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33/44/55 MVA 3‑Phase Power Transformer

The 33/44/55 MVA 3‑Phase Power Transformer is a high‑performance, three‑winding, oil‑immersed unit tailored for utility and renewable energy infrastructures. Engineered to IEEE/ANSI/NEMA standards, it offers three cooling modes—natural ONAN (33 MVA), single‑fan ONAF1 (44 MVA), and dual‑fan ONAF2 (55 MVA)—to match load demands without interruptions. Dual primary configurations (138 kV/34.5 kV or 69 kV/34.5 kV) feed a grounded 13.8 kV secondary via a Dyn11 vector group. Low‑loss silicon‑steel cores and copper windings deliver exceptional efficiency, while a conservator with silica‑gel breather preserves oil integrity. Designed for harsh environments (–20 °F to +110 °F, heavy icing, 100 mph winds), this transformer integrates comprehensive protection relays and temperature monitoring, ensuring reliable step‑up/step‑down service in solar farms, substations, and critical power hubs.

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Product Accessories

On‑Load Tap Changer (OLTC)
Vacuum diverter switch with eight positions for ±8.4 % to +7.2 % voltage regulation under load.

Buchholz & Pressure‑Vacuum Relays
Dual‑float gas detection plus vacuum gauge for rapid fault detection and tank monitoring.

Oil & Winding Temperature Sensors
PT100 probes with dual alarm/trip contacts driving fan sequencers.

Conservator & Breather Assembly
Elastic membrane conservator tank paired with self‑regenerating silica‑gel breather.

Porcelain HV/MV Bushings
ANSI‑compliant, top‑cover bushings with integrated CTs and cable termination kits.

Station‑Class Surge Arresters
High‑ and medium‑voltage porcelain arresters for lightning and switching protection.

Removable Radiators & Fans
Bolt‑on cooling panels with visual isolation valves allow quick ONAF maintenance.

Drain, Sampling & Filter Valves
Captive‑cap design for safe oil sampling and in‑field filtering.

GPS Shock Recorder
Three‑axis transit shock logging ensures damage‑free delivery.

IP55 Control Cabinet
Stainless‑steel enclosure with lighting, outlets, heater, and SCADA interface.

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Product Specifications

Capacity (ONAN/ONAF1/ONAF2)

33 MVA / 44 MVA / 55 MVA

Primary Voltages

138/34.5 kV or 69/34.5 kV

Secondary Voltage

13.8 kV

Vector Group

Dyn11

Tap Changer Range

±8.4 % to +7.2 % (8 steps)

Cooling Method

ONAN, ONAF1, ONAF2

Impedance

10 %

Lightning Impulse Withstand (Full)

HV: 500 kV; MV: 200 kV; LV: 125 kV

Ambient Conditions

–20 °F to +110 °F; 100 mph wind; 0.5 in ice

Insulation Oil

ASTM D3487 mineral oil

Product Applications

Economy is more affordable

Steps up photovoltaic array voltage for transmission-level interconnection.

Solar EPC Projects
Facilitates grid-level voltage control and feed-in from multiple sources.

Utility Transmission Substations
Integrates large-capacity BESS installations into medium-voltage networks.

Battery Energy Storage Systems
Provides dependable medium-voltage supply to data centers, hospitals, and industrial complexes.

Critical Infrastructure Power

Product Advantages

Adaptive Cooling Performance

Three-stage cooling seamlessly ramps capacity from 33 MVA to 55 MVA without service disruption.

Enhanced Grid Compatibility

Dual primary voltage options and high-resolution tap changer ensure alignment with diverse transmission standards.

Built‑In Durability & Monitoring

Heavy-duty construction, station-class relays, and GPS‑recorded transport verification safeguard long-term reliability.

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.