35KV Oil-Immersed Power Transformers
Nov 11, 2025
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introduction of 35KV Oil-Immersed Power Transformers
35kV series transformers are with the following characteristics: low loss, low noise, protection against thunder and lightning, high short-circuit withstand capacity and beautiful appearance etc. It is made by advanced assembling lines and method, with qualified and refined accessories. it enjoys four remote functions: "remote communication remote test, remote adjustment and remote control". By remote control from a computer, the power station could be free from supervision in the office. 35kV series energy saving transformers have passed the identification Test by State Bureau of Machinery Industry, and State Power Corporation.
35kV series transformers are mainly used in urban and rural power grids and other industrial, mining enterprises, power transmission and distribution industry and also agriculture projects.
The core is processed by advanced vertical cut, horizontal cut, and stacking with stepped lap core and grade 3 seams. It disperses the air distribution, improves flux trend, thus, anddecreases the no-load loss, no-load current and noise.
The core uses particular adhesive for the plate, press ring, and silicon steel surface; and a range of overall structure and measures are used to increase the mechanical strength.
New structure of HV, LV windings and reasonable layout of oil duct and connecting area increases the capacity of mechanical strength and short-circuit withstand capacity.
The tank is bell type or core-lifting type, and the tank side is as corrugated form, with flowing lines, simplicity and beauty.
35KV Oil-Immersed Transformers Feature
Low Loss, Low Noise, Protection Against Thunder and Lightning, High Short-circuit Withstand Capacity and Beautiful Appearance etc.
Made by Advanced Assembling Lines and Method, with Qualified and Refined Accessories
Enjoys Four Remote Functions:Remote Communication Remote Test, Remote Adjustment and Remote Control,Remote Control From a Computer, the Power Station Could be Free from Supervision in the Office
Passed the Identification Test by State Bureau of Machinery Industry, and State Power Corporation.
The Core is Processed by Advanced Vertical Cut, Horizontal Cut, and Stacking with Stepped Lap Core and Grade 3 Seams
The Tank is Bell Type or Core-lifting Type, and the Tank Side is as Corrugated Form, with Flowing Lines, Simplicity and Beauty
Oil Transformer Technical Parameters
50-1600/35 Series Three-phase Double-winding Distribution Transformers with Off-circuit Tap Changer
| Rated Capacity | Voltage Raito (kv) | Vector Group | Loss values for S9 serial transformer |
Loss values for S10 serial transformer |
Loss values for S11 serial transformer |
No-load current | Impedance | Weight | Outline Dimension | Gauge | |||||||
| (kVA) | HV | LV | No- load Loss |
Full- load Loss |
No- load Loss |
Full- load Loss |
No- load Loss |
Full- load Loss |
(%) | (%) | Oil weight | Total weight | L | W | H | (mm) | |
| 50 | 35 38.5±5% or ±2x2.5% |
0.4 | Ydn0 Dyn11 |
0.21 | 1.21 | 0.19 | 1.15 | 0.17 | 1.15 | 2 | 6.5 | 275 | 740 | 1100 | 1000 | 1700 | 660 |
| 100 | 0.29 | 2.02 | 0.26 | 1.92 | 0.23 | 1.92 | 1.8 | 350 | 995 | 1100 | 1150 | 1750 | 660 | ||||
| 125 | 0.34 | 2.03 | 0.31 | 2.26 | 0.27 | 2.26 | 1.7 | 430 | 1250 | 1100 | 1150 | 1800 | 660 | ||||
| 160 | 0.36 | 2.83 | 0.32 | 2.69 | 0.29 | 2.69 | 1.6 | 450 | 1405 | 1160 | 1150 | 1860 | 660 | ||||
| 200 | 0.43 | 3.33 | 0.39 | 3.16 | 0.34 | 3.16 | 1.5 | 495 | 1460 | 1230 | 1300 | 1950 | 660 | ||||
| 250 | 0.51 | 3.96 | 0.46 | 3.76 | 0.41 | 3.76 | 1.4 | 520 | 1625 | 1250 | 1300 | 2000 | 660 | ||||
| 315 | 0.61 | 4.77 | 0.55 | 4.53 | 0.49 | 4.53 | 1.4 | 590 | 1915 | 1400 | 1320 | 2070 | 820 | ||||
| 400 | 0.73 | 5.76 | 0.66 | 5.47 | 0.58 | 5.47 | 1.3 | 680 | 2175 | 1510 | 1350 | 2150 | 820 | ||||
| 500 | 0.86 | 6.93 | 0.77 | 6.58 | 0.69 | 6.58 | 1.2 | 760 | 2485 | 1620 | 1370 | 2240 | 820 | ||||
| 630 | 1.04 | 8.28 | 0.94 | 7.87 | 0.83 | 7.78 | 1.1 | 830 | 2950 | 1750 | 1390 | 2330 | 820 | ||||
| 800 | 1.23 | 9.9 | 1.11 | 9.41 | 0.94 | 9.41 | 1 | 880 | 3370 | 1900 | 1420 | 2400 | 820 | ||||
| 1000 | 1.44 | 12.15 | 1.3 | 11.54 | 1.15 | 11.54 | 1 | 1005 | 4140 | 2165 | 1450 | 2485 | 820 | ||||
| 1250 | 1.76 | 14.67 | 1.58 | 13.94 | 1.41 | 13.94 | 0.9 | 1160 | 4700 | 2230 | 1500 | 2600 | 1070 | ||||
| 1600 | 2.21 | 17.55 | 1.91 | 16.67 | 1.7 | 16.67 | 0.8 | 1250 | 5570 | 2250 | 1650 | 2650 | 1070 | ||||
630-2500/35 Series Three-phase Double-winding Distribution Transformers with Off-circuit Tap Changer
| Rated Capacity | Voltage Raito (kv) | Vector Group | Loss values for S9 serial transformer |
Loss values for S10 serial transformer |
Loss values for S11 serial transformer |
No-load current | Impedance | Weight | Outline Dimension | Gauge | |||||||
| (kVA) | HV | LV | No- load Loss |
Full- load Loss |
No- load Loss |
Full- load Loss |
No- load Loss |
Full- load Loss |
(%) | (%) | Oil weight | Total weight | L | W | H | (mm) | |
| 630 | 35 38.5±5% or ±2x2.5% |
6.3 6.6 10 10.5 11 |
Yd11 | 1.04 | 8.28 | 0.94 | 7.87 | 0.83 | 7.78 | 1.1 | 6.5 | 0.65 | 2.9 | 2100 | 1300 | 2300 | 820 |
| 800 | 1.23 | 9.9 | 1.11 | 9.4 | 0.98 | 9.4 | 1 | 0.7 | 3.2 | 2200 | 1350 | 2350 | 820 | ||||
| 1000 | 1.44 | 12.15 | 1.3 | 11.54 | 1.15 | 11.54 | 1 | 0.85 | 3.5 | 2350 | 1450 | 2400 | 820 | ||||
| 1250 | 1.76 | 14.67 | 1.58 | 13.94 | 1.41 | 13.94 | 0.9 | 1.01 | 3.84 | 2500 | 1600 | 2450 | 1070 | ||||
| 1600 | 2.12 | 17.55 | 1.91 | 16.67 | 1.7 | 16.67 | 0.8 | 1.2 | 5 | 2600 | 1700 | 2500 | 1070 | ||||
| 2000 | 2.72 | 19.35 | 2.45 | 18.38 | 2.18 | 18.38 | 0.7 | 1.28 | 6 | 2730 | 1800 | 2600 | 1070 | ||||
| 2500 | 3.2 | 20.7 | 2.88 | 19.67 | 2.56 | 19.67 | 0.6 | 1.4 | 7 | 2870 | 1900 | 2700 | 1070 | ||||
Type of oil filled Transformers
Oil-immersed transformers are categorized based on function, design, and cooling method:
a. Power Transformers
Typically rated above 1 MVA.
Used in transmission networks for stepping voltage up or down over long distances.
b. Distribution Transformers
Typically rated below 1 MVA.
Installed near end-users to lower voltages for household or light industrial use.
c. Hermetically Sealed vs Conservator-Type
Sealed Type: The oil tank is fully enclosed; ideal for small-to-medium units in harsh environments.
Conservator Type: Features an external oil reservoir to accommodate oil expansion and contraction.
d. ONAN, ONAF, OFAF Cooling Types
ONAN: Oil Natural Air Natural – uses natural convection.
ONAF: Oil Natural Air Forced – adds fans to enhance air cooling.
OFAF: Oil Forced Air Forced – pumps and fans both used for intensive cooling in large units.
Maintenance and Safety Considerations
- Despite their durability, oil-immersed transformers require:
- Routine oil testing (dielectric strength, water content, acidity)
- Thermal imaging to detect hot spots
- Sealing checks to prevent moisture ingress
- Buchholz relay monitoring for gas build-up in conservator-type units
- With proactive maintenance, potential faults can be identified early, preventing failures and costly downtimes.
company profile
GNEE TRANSFORMER has strong production capacity and an efficient marketing team.
Our transformer products include 500kV, 400kV, 330kV, 220kV, and 110kV ultra-high voltage transformers, various dry-type transformers/oil immersed transformers/amorphous alloy transformers of 35kV and below, new energy transformers, and prefabricated substations,
Export series: single-phase transformer, three-phase transformer, cylindrical transformer, isolation transformer, control transformer, voltage regulator and other products, And various specifications of special transformers such as grounding transformers, arc suppression coils, Bitcoin transformers, prefabricated cabins, reactors, electric furnace transformers, rectifier transformers, mining transformers, marine transformers, etc.
GNEE TRANSFORMER has successively passed ISO9001, ISO14001, ISO45001, SA8000 system certification. At the same time, 10kV and 35KV level distribution transformers and box type substations have obtained interna- tional Electrotechnical Commission IEC certification, US UL certification, German TUV certification, EU CE certification, Dutch KEMA certification, and GOST certification. Our product sales cover the global market, including 72 countries and regions such as the United States, Europe, Canada, Mexico, etc.
transformer Workshop equipment display
types of transformer from GNEE
Get Transformer Order specification
GNEE Transformer Order specification
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When choosing our company's products, please provide the following data to better serve you. |
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Demander |
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Demander: |
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Fax: |
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Project technical leader: |
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Mailbox: |
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Transformer type selection |
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□Dry transformer {□SC(B) Epoxy resin □SC(B) Non-encapsulated} □American Box(ZGS) {□Terminal type(-Z-) □Ring network type(-H-)} □European Box change(YBM){□ Dry change □Oil change} |
□ Oil-immersed transformer{□ Fully sealed(-M-) □Oil-bearing pillow} □Amorphous alloy transformer{□Dry amorphous □ Oil amorphous} □ Special transformer{Rectifier, Furnace, Mine, Etc} |
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Transformer basic data selection
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Country of use: |
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Phase number: |
□Three-phase(S conventional) □ Monophase □Other( ) |
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Frequency: |
□50Hz(conventional) □60Hz □ Other( ) |
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Transformer oil: |
□#25(conventional) □#45(minimum temperature below-25℃) |
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Rated capacity: |
□( )kVA Conditions of use □Outdoor type □Indoor type |
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Altitude: |
□Less than 1000m(conventional) □1000-2000m □3000m以上 over |
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Rated voltage(High voltage) |
□6kV □10kV □20kV □35kV □66kV □110kV □220kV □Other( ) |
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Rated voltage(Low pressure) |
□0.4kV □0.66kV □10kV □10.5kV □35kV □其他 Other( ) |
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Connected group |
□Dyn11(conventional) □Yyn0 □YNd11 □li0(Single-phase) □Other( ) |
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Impedance(%): |
□4% □4.5% □5.5% □6% □6.5% □7.5% □8% □Other( ) |
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Voltage regulation mode |
□Voltage regulation without excitation(conventional) □On-load voltage regulation(Z) |
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Voltage regulation range |
□±2*2.5% □±5% □±3*2.5% □Other( ) |
Transformer accessory selection
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□Fan □Temperature control{□ Common □With 485 computer interface} □Dry case{□ Ordinary steel sheet □Aluminum alloy » Stainless steel} □Protection level of dry case(□IP20(Conventional) □IP( )} □Dry case height requirements{□None □Requirements[ ]} □ Cable out mode of the dry variable shell {□ Up-and-out □ Up-and-down □Down-in/DOWN-out □Down-in/UP-out □Down-in/DOWN-out □Down-in/ side-out [□Left □ Right-out]} |
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Note: 1. (Dry change requirements s 100kVA transformer does not include fans, such as fans, need to be charged 2. (Oil changes <630kVA transformer does not include temperature control, gas relay, if necessary, need to increase the fee) |
Other special requirements(additional charges apply below)
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Dry transformer |
□Shell and bottom plate{□Ordinary □Fully sealed} □Travel switch □Magnetic lo □Zero sequence transformer □Copper bar to the low voltage cabinet □Protective mesh □Lighting □100kVA or less Fan □Shock absorber |
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Oil-immersed transformer |
□No.45 oil for non-low temperature areas □Designated brand on-load voltage regulator □400kVA and below low voltage outlet OABC phase with wiring terminals □630kVA or below requires temperature control □800kVA or below Low voltage outlet phase 0 requires wiring terminals □630kVA and below must be equipped with gas relay |
GNEE TRANSFORMER Industrial Layout
Asia:China, Philippines, Cambodia, Malaysia, Pakistan, Indonesia, Vietnam, Mongolia, Japan, Taiwan Province, Bangladesh, Sri Lanka, Lebanon, Saudi Arabia, Turkey, Armenia, Saudi Arabia, Saudi Arabia, Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan
Africa:Egypt, Ethiopia, Angola, Botswana, Burundi, Cape Verde, Congo, Guinea, Ghana, Gabon, Zimbabwe, Cameroon, Kenya, Rwanda, Malawi, Mauritius, Mauritania, Mozambique, South Africa, Nigeria, Somalia, Chad, Central Africa
North America: Aruba, Panama, Dominican Republic, Costa Rica, Honduras, Caribbean region,Canada, United States, Mexico, El Salvador, Guatemala, Jamaica
Europe: Bulgaria, North Macedonia, Finland, Norway, Ukraine, Greece, Hungary, Italy, United Kingdom
South America: Argentina, Paraguay, Ecuador, Colombia, Guyana, Mexico, Uruguay, Chile
Middle East: The Middle East region
Oceania: Australia, Papua New Guinea. Fiji