APAC TEC1-002 Coil Guidance Document

ANAB is pleased to announce the publication of APAC TEC1-002 APAC Guidance on the Assessment of Metrological Traceability of Measurements Made with Multi-Turn Coils Used to Calibrate Clamp-Style Current Meters, produced by the Asia Pacific Accreditation Cooperation (APAC). This guidance document seeks to establish confidence in the continued stability and performance of a current coil after its initial calibration performed by a laboratory.

About APAC

APAC’s primary role is to manage and expand a mutual recognition arrangement (MRA) among accreditation bodies in the Asia Pacific region. APAC is recognized by the International Accreditation Forum (IAF) and the International Laboratory Accreditation Cooperation (ILAC). APAC has published numerous series: Gov, MS, COM, MRA, CBC, PER, FIN, Tec1, Tec2, Tec3, and more.

APAC TEC1-002 Background

There are few devices that are capable of directly providing metrologically traceable output currents above 100 Amperes. Many laboratories, however, have used current coils together with a metrologically traceable output current to conduct calibrations above the commonly available current outputs provided by existing calibrators. Some manufacturers have designed current coils for use with their calibrators and may provide calibrations for those coils. APAC TEC1-002 covers guidance for the construction, design, and laboratory’s calibration program of such coils.

The APAC Tec1 or Technical Committee 1 (Laboratories, Inspection Bodies, Reference Materials Producers, Proficiency Testing and Biobanks) produced the APAC TEC1-002 document.

The APAC TEC1-002 coil guidance document was primarily influenced by ANAB Heads Up #45 of 16 February 2018. ANAB Senior Manager of Accreditation, Randy Long was a key contributor in this working group of APAC Technical Committee 1 (TEC1) serving Laboratories, Inspection Bodies, Reference Material Producers, Proficiency Testing Providers, and Biobanks.

What Is the APAC TEC1-002?

APAC has released Guidance on the Assessment of Metrological Traceability of Measurements Made with Multi-Turn Coils Used to Calibrate Clamp-Style Current Meters, which is one of APAC’s TEC1 publications. The document is intended as guidance for the assessment of metrological traceability of the measurements made by conformity assessment bodies with current coils (multi-turn wire coil assemblies) for the calibration of clamp-style current meters. Manufacturers and laboratories that provide accredited calibrations of these multi-turn coils will find this document useful.

Guidance in APAC TEC1-002 for Metrological Traceability of Multi-Turn Coil Measurements

The practice of periodic checks (i.e. visual inspection, checking the current using a suitable, calibrated clamp-style current meter, etc.) consistent with the risk associated with the laboratory’s services is well established. Such periodic checks establish confidence in the continued stability and performance of a current coil after its initial calibration.
Laboratories that construct current coils for their own use should verify they conform to specified requirements before being placed into service through calibration. When using such devices, the laboratory should ensure it is capable of achieving the measurement accuracy and/or measurement uncertainty required to provide valid results.
Coil design should develop an essentially uniform magnetic field in the region for the clamp jaws, as would be the case for a straight conductor.
These coils, if properly constructed, also are considered relatively stable. The laboratory’s calibration program should establish metrological traceability and also determine the interval for checks necessary to maintain confidence in the status of calibration.
Only current coils or assemblies that have undergone measures to ensure metrological traceability should be used to support a calibration performed by a laboratory accredited to ISO/IEC 17025.

What Publications Are in the APAC TEC 1 Series?

APAC TEC1 documents can be found here.

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