![]() ![]() Measurement of electric and magnetic fields However, wearing a meter on the body perturbs the electric field being measured in unpredictable ways. ![]() Personal exposure meters do exist for electric fields. This can reduce perturbation to acceptable levels, but care is still needed to get accurate readings. To measure the unperturbed field, the meter is usually held at the end of a long non-conductive horizontal rod or a vertical tripod. Three-axis electric-field meters are available, but single-axis meters are more common.Ī person holding an electric-field meter would perturb the field. based on rotation of polarised light, are less common. Meters for electric fields usually use as sensors two parallel conducting plates. The coils themselves can either be made as small as possible, for use in personal exposure meters where size and weight are important criteria, or they can be larger, often 0.1 m across, to increase sensitivity and provide some spatial averaging. Most practical instruments for power frequencies use search coils, either a single coil or three orthogonal coils. There are three different sensors widely used for measuring magnetic fields: search coils, fluxgate magnetometers, and Hall-effect devices. The best meter to use depends on the purpose it is to be used for. There are now many instruments available, which vary in the number of axes they measure, how sophisticated the electronics are, whether they record fields, and whether they are meant for survey use or as a personal monitor. The first commercial instruments designed specifically for measuring power-frequency fields became available in the 1980s. A more detailed technical description of the issues is also available in the next toggle below. This is a summary of instruments for measuring fields. ![]() EMF measurement and commercial services.SAGE Second Interim Assessment – the full list of recommendations.Government response to SAGE Second Interim Assessment.Government response to SAGE First Interim Assessment.Childhood leukaemia and night-time exposure.Standards relating to pacemakers and other AIMDs.Other factors that vary with magnetic fields.Screening fields from underground cables.Effect of height on fields from underground cables. ![]() Underground cables with multiple conductors.Power law variations in the field from a power line.The direction of the field from a power line.Fields from power lines – more detail on the physics.Calculating and measuring fields from power lines.Factors affecting the field from a power line.Summaries of fields from all power lines.Replacing a 132 kV line with a 400 kV line. ![]()
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