Overview
ISO 5826:2014 - Resistance welding equipment - Transformers - General specifications applicable to all transformers - defines the general technical and safety requirements for transformers used in resistance welding equipment. The standard covers single‑phase and three‑phase transformers, including transformer‑rectifier units and inverter transformers, and applies to protection class I and II devices (per IEC 61140). ISO 5826:2014 is essential for manufacturers, designers, test laboratories and procurement teams specifying welding transformers for industrial resistance welding systems.
Key topics and technical requirements
ISO 5826:2014 addresses the following core technical areas:
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Transformer types covered
- Single‑phase transformers for a.c. welding (typically 50 Hz or 60 Hz)
- Single‑phase transformers with connected rectifier for d.c. welding (50 Hz or 60 Hz)
- Single‑phase inverter transformers with rectifier for d.c. welding (typically 400 Hz to 2 kHz)
- Three‑phase transformers with connected rectifier for d.c. welding (50 Hz or 60 Hz)
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Protection and insulation
- Compliance with IEC 61140 protection class I or II
- Insulation resistance and dielectric strength test requirements to ensure protection against electric shock
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Thermal management and ratings
- Thermal protection requirements, temperature‑rise limits and heating test procedures
- Specification of permanent output/current ratings, input apparent power and methods for temperature measurement
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Electrical performance and measurement
- No‑load input current and a.c./d.c. no‑load voltage definitions
- Short‑circuit (rated) voltage, output current under load, and dynamic behaviour
- Output current sensing coil calibration and welding current measurement references (ISO 17657 series)
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Environmental, mechanical and cooling considerations
- Operating conditions: ambient temperature, humidity, altitude, transport/storage and handling provisions
- Cooling liquid circuit and temperature limits for liquid‑cooled transformers
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Documentation and marking
- Requirements for rating plates and instruction manuals, including required data fields and examples
Practical applications - who uses ISO 5826:2014
- Transformer manufacturers - design and certify resistance welding transformers to internationally accepted specifications.
- Welding equipment OEMs - select compliant transformer or transformer‑rectifier units for spot, projection or seam welding machines.
- Test laboratories and certification bodies - perform type and routine tests (insulation, dielectric, thermal and performance tests).
- Procurement and quality teams - create technical specifications and ensure supplier compliance.
- Safety and maintenance engineers - interpret temperature, insulation and cooling requirements to ensure safe operation.
Related standards
- ISO 669 (Resistance welding equipment - Mechanical and electrical requirements)
- ISO 17657 parts (Welding current measurement and calibration)
- IEC 61140 (Protection against electric shock)
- Supplementary welding transformer standards such as ISO 22829 and ISO 10656
Keywords: ISO 5826:2014, resistance welding transformer, transformer‑rectifier, welding transformer standards, insulation, thermal rating, output current sensing.