MEANS OF NORMALISING THE LEVELS OF PHYSICAL FACTORS AT HIGH-VOLTAGE ELECTRICAL SUBSTATIONS

Abstract

The levels of electromagnetic fields, noise, and concentrations of air ions in the air of the premises of the control rooms of high-voltage electrical substations are investigated. It was found that the intensity of electromagnetic fields of industrial frequency and the density of energy flows of ultra-high frequency electromagnetic fields is at the standard level. Radio frequency electromagnetic fields and impulse noise exceed the maximum permissible levels. Air deionization is observed. It was established that the source of abnormal field levels is relay protection devices. At the same time, near the relay cabinets, the concentrations of air ions are significantly higher than the minimum permissible levels. Normalization of electromagnetic and acoustic field levels is achieved by using a universal perforated screen made of carbonyl iron composite material. The matrix was made of standard XC varnish. As a result of the shielding, the levels of electromagnetic fields in the radio range have been reduced to values far below the standard. The noise reduction indices for medium and high frequencies are 8–12 dB. Given that impulse noise is of medium and high frequency, this result is satisfactory. Normalization of air ion concentrations of both polarities is achieved by moving air ions from relay protection devices to workplaces by directed air movement through the openings of the electromagnetic and acoustic shield. The advantage of the composite screen is the absence of static charges that neutralize the charges of air ions.