CEEG 35kV Oil-Immersed Transformer for Energy Storage

PRODUCT OVERVIEWS

CEEG oil-immersed transformer for energy storage is specially designed for energy storage systems (ESS). It features strong short-circuit and harmonic resistance, efficient temperature control and cooling management, advanced insulation and material technology, and a compact modular structure. In addition, it offers excellent corrosion resistance and environmentally friendly characteristics. This product is widely applicable to renewable energy grid integration and battery storage system integration, ensuring reliable performance and strong adaptability.

Product Features

1. The transformer core cross-section adopts an oval-like structure, which is more compact and provides significantly improved resistance to sudden short circuits compared with the traditional long-oval design. It has successfully passed the sudden short-circuit withstand test conducted by Shenyang Transformer Research Institute.

2. The transformer core clamps are made of high-density electrical laminated wood, making the overall structure more compact while also helping to suppress stray losses caused by leakage flux.

3. By adjusting the internal body positioning and switch installation method, the high-voltage riser has been redesigned into a structure without hand holes, thereby reducing the risk of oil leakage.

Quality Control

The transformer is designed with full consideration of harmonic current losses, preventing the top oil temperature and winding temperature rise from exceeding specified limits. At the same time, the capacity increase demand caused by harmonic currents is also taken into account, ensuring the service life of the transformer.

For each batch of products of the same model, 10% of the total units (at least one unit) are randomly selected for lightning impulse and temperature rise tests, further ensuring the electrical and mechanical performance of the product.

According to national standard GB/T 1094.3, there is no requirement for partial discharge tests on 35 kV oil-immersed power transformers. However, from a product quality perspective, stricter measures are implemented. Following the test method of GB/T 7354, every new energy transformer undergoes a partial discharge test, ensuring that the partial discharge level is ≤ 50 pC at 1.2Ur and ≤ 100 pC at 1.4Ur (Ur being the rated voltage of the transformer).

Implementation Standards

GB/T 1094.1 Power Transformers - Part 1: General

GB/T 1094.3 Power Transformers - Part 3: Insulation Levels, Insulation Tests, and External Insulation Air Clearances

GB/T 1094.5 Power Transformers - Part 5: Short-Circuit Withstand Ability

GB/T 1094.16 Power Transformers - Part 16: Wind Power Transformers

GB/T 6451 Technical Parameters and Requirements for Oil-Immersed Power Transformers

GB20052 Energy Efficiency Limits and Energy Efficiency Grades for Power Transformers

IEC60076-20 Power transformers –Part 20: Energy efficiency

Oil-Immersed Transformer for Energy Storage-CEEG (2).jpg

PARAMETERS

Parameter Category	Parameter Name	Data/Content
Basic Information	Product Model	S13-M-2500/35
Basic Information	Type	Oil-immersed double-split transformer for energy storage
Rated Parameters	Number of Phases	Three-phase
	Frequency	50Hz
	Rated Capacity	2500 kVA
	High Voltage Rated Voltage	35 ± 2×2.5% or ± 5% kV
	Low Voltage Rated Voltage	0.8 kV or 2×0.8 kV (split type)
Performance Parameters	Vector Group	Dyn11
	Impedance Voltage	8% (or calculated according to the system)
	No-Load Loss (P₀)	≤ 2.5 kW
	Load Loss (Pₖ)	≤ 18 kW (@ 120°C)
Insulation Level	No-Load Current (I₀%)	≤ 0.5%
	Sound Level	≤ 55 dB (A)
	Temperature Rise Limit	Top oil temperature rise ≤ 55K, average winding temperature rise ≤ 65K
	High Voltage Lightning Impulse Withstand Voltage	170 kV (for 35kV rating)
	High-voltage short-time power-frequency withstand voltage	70 kV
	Low Voltage Lightning Impulse Withstand Voltage	5 kV
Structure and Materials	Winding Material	Oxygen-free copper foil/oxygen-free copper wire
	Core Material	High-quality, high-permeability cold-rolled silicon steel sheets with step-lap joints
	Oil Tank Structure	Fully sealed
	Insulating Oil	25# or 45# mineral insulating oil
Protection and Auxiliary	Protection Devices	Pressure relief valve, gas relay, oil level gauge, thermometer
	Outlet method	High voltage: Cable compartment or bushing
	Outlet method	Low voltage: Copper busbar
Special Requirements	Overload capacity	150% load capable for 2 hours
	Harmonic tolerance	Withstands load current with a THDi > 5%
	Protection level	IP55 or higher
	Environmental adaptability	-25°C ~ +45°C outdoor alternate location

CEEG 35kV Oil-Immersed Transformer for Energy Storage

2500kVA Oil-immersed double-split transformer for energy storage