Overview
EN ISO 17657-4:2007 (ISO 17657-4:2005) defines calibration systems and procedures for measuring welding current in resistance welding. It covers calibration of complete welding current measuring systems, current sensors, welding current meters and monitoring devices used with alternating current (50 Hz or 60 Hz) or direct current, for the current range 0.5 kA to 25 kA. The standard is Part 4 of the ISO 17657 series and complements measurement and verification guidance in related parts.
Key topics and technical requirements
- Scope and applicability
- Calibration procedures for sensors, meters and integrated measuring systems used in resistance welding (0.5–25 kA).
- Construction of calibration systems
- Components of a reference welding current measuring system: calibrated reference sensor, data acquisition system (ADC/integrator) and display/recorder.
- Test set-up: high-current circuit or test stage, power source with current control, twisted/shielded signal cabling; a resistance welding machine/transformer may be used.
- Options for calibrating: welding current meter with sensor, standalone current sensor, and welding current meter without sensor (high‑ or low‑impedance integrator types).
- Measurement components
- Use of reference (current) sensor, non‑inductive shunts, ADCs and calibrated data acquisition devices.
- Environmental and operating conditions
- Calibration systems must operate without accuracy degradation at +5 °C to +40 °C, relative humidity up to 95%, and altitudes up to 1 000 m unless otherwise agreed.
- Calibration practice and traceability
- Reference system components shall be calibrated by certified reference equipment (traceable) - typically at least once a year.
- Test procedures, test reports and documentation requirements are specified (see Clauses 6–8 and informative annexes with example reports and set-ups).
Applications and users
Who uses EN ISO 17657-4:2007:
- Calibration and metrology laboratories performing high-current calibration for resistance welding equipment.
- Welding equipment manufacturers and R&D teams validating current measurement systems.
- Quality/Process engineers and production managers ensuring weld-process control and traceability.
- Third‑party auditors and compliance officers verifying measurement systems for production acceptance or certification.
Practical uses:
- Establishing traceable calibration workflows for welding current meters and sensors.
- Verifying and commissioning measurement systems on resistance welding machines.
- Periodic recalibration and documentation to support quality control and process validation.
Related standards
- ISO 17657-1: Guidelines for measurement (series context)
- ISO 17657-2: Welding current meter with current sensing coil
- ISO 17657-3: Current sensing coil
- ISO 17657-5: Verification of welding current measuring system
- ISO 669: Resistance welding equipment - mechanical and electrical requirements
Keywords: EN ISO 17657-4:2007, calibration, resistance welding, welding current measurement, current sensors, welding current meter, calibration procedures, reference sensor, data acquisition.
