BS IEC 61786-2:2014

What is BS IEC 61786-2- Measurement of DC magnetic, AC magnetic and AC electric fields about? 

BS IEC 61786-2 discusses the measurement of DC magnetic, AC magnetic, and AC electric fields from 1 Hz to 100 kHz about the exposure of human beings. 

BS IEC 61786-2 provides requirements for the measurement of quasi-static magnetic and electric fields that have a frequency content in the range 1 Hz to 100 kHz, and DC magnetic fields, to evaluate the exposure levels of the human body to these fields. 

BS IEC 61786-2 covers the magnitude ranges of 0.1 T to 200 mT for AC (1 T to 10 T for DC) for magnetic fields, and 1 V/m to 50 kV/m for electric fields. 

Examples of sources of fields that can be measured with this standard include: 

• Devices that operate at power frequencies (50/60 Hz) and produce power frequency and power-frequency harmonic fields (examples: power lines, electric appliances…) 
• Devices that produce fields that are independent of the power frequency. (Examples: electric railway (DC to 20 kHz), commercial aeroplanes (400 Hz), induction heaters (up to 100 kHz), and electric vehicles.) 

Devices that produce static magnetic fields:  

• MRI, DC power lines, DC welding, electrolysis, magnets, electric furnaces, etc. DC currents are often generated by converters, which also create AC components (power frequency harmonics), which should be assessed 

Note 1: Requirements on field meters and calibration are described in IEC 61786-1. 

Note 2: When measurements outside this range are performed, most of the provisions of BS IEC 61786-2 will still apply, but special attention should be paid to specified uncertainty and calibration procedures. 

Note 3: About electric field measurements, BS IEC 61786-2 considers only the measurement of the unperturbed electric field strength at a point in space (i.e., the electric field prior to the introduction of the field meter and operator) or on conducting surfaces. 

Who is BS IEC 61786-2- Measurement of DC magnetic, AC magnetic and AC electric fields for?  

BS IEC 61786-2 on the measurement of DC magnetic, AC magnetic and AC electric fields is relevant to: 

• Manufacturers of measuring instruments  
• Manufacturers of field meters, probes, detectors 
• Manufacturers of electrical equipment 
• EMC testing authorities 
• Electrical engineers 
• Regulatory authority 

Why should you use BS IEC 61786-2- Measurement of DC magnetic, AC magnetic and AC electric fields? 

Magnetic and electric fields are characterized according to several parameters, i.e., magnitude, frequency, polarization, etc. Characterization of one or more of these parameters and how they might relate to human exposure may serve as goals of a measurement program. As an aid for readers interested in developing a field measurement protocol, BS IEC 61786-2 provides a list of such measurement goals and methods for their accomplishment.  

BS IEC 61786-2 is about the measurement protocol that specifies the measurement distances between the measurement point and the sources. BS IEC 61786-2 states the main difference between measuring AC and DC magnetic fields, i.e., the influence of the geomagnetic field. BS IEC 61786-2 gives requirements for establishing measurement procedures specifically that achieve defined goals pertaining to human exposure. It lays out the specific measurement procedures that are different in the various environments, as the differences in the characteristics of the fields from sources in the various environments, e.g., frequency content, temporal and spatial variations, polarization, and magnitude, and differences in the goals of the measurements. 

Overall, BS IEC 61786-2 is useful as it provides guidance on the magnetic and electric fields produced by power lines, appliances, and transportation systems which helps users for characterizing them according to their magnitude, frequency, waveform (harmonic content), degree of polarization, spatial variation, and temporal variation.