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Secondary Voltage Ratings: 480/277-480/277V
H.V. TAP RANGE: 13110-14490V
CONNECTION TYPE: Dyn1yn1
TYPE: Pad mounted
BIL: 125/45/45kV
Standards: IEEE STD C57.12.34
Application: BESS
Power Rating: 5000kVA
Certificate: UL
Cooling Method: KNAN
Daelim Transformer has just delivered 15 untis BESS transformers for a 75MW solar energy storage project in the United States. These transformers are custom-designed for the unique requirements of the BESS project, with a lifespan of 30 years, taking into account over-voltages, inverter applications, harmonics, saturation, and power factors.
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HINGED DOOR PARKING STAND BRACKET TANK COVER LV BUSHING BIL:45KV VACUUM PRESSURE GAUGE FILL PLUG(1 INCH) 1″DRAIN VALVE WITH 3/8″ SAMPLE RPRESSURE RELIEF DEVICE HV INTEGRATED BUSHING (25kV,600A) GROUND BAR NAME PLATE |
PRESSURE RELIEF VALVE
TAP CHANGER(5-position) TWO POSITION LOADBREAK SWITCH BAYONET FUSE(6) DRIP TRAY 1″ UPPER FILL VALVE WITH SCHADER VALVE NEMA 4 TERMINAL BOX DOOR HANDLE OIL TEMPERATURE INDICATOR OIL LEVEL GAUGE GROUND STEEL PADS GROUND BAR (2-ROW OF HOLES)
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Daelim Transformer possesses extensive project experience and professional technical expertise in the BESS market. We ensure that our transformers are perfectly matched and integrated with various energy storage systems and equipment, enabling the entire energy storage system to operate safely, stably, and efficiently. Contact us today to discuss your BESS Transformer needs.

These pad mounted transformers for the BESS project feature a dual low-voltage split design with a high voltage of 13800V Delta and a low voltage of 480/277V-480/277V, with a capacity of 5000kVA. This dual split design not only perfectly matches the photovoltaic panel circuits but also ensures that if a fault occurs on one low-voltage side, the other side can continue to operate normally.
The insulating liquid used in this transformer is FR3 green vegetable oil, which not only offers excellent insulation performance but also features safety, environmental protection, high temperature resistance, effective heat dissipation, anti-oxidation properties, and low catalytic activity. This makes it an ideal choice for photovoltaic energy storage transformers.
Additionally, the insulation of the BESS transformer employs high-quality insulating paper and insulating boards to ensure optimal winding insulation.


The high voltage winding process is depicted in the image, ensuring the reliability of each transformer under high voltage conditions.
The completed low voltage foil wound coils, shown in the image, utilize efficient winding techniques that ensure stable performance.
In this video, Daelim Transformer workers are assembling the core and coils of the BESS transformers, ensuring precision and durability in every component.

The high voltage compartment is equipped with three plug-in bushings, six bay-o-net fuses, a two-position load-break switch, a tap changer, and a ground bar, ensuring safe operation on the high voltage side.
The BESS transformers feature uniquely designed low voltage compartments located on either side of the tank, equipped with four low voltage terminals (X1, X2, X3, and X0) and two ground bars. Each low voltage terminal is equipped with 12 holes for additional support.


The BESS transformers are packaged in wooden crates. To facilitate transportation, the low voltage compartments on either side of the transformer are disassembled and packaged separately. Users can assemble them upon receipt. The transformer body is placed on a wooden pallet, secured with bolts to prevent movement and impact during transport, surrounded by sturdy wooden boards for protection. The crate is reinforced with metal clamps on all sides and corners.
These 15 BESS transformers were shipped using 5 40-foot frame containers and 4 high cube containers.
After production, each of the 15 BESS transformers was tested according to IEEE Std C57. 12.34-2021, ensuring that every unit complies with IEEE standard inspection and testing requirements before shipment.

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