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How to check a transformer before buying: instructions for engineers and purchasers

Checking a power transformer before purchase: data sheet, labeling, testing and packaging

The purchase of a power transformer is not just a transaction, but a strategic decision that affects the reliability, safety and efficiency of the entire power system. A mistake at the selection stage can lead to overheating, power outages, additional costs and even emergencies.

In this article, we take a detailed look at how to properly inspect a transformer before you buy it: from certification and technical parameters to factory testing and packaging.

1. Verification of documentation and certification

The first place to start is to make sure you have all the necessary documents:

  • Product data sheet with serial number, wiring diagram and main characteristics

  • Certificates of Conformity: GOST, EAC (EAEC), CE (for international projects), ISO 9001, ISO 14001, UL/ANSI (if exporting to USA or Canada)

  • Factory test reports stamped and signed

If the supplier is unable to provide these documents promptly, this is a red flag.

✅ Tip: request a scan of all documents before signing the contract.

2. analysis of technical specifications and labeling

Make sure that the transformer parameters correspond to the project documentation:

  • Rated voltage: e.g. 10/0.4 kV or 6/0.4 kV

  • Power: 25 to 2500 kVA (depending on the task)

  • Frequency: 50 Hz (in Russia), 60 Hz - for export to USA/Canada

  • Schematic and connection groupDyn11, Yyn0, et al.

  • Insulation level, voltage class, idling and short-circuit losses

  • Climatic versionU1, UHL1, T1, etc.

✅ Tip: always compare the nameplate with the TOR. Especially the connection group and losses.

Read more：Why more and more companies in Russia and Central Asia are buying power transformers directly from China

3. evaluation of the design and materials used

The quality of the materials directly affects the service life and reliability of the transformer:

  • Windings: copper (preferred) or aluminum

  • Magnetoconductor: cold-rolled electrical steel

  • Case: IP23-IP55 protection depending on operating conditions

  • Cooling type: oil (ONAN, ONAF), dry (AN, AF)

  • Optional extras: temperature sensors, fans, fuses, arresters

When installing outdoors, be sure to check the anti-corrosion treatment and type of paint finish.

4. factory test requirements

A reliable manufacturer always provides protocols for the following tests:

  • Routine testing: winding resistance measurement, insulation resistance, phase and polarity check

  • Type tests: sound level, thermal resistance, no-load and short-circuit currents

  • Overvoltage test: to confirm isolation

You can also request:

  • FAT (Factory Acceptance Test): In person, by video or online

  • Photos/videos of the testing process

Read more：Transformer TMG 1600 10 0,4

5. Checking packaging and transportation conditions

Proper packaging ensures that the equipment will not be damaged in transit:

  • Packaging: wooden packaging, pallets, film, moisture protection

  • Equipment: passport, instructions, warranty card, fasteners

  • Labeling: may contain logo, project code, customer

  • Options: container shipment, export packaging, labeling in Russian language

6. How to choose a reliable transformer supplier

The right supplier isn't just about low price. Pay attention to:

  • Experience in the market and real completed projects

  • Availability of own production and engineering department

  • Flexibility: OEM/ODM support, SKD deliveries, TOR assistance

  • Reviews, packaging examples, production photos

  • Warranty: 12 to 36 months, technical support, spare parts

✅ Tip: check whether the company has successful deliveries to Russia, Kazakhstan, Belarus.

Conclusion

Transformer inspection before purchase is the responsibility of every competent engineer and purchaser. The right approach includes not only a comparison of characteristics, but also an in-depth analysis of the documentation, design, delivery conditions and reliability of the manufacturer.

If you are looking for a reliable partner for the supply of power transformers, look no further than Evernew Transformer - China's leading transformer manufacturer. We offer:

  • 📌 High quality products with full control of all stages of production

  • 💰 Competitive prices without hidden surcharges

  • ⚡ Fast development and production according to your requirements (OEM / ODM / SKD)

  • 🚚 Prompt shipment and export to Russia, Kazakhstan, Belarus and other CIS countries

  • 📐 Compliance with design standards and GOST / CE / ISO / EAC certification

  • ❌ No counterfeit or uncertified products - only proven solutions

Contact usto get technically and economically optimal offer for your project. We value honesty, reliability and long-term cooperation.

    Evernew Transformer
    Evernew Transformer

    Evernew Transformer is one of the leading power transformer manufacturers in China. We specialize in the design and manufacture of 6 to 500 kV transformers, including oil, dry, amorphous, modular substation and renewable energy transformers. Our products are exported to Russia, Kazakhstan, Uzbekistan and other CIS countries, and meet international standards GOST, CE, ISO, UL and IEC. We offer factory prices, fast delivery times and full technical support.