This part of ISO 17657 specifies a welding current meter with a current sensing coil to measure the weld time and the r.m.s. value of the welding current during a certain interval using single-phase alternating current of frequency of 50 Hz or 60 Hz, or direct current.
This part of ISO 17657 is applicable for a welding current measuring system, with a display or calibrated output port, which may be connected to a welding controller.