearance.
Upon arrival, we recommend immediate inspection for transit damage and verification of oil levels/seals before offloading. Professional rigging equipment is advised for unloading to preserve the transformer's integrity. Our logistics team provides end-to-end support, including export crating certifications, freight quotes, and coordination with freight forwarders to minimize delays and ensure the transformer reaches your site ready for pad installation and commissioning.
Standard packing utilizes heavy-duty wooden crating reinforced with steel bands and internal bracing tailored to the transformer's dimensions and weight (approximately 2200-2500 lbs dry). For international shipments, crates comply with ISPM 15 heat-treated standards to prevent pest issues, often combined with plastic film wrapping and desiccant packs for humidity control. When shipped oil-filled, leak-proof seals and absorbent materials are added around potential seep points, adhering to DOT and international hazardous material regulations for insulating fluids. Domestic deliveries may employ flatbed trucking with secure tie-downs, while export orders favor containerization (20ft or 40ft open-top/high-cube) or RoRo vessels for larger volumes.
Shipping methods prioritize safety, efficiency, and cost-effectiveness based on destination and urgency. For North American routes, reliable trucking partners handle door-to-site delivery with specialized lowboy trailers for heavy equipment. Overseas shipments typically involve multimodal transport—truck to port, ocean freight via secure carriers, then final delivery—coordinated with full tracking and insurance coverage. Lift points and center-of-gravity markings are clearly indicated on the crate for safe handling using cranes or forklifts at all transfer points. Documentation includes packing lists, test reports, installation manuals, and customs declarations to facilitate smooth clearance.
Upon arrival, we recommend immediate inspection for transit damage and verification of oil levels/seals before offloading. Professional rigging equipment is advised for unloading to preserve the transformer's integrity. Our logistics team provides end-to-end support, including export crating certifications, freight quotes, and coordination with freight forwarders to minimize delays and ensure the transformer reaches your site ready for pad installation and commissioning.
32
32 years of industry experience
Manufacturer Test
250kVA Single Phase Pad Mounted Transformer
Progress Test
NPC Electric manufacturer pad mounted transformer have the strict quality control. The progress test for a 250kVA Single Phase Pad Mounted transformer typically involves a series of inspections and performance checks conducted at various stages of manufacturing to ensure the transformer meets quality and safety standards. This includes verifying the electrical parameters, such as voltage ratios, insulation resistance, and load performance, as well as checking for any physical defects or manufacturing discrepancies. The test also ensures that the transformer operates efficiently under both no-load and full-load conditions. Additional tests may include temperature rise tests, mechanical strength tests, and partial discharge testing to confirm the durability and reliability of the transformer in real-world conditions. These progress tests are crucial for ensuring the transformer’s compliance with industry standards and its readiness for safe, reliable operation.
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)
♦ Lightning Impulse
♦ Insulation Resistance (Rated Voltage)
♦ Temperature Rise
♦ Dielectric Withstand (Hipot)
Transformer Factory Acceptance Test
Induced voltage withstand and applied potential tests apply elevated voltages to verify dielectric strength without breakdown. Impedance and load loss tests under short-circuit conditions confirm performance parameters. Oil dielectric breakdown and moisture tests (if filled) ensure fluid quality. Functional checks include operation of pressure relief devices, liquid level indicators, drain/sampling valves, and fusing systems. Special tests like sound level measurement or temperature rise simulation may apply per client request. All results are recorded, compared against guaranteed values, and witnessed by client/third-party representatives if required. Successful FAT completion with signed protocol certifies the transformer ready for shipment, fully compliant with IEEE C57.12.00, C57.12.38, ANSI, and applicable standards for dependable field performance.
Routine Test - Excitation & No-Load Loss (Rated Voltage)
Purpose of Testing
The purpose of testing Excitation & No-Load Loss at rated voltage is to assess the transformer's core loss and magnetizing current under normal operating conditions, ensuring efficient performance and identifying any potential issues in the core or windings. This test helps verify that the transformer operates within specified parameters and meets its design requirements.
Testing Equipment
Test equipment: Excitation Test instrument (such as OMICRON, Megger, etc.)
Voltage source: usually rated voltage (such as 230V, 400V, 660V, customized according to equipment requirements)
Temperature and humidity meter: used to record ambient temperature and humidity conditions
Voltage source: usually rated voltage (such as 230V, 400V, 660V, customized according to equipment requirements)
Temperature and humidity meter: used to record ambient temperature and humidity conditions
Pre-Test Preparation
Disconnect and make sure the device is powered off and properly grounded and discharged.
Check the device terminals and wiring to ensure that the connection is secure and not loose or contaminated.
Ensure the test environment is suitable: relative humidity below 75%, no rain, and recommended temperature is 20-30°C.
Check the device terminals and wiring to ensure that the connection is secure and not loose or contaminated.
Ensure the test environment is suitable: relative humidity below 75%, no rain, and recommended temperature is 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 connection points are properly grounded to avoid current leakage during the test.
Apply Test Voltage:
Select a suitable test voltage according to the rated voltage of the equipment (for example, the rated voltage is 11kV, 33kV or others), and ensure that the applied voltage is stable.
Connect the test equipment to the appropriate terminals of the device under test and ensure that all connection points are properly grounded to avoid current leakage during the test.
Apply Test Voltage:
Select a suitable test voltage according to the rated voltage of the equipment (for example, the rated voltage is 11kV, 33kV or others), and ensure that the applied voltage is stable.
Measure and Record
No-load current
No-load loss
Excitation loss
Power factor
Voltage
Current
Ambient temperature and humidity during testing
No-load loss
Excitation loss
Power factor
Voltage
Current
Ambient temperature and humidity during testing
Temperature Correction
The measured loss values and currents are corrected to a reference temperature (typically 20°C) for an accurate evaluation.
Repeat Testing (if necessary)
If necessary, measure the no-load loss and excitation loss of different windings (high voltage, medium voltage, low voltage) and at different voltage levels for comparative analysis.
Evaluation Criteria (Reference)
No-load loss ≤ rated loss (meets specifications)
No-load loss > rated loss (further inspection or corrective action required)
No-load loss > rated loss (further inspection or corrective action required)
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
Perfectly suited for light industrial parks, transportation centers such as airports or rail stations, and utility upgrades in urban areas demanding compact, tamper-proof installations; effectively combines with renewable energy setups like solar farms or EV charging stations, plus commercial complexes including schools, hospitals, and shopping areas for efficient, high-reliability power delivery.
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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