66kV Oil-Immersed Three-Phase Two-Winding Power Transformer

Yulan Transformer (Jiangshan Yulan Transformer Co., Ltd.) supplies 66kV oil-immersed three-phase two-winding power transformers, 630–63,000 kVA, with off-circuit or on-load tap changers. Custom voltage, vector group and cooling options available. Request a quote or place an order.

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Product Description

Jiangshan Yulan Transformer Co., Ltd. has been manufacturing oil-immersed power transformers since 1999. The 66kv Oil-immersed three-phase two-winding power transformer is built for regional substations, utility distribution networks and industrial power systems where a single secondary voltage is required. The standard range covers rated capacities from 630 kVA to 63,000 kVA, with either off-circuit tap changing or on-load tap changing on the high-voltage side. Design, manufacture and routine testing follow IEC 60076 and GB 1094, and the factory holds ISO 9001:2015, ISO 14001 and ISO 45001:2018 certifications.

Design and Construction

The core uses cold-rolled grain-oriented silicon steel laminations with step-lap joints, which reduces no-load loss and magnetizing current compared with conventional butt-lap cores. Windings are made from copper conductor, with paper or enamel insulation selected according to voltage class and current rating. The high-voltage winding is placed outside the low-voltage winding to improve impedance control and short-circuit strength. Core and winding assemblies are clamped to withstand mechanical forces during external short circuits.

The tank is welded steel, designed for oil filling under vacuum and for transport lifting. Off-circuit tap changers are normally specified with ±5% or ±2×2.5% tapping range, while on-load tap changers typically use ±8×1.25% on the high-voltage winding. A conservator with silica gel breather, Buchholz relay, magnetic oil level gauge, winding temperature indicator and pressure relief device are provided as standard on this transformer class.

66kv Oil-Immersed Three-Phase Two-Winding Power Transformer

Technical Parameters

The values below are based on 11-type loss levels. The 10-type no-load loss values are also available and are shown alongside the 11-type values for reference. Load loss values are common to both loss levels. Final parameters are confirmed in the technical agreement.

Off-Circuit Tap Changer

Rated Capacity (kVA)	HV (kV)	LV (kV)	Vector Group	No-load Loss 10/11 (kW)	Load Loss (kW)	No-load Current (%)	Impedance (%)
630	63±5%, 66±5%, 69±5%	6.3 / 6.6 / 10.5 / 11	Yd11	1.5 / 1.3	7.1	1.40	8
800	63±5%, 66±5%, 69±5%	6.3 / 6.6 / 10.5 / 11	Yd11	1.7 / 1.6	8.6	1.35	8
1000	63±5%, 66±5%, 69±5%	6.3 / 6.6 / 10.5 / 11	Yd11	2.0 / 1.8	9.9	1.30	8
1250	63±5%, 66±5%, 69±5%	6.3 / 6.6 / 10.5 / 11	Yd11	2.4 / 2.2	12.0	1.30	8
1600	63±5%, 66±5%, 69±5%	6.3 / 6.6 / 10.5 / 11	Yd11	2.8 / 2.6	14.1	1.25	8
2000	63±5%, 66±5%, 69±5%	6.3 / 6.6 / 10.5 / 11	Yd11	3.3 / 3.0	16.7	1.20	8
2500	63±5%, 66±5%, 69±5%	6.3 / 6.6 / 10.5 / 11	Yd11	3.9 / 3.6	19.7	1.10	8
3150	63±2×2.5%, 66±2×2.5%, 69±2×2.5%	6.3 / 6.6 / 10.5 / 11	YNd11	4.6 / 4.3	23.1	1.05	9
4000	63±2×2.5%, 66±2×2.5%, 69±2×2.5%	6.3 / 6.6 / 10.5 / 11	YNd11	5.5 / 5.0	27.4	1.00	9
5000	63±2×2.5%, 66±2×2.5%, 69±2×2.5%	6.3 / 6.6 / 10.5 / 11	YNd11	6.5 / 6.0	30.9	0.85	9
6300	63±2×2.5%, 66±2×2.5%, 69±2×2.5%	6.3 / 6.6 / 10.5 / 11	YNd11	8.4 / 7.7	34.3	0.75	9
8000	63±2×2.5%, 66±2×2.5%, 69±2×2.5%	6.3 / 6.6 / 10.5 / 11	YNd11	10.2 / 9.3	40.7	0.75	9
10000	63±2×2.5%, 66±2×2.5%, 69±2×2.5%	6.3 / 6.6 / 10.5 / 11	YNd11	12.0 / 11.0	48.0	0.70	9
12500	63±2×2.5%, 66±2×2.5%, 69±2×2.5%	6.3 / 6.6 / 10.5 / 11	YNd11	14.2 / 13.0	57.0	0.70	9
16000	63±2×2.5%, 66±2×2.5%, 69±2×2.5%	6.3 / 6.6 / 10.5 / 11	YNd11	17.1 / 15.7	70.0	0.65	9
20000	63±2×2.5%, 66±2×2.5%, 69±2×2.5%	6.3 / 6.6 / 10.5 / 11	YNd11	20.0 / 18.3	84.9	0.65	9
25000	63±2×2.5%, 66±2×2.5%, 69±2×2.5%	6.3 / 6.6 / 10.5 / 11	YNd11	23.6 / 21.7	100.3	0.60	9
31500	63±2×2.5%, 66±2×2.5%, 69±2×2.5%	6.3 / 6.6 / 10.5 / 11	YNd11	28.0 / 25.7	120.9	0.53	9

On-Load Tap Changer

Rated Capacity (kVA)	HV (kV)	LV (kV)	Vector Group	No-load Loss 10/11 (kW)	Load Loss (kW)	No-load Current (%)	Impedance (%)
6300	63±8×1.25%, 66±8×1.25%, 69±8×1.25%	6.3 / 6.6 / 10.5 / 11	YNd11	9.1 / 8.3	34.3	0.75	9
8000	63±8×1.25%, 66±8×1.25%, 69±8×1.25%	6.3 / 6.6 / 10.5 / 11	YNd11	10.9 / 10.0	40.7	0.75	9
10000	63±8×1.25%, 66±8×1.25%, 69±8×1.25%	6.3 / 6.6 / 10.5 / 11	YNd11	12.9 / 11.8	48.0	0.70	9
12500	63±8×1.25%, 66±8×1.25%, 69±8×1.25%	6.3 / 6.6 / 10.5 / 11	YNd11	15.3 / 14.0	57.0	0.70	9
16000	63±8×1.25%, 66±8×1.25%, 69±8×1.25%	6.3 / 6.6 / 10.5 / 11	YNd11	18.4 / 16.8	70.0	0.65	9
20000	63±8×1.25%, 66±8×1.25%, 69±8×1.25%	6.3 / 6.6 / 10.5 / 11	YNd11	21.8 / 20.0	84.9	0.65	9
25000	63±8×1.25%, 66±8×1.25%, 69±8×1.25%	6.3 / 6.6 / 10.5 / 11	YNd11	25.8 / 23.7	100.3	0.60	9
31500	63±8×1.25%, 66±8×1.25%, 69±8×1.25%	6.3 / 6.6 / 10.5 / 11	YNd11	30.6 / 28.1	120.9	0.53	9
40000	63±8×1.25%, 66±8×1.25%, 69±8×1.25%	6.3 / 6.6 / 10.5 / 11	YNd11	36.6 / 33.6	141.8	0.53	9
50000	63±8×1.25%, 66±8×1.25%, 69±8×1.25%	6.3 / 6.6 / 10.5 / 11	YNd11	43.3 / 39.7	175.7	0.50	9
63000	63±8×1.25%, 66±8×1.25%, 69±8×1.25%	6.3 / 6.6 / 10.5 / 11	YNd11	51.1 / 46.8	211.7	0.45	9

Cooling method, tapping range, vector group and secondary voltage can be adjusted according to project requirements. Dimensions, weights and final loss values are confirmed in the factory documentation.

66kv Oil-Immersed Three-Phase Two-Winding Power Transformer

Quality Assurance and Testing

Each 66kv Oil-immersed three-phase two-winding power transformer is subjected to routine tests before dispatch: winding resistance, voltage ratio and vector group, insulation resistance, dielectric loss, separate-source voltage withstand, induced overvoltage, no-load loss and current, load loss, and short-circuit impedance. Type tests and special tests, including lightning impulse, temperature rise and noise measurement, can be arranged when specified.

Yulan Transformer maintains quality management certification to ISO 9001:2015, environmental management to ISO 14001, and occupational health and safety management to ISO 45001:2018. Material certificates, winding inspection records, core loss data, tank weld reports and final routine test results are retained in a traceable manufacturing file for each transformer.

66kv Oil-Immersed Three-Phase Two-Winding Power Transformer

Frequently Asked Questions

Can the low-voltage side be supplied at a voltage other than 6.3, 6.6, 10.5 or 11 kV?

Yes. The low-voltage winding can be designed for other standard or non-standard voltages within the insulation class of the transformer. The required secondary voltage should be stated during the specification stage.

What is the difference between off-circuit and on-load tap changing?

Off-circuit tap changing requires the transformer to be de-energized before the tap position is changed. On-load tap changing allows voltage adjustment while the transformer carries load, and is normally supplied with a motor drive and remote control interface for 66 kV applications.

Does the transformer need a conservator and silica gel breather?

For 66 kV power transformer ratings shown above, a conservator with silica gel breather is standard. The breather should be inspected periodically, and silica gel replacement depends on site humidity and operating conditions.

Can Yulan Transformer provide installation supervision?

Yes. Site supervision, oil processing guidance and commissioning support can be included in the supply contract or ordered as a separate service item.

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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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