ISO 10656:2016

Overview

ISO 10656:2016 - Resistance welding equipment - Transformers - Integrated transformers for welding guns - provides additional, specific requirements for single‑phase AC transformers used inside welding guns. It is intended to be used together with ISO 5826 (general transformer requirements) and amends or supplements those requirements for integrated transformer designs used in resistance welding applications.

Keywords: ISO 10656:2016, resistance welding, integrated transformers, welding guns, single‑phase transformer, welding equipment.

Key topics and requirements

• Scope and interaction with ISO 5826: ISO 10656 supplements ISO 5826; where this standard applies, its requirements modify or add to the general rules in ISO 5826.
• Transformer types and dimensions: Defines Type H and Type J integrated transformers with referenced dimension figures and tables for 50 Hz and 60 Hz variants (no‑load voltages and approximate masses included in the tables).
• Cooling: Cooling water flow rate specified as 4 l/min.
• Duty cycle: Transformers are suitable for duty cycles up to 20% (see Annex A for current/duty relationships).
• Grounding: Centre point of the secondary coil must be connected to the transformer case by a removable link.
• Thermal protection: Primary and secondary windings require thermoswitches; wiring colours specified (primary = light blue, secondary = black).
• Output current sensing: An output current sensing coil is mandatory and must conform to ISO 5826.
• Marking and identification: Voltage and earth connections must be clearly marked (U, V and earth symbol per IEC 60417). Rating plate must follow ISO 5826 format and reference ISO 10656.
• Exterior colour coding: Colour of transformer finish is specified by no‑load voltage for both 50 Hz and 60 Hz units (enables quick identification).
• Designation format: Prescribed sequence for type, voltages, current, presence of thermoswitch (T) and measuring coil (M). Example: ISO 10656 - J – 7,1 – 5,4 – 400 – TM.
• Type tests and test conditions:
  • Mechanical strength: tensile load test (10 kN progressive load, hold).
  • Dynamic output terminal test: up to 5× secondary permanent current, duty 1%, weld time 160 ms, 2 500 cycles.
  • Thermal test: heat rise limits per ISO 5826 at 20% duty, nominal primary voltage, load time 240 ms.

Applications and who uses it

• Manufacturers of resistance welding guns and integrated welding transformers
• Welding equipment designers and system integrators specifying gun‑mounted transformers
• Quality, test and compliance engineers in automotive, appliance and metal‑fabrication industries
• Procurement and certification teams ensuring equipment meets IEC/ISO welding standards

Related standards

• ISO 5826 - General specifications for resistance welding transformers
• IEC 60417 - Graphical symbols for equipment marking (referenced for earth and connection symbols)

ISO 10656:2016 helps ensure safe, interchangeable, clearly marked and tested integrated transformers for resistance welding guns - reducing integration risk and simplifying maintenance and procurement.