330kV Oil-Immersed Three-Phase Two-Winding Power Transformer

Our 330kV oil-immersed three-phase two-winding off-circuit tap-changing power transformers are designed for 330kV transmission networks and large-scale power systems.

• Rated from 90 MVA to 720 MVA with HV options at 345kV and 363kV.

• ±2×2.5% off-circuit tapping range; LV options from 10.5kV to 20kV.

• No-load current as low as 0.16% with optimized losses reduces lifecycle operating costs.

• YNd11 vector group with 14%–15% short-circuit impedance ensures reliable protection and system stability.

• Oil-immersed construction for main substations, power plants, and renewable energy step-up applications. ```

Core Positioning

This product series is a standardized main transformer developed for 330kV extra-high voltage power grids and large-scale power systems. As the core equipment for power transmission and voltage conversion in regional networks, it has become the most widely adopted main transformer choice in substation configurations due to its cost-effectiveness and broad applicability.

Technical Parameters

(MVA) Rated Capacity	Rated Voltage and Tapping Range			Vector Group	No Load Current (%)	Short-circuit Impedance (%)	No load Losses (kW)	On load Losses (kW)
(MVA) Rated Capacity	HV (kv)	Tapping Range	LV (kv)	Vector Group	No Load Current (%)	Short-circuit Impedance (%)	No load Losses (kW)	On load Losses (kW)
90000	345 363	±2×2.5	10.5 13.8 15.75 18 20	YNd11	0.35	14~15	37	247
120000					0.35		47	306
150000					0.33		56	362
180000					0.3		64	415
240000					0.27		80	515
360000					0.27		109	722
370000					0.24		111	736
400000					0.24		118	780
720000					0.16		183	1212

Advantages

1. Broad Capacity Coverage and Application Flexibility

The series covers a complete capacity range from 90 MVA to 720 MVA, providing suitable solutions for applications from regional load centers to large-scale power source grid integration. The HV side accommodates both 345kV and 363kV system voltages with ±2×2.5% off-circuit tapping capability to meet operational requirements across different regional networks.

2. Refined Electrical Performance

Five standard LV voltage options are available from 10.5kV to 20kV, matching the requirements of power plant auxiliary systems, industrial distribution networks, and urban power grids. The no-load current ranges from 0.16% to 0.35%, reflecting advanced core material and assembly techniques. Load losses are precisely controlled across all capacities. This low-loss design translates directly into reduced lifecycle operating costs.

3. Proven Reliability

The YNd11 vector group is a well-established connection scheme ensuring broad system compatibility and simplified protection coordination. Short-circuit impedance is maintained in the 14% to 15% range, effectively limiting fault currents while maintaining proper voltage regulation. The oil-immersed construction provides reliable insulation and cooling performance for long-term operation.

Applications:

- Main transformers for 330kV regional substations and terminal substations

- Generator step-up units or HV auxiliary transformers for thermal, hydro, and nuclear power plants

- Main step-up transformers for wind and solar PV farm collection substations

- Primary transformation equipment for large industrial and mining facility substations

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