35KV-110KV Oil Immersed Power Transformer

Covering 6.3 MVA to 120 MVA at 35 kV, 66 kV and 110 kV voltage levels, our 3 phase oil-immersed transformers are engineered for transmission substations, heavy industry and renewable-energy collector stations. Multi-step, mitered CRGO cores with 45°-45° step-lap joints cut no-load losses by 18 % versus IEC 60076 tolerances, translating into 200 MWh+ annual energy savings on a 50 MVA unit and a 2-year payback on premium efficiency.

High-purity, diamond-transposed copper conductors and kraft-oil insulation are dried-vacuum-impregnated at 1 mPa, achieving partial discharge < 5 pC at 1.5 Um and a 40-year design life. The robust assembly withstands 105 kA short-circuit for 3 s; adjustable axial clamping allows re-tightening after transport to maintain short-circuit strength throughout service life.

Cooling modes progress from ONAN to ONAF (up to 50 % extra capacity) or OFAF with motor-driven oil pumps, enabling up to 65 % footprint reduction in space-critical EPC projects. An in-tank, on-load tap-changer (OLTC) with 17 or 33 steps regulates voltage within ± 10 % under full load, while vacuum-type diverters guarantee 300 000 operation cycles maintenance-free.

Corrugated-steel radiators or detachable panel radiators are sized for hot-spot ≤ 98 °C at 40 °C ambient; optional hermetically sealed tank eliminates conservator and nitrogen padding, cutting inspection time by 50 %. Built-in Pt100 RTDs, oil-level and Buchholz relays feed SCADA or IEC 61850 IEDs for real-time diagnostics and 20 % emergency overload capability.

Units meet IEC 60076, IEEE C57.12.00, GB/T 6451, are seismic-qualified to 0.4 g, altitude-rated to 4 000 m, and certified for – 50 °C cold-start with special low-pour-point oil. Delivered fully assembled, vacuum-filled and third-party witnessed, ready for energization 48 hours after arrival.