10000 Kva Oil-filled Transformer

The 10000 kVA Oil Immersed Transformer acts as the heart of municipal substations and large-scale industrial power rings. At this capacity, the unit is responsible for energizing entire districts or massive production lines. Consequently, engineering priority shifts from simple power conversion to asset longevity and fault containment.

As a heavy-duty three phase oil immersed transformer, this unit is built to operate continuously for 30+ years. To achieve this, we move beyond standard sealing methods and employ an Air Cell (Rubber Bag) Conservator System.

• The Logic: Instead of allowing air to contact the oil directly (even through a breather), a flexible rubber bladder inside the conservator "breathes" the air. The oil surrounds this bladder, remaining completely isolated from oxygen and moisture. This technology virtually eliminates oil oxidation/sludging, significantly extending the intervals between oil filtration maintenance.

A 10 MVA fault releases massive energy. Therefore, safety mechanisms are non-negotiable:

• Double-Float Buchholz Relay: We equip the unit with a two-stage relay. The first stage (alarm) detects minor gas accumulation from slow insulation degradation (e.g., partial discharge), while the second stage (trip) instantly isolates the transformer during a sudden oil surge caused by a short circuit.
• Directional PRD: A large Pressure Relief Device is mounted on the tank cover. Crucially, for a unit of this size, it is fitted with a directional cowl to channel hot oil away from the operator walkways in the event of an internal explosion.

Two-stage Buchholz relay installed on the pipe connecting the

main tank and conservator.

To integrate safely into the 11kV or 33kV network, impedance control is vital.

• Fault Limitation: Standard 4-5% impedance is dangerous at 10 MVA because the short-circuit current would be too high for breakers to handle. This unit is engineered with a standard impedance of 8.0% to 9.0%. This intentionally higher reactance limits the fault current to <25kA on the secondary side, matching the standard breaking capacity of medium-voltage switchgear.

• City Grid Substations: Stepping down 33kV transmission to 11kV to feed a network of 20-30 smaller distribution transformers scattered across a residential zone.
• Hyperscale Data Centers: Used in an N+1 configuration to power large server halls, where the high impedance helps limit arc-flash energy downstream.
• Cement & Steel Plants: Feeding the main MV switchboard that powers large crushers and mills (often requiring 6.6kV motors).

10000 kVA oil immersed transformer operating in a city grid

distribution substation.