300 kVA Three Phase Oil-Immersed Medium Voltage Transformer – Product Overview and Key Features
The 300 kVA three phase oil-immersed medium voltage (MV) transformer is a premium solution designed for substation, industrial, and commercial power distribution networks worldwide. Supporting 11 kV, 13.8 kV, and 20 kV primary voltages and 480Y/277V and 400Y/230V secondary outputs, this transformer ensures efficient voltage transformation, reliable operation, and long-term stability for diverse applications.
Manufactured by PowerNex, a China-based leading transformer manufacturer, this transformer complies with ANSI, IEC, and IEEE standards, with optional certifications including UL, cUL, CSA, and CE. PowerNex provides OEM customization, factory-direct pricing, and global supply, making it a trusted partner for utilities, industrial plants, and commercial projects.
Key Highlights:
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Power Rating: 300 kVA (customizable 10–5000 kVA range)
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Primary Voltage: 11 kV, 13.8 kV, 20 kV
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Secondary Voltage: 480Y/277V, 400Y/230V
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Connection: Three Phase Delta–Wye or Wye–Wye
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Cooling: Oil-immersed ONAN, optional ONAF
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Mounting: Pad-mounted or substation installation
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Applications: Industrial plants, utility substations, commercial complexes, renewable energy integration
Technical Specifications of 300 kVA MV Transformer
| Parameter | Specification |
|---|---|
| Rated Power | 300 kVA (10–5000 kVA customizable) |
| Primary Voltage | 11 kV / 13.8 kV / 20 kV |
| Secondary Voltage | 480Y/277V, 400Y/230V |
| Frequency | 50/60 Hz |
| Connection Type | Delta–Wye, Wye–Wye |
| Cooling Method | ONAN oil-immersed (ONAF optional) |
| Standards | ANSI, IEC, IEEE |
| Certifications | UL, cUL, CSA, CE optional |
| Mounting Type | Pad-mounted or substation installation |
| Enclosure | Outdoor sealed steel tank |
| Ambient Temperature | -40°C to 50°C |
| Altitude | Up to 1000 m (customizable for higher elevations) |
| Short-Circuit Impedance | 4–6% typical, customizable |
| Noise Level | ≤55 dB at rated load |
Transformer Structural Design and Features
The 300 kVA oil-immersed MV transformer is engineered with high-quality core and winding materials to minimize losses and maximize efficiency. Its robust construction includes:
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Oil-immersed steel tank: Provides reliable insulation, cooling, and corrosion resistance
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Conservator and silica gel breather: Maintains oil quality and prevents moisture ingress
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Primary and secondary bushings: Multiple options for 11–20 kV and 480Y/277V or 400Y/230V connections
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Cooling radiators or optional fans: Enhances thermal performance for continuous heavy loads
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Tap changer (optional): Provides voltage regulation for system stability
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Protective devices: Includes oil temperature indicators, pressure relief valves, and lightning arresters
This design ensures long-term operational stability, low maintenance, and adaptability to different environmental and load conditions.
Applications and Industry Use Cases
The 300 kVA MV transformer is versatile, suitable for:
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Utility Substations: Converts medium voltage to low voltage for distribution to commercial and residential areas
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Industrial Plants: Provides stable power for factories, workshops, and production lines
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Commercial Complexes: Reliable electricity for shopping malls, office buildings, and mixed-use developments
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Renewable Energy Integration: Connects solar PV farms, wind turbines, and hybrid grids
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Medium-Voltage Distribution Networks: Rural electrification, agricultural systems, and light commercial loads
Regional Adaptability:
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North America: 11–13.8 kV primary voltages to 480Y/277V secondary
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Europe: 20 kV primary to 400Y/230V secondary
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South America, Asia-Pacific, Middle East: Flexible OEM voltage configurations based on local grids
Installation Guidelines
Pad-Mounted Installation:
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Ensure a level concrete foundation
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Properly ground according to ANSI/IEC standards
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Connect primary and secondary bushings according to voltage specifications
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Install tap changer (if included) and protective devices
Substation Installation:
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Position transformer on substation plinth with correct spacing
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Install surge arresters, disconnect switches, and protective relays
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Connect to grid with proper cable terminations and grounding
Maintenance Recommendations:
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Inspect oil level and quality regularly
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Test insulation and dielectric strength periodically
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Check bushings and connections for corrosion or wear
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Monitor load and temperature for safe operation
Testing and Quality Assurance
PowerNex transformers undergo rigorous quality assurance testing including:
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Electrical tests: Turns ratio, winding resistance, insulation resistance
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Load and no-load loss measurements
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Dielectric tests: High-voltage withstand and insulation integrity
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Thermal performance tests under ONAN or ONAF cooling
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Noise and vibration testing
All testing conforms to ANSI, IEC, and IEEE standards, ensuring global compliance and customer confidence.
Technical Drawings and Documentation
Every 300 kVA transformer comes with:
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Dimension and layout drawings
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Wiring diagrams for primary and secondary connections
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Installation and maintenance manuals
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Optional customized OEM diagrams
Technical documentation helps engineers and EPC contractors integrate the transformer into complex systems efficiently.
Case Studies
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USA Utility Substation Upgrade: 300 kVA, 13.8 kV to 480Y/277V, pad-mounted, supplied to a city utility for urban distribution
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Germany Industrial Plant: 300 kVA, 20 kV to 400Y/230V, substation transformer delivered to a manufacturing facility
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Brazil Mining Operation: 300 kVA, 13.8 kV to 480Y/277V, customized oil-immersed transformer for harsh outdoor conditions
FAQ – Medium Voltage Transformer 300 kVA
Q1: Can this transformer be used for both industrial and utility applications?
Yes, it is suitable for industrial plants, commercial complexes, and utility substations.
Q2: What is the standard installation type?
Pad-mounted and substation installations are standard. Pole-mounted installation is generally not recommended for 300 kVA.
Q3: Are custom voltages supported?
Yes, PowerNex provides OEM customization for primary voltages (11–20 kV) and secondary outputs (480Y/277V, 400Y/230V).
Q4: What certifications are available?
Optional certifications: UL, cUL, CSA, CE. Standards compliance: ANSI, IEC, IEEE.
Q5: Expected lifespan?
25–30 years with proper maintenance.
Q6: Can transformers be paralleled?
Yes, parallel operation is supported following manufacturer guidelines.
Global Supply, OEM, and Customization Capabilities
PowerNex is a China-based leading transformer manufacturer, offering:
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Capacities from 10 kVA to 5000 kVA
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Distribution transformers, substation transformers, voltage regulators, stabilizers, frequency converters, tap changers, marine transformers, and mining transformers
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OEM customization for voltages, taps, enclosures, and accessories
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Global wholesale and direct supply
Global Markets Served:
USA, Canada, Brazil, Argentina, Australia, Indonesia, Malaysia, Philippines, UAE, Saudi Arabia, Russia, Germany, France, South Africa, Venezuela, Mexico, New Zealand, and others
Customization Options Include:
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Primary and secondary voltage adaptation
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Tap changers and cooling upgrades
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Enclosure design for extreme environments
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OEM branding and technical documentation
Conclusion and Call to Action
The 300 kVA three phase oil-immersed medium voltage transformer by PowerNex is an efficient, reliable, and durable solution for substation, industrial, and commercial power distribution projects worldwide. With customizable primary and secondary voltages, flexible OEM configurations, global supply capability, and factory-direct pricing, it is ideally suited for applications across utility grids, industrial facilities, commercial complexes, and renewable energy systems.
In addition to the 300 kVA model, PowerNex supplies a full range of medium voltage oil-immersed transformers, including 150 kVA, 225 kVA, 500 kVA, 700 kVA, 1000 kVA, 1500 kVA, and other customized capacities up to 5000 kVA, supporting diverse load requirements and grid designs in different regions.
Contact PowerNex today to request:
• Quotations for 300 kVA and other available capacities such as 150 kVA, 225 kVA, 500 kVA, 700 kVA, 1000 kVA, and 1500 kVA
• Detailed technical drawings, dimensions, and installation guidance
• OEM customization, wholesale supply, and bulk procurement solutions for global projects
Ensure reliable, efficient, and long-lasting power distribution with PowerNex medium voltage transformers, trusted by utilities, EPC contractors, and industrial customers worldwide.
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