An improved pulsed electroacoustic system for space charge measurements under high temperatures and arbitrary waveform voltages

Abstract

This paper presents the design and calibration method of an improved pulsed electroacoustic (PEA) system for space charge measurements, including a novel nanosecond pulse generator and an improved electrode system, which can be used under various temperatures and arbitrary waveform voltages. The measurement principle of the PEA system is first analyzed, and the calibration method for the applied voltage is proposed to solve the problem of waveform distortion caused by voltages with different frequency components. For the pulse generator, the main parameters of output pulses are an amplitude of ∼700 V, a full width of 4.6 ns, a jitter of 0.24 ns, and a repetition rate of 10 kHz on the 50 Ω load. For the electrode system, the flexible upper electrode design is first introduced to achieve consistently close contact between the sample and the electrode. Besides, the hybrid heating method and the replaceable coupling capacitor and high voltage electrode head are adopted. Space charge measurements are conducted at different conditions using this PEA system, which includes different temperatures and different voltage waveforms. The experimental results verify the effectiveness of the calibration method and the feasibility of the improved PEA system.

Space charge dynamics of epoxy/micro-Al2O3 composites under multi-physical fields

“…As a matter of fact, the electric field and temperature field are two primary physical fields that most studies have focused on [36][37][38][39][40][41]. The experiments above aim at exploring the dynamic charge characteristics of EP-Al composites, which enables the further structural design of DC GIL considering charge threshold and electric field control.…”

“…a grounded metal plate, is designed to safely accommodate thermoelectric couples and provide higher heating efficiency. This design follows our previously conducted research work [40]. Mechanical stress was applied using a stepper motor and scale, which can continuously adjust the pressure within the spring's limitations.…”

Interface Charge Characteristics in Polymer Dielectric Contacts: Analysis of Acoustic Approach and Probe Microscopy

“…With an improved pulse source having an amplitude of 700 V, a full width of 4.6 ns, and a maximum repetition rate of 10 kHz, multiple space charge distribution measurements can be completed in a single AC voltage cycle. [157] Moreover, precise phase [60,143] Fast test speed/ High noise immunity/ Simplicity of the measurement cell/ Non-destructive [16] Low resolution [31,77] / Acoustic signal needs calibration [63,69] PWP Fast test speed/ High signal-to-noise ratio/ Non-destructive [144] Low resolution/ Pressure wave signal needs calibration [143] Optical Pockels effect Calculation of electric field using the change of optical refractive index to deduce charge signal [11,139] High spatial resolution/ Suitable for solid dielectric films [141,145] Destructive to the sample [139] Kerr effect High spatial resolution/ Suitable for liquids [146] Thermal TPM Thermal diffusion disturbs charge and induces electrical signal [56,140] Non-destructive/ Suitable for thin samples [147] Low resolution/ Sensitivity and resolution are strongly related to spatial position TSM Non-destructive/ Suitable for thick samples [148] LIMM Three-dimensional electric field distribution can be provided…”

Study on the Partial Surface Discharge Process of Oil-Paper Insulated Transformer Bushing with Defective Condenser Layer

“…For the PD characteristics of an oil-impregnated pressboard system, the internal PD signal of a bushing insulation system can be detected by the pulse current method and the UHF method [12]. In addition, its space charge distribution can be measured using the electroacoustic pulse method [13], etc. However, the charge transfer characteristics and the discharge mechanism of the oil-paper insulation system cannot be tested with the current experimental methods.…”