Why manufacturers are shifting to IEC 61238-1 certified crimping systems in power transformers
– A comparison with brazing and welding.
Internal connections inside a power transformer are essential for electrical performance, thermal stability and long-term reliability. Although brazing and welding have been used for decades, these manual processes involve variability, safety risks and limited traceability — major concerns for high-value equipment.
This is why transformer manufacturers worldwide are transitioning to IEC 61238-1 certified crimping systems, which deliver repeatability, safety and measurable quality, especially in coil lead-out connections.
Article by Victor Moraes
Key Segment Manager
Electrical Machines
Limitations of brazing and welding
While widely known, brazing and welding suffer from issues that are increasingly problematic:
- Strong dependency on operator skill
- High process variability
- Hidden internal defects are difficult to identify
- Longer and riskier manufacturing processes (heat, flame, fumes)
- No objective criteria to verify joint quality
In a transformer, where every internal joint is critical, this variability becomes unacceptable.
Why IEC 61238-1 certified crimping is becoming the global standard
IEC 61238-1 sets rigorous requirements for:
- temperature rise
- contact resistance
- thermal cycling
- mechanical stability
- long-term performance
Certified crimping systems meet these standards and provide clear advantages:
1. Repeatability and process control
Hydraulic tools ensure consistent force and deformation in every cycle.
2. Higher operational safety
No heat, flame or fumes.
3. Traceability and objective inspection
Modern systems provide:
- die identification embossed on the terminal, and
- specified crimp height, measurable with a caliper
This makes the process fully verifiable — something impossible with brazing or welding.
4. Superior electrical and thermal performance
Proper compression eliminates voids, reduces resistance and improves thermal behavior under load cycling.
Cost of poor quality: the decisive factor
A failure in an internal transformer connection is one of the most expensive and damaging events a manufacturer can experience.
Consequences include:
- extremely difficult or impossible rework
- production delays
- loss of oil, copper and insulation materials
- warranty and logistics costs
- customer dissatisfaction and reputational damage
- in severe cases, catastrophic field failure
Because brazing and welding are operator-dependent, the probability of failure is significantly higher — and so are the financial risks.
This is the key reason manufacturers are moving to IEC-certified crimping systems:
they ensure reliable connections even in coil lead-out conductors, using terminals and tools engineered for severe mechanical, electrical and thermal stress.
In short: Certified crimping = controlled quality + reduced risks + lower failure costs.
Conclusion
IEC 61238-1 certified crimping is not just a technical improvement — it is a strategic decision that brings:
- higher safety
- greater productivity
- consistent quality
- full traceability
- superior electrical performance
- strong reduction of failure-related costs
For power transformer manufacturers, where reliability is non-negotiable, certified crimping represents the safest, most modern and most robust approach.
