5000 Kva Dry Type Transformer

The 5000 kVA Dry Type Transformer is a massive power node, serving as the central heartbeat for urban substations and large industrial complexes. At this 5 MVA capacity, the unit typically moves beyond simple end-user distribution, acting instead as a bridge between the sub-transmission grid and the local distribution network.

This unit is most commonly deployed in a Sub-Transmission Configuration.

• Primary Side: Engineered as a 35kv dry type transformer, it accepts high-voltage inputs (33kV or 35kV) directly from the utility grid.
• Secondary Side: Instead of low voltage, it steps down to a medium-voltage level, functioning as an 11kv dry type transformer (or 6.6kV/10kV). This output feeds downstream Ring Main Units (RMUs) or distributed substation loops.
• The Benefit: This architecture allows facility planners to create a 100% oil-free MV-to-MV power network, strictly complying with fire safety regulations for indoor or underground city infrastructure.

At 5000 kVA, the electromechanical forces inside the coil during a fault are immense. The structural integrity of the dry type transformer winding is the primary determinant of asset life.

• HV Disc Architecture: For voltage classes above 3kV, we abandon simple layering in favor of Continuous Disc Windings. This geometry creates a high series capacitance, which evenly distributes the electrical stress of transient overvoltages (like lightning strikes) across the entire coil, preventing insulation failure at the line terminals.
• Foil LV Winding: To handle the massive current, the Low Voltage winding is constructed using full-width copper or aluminum foil. This eliminates the helical angle found in wire windings, effectively neutralizing the axial short-circuit forces that would otherwise attempt to telescope the coil during a grid fault.

The foundation of this 15-ton unit is its magnetic circuit. As a premium dry core transformer, we utilize High-Permeability Grain Oriented (H-GO) silicon steel.

• Vibration Dampening: A 5 MVA core generates significant magnetostriction forces. To preventing loosening over decades of operation, the core limbs are bound with resin-impregnated fiberglass tape, and the yokes are clamped by non-magnetic steel pull-plates.
• Step-Lap Miter: The laminations are cut at 45° angles and stacked in a 7-step lap pattern. This precision joint reduces no-load current and minimizes stray flux losses, ensuring the core remains cool even without the aid of liquid cooling.

• Metro & Tunnel Systems: Stepping down 35kV city power to 10kV for traction rectifiers, where fire load must be zero.
• Data Center Campuses: Serving as the primary on-site substation (33kV/11kV), feeding multiple downstream transformer blocks.
• Petrochemical Refineries: Powering large 6.6kV or 11kV compressors in Zone 2 hazardous areas where oil-filled transformers are a safety liability.

5000 kVA dry type transformer installed in an underground metro

substation powering traction systems.