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150KV 250MVA 3 Phase Power Transformer

The 150 kV 250 MVA 3-Phase Power Transformer is a heavy-duty, oil-immersed unit tailored for high-capacity transmission corridors and major substations. Engineered to meet IEC 60076 and ANSI/IEEE C57.12 requirements, it delivers continuous 250 MVA operation in ONAN mode and scales to 300 MVA/350 MVA under staged forced-air cooling (ONAF1/ONAF2). Its conservator-type tank—equipped with a self-regenerating silica-gel breather—ensures moisture-free insulation and stable oil levels across –20 °C to +100 °C. A 17-step on-load tap changer on the high-voltage side provides ±8 × 1.25 % regulation, maintaining precise output under load swings. With IP55 protection, robust porcelain bushings, and full type- and routine-test certification including lightning impulse and two-second short-circuit withstand, this transformer guarantees reliable service in challenging outdoor environments.

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Product Accessories

17-Step On-Load Tap Changer (OLTC): Motor-driven unit with position indicator for ±8 × 1.25 % voltage adjustment

Conservator Tank & Breather: Magnetic oil level gauges and silica-gel desiccant to prevent moisture ingress

Twin-Float Buchholz Relay: Gas and oil surge detection with separate alarm/trip contacts

Pressure-Vacuum Gauge: Monitors internal pressure/vacuum integrity and triggers alarms on divergence

Oil & Winding Temperature Indicators: Dial-type gauges with adjustable alarm/trip contacts for main tank and OLTC

Porcelain HV/LV Bushings: Capacitive-graded, oil-filled bushings rated 150 kV/33 kV with high BIL

Detachable Radiators & Fans: Hot-dip galvanized radiators with staged ONAF fans for enhanced heat rejection

Overpressure Relief Valve: Semaphore visual indicator plus electrical trip contacts

316 Stainless-Steel Nameplates & Grounding Lugs: Durable identification and safety hardware

NEMA 3R Marshalling Box: Stainless-steel enclosure organizing all control and signal wiring

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Product Specifications

Rated Power

250 MVA (ONAN) / 300 MVA (ONAF1) / 350 MVA (ONAF2

Primary Voltage

150 kV

Secondary Voltage

33 kV

Frequency

50 Hz (60 Hz optional)

Cooling Method

ONAN / ONAF (two-stage)

Tap Changer

17-step OLTC, ±8 × 1.25 % on HV side

Efficiency

≥ 99 % at full load

Impedance

10 % at rated MVA

BIL (HV/LV)

650 kV / 150 kV

Ingress Protection

IP55

Product Applications

Economy is more affordable

Efficiently step down 150 kV feeders to regional levels with minimal losses.

Utility Transmission Substations
Supply continuous, high-capacity power to steel mills, petrochemical complexes, and mining operations.

Heavy Industrial Plants
Interface 150 kV wind or solar farms, providing stable voltage despite fluctuating generation.

Renewable Energy Integration
Ensure uninterrupted power for data centers, airports, and hospitals, where reliability is non-negotiable.

Critical Infrastructure

Product Advantages

Scalable Cooling Performance

Dual-stage forced-air cooling (ONAF1/ONAF2) allows safe operation beyond nominal capacity (up to 350 MVA) without thermal degradation.

Precision Voltage Management

High-resolution OLTC maintains voltage within ±2 % of nominal under dynamic loads, protecting downstream equipment.

Robust Environmental Resilience

IP55 enclosure, silica-gel breather, and galvanized radiators ensure moisture-free, corrosion-resistant performance in harsh climates.

WellDone Power Transformer Plan Drawing

FAQ

What range of transformer products do you offer and which standards do they meet?

We manufacture a diverse array of transformers including Oil-Immersed Distribution Transformers, Dry Type Transformers, Power Transformers, Three Phase Pad Mounted Transformers, Single Phase Pad Mounted Transformers, Substation Transformers, and Pole Mounted Transformers. Our technical team, with nearly 20 years of industry experience, ensures that our designs comply with international standards such as ANSI, IEEE, DOE, CSA, AS, AZS, GOST, IEC, and more. Additionally, many of our products have obtained UL, cUL, and CSA certifications, affirming their safety and performance in global markets.
How do you ensure the quality and reliability of your transformers?

Our transformers are produced under a rigorous quality management system covering every stage from material selection to final testing. Each product comes with a minimum 24-month warranty, ensuring long-term safety and reliability. This commitment to quality has earned the trust of global customers and leading industry players.
What are your production lead times, customization options, and global market reach?

For standard models, our production lead time is typically 10 to 25 days, and we offer flexible OEM/ODM services for customized projects. We also tailor packaging solutions to meet specific customer requirements. Our transformers are exported worldwide—including North America, Europe, South America, Australia, Asia, and Africa—with successful partnerships involving renowned companies. For more details or personalized support, please contact us via email or WhatsApp.

150KV 3 Phase Power Transformer 250MVA 3 Phase Power Transformer 150KV 250MVA 3 Phase Power Transformer

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