110kV Oil-Immersed 3-Phase 3-Winding NLTC Power Transformer

Our 110kV oil-immersed three-phase two-winding off-circuit tap-changing power transformers are standard, cost-effective solutions for high-voltage transmission networks and large-scale power users.

• Off-circuit tap-changing design with simple structure and fewer mechanical components ensures high reliability, low maintenance, and excellent total cost of ownership.

• HV options at 110kV, 115kV, and 121kV with ±2×2.5% tapping range; LV options from 6.3kV to 21kV covering diverse industrial and distribution needs.

• Rated from 6.3 MVA to 180 MVA with no-load current as low as 0.16% for outstanding operational economy.

• YNd11 vector group with optimized short-circuit impedance ensures system compatibility and voltage stability.

• Fast delivery, reliable quality, responsive service, and extensive project experience backed by our company.

Products Description

This product series represents a multifunctional, compact three-winding hub transformer designed for 110kV medium-high voltage grids. By integrating multiple interface functions - including high-voltage transmission, medium-voltage distribution, and low-voltage reactive power compensation/auxiliary power supply - within a single unit, it provides an ideal and economical solution for simplifying substation layouts and enabling flexible conversion and distribution across multiple voltage levels.

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)
Rated capacity (kVA)	HV	Tapping range	LV	Vector group	No Load Current (%)	Principal Tap	Maximum Tap	No load Losses (kW)	On load Losses (kW)
6300	110 115 121	±2×2.5	36 37 38.5	YNyn0d11	0.53	HV~MV: 17.5~18.5 HV~LV: 10.5 MV~LV: 6.5	HV~MV: 10.5 HV~LV: 17.5~19 MV~LV: 6.5	4.9	40
8000					0.5			5.8	48
10000					0.47			6.9	56
12500					0.45			8.1	67
16000					0.42			9.8	81
20000					0.42			11.6	95
25000					0.38			13.5	113
31500					0.38			16.2	134
40000					0.35			19.1	161
50000					0.35			22.9	192
63000					0.32			27.1	230

Advantages

1. Integrated Multifunctional Design:

- Employs a three-winding (High Voltage, Medium Voltage, Tertiary Winding) structure, capable of simultaneously connecting to 110kV transmission grids, 35kV distribution networks, and user-side or compensation devices at 10kV or other voltage levels. This significantly reduces substation footprint and primary circuit complexity, lowering overall investment costs.

2. Unique Dual-Mode Impedance Configuration:

- Offers two standardized impedance configurations: Boost and Decompression. Users can flexibly select based on the transformer's actual operating mode within the system to optimize short-circuit current levels and power flow distribution between voltage levels:

- Boost Mode: Higher HV-MV impedance (17.5~18.5%), suitable for scenarios such as grid connection from the generation side or prioritizing medium-voltage side short-circuit current limitation.

- Decompression Mode: Higher HV-LV impedance (17.5~19%), suitable for scenarios such as step-down power supply on the load side or prioritizing low-voltage side short-circuit current limitation.

3. Flexible Voltage Adaptation Capability:

- The high-voltage side is compatible with three common system voltages: 110kV, 115kV, and 121kV, and is equipped with a ±2×2.5% off-circuit tap-changer.

- The low-voltage (tertiary) winding is standardly configured for 36kV, 37kV, and 38.5kV, allowing direct use for reactive power compensation, auxiliary power supply, or specific industrial voltage requirements.

4. Excellent Energy Efficiency and Economy:

- Capacity range covers 6.3 MVA to 63 MVA, suitable for small-to-medium regional hub substations, main step-down substations for industrial enterprises, and renewable energy collection stations.

- Utilizes the standard YNyn0d11 vector group, a mature and widely compatible technology that facilitates protection configuration.

- Across the entire series, no-load current is as low as 0.32% to 0.53%. Both no-load and load losses are optimized, ensuring good operational economy.

Applications

- 110kV/35kV/(10kV) regional substations or main step-down substations for industrial enterprises.

- Grid-connection transformers for step-up substations in wind and photovoltaic power plants.

- Substations requiring connection to compensation devices such as Static Var Generators (SVGs) or synchronous condensers.

- Multifunctional hub nodes in urban power grids responsible for voltage transformation and power distribution.

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