Frequency Spectrum Analysis of Electromagnetic Waves Radiated by Electric Discharges

Abstract

-In this paper, we analyzed the frequency spectrum of the electromagnetic waves radiated by an electric discharge as a basic study to develop an on-line diagnostic technique for power equipment installed inside closed-switchboards. In order to simulate local and series arc discharges caused by an electric field concentration and poor connections, three types of electrode systems were fabricated, consisting of needle and plane electrodes and an arc generator meeting the specifications of UL 1699. The experiment was carried out in an electromagnetic anechoic chamber, and the measurement system consisted of a PD free transformer, a loop antenna with a frequency bandwidth of 150 kHz-30 MHz, an ultra log periodic antenna with a frequency bandwidth of 30 MHz-2 GHz, and an EMI test receiver with a frequency bandwidth of 3 Hz-3 GHz. According to the experimental results, the frequency spectra of the electrical discharges were widely distributed across a range of 150 kHz-400 MHz, depending on the defects, while commonly found between 150 kHz and 10 MHz. Therefore, considering the ambient noise and antenna characteristics, the best frequency bandwidth for a measurement system to monitor abnormal conditions by detecting electromagnetic waves in closedswitchboards is 150 kHz-10 MHz.

Trichel Pulse in Negative DC Corona discharge and Its Electromagnetic Radiations

“…Although a physical model was used in discussions, the effects of discharge parameters on the radiation were not discussed. The frequency spectrum of radiation from discharges was analyzed by Park et al but their works mainly focused on the best frequency width for measurement [7]. On one hand, knowing the radiation characteristics is essential for both evaluation and measurement of EM environment, as well as protection against EMI.…”

Nonlocal or Possibly Superluminal Maxwell Displacement Current Observed in the Near-field of a Spherical Capacitor

“…It has been experimentally confirmed that it also generates radio frequencies, which can range from 150 KHz up to 30 GHz, although they are more commonly found in the range of 150 KHz to 10 MHz. [6] Each channel of the the two oscilloscope channels is passed through an RC low-pass filter circuit, as shown in Figure 4.…”

Prognostication of Failures Using Signal-to-Noise Ratio to Determine Partial Discharges Activities in Power Transformers

“…However, the resulting hotspots are difficult to determine and therefore cannot be used as a suitable indicator. The breakdown in void or cavity is intermittent, highly localized and is accompanied with the generation of energy in the acoustic, visible and radio range with a wide frequency band of electromagnetic spectrum between 300 MHz and 3 GHz [16,17] besides producing hotspots. The void in the winding insulation thus acts as a potential source of electromagnetic radiations.…”