220kV Oil-Immersed 3-Phase 2-Winding OLTC Power Transformer

Our 220kV oil-immersed three-phase two-winding on-load tap-changing power transformers are designed for critical grid nodes requiring precise voltage control and high reliability.

• Equipped with on-load tap-changer offering ±4×1.25%, ±6×1.25%, or ±8×1.25% ranges for real-time voltage adjustment without power interruption.

• HV options at 220kV and 230kV; LV options from 6.3kV to 21kV, with 66kV and 69kV available for medium-voltage applications.

• Rated from 31.5 MVA to 240 MVA with no-load current as low as 0.24% for balanced functionality and energy efficiency.

• YNd11 vector group with 12%–14% short-circuit impedance ensures system compatibility and stable voltage regulation.

• Ideal for urban core substations, data centers, high-end manufacturing, and sensitive load applications requiring superior power quality.

Core Positioning

This product series represents a high-end two-winding main power transformer designed for critical nodes within 220kV high-voltage grids requiring precise voltage control and reliable power supply. It integrates proven transformer technology with online on-load tap-changing (OLTC) capability, making it an ideal choice for achieving high-quality, highly stable power supply, particularly suited for important load areas sensitive to voltage fluctuations.

Technical Specifications

Rated capacity (kVA)		Rated voltage and tapping range			Vector group	No Load Current (%)	Short-circuit impedance (%)	No load Losses (kW)	On load Losses (kW)
		HV (KV)	Tapping range	LV (KV)
31500		220 230	±4×1.25 ±6×1.25 ±8×1.25	6.3 6.6 10.5 21	YNd11	0.46	12~14	17	115
40000						0.46		20	134
50000						0.42		24	161
63000						0.42		28	188
90000				10.5 21 36 37 38.5		0.36		35	246
120000						0.36		43	304
150000						0.33		51	360
180000						0.3		59	413
120000	LV 66kV 69kV			66 69		0.36		45	303
150000						0.33		53	355
180000						0.3		62	406
240000						0.24		77	504

Core Advantages and Features

1. Online Precise Voltage Regulation Capability:

- Equipped with an On-Load Tap-Changer (OLTC), offering multiple tap range options such as ±4×1.25%, ±6×1.25%, and ±8×1.25%. It enables real-time adjustment of the high-voltage side voltage without interrupting power supply, ensuring the low-voltage side output remains highly stable despite grid fluctuations or load changes. It is a core asset for guaranteeing power quality.

2. Flexible Adaptation to Multiple Voltage Scenarios:

- The high-voltage side is compatible with standard system voltages of 220kV and 230kV.

- The low-voltage side offers flexible and diverse voltage options:

- Standard configurations cover common distribution voltages such as 6.3kV, 6.6kV, 10.5kV, and 21kV.

- For specific requirements, medium-voltage output options of 66kV and 69kV are also available (e.g., for 120/150/180 MVA models), suitable for direct medium-voltage supply to regional grids or large industrial users.

3. High Performance and Operational Economy:

- The capacity range spans from 31.5 MVA to 240 MVA, meeting the main transformer capacity requirements of most substations.

- Utilizes the standard YNd11 vector group, ensuring good system compatibility.

- Short-circuit impedance is designed between 12% and 14%, effectively limiting short-circuit currents while ensuring good voltage stability.

- While providing dynamic voltage regulation, the no-load current (minimum 0.24%) and loss values are well controlled, balancing functionality with operational energy efficiency.

Typical Applications

- 220kV urban core substations and dedicated substations for important users with stringent requirements for power supply quality and voltage stability.

- Regional grid interconnection substations serving voltage regulation and support functions.

- Power supply hubs for sensitive loads such as large data centers, high-end manufacturing, and precision industries.

- Key nodes in large industrial parks or regional grids requiring direct medium-voltage (66/69kV) supply.

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