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138KV 3 Phase Power Transformer

The 138 kV 3‑Phase Power Transformer is an oil‑immersed, conservator‑type unit engineered for high‑voltage transmission and substation use, delivering up to 120 MVA in ONAN/ONAF cooling modes with efficiency exceeding 99 % under full load. Its ±8×1.25 % on‑load tap changer provides fine voltage regulation, maintaining stable output despite load fluctuations. Built to GB 6451, IEC 60076, ANSI/IEEE C57.12, and EN 60076 standards, it features an IP55‑rated tank, self‑regenerating silica‑gel breather, and robust porcelain bushings rated up to 650 kV BIL for long‑term reliability. With comprehensive type and routine testing—including lightning impulse and 2‑second short‑circuit withstand—this transformer ensures exceptional performance in demanding outdoor environments.

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Product Accessories

On‑Load Tap Changer (OLTC): 17‑step unit with motor drive and position indicator for ±8×1.25 % voltage adjustment

Conservator Tank Assembly: Includes magnetic oil level indicators (–20 °C to +100 °C) and silica‑gel breather to prevent moisture ingress

Buchholz Relay (Twin‑Float): Dual‑contact gas and oil surge detection for early fault warning and tripping

Pressure‑Vacuum Gauge: Monitors tank pressure and vacuum integrity, triggering alarms on deviation

Oil & Winding Temperature Indicators: Dial‑type gauges with adjustable alarm/trip contacts to safeguard against overheating

Porcelain HV/LV Bushings: Oil‑filled, capacitance‑graded POC type, rated 138 kV/11 kV with high seismic resilience

Radiators & Cooling Fans: Hot‑dip galvanized, detachable radiators with ONAF fans for forced‑air cooling stage

Overpressure Relief Valve: Semaphore visual indicator with electrical trip contacts for safety

Grounding Lugs & Nameplates: 316 stainless‑steel hardware for secure earthing and durable identification

Marshalling Box: NEMA 3R control cabinet housing all signal and control wiring with labeled terminals

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Product Specifications

Rated Power

Up to 120 MVA (ONAF)

Primary Voltage

138 kV

Secondary Voltage

11 kV (others optional)

Cooling Method

ONAN / ONAF

Tap Changer

±8×1.25 % OLTC on HV side

Efficiency

≥ 99 % at full load

Impedance

10 % at rated MVA

BIL (HV/LV)

650 kV / 150 kV

Temperature Rise (Oil/Winding)

50 °C / 65 °C per IEC 60076‑2

Ingress Protection

IP55

Product Applications

Economy is more affordable

Step‑down from 138 kV to distribution levels in utility grids, ensuring stable delivery to regional networks.

High‑Voltage Substations
Supply heavy‑duty manufacturing plants (steel, petrochemical) with reliable high‑capacity power under fluctuating loads.

Industrial Complexes
Interface wind and solar farms to transmission systems, providing precise voltage control despite variable generation profiles.

Renewable Energy Plants
Support data centers, airports, and large campuses requiring uninterrupted, high‑quality power with minimal downtime.

Critical Infrastructure

Product Advantages

Ultra‑High Efficiency

Advanced core materials and optimized winding geometry reduce no‑load and load losses, lowering operational costs.

Robust Environmental Protection

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

Precision Voltage Regulation

High‑resolution OLTC enables fine adjustments under load, stabilizing downstream equipment and enhancing grid resilience.

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.

138KV Power Transformer 3 Phase Power Transformer 138KV 3 Phase Power Transformer

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