Electromagnetic radiation emissions from remote area power supply systems

Phillip John Knipe

There has been growing concern about the potential link between various health effects, such as cancer and chronic exposure to low level Electromagnetic Radiation (EMR). A report on residential exposure to 50 / 60 Hz electromagnetic radiation, published by the United Kingdom’s National Radiation Protection Board (NRPB) found: “that there is some epidemiological evidence that prolonged exposure to higher levels of power frequency magnetic fields is associated with a small risk of leukaemia in children (AGNIR, 2001).” The report concluded that: “heavy exposures of 0.4μT (4 mG) or more are associated with a doubling of the risk of leukaemia in children under fifteen years of age. The evidence is, however, not conclusive (AGNIR, 2001).” Even though there has been no conclusive scientific evidence that there is a direct relationship between cancer and chronic exposure to low level EMR there is sufficient evidence to justify minimising exposure levels. Regions of particular interest in the electromagnetic spectrum are the Extremely Low Frequency (ELF) 50 - 60 Hz, Very Low Frequency (VLF) 10 - 100 kHz and Radio Frequency (RF) 100 kHz - 300 GHz bands. Remote area power supply (RAPS) systems are becoming increasingly prevalent. These systems tend to use renewable energy sources and their associated technology rather than the conventual power supply systems. Recently some concerns have been raised about the levels of EMR being emitted from these new forms of technology. Some of the inverters transforming the generated direct current (dc) to alternating current (ac) have produced significant levels of EMR. These devices are often located close to living areas and therefore increase the hazards to residents. While the main aim of these systems is to replace non-renewable energy sources and reduce greenhouse gas emissions, they should also be designed to minimise the doses of EMR to which users are exposed. This type of technology is still immature, and innovations are occurring rapidly. While there is currently no proven link between exposure to EMR and health effects, various concerns have been raised and the design and production of renewable energy technology that has reduced or very low emissions of EMR has obvious advantages. This thesis examines the various frequencies of EMR produced by typical remote area power supply systems (RAPS). The strengths of these fields are measured using various types of monitoring equipment and the health hazards examined. This research was conducted on a range of RAPS equipment including diesel generators and inverters. Fields were measured at various orientations as a function of distance from the sources. Even though no levels above the current health standards were found some magnetic fields above the 4 mG mark were measured. This level has been identified as a possible action level for chronic exposure to EMR. The analysis of these results enables the qualitative assessment of the hazards associated with RAPS systems. This leads to a set of recommendations to health authorities on sensible measures to be adopted to minimise the hazards to the users of these systems.

Electromagnetic radiation emissions from remote area power supply systems

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