Oil-Immersed Three-Dimensional Wound Core Distribution Transformer

Yulan Oil-Immersed Three-Dimensional Wound Core Distribution Transformers adopt advanced three‑dimensional wound core construction. Covering rated capacities from 30 kVA up to 2500 kVA, the units support primary input voltages of 6 kV, 10 kV and 35 kV, paired with a 0.4 kV secondary output. Feel free to reach out for product enquiries, quotation comparisons and purchase orders.

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Product Description

In distribution transformers, the 3D wound core structure represents an improvement over the traditional planar stacked core design. Yulan Transformer manufactures this Oil-Immersed Three-Dimensional Wound Core Distribution Transformers with capacities ranging from 30 kVA to 2,500 kVA; primary voltage options include 6 kV, 10 kV, or 35 kV, with a secondary output of 0.4 kV. The products comply with relevant IEC, GB, ANSI/IEEE, and NEMA standards, and are manufactured and tested under conditions equivalent to those for 110 kV class transformers.

Structural and Loss Characteristics

The three-phase magnetic circuit is formed by winding continuous strips of silicon steel, resulting in a joint-free magnetic path. The direction of magnetic flux aligns closely with the orientation of the silicon steel, leading to significant reductions in no-load loss, no-load current, and noise levels. The three-phase magnetic paths are equal in length and highly symmetrical, resulting in lower phase-to-phase no-load current imbalance compared to traditional stacked core structures.

The core utilizes cold-rolled grain-oriented silicon steel, with winding and annealing processes carried out according to precise parameters. As there is no need for the overlapping joints found in traditional stacked cores, material utilization is improved; consequently, for a given capacity, the unit's volume and weight are generally lower than those of planar stacked core designs.

Oil-Immersed Three-Dimensional Wound Core Distribution Transformer

Key Technical Parameters

Item	Standards
Executive Standard	IEC, GB, ANSI/IEEE, NEMA
Rated Capacity	30 kVA to 2500 kVA
Primary Rated Voltage	6 kV, 10 kV, 35 kV (depending on specific model)
Secondary Rated Voltage	0.4 kV
Number of Taps	5 taps (off-circuit tap changing)
Rated Frequency	50 Hz / 60 Hz
Number of Phases	Three-phase
Vector Group	Dyn11, Yyn0, etc.
Short-circuit Impedance	4.0% / 4.5% / 6.0% / 6.5% (varies by capacity range)
Cooling Method	ONAN (Oil-immersed natural cooling)
Insulation Class	Class A (Oil-immersed type)
Voltage Regulation Method	Off-circuit tap changing

Energy Efficiency and Loss Data

The following data is based on cores made of electrical steel strip and batch test results, complying with the energy efficiency limit values specified in GB 20052-2020. Specific loss parameters can be obtained from the technical department based on the capacity range, or estimated by referencing the energy efficiency data for products of the same capacity using planar stacked cores; the no-load loss of the 3D wound core structure is typically 10% to 20% lower.

Rated capacity KVA	Level 1						Level2						Level3						Short-circuit impedance%
	Electrical steel strip			Amorphous alloy			Electrical steel strip			Amorphous alloy			Electrical steel strip			Amorphous alloy
	No-load loss W	Load loss W		No-load loss W	Load loss W		No-load loss W	Load loss W		No-load loss W	Load lossW		No-load loss W	Load loss W		No-load loss W	Load loss W
	No-load loss W	Dyn11/Yzn1	Yyn0	No-load loss W	Dyn11/Yzn1 Yyn0		No-load loss W	Dyn11/Yzn1 Yyn0		No-load loss W	yn11/Yzn11	Yyn0	No-load loss W	Dyn11/ 1 Yyn0		No-load loss W	Dyn11/Yzn1	Yyn0
30	65	455	430	25	510	480	70	505	480	33	535	510	80	630	600	33	630	600	4.0
50	80	655	625	35	735	700	90	730	695	43	780	745	100	910	870	43	910	8700
63	90	785	745	40	880	840	100	870	830	50	930	890	110	1090	1040	50	1090	1040
80	105	945	900	50	1060	1010	115	1050	1000	60	1120	1070	130	1310	1250	60	1310	1250
100	120	1140	1080	60	1270	1215	135	1265	1200	75	1350		150	1580	1500	75	1580	1500
125	135	1360	1295	70	1530	1450	150	1510	1440	85	1615	1540	170	1890	1800	85	1890	1800
160	160	1665	1585	80	1870	1780	180	185C	1760	100	1970	1880	200	2310	2200	100	2310	2200
200	190	1970	1870	95	2210	2100	215	2185	2080	120	2330	2225	240	2730	2600	120	2730	2600
250	230	2300	2195	110	2590	2470	260	2560	2440	140	2735	2640	290	3200	3050	140	3200	3050
345	270	2760	2630	135	310C	2950	305	3065	2920	170	3275	3120	340	3830	3650	170	3830	3650
400	330	3250	3095	160	3660	3480	370	3615	3440	200	3865	3675	410	4520	4300	200	4520	4300
500	385	3900	3710	190	4380	4170	430	4330	4120	240	4625	4400	480	5410	5150	240	5410	5150
630	460	4460		250	5020		510	4960		320	5300		570	6200		20	6200		4.5
800	560	5400		300	6075		630	6000		380	5415		700	7500		380	7500
1000	665	7415		360	8340		845	8240		450	8800		830	10300		450	10300
1250	780	8640		425	9720		870	9600		530	10260		970	12000		530	12000
1600	940	10440		500	11745		050	11600		630	12400		1170	14500		630	14500
2000	1085	13180		550	14000		1225	4640		710	14800		360	18300		720	18300		5.0
2500	1280	13360		670	15450		1440	14840		860	16300		1600	21200					5.0

Oil-Immersed Three-Dimensional Wound Core Distribution Transformer

Coils and Assembly

Low-voltage coils are wound using copper foil, while high-voltage coils are formed using adhesive-coated paper, followed by heat-curing under pressure. After assembly, the active part undergoes treatment in a kerosene vapor phase vacuum drying system to remove moisture and gases from the insulation materials. The tank and external structural components are treated via shot-blasting for rust removal and finished with electrostatic powder coating; the coating uniformity and adhesion meet the requirements for outdoor use.

Quality Assurance and Testing

Before leaving the factory, every Oil-Immersed Three-Dimensional Wound Core Distribution Transformer undergoes routine tests, including winding DC resistance, voltage ratio, insulation resistance, power-frequency withstand voltage, induced withstand voltage, no-load loss, load loss, and short-circuit impedance. The company holds ISO 9001:2015, ISO 14001, and ISO 45001 certifications.

FAQs on Model Selection

Q: How do I choose between 3D wound-core and stacked-core transformers?

If there are strict requirements regarding no-load loss, noise levels, or installation space, the 3D wound-core structure offers distinct advantages. While there is little difference in load loss between the two, the manufacturing process for 3D wound cores is more complex, which may result in slightly longer lead times for small-batch orders.

Q: Is the 3D wound-core structure suitable for on-load tap changing?

Yes, though it requires a redesign of the tap lead layout and the internal tank space. Standard products feature off-circuit tap changing; on-load tap changing capabilities must be confirmed at the time of ordering.

Q: What are the requirements for the silicon steel sheets used in this structure?

Grain-oriented silicon steel sheets suitable for winding processes are required, as the annealing process directly impacts the recovery of magnetic properties. Yulan Transformer utilizes material sources with consistent batch quality and controls the post-winding annealing process according to a fixed temperature curve.

Q: How low can the noise level be?

Compared to stacked-core products of the same capacity, noise levels are typically reduced by 3 to 5 dB. Specific values depend on capacity, cooling method, and installation environment; measurement methods can be specified in the contract.

Application Scenarios

These products are suitable for urban and rural grid upgrades, power distribution for industrial and mining enterprises, commercial buildings, and step-up or step-down applications in new energy generation. The low-noise characteristics of the 3D wound-core structure are particularly valuable for noise-sensitive locations, such as distribution substations in residential areas and indoor substations.

Please contact the Yulan Transformer sales or technical department for specific model dimensions, weights, or foundation installation drawings.

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Contact Info

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Address

No. 20, Bai'e Road, Hecun Town, Jiangshan City, Zhejiang Province,CHINA
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Tel

+86-570-4721985
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Email

jsdlbyq@163.com

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