CHINT Electric completes testing of 1000kV UHV transformer

China’s expansion of long-distance power transmission is increasing the importance of Ultra-High Voltage AC infrastructure for transferring electricity between regions. These networks require transformers capable of handling very high voltage levels and large power ratings while controlling insulation stress, losses, temperature rise, mechanical forces and acoustic emissions.

CHINT Electric’s 1000kV/1000MVA transformer is intended for UHV transmission applications where large quantities of electricity must be transferred through high-voltage networks. The company completed the full routine and type test program with experts from the State Grid Electric Power Research Institute (SGRI) Wuhan NARI and Shenyang Transformer Research Institute witnessing the testing.

The transformer passed the reported test program on its first attempt.

Insulation performance at 1000kV voltage levels
At the 1000kV class, transformer insulation is exposed to high electrical stresses during normal operation and transient conditions. The design therefore has to address both main insulation between windings and ground and longitudinal insulation within the winding structure.

CHINT Electric said it optimized the winding structure to improve these insulation characteristics while reducing manufacturing complexity and associated quality risks. Electromagnetic and structural simulation was used during development, followed by impulse, induced-voltage and partial-discharge testing.

The reported partial-discharge levels were below 10 pC for the high-voltage side and below 15 pC for the medium-voltage side. Partial discharge is an important diagnostic parameter because localized electrical discharges can indicate weaknesses in insulation systems.

IEC 60076-3 specifies insulation requirements and dielectric tests for power transformers and includes requirements applicable to equipment with maximum system voltages above 800kV. The standard also specifies procedures for induced-voltage testing with partial-discharge measurement.

Mechanical design and fault withstand
The transformer incorporates an upgraded tank structure and reinforced support for the high-voltage bushing. These changes are intended to improve mechanical strength and pressure resistance under operating and fault conditions.

The lead arrangement was also optimized to increase insulation margins and reduce the possibility of internal insulation faults. Large-capacity pressure-relief devices provide an additional protection mechanism if abnormal internal pressure develops.

For a transformer at this voltage and power rating, mechanical design is closely linked to electrical performance. Short-circuit forces can impose substantial mechanical stresses on windings and supporting structures, making structural integrity an important part of transformer qualification.

Loss reduction and thermal management
The 1000MVA rating corresponds to a substantial power-transfer capability, making losses and thermal performance important design parameters for continuous grid operation.

CHINT Electric said the transformer uses optimized conductor selection, magnetic shielding, refined core manufacturing and an upgraded cooling system to reduce no-load and load losses. The design also targets a lower temperature rise and reduced operating noise.

The reported noise level is below 63.7 dB(A). Noise performance is relevant for large transformers because cooling equipment, magnetostriction and electromagnetic forces can contribute to acoustic emissions around substations.

The company has not disclosed the transformer’s absolute no-load loss, load loss, impedance, temperature-rise limit or cooling-system rating in the announcement, so the overall efficiency improvement cannot be independently quantified from the available product information.

UHV transformer manufacturing capability
CHINT Electric said its power-equipment portfolio covers voltage levels from 10kV to 1000kV. Its Shanghai Transmission & Distribution Industrial Base and Wuhan manufacturing facility support different parts of its high-voltage equipment activities, with Wuhan specializing in the research, development and production of 1000kV “Double Million” UHV transformers.

The company’s published product information also identifies power transformers with ratings up to 1000kV and 1000MVA and states that its transformers are supplied for power generation, transmission and distribution applications.

The development is relevant to transmission systems integrating large-scale generation resources over long distances. Higher-voltage transmission can move large amounts of electrical power while reducing current for a given transmitted power level, which helps limit resistive losses in transmission conductors.

Testing and qualification of 1000kV equipment
Routine and type testing provide different forms of design and manufacturing validation. For high-voltage transformers, dielectric tests are particularly important because insulation failure can result in severe equipment damage and service interruption.

IEC 60076-3 defines applicable dielectric tests and minimum test levels and introduced additional test levels for equipment with maximum system voltages above 800kV.

China also has dedicated technical requirements for 1000kV transformer equipment. GB/T 6451-2023 includes specifications for 1000kV single-phase transformers and lists 1000kV, 1000MVA to 1500MVA configurations among its transformer categories.

Additional Context:
This section details technical specifications and competitive benchmarking not included in the original product announcement

The 1000kV/1000MVA rating is not unique to a single manufacturer or a new industry benchmark. China’s UHV AC transformer standards already cover 1000kV equipment, including single-phase three-winding autotransformers in the 1000MVA to 1500MVA range.

CHINT Electric’s stated 1000kV/1000MVA capability therefore places the transformer within an established UHV AC equipment class rather than establishing a new voltage or capacity category. The technical significance of the announcement is the completion of testing for CHINT Electric’s first self-developed transformer in this class.

The reported partial-discharge results of below 10pC on the high-voltage side and below 15pC on the medium-voltage side provide measurable insulation-performance data, although direct comparison with competing transformers requires equivalent test conditions, measurement methods, rated configurations and acceptance criteria.

IEC 60076-3 specifies that partial discharge measurements are expressed in apparent charge and references IEC 60270 for the measurement method. It also provides specific dielectric-test requirements for transformers at very high voltage levels.

CHINT Electric’s published specifications indicate power-transformer capability up to 1000kV and 1000MVA, with applications in power generation, transmission and distribution.

Edited by Sucithra Mani, Induportals editor – adapted by AI.

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