Why Your Inquiry Isn’t Getting a Real Quote
“I need a transformer, please quote.”
This is the typical inquiry a transformer manufacturer receives every week. It looks like a simple sentence — but behind it is usually the start of a delayed quotation, an inflated “safe” price, or a supplier who quietly stops replying.
The reason is simple: a transformer isn’t a standardized, off-the-shelf product. It’s equipment “customized” around your grid conditions, load characteristics, and installation environment. Without the key parameters, a supplier has two options — quote the most conservative (and most expensive) configuration to cover every risk, or go back and forth over several rounds of clarifying emails. A solution that could have been finalized the same day the inquiry arrived instead takes two weeks to settle.
This guide lists exactly what our engineering team needs to prepare an accurate quotation, organized the same way we organize it internally — illustrated with nameplate data from three transformers we’ve actually built: a 250 kVA dry-type unit, a 5000 kVA oil-immersed unit, and an 8000 kVA OLTC oil-immersed unit.
1. Function & Type
Start with the basics:
- Step-up or step-down?
- Type: oil-immersed / dry-type (cast resin) / prefabricated substation
- Installation environment: indoor or outdoor
These three answers alone eliminate most of the wrong-product guesswork before any electrical parameter is even discussed.
2. Grid Voltage & Electrical Parameters
This is the core of any transformer specification:
- Primary (input) voltage — kV
- Secondary (output) voltage — V or kV
- Rated capacity — kVA
- Rated current — A
- Phases / frequency — 50 Hz or 60 Hz
- Impedance voltage — %
- Vector group (e.g. Dyn11, YNd11)
- Tap-changer type
- Tap range — %
- Winding material — copper or aluminium
A real example: our SCB14-250/10 cast resin dry-type transformer is rated 250 kVA, stepping 10 kV down to 400 V, Dyn11 vector group, with a 5-position off-circuit tap changer (10,500–9,500 V in 250 V steps). That single nameplate answers almost every question in this section — which is exactly the level of detail we need from you, in reverse, to quote your project.
Technical Specifications
| Parameter | Value |
|---|---|
| Model | SCB14-250/10 |
| Product Code | 1ZX.710.1512A |
| Rated Capacity | 250 kVA |
| Phases | 3-Phase |
| Rated Frequency | 50 Hz |
| High Voltage (5 Taps) | 10,500 / 10,250 / 10,000 / 9,750 / 9,500 V |
| Rated HV Current | 14.4 A |
| Low Voltage | 400 V |
| Rated LV Current | 360.8 A |
| Vector Group | Dyn11 |
| Insulation Level | LI75 AC35 / LI AC3 |
| Insulation Class | H (180 °C) |
| Permissible Temperature Rise | 125 K |
| Cooling Mode | AN / AF |
| Short-Circuit Impedance | 4.02% |
| Service Conditions | Indoor |
| Protection Level | IP00 |
| Total Weight | 1,170 kg |
| Standard Codes | GB1094.1, GB1094.2-2013 · GB20052-2024 · GB/T 10228-2023 · GB1094.3-2017 |
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 — 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.
3. Energy Efficiency & Loss Requirements
Efficiency standards vary by destination market and directly affect core material and winding cross-section:
- Efficiency standard (e.g. China GB 20052-2024, EU 548/2014 & 2019/1783, or another national standard)
- No-load loss limit — kW
- Load loss limit — kW
If you don’t know your local requirement, tell us the destination country — we can confirm the applicable grade.
4. Cooling & Insulation
- Cooling method — e.g. ONAN, ONAF (oil-immersed) or AN/AF (dry-type)
- Insulation class — e.g. Class H (180°C) for dry-type
- Permissible temperature rise — °C or K
Our S-5000/33GY oil-immersed transformer, for comparison, is rated 5000 kVA at 33kV/6.3kV, YNd11, ONAN-cooled, with 7.34% impedance — a spec sheet built for a hydropower step-up application, and one of the reasons cooling method and impedance can’t be left blank on an inquiry.
Technical Specifications
| Parameter | Value |
|---|---|
| Product Name | Power Transformer |
| Model | S-5000/33GY |
| Product Code | 1ZX.710.3306 |
| Rated Capacity | 5000 kVA |
| Frequency | 50 Hz |
| Impedance | 7.34% |
| No-load Loss | 3249 W |
| No-load Current | 0.23% |
| Load Loss | 29170 W |
| Insulation Level | HV terminal LI200 AC85 kV; LV terminal LI60 AC25 kV |
| Vector Group | YNd11 |
| Phases | 3-Phase |
| Service Conditions | Outdoor |
| Cooling Mode | ONAN |
| Oil Tank Vacuum Tolerance | 49 kPa |
| Weight of Oil | 2055 kg |
| Active Part Mass | 5575 kg |
| Gross Weight | 9870 kg |
| Standard Codes | GB1094.1, 2-2013; GB1094.3-2017; GB/T6451-2023; GB20052-2024 |
| Manufacturer | Sichuan Zhongxin General Electric Energy Co., Ltd. |
Tapping Step Table
| Step | HV (V) | HV (A) | LV (V) | LV (A) |
|---|---|---|---|---|
| 1 | 36300 | 79.5 | 6300 | 458.2 |
| 2 | 35475 | 81.4 | ||
| 3 | 34650 | 83.3 | ||
| 4 | 33825 | 85.3 | ||
| 5 | 33000 | 87.5 | ||
| 6 | 32175 | 89.7 | ||
| 7 | 31350 | 92.1 |
The nameplate parameters shown above are from the actual S-5000/33GY unit manufactured at Zhongxin General’s Sichuan facility. Every parameter is verified through routine factory acceptance testing before dispatch.
5. Voltage Regulation
- Off-circuit tap changer (OCTC) or on-load tap changer (OLTC)?
- Regulation range — %
OLTC adds cost and complexity but allows voltage adjustment without taking the transformer offline — essential for industrial loads that can’t tolerate interruption.
6. Environmental & Protection Requirements
- Ambient temperature range — °C to °C
- Altitude — m
- IP protection rating
- Noise limit (if applicable) — dB
At the higher end of the range, our SZ20-8000/120 — 8000 kVA, 120kV class, with a 17-position on-load tap changer — was built for outdoor service at standard altitude with oil-filled transport as default; a project at 3,000 m altitude or with a strict noise limit would need those parameters flagged before we finalize a design.
Technical Specifications
| Parameter | Value |
|---|---|
| Model | SZ20-8000/120 |
| Product Code | 1ZX.710.8802 |
| Rated Capacity | 8000/8000 kVA |
| Voltage Combination | 120±8×1.25%/10.5 kV (17-position OLTC) |
| Vector Group | YNd11 |
| Cooling Method | ONAN / 100% |
| Phases / Frequency | 3-Phase, 50 Hz |
| Service Condition | Outdoor |
| Impedance Voltage | 10% |
| Load Loss / No-Load Loss | 37.86 kW / 6.15 kW |
| No-Load Current | 0.51% |
| Insulation Level — HV | LI/AC 480/200 kV |
| Insulation Level — HV Neutral | LI/AC 325/140 kV |
| Insulation Level — LV | LI/AC 75/35 kV |
| Total Weight | 27.8 t (22.9 t oil-filled transport / 17.5 t N₂-filled transport) |
| Standard Codes | GB1094.1, 2-2013; GB1094.3-2017; GB/T6451-2023; GB20052-2024 |
This unit complies with GB20052-2024 as standard. Zhongxin General can also produce Grade 1 energy efficiency versions upon request, with technical standards equivalent to or higher than COMMISSION REGULATION (EU) No 548/2014 and Commission Regulation (EU) 2019/1783 of 1 October 2019. As a manufacturing factory.
Quick Reference Checklist
Copy this list into your next inquiry and fill in what applies:
| Category | Parameter |
|---|---|
| Function & Type | Step-up / step-down |
| Type: oil-immersed / dry-type / prefabricated | |
| Installation: indoor / outdoor | |
| Electrical | Primary voltage (kV) |
| Secondary voltage (V/kV) | |
| Rated capacity (kVA) | |
| Rated current (A) | |
| Phases / frequency | |
| Impedance voltage (%) | |
| Vector group | |
| Tap type & range (%) | |
| Winding material (Cu/Al) | |
| Efficiency | Efficiency standard |
| No-load loss limit (kW) | |
| Load loss limit (kW) | |
| Cooling & Insulation | Cooling method |
| Insulation class | |
| Temperature rise limit (°C) | |
| Voltage Regulation | OCTC or OLTC |
| Regulation range (%) | |
| Environment | Ambient temperature range (°C) |
| Altitude (m) | |
| IP protection rating | |
| Noise limit (dB) |
How Zhongxin General Uses These Parameters
Zhongxin General (Sichuan Zhongxin General Electric Energy Co., Ltd.) Our product range includes dry-type power transformers, from 30 kVA to 20 MVA with voltage ratings up to 35 kV, and oil-immersed power transformers, from 30 kVA to 100 MVA with voltage ratings up to 110 kV., alongside HV/MV/LV switchgear and prefabricated substations, at our own factory in Chengdu, Sichuan. Every parameter above maps directly to a design decision on our production floor — which is why a complete inquiry gets a faster, more accurate quotation than a one-line request.
You can see how these specifications translate into finished projects in our case studies and track ongoing production and shipments in our company news.
Ready to Get Your Transformer Quotation?
Fill in as many fields from the checklist above as you can — even a partial list gets you a faster, more accurate response than none at all. Missing a parameter? Tell us your application and destination country, and our engineers will help fill in the rest.
