Development of a novel 20 kV 0.1 Hz very low frequency cosine‐rectangular voltage generator for multi‐functional insulation testing of MV power cables

Diagnostic challenges in dielectric loss assessment and interpretation: a review

“…Previously, the generation of the cos-rect waveform was extensively performed by an arrangement of a DC source, a high value capacitor and an inductance controlled externally by a rotor switch [55,56]. The extensive developments of power electronics nowadays replace this manually controlled switch by an automated thyristor switch, which results in a lighter, cheaper and more convenient test system.…”

“…The extensive developments of power electronics nowadays replace this manually controlled switch by an automated thyristor switch, which results in a lighter, cheaper and more convenient test system. During polarity reversal of the waveform, the technology offers recycling of power [56]. Resonance based, this automated approach can reduce power consumption and increase load capacity at the output terminal.…”

“…It is also advisable that the polarity reversal of cos-rect takes a cosine in shape and contains a frequency close to 50 Hz. Owing to the rectangular shape, it also possesses the advantage of measuring the leakage current [56]. For example, the block diagram of producing a VLF cos-rect waveform is illustrated in Fig.…”

Fuzzy evaluation analysis and extraction of H‐N parameters for On‐site distribution cable

“…These two methods are not satisfactory enough for quantitative evaluation. Moreover, conventional withstanding voltage test under 50 Hz need much too large capacity and may do harm to cables’ insulation [11]. In order to avoid this problem, very low frequency (VLF) method and corresponding diagnostic criteria are proposed by IEEE [12].…”

On‐site partial discharge detection of power cables using a novel DAC technique supplied by a capacitor bank

“…PD detection at line frequency is unreasonable on-site due to the high reactive power demand of the cable load [7]. As a consequence, several feasible on-site PD detection methods have been put forward and put into application.…”