Technical Specifications
| Parameter | Value |
|---|---|
| Product Name | Power Transformer |
| Model | SZ20-16000/35 |
| Product Code | 1ZX.710.9030 |
| Standard Codes | GB1094.1, 2-2013; GB1094.3-2017; GB/T6451-2023; GB20052-2024 |
| Rated Capacity | 16000 kVA |
| Phases | 3-Phase |
| Rated Frequency | 50 Hz |
| Vector Group | YNd11 |
| Short-Circuit Impedance | 8.0% |
| Service Condition | Outdoor |
| No-Load Loss | 8420 W |
| No-Load Current | 0.28% |
| Load Loss | 62800 W |
| Cooling Method | ONAN |
| Insulation Level — HV Terminal | LI 200 / AC 85 kV |
| Insulation Level — LV Terminal | LI 75 / AC 35 kV |
| Weight of Oil | 5720 kg |
| Weight of Active Part | 16900 kg |
| Total Weight | 27500 kg |
| Vacuum Tolerance of Tank | 49 kPa |
| Manufacturer | Sichuan Zhongxin General Electric Co., Ltd. |
On-Load Tap Changer (OLTC) — 9 Tap Positions
| Tap Position | HV Voltage (V) | HV Current (A) | LV Voltage (V) | LV Current (A) |
|---|---|---|---|---|
| 1 | 37625 | — | 10500 (rated) | 879.8 |
| 2 | 36750 | — | ||
| 3 | 35875 | — | ||
| 4 (Rated) | 35000 | 264 | ||
| 5 | 34125 | — | ||
| 6 | 33250 | — | ||
| 7 | 32375 | — | ||
| 8 | — | — | ||
| 9 | — | — |
The LV winding stays fixed at its rated 10,500 V regardless of tap position — voltage regulation happens entirely on the HV side. Across the tested tap range shown above, the HV voltage moves in 875 V (2.5%) steps around the rated 35,000 V tap (position 4), giving the on-load tap changer the ability to correct HV grid voltage variation without interrupting supply — the defining advantage of an on-load design over an off-circuit tap changer at this capacity.
This unit complies with China GB 20052-2024 at the Grade 3 energy efficiency level as standard. Zhongxin General can also produce Grade 1 and Grade 2 versions on request — the technical standards for Grade 1 products meet and exceed the requirements of COMMISSION REGULATION (EU) No 548/2014 and Commission Regulation (EU) 2019/1783 of 1 October 2019.
16000 kVA — Where On-Load Tap Changing Becomes Necessary
At 16,000 kVA, the rated HV current at the 35,000 V tap reaches 264 A and the active part alone weighs 16.9 tonnes — figures that put this capacity firmly in the large industrial and dedicated-substation category, well beyond what an off-circuit tap changer can practically serve. Loads at this scale typically cannot tolerate a supply interruption every time grid voltage drifts, which is exactly the problem the SZ20-16000/35’s on-load tap changer solves: voltage ratio can be adjusted while the transformer stays energised and connected.
Every image on this page documents the actual 16,000 kVA SZ20-16000/35 unit — this specific capacity, at the tank, insulator, cooling cabinet, and OLTC mechanism level. Zhongxin General holds dedicated production tooling across the full oil-immersed transformer range, so what is shown here is what ships.
Tank Assembly & Installation
At 16,000 kVA the tank and active part are handled by overhead crane throughout assembly — the completed active part alone weighs 16,900 kg, and the tank has to hold that mass plus 5,720 kg of insulating oil under a 49 kPa vacuum tolerance. A technician inspects the top of the tank during each lift, checking weld seams, flange alignment and lifting-lug condition before the unit proceeds to the next assembly stage.
The oil conservator top cover — the component that will later cap the cylindrical oil-storage pillow tank — is fitted and inspected separately before being mounted onto the transformer body. Building and checking this sub-assembly independently, rather than only at final assembly, is standard practice for catching fit and seal issues early on a unit this size.
Final assembly and fitting on a 16,000 kVA unit is a two-person job at minimum — coordinating lifting, alignment, and torque on fasteners across a tank and active part of this mass requires more than one set of hands working in sync.
Insulation & Bushings
The top-mounted insulator bushings on the SZ20-16000/35 are rated to the LI 200 / AC 85 kV insulation level on the HV terminal — the lightning impulse and power-frequency withstand values that determine how the transformer handles switching surges and lightning-induced overvoltage on a 35 kV system. The LV terminal carries a separate LI 75 / AC 35 kV rating, matched to the 10.5 kV secondary.
Oil Conservator & Level Monitoring
The conservator tank’s side-mounted oil level gauge gives a direct visual read of insulating oil volume as it expands and contracts with load and ambient temperature — a simple but essential check point during routine inspection of a unit holding 5,720 kg of oil.
Cooling System — ONAN with Fan-Assisted Control
Cooling on the SZ20-16000/35 is ONAN (Oil Natural Air Natural), with a stainless steel control cabinet housing the switching and monitoring electronics for the cooling system. Inside the cabinet, operators find start/stop buttons, running-status indicator lights, and a manual/automatic mode selector — giving the option of automatic cooling response to load and temperature, or manual override during maintenance or testing. The stainless steel enclosure is specified for corrosion resistance in outdoor substation environments over the transformer’s service life.
On-Load Tap Changer — Motor Drive Mechanism
Inside the OLTC motor drive mechanism box: a tap-position indicator dial that shows which of the 9 tap positions is currently in circuit, a manual operating handle for hand-cranking the tap changer during commissioning or in the event of a motor fault, local control switches, and a wiring terminal block connecting the mechanism to the substation’s control and protection system. This mechanism is what allows the SZ20-16000/35 to shift HV taps under load without interrupting the connected supply — the core functional difference between this unit and a fixed-tap or off-circuit-tap transformer.
Completed Unit — HV Side
The completed SZ20-16000/35 carries an oil conservator to manage oil volume expansion across its full operating range, top-mounted HV insulators rated for 35 kV class service, and the full cooling and tap-changer control infrastructure described above. Every unit passes the full routine test programme — winding resistance, ratio and vector group, no-load and load loss, impedance, and dielectric withstand — before being approved for dispatch, and no unit leaves the factory without a complete test report.
Key Features — 16000 kVA Oil-Immersed OLTC Transformer
On-load tap changer, 9 positions. Voltage can be adjusted under load, in 2.5% steps around the rated 35,000 V tap, without interrupting the connected supply — the practical requirement for large industrial and substation loads that cannot tolerate switching interruptions.
8.0% short-circuit impedance. Verified by routine test on every unit, giving system designers a confirmed value for fault-current and voltage-drop calculations rather than a nominal estimate.
LI 200 / AC 85 kV HV insulation level. Engineered for reliable operation on 35 kV systems exposed to lightning-induced overvoltage and switching surges.
ONAN cooling with monitored control cabinet. Natural oil and air cooling backed by a stainless steel control cabinet with manual and automatic operating modes.
Copper winding standard, aluminium available. As a manufacturing factory rather than a trading company, Zhongxin General produces both copper and aluminium winding configurations, letting customers balance upfront cost against long-term losses according to project budget.
GB 20052-2024 efficiency grades on request. The standard unit ships at Grade 3; Grade 1 and Grade 2 versions are available, with Grade 1 meeting and exceeding EU Commission Regulation No. 548/2014 and 2019/1783 requirements for projects bound for European or EU-aligned markets.
Why Zhongxin General — Our Advantages Over Other Suppliers
Real production photographs of the actual 16000 kVA unit. Every image on this page documents this specific capacity — tank handling, conservator components, insulators, cooling control, and the OLTC mechanism itself. It is common in this industry for suppliers to illustrate a large-capacity product page using photographs of a different unit, or generic stock images, because they lack real production evidence at that specific capacity. What we show here is what we ship.
Complete capacity-range production tooling. Zhongxin General holds dedicated molds, winding fixtures, and tank tooling spanning the full oil-immersed capacity range — from small distribution units through large OLTC transformers like this 16,000 kVA unit — and the complete 30 kVA to 8,000 kVA dry-type range. This breadth of in-house tooling is something smaller workshops and trading companies typically cannot match, and it means purpose-built fixtures rather than adapted tooling from an adjacent capacity.
Factory, not trading company. Sichuan Zhongxin General Electric Energy Co., Ltd. is a National “Little Giant” Enterprise and National High-Tech Enterprise, manufacturing at our own facility in Xinjin District, Chengdu. Winding, tank fabrication, assembly, oil treatment, and testing all happen on one site — there is no intermediary between you and the production line.
Both copper and aluminium winding options. Many suppliers offer one or the other; as a manufacturer running both production lines, we offer genuine choice based on project economics rather than whatever happens to be in stock.
Full routine testing on every unit, as standard documentation. Test reports are issued with every order by default, not provided only when specifically requested — winding resistance, ratio verification, no-load and load loss, impedance, and dielectric withstand testing are run on every 16,000 kVA unit before it leaves the factory.
EU-compliant efficiency grades available on request. Our Grade 1 efficiency products meet and exceed EU Commission Regulation No. 548/2014 and 2019/1783 requirements, making them directly usable for European, Middle Eastern, and other international projects without separate compliance engineering.
Documented international project experience. Export documentation, IEC-aligned testing, FAT witness arrangements, and shipping logistics to difficult destinations are all handled in-house, backed by real, published project case studies — including our 16,730 kVA intelligent power system for Xinjin District People’s Hospital and a 63 MVA / 110 kV OLTC transformer delivered to a Ningxia LNG and helium production facility — rather than generic claims.
Applicable Standards & Testing
Every 16000 kVA on-load tap-changing oil-immersed transformer manufactured by Zhongxin General undergoes a complete routine test programme before dispatch.
Routine tests (every unit): winding resistance measurement; voltage ratio and vector group verification; no-load loss and no-load current; load loss and short-circuit impedance; induced overvoltage withstand test; separate-source AC withstand test; on-load tap changer operation test.
Type tests (reports available on request): temperature rise test; lightning impulse test.
Special tests (available on request): partial discharge measurement; sound level (noise) measurement; short-circuit withstand test.
All tests are conducted to IEC 60076 and GB 1094 / GB/T 6451. Factory Acceptance Test (FAT) with client witness is supported, and test reports are provided as standard documentation with every order.
Available Options & Configurations
Winding material: copper (standard) or aluminium. Voltage class: 35 kV; HV customizable to match local grid standards. Low voltage: 10.5 kV or other values on request. Frequency: 50 Hz (standard) or 60 Hz. Energy efficiency grade: GB 20052-2024 Grade 1, Grade 2, or Grade 3. Tap changer: on-load tap changer (OLTC) as standard at this capacity. Oil type: mineral oil (standard); silicone oil available for high-fire-safety environments. Nitrogen-sealed tank for long-distance sea freight. Export wooden crating with full documentation package.
Typical Applications
The 16000 kVA on-load tap-changing oil-immersed transformer is specified for large industrial facilities, dedicated 35 kV substations serving major single loads, industrial park power supply, and as a main step-down transformer within larger multi-transformer substation projects. At 35 kV / 10.5 kV with YNd11 vector group and ONAN cooling, it delivers stable voltage regulation under load for demanding, capacity-critical installations.
Inquire About 16000 kVA Oil-Immersed OLTC Transformer
Need a quotation, technical datasheet, or Factory Acceptance Test arrangement for the 16000 kVA on-load tap-changing oil-immersed transformer? Tell us your grid voltage, required LV output, frequency, efficiency grade, winding material, and any special installation conditions — and we will configure the right unit for your project.
Contact Us for Price & Datasheet
About Zhongxin General — Oil-Immersed Transformer Manufacturer & Factory
Zhongxin General (Sichuan Zhongxin General Electric Energy Co., Ltd.) is a China-based manufacturer and factory specialising in oil-immersed power transformers and dry-type power transformers, HV/MV/LV switchgear, prefabricated substations, and energy storage systems. Headquartered in Xinjin District, Chengdu, Sichuan Province, the company holds National “Little Giant” Enterprise status alongside National High-Tech Enterprise certification.
Our oil-immersed transformer portfolio covers 30 kVA to 100 MVA, configurable to 6 kV, 10 kV, 35 kV, 66 kV, 110 kV, and higher voltage classes, in both GB and IEC standard configurations. Every unit undergoes full routine testing before dispatch; test reports are issued as standard documentation with every order.
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