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An RF survey meter is often used to evaluate the safety of human exposure to RF electromagnetic fields. However, it has been noted that erroneous meter indications occur when the meters are used in strong, extremely low-frequency (ELF) electric fields, such as those found near electric power transmission and distribution facilities. In this paper, coupling between an ELF electromagnetic field and an RF survey meter has been studied theoretically and experimentally. It has been shown that coupling large enough to result in erroneous readings can be caused by unbalanced currents as small as 0.1% of the balanced currents on the transmission line that connects the probe to the readout unit. Unbalanced currents of this magnitude can be caused by capacitive coupling to the probe and readout unit. Index Terms--Electric field, interference, power line, RF survey meter, reciprocity theory.

The conditions under which corona first occurs for any set of electrodes are an important design consideration since corona can limit the performance of any given configuration of electrical conductors. Here, the 60 Hz ac corona onset voltage for a stranded wire in air is calculated. The criterion involves the characteristics, i.e. composition and pressure, of the gas in which the conductor is immersed and the electric field in the vicinity of the conductor surface. It is found that the calculated corona onset voltage agrees reasonably well with experimental data and that its behavior as a function of overall conductor radius and number of strands is as expected. Index Terms--Corona onset, stranded conductor, surface irregularity, roughness.

A previously proposed simple method to characterize magnetic fields near electric appliances was extended to intermediate frequencies of up to 100 kHz. The method consists of identification of the magnetic dipole moment that is equivalent to a magnetic field source of an electric appliance and simple estimation of the magnetic field distribution around the appliance. In addition, frequency characteristics of the magnetic field were taken into account by considering the harmonic components in the magnetic-field waveform for both power frequency and intermediate frequency ranges. For the application of the method, a wide-frequency range (from power frequency to 100 kHz) magnetic-field measuring instrument was developed and applied to appliances that generate intermediate frequency magnetic fields, i.e., an induction heating cooker, a TV set, and a metal detector. The results revealed that the method is adequate to quantify the magnetic field near the electric appliances at frequencies of up to 100 kHz. Index Terms--Electric appliance, induction heating (IH), intermediate-frequency magnetic field, magnetic dipole moment.