This International Standard gives specifications applicable to the following types of transformers for use in resistance welding equipment:
single-phase transformers for a.c. welding, typically operating at 50Hz or 60Hz;
single-phase transformers with connected rectifier for d.c. welding, typically operating at 50Hz or 60Hz;
single-phase inverter transformers with connected rectifier for d.c. welding, typically operating at 400Hz to 2kHz;
three-phase transformers with connected rectifier for d.c. welding, typically operating at 50Hz or 60Hz.
For the purposes of this International Standard, the term transformer can refer to the transformer alone or with connected rectifier (transformer-rectifier unit).
This International Standard applies to transformers built to protection class I or II according to IEC61140.
NOTE The requirements of this International Standard can be supplemented by other resistance welding transformer standards, e.g. ISO22829 and ISO10656.