The Rockwill pad-mounted transformer is an integrated power distribution solution that combines the transformer body, high-voltage load switch, fuse system, and auxiliary equipment into a single compact unit. Using a fully insulated and sealed design with all major electrical components immersed in insulating oil, it achieves exceptional space efficiency while maintaining high performance. Supporting both loop and radial network configurations, the unit offers flexible adaptation to various distribution requirements and is particularly suited for space-constrained installation sites.
Key Features
Fully insulated construction： All live components are enclosed within the sealed oil-filled tank, eliminating exposed energized parts for enhanced personnel safety
Dual-fuse protection： Primary fuse and backup fuse provide coordinated over-current protection for reliable fault clearing
Hermetically sealed tank： Prevents oil oxidation and moisture ingress, extending insulation life and reducing maintenance
Flexible core option： Available with conventional silicon steel or amorphous alloy core to meet specific efficiency and loss requirements
Loop / radial switchable： Internal load-break switch supports both loop-feed and radial-feed configurations without external modification
Technical Parameters
Parameter
Value
Phase
Three-phase
Rated capacity
400 kVA
Frequency
50 / 60 Hz
Primary voltage
10 kV
Secondary voltage
0.4 kV, or as specified
Insulation level
12 / 28 / 75 kV (Um / PF / LI) per IEC 60071-1
Vector group
Dyn11, or as specified
Tapping range
±2 × 2.5 % (off-circuit)
Winding material
Copper / Aluminum (optional)
Cooling method
ONAN (Oil Natural Air Natural)
Insulation medium
Mineral oil
High-voltage protection
Load-break switch + dual fuses (primary + backup)
High-voltage bushings
Dead-front plug-in elbow connectors
Enclosure
Tamper-resistant, weatherproof, lockable
Standards
IEC 60076, ANSI C57.12.34 (as specified)
Operating Conditions
Parameter
Specification
Ambient temperature
–45 °C to +40 °C
Altitude
≤ 1,000 m above sea level
Relative humidity
Average ≤ 85 %
Installation site
Indoor or outdoor, free of fire, explosion, and corrosive gas hazards
Installation incline
≤ 3 degrees
Applications
Urban and suburban power distribution networks
Residential communities and commercial complexes
Industrial parks and public facilities
Space-constrained sites requiring a compact integrated transformer and switchgear solution
Custom ratings, voltages, impedances, core materials, and accessory configurations are available on request. Contact Rockwill for application-specific design and quotation.
Documentation Resource Library Pad Mounted Transformer
Main Categories: Medium and High Voltage Switchgear/Power and Distribution Transformers/Instrument Transformers and Sensors/Lightning Protection and Electrical Insulation/Substations and E-Houses/Electrical Panel and Controlgear
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