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The 2050 carbon‐neutral vision spawns a novel energy structure revolution, and the construction of the future energy structure is based on equipment innovation. Insulating material, as the core of electrical power equipment and electrified transportation asset, faces unprecedented challenges and opportunities. The goal of carbon neutral and the urgent need for innovation in electric power equipment and electrification assets are first discussed. The engineering challenges constrained by the insulation system in future electric power equipment/devices and electrified transportation assets are investigated. Insulating materials, including intelligent insulating material, high thermal conductivity insulating material, high energy storage density insulating material, extreme environment resistant insulating material, and environmental‐friendly insulating material, are categorised with their scientific issues, opportunities and challenges under the goal of carbon neutrality being discussed. In the context of carbon neutrality, not only improves the understanding of the insulation problems from a macro level, that is, electrical power equipment and electrified transportation asset, but also offers opportunities, remaining issues and challenges from the insulating material level. It is hoped that this paper envisions the challenges regarding design and reliability of insulations in electrical equipment and electric vehicles in the context of policies towards carbon neutrality rules. The authors also hope that this paper can be helpful in future development and research of novel insulating materials, which promote the realisation of the carbon‐neutral vision.

Space charge accumulates near electrodes in insulating materials under high voltage direct current. Electric stress created by charge accumulation distorts electric field, reduces the remaining useful life of insulating materials, and decreases partial discharge inception voltage that are critical for ensuring the dielectric integrity of power applications. In this article, a novel approach that mitigates space charge accumulation using electrets is presented. Electrets are used to reduce electric fields that cause charge injection and space charge accumulation in dielectric materials. The validity of using electrets for preventing space charge accumulation is numerically and experimentally demonstrated. Bipolar charge transport model is developed to simulate space charge injection and accumulation in silicone rubber without and with the incorporation of electret. Space charge experiments are performed to confirm the numerical results. The results show that electrets can effectively mitigate space charge accumulation in dielectric materials. The results also show that the incorrect use of electret such as reversing the polarity can lead to more substantial space charge accumulation. An entirely new way of preventing space charge accumulation is proposed. Incorporating an electret film into a metal‐dielectric interface prevents space charge from being injected into the main dielectric. Electrets generate electric fields that can be utilized to counter high electric field originating from high‐voltage metal surfaces, increase charge injection barrier height, and mitigate space charge injection and accumulation.

Epoxy-based composites exhibit mechanical compatibility at cryogenic temperatures. Owing to these properties, composites based on epoxy are used as electrical insulators in high temperature superconducting (HTS) power applications. However, the inevitable presence of voids in solid insulators, triple points, and airgaps at high-voltage conductor-insulator interfaces increase electric fields locally. The intensified electric field around these defects and interfaces is the main cause of partial discharge (PD), which is a dielectric challenge for numerous power applications including HTS cables. Recently, electret has been introduced as a promising solution to mitigate PD activities caused by voids and triple points. In this work, we intend to report the PD mitigation performance of electrets fabricated from epoxy resin, which is suitable for cryogenic power applications.

Conductive nanofillers, such as carbon nanotube, graphene nanoplatelets, and carbon black particles (with diameters in nanometers) have been shown to enhance the electrical conductivity of fiber reinforced polymer matrix composites in many existing studies. The motivation is primarily for lightning strike protection, electromagnetic interference shielding, de-icing, and the manufacturing of lightweight electronic components. In this paper, we evaluate the lightning strike damage tolerance of carbon fiber reinforced polymer (CFRP) matrix composite laminates containing conductive nanofillers with varying weight fractions, including carbon black (CB), carbon nanotubes (CNT), and a mix of CB and CNT, through simulated lightning strike tests, followed by both non-destructive ultrasonic inspection and destructive sectioning to characterize the damage inflicted by the simulated lightning strike. Three-point flexural tests are performed to evaluate the residual strength retained by all CFRP specimens. Results show that lightning strike damage experienced varying levels of reduction for CFRP composite specimens containing conductive fillers in comparison to the baseline specimen without fillers. Notably, the delamination only penetrated to the interface between the 1st and 2nd layer for the specimen with 0.25 wt.% CNT in comparison to the baseline CFRP specimen for which the delamination penetrated to the interface between the 5th and 6th layer. Moreover, the retention of the flexural modulus increased from 26.5% to a maximum of 95.0% for the specimen with 0.25 wt.% hybrid CB and CNT. Yet, we show that using our chosen conductive fillers cannot fully eliminate lightning strike damage. Additionally, adding conductive fillers could compromise the flexural properties. We provide discussions on future recommendations on using conductive fillers for the lightning strike protection of CFRP composites.

With the goal of improving the dielectric strength of gaseous cryogens, this dissertation discusses the dielectric properties of cryogenic gas mixtures based on electron kinetics, dielectric modeling, and plasma diagnostics. The electron kinetics work involves the numerical analysis of electron ensembles in cryogenic gas mixtures. The results of the analysis qualitatively predict the varying dielectric strength of the cryogenic gas mixtures. The dielectric modeling work provides the quantitative predictions of gas dielectric strength in terms of breakdown voltages. Specifically, the work develops a new dielectric strength model that can accurately estimate the dielectric strength variations caused by the variation of cryogenic gas mixture composition. The plasma diagnostics work involves the design and development of a plasma experiment, which is used for measuring DC plasmas generated from potential cryogenic gas mixtures. By analyzing the measured results, the electron energy distribution function of each gas mixture is derived, which is subsequently used for calculating plasma parameters including plasma density and plasma temperature. Research tasks discussed in this dissertation are dedicated for the dielectric enhancement of gaseous cryogens, which is pivotal for the development of medium- and high-voltage superconducting power applications.

Use of the Langmuir probe plasma diagnostics to investigate the dielectric properties of gas mixtures is discussed as a continuation our previous experimental and theoretical work on understanding the dielectric strength of helium gas mixtures for superconducting and other cryogenic applications. Here we report the results of Langmuir probe experiments conducted on the gas mixtures to obtain plasma parameters including plasma density and the electron temperature. The experimental procedure used in the Langmuir probe plasma measurements, the derivation of the plasma characteristic parameters, and the implications of the results to the dielectric characteristics are discussed. The plasma characteristics obtained under various discharge power, gas pressure, and gas composition are also discussed. The results support the findings of the our previous theoretical and experimental studies that showed substantial enhancement of dielectric strength of He gas obtained by the addition of small mol% of H2 and relate the enhancements to the plasma characteristics observed.

Accurate measurement circuit and high-frequency sensors with sufficient bandwidth are necessary for the analysis of individual partial discharge (PD) pulses. In this paper, a testbed is designed and constructed for the investigation of DC PD pulses. The testbed is equipped with a 50 ohm transmission line (TL) that terminate to an oscilloscope for measuring the charge displacement current generated by PD pulses. Besides the oscilloscope measurements, two types of electromagnetic field sensors (D-dot and B-dot) were developed to capture the EM fields of the PD pulses propagating through the TL. The main goal of this paper is to investigate the DC PD pulses through the EM fields and the corresponding discharge current pulses that are considered as calibrating signals for the developed D-dot and B-dot sensors. The results of DC cavity discharge measured by the constructed testbed and the EM field sensors demonstrate close agreement with the reference PD pulses measured via oscilloscope.

Despite the roll-to-roll (R2R) gravure printing method emerging as an alternative sustainable technology for fabricating logic circuits based on p- and n- types of single-walled carbon nanotube thin film transistors ( p,n- SWCNT-TFTs), the wide variation of large threshold voltage ( V th  > ~8) in the R2R printed p,n- SWCNT-TFTs prevents the integration of complementary logic circuit. Here, the V th variation of the p,n- SWCNT-TFTs was narrowed down by developing a method of using the first gravure roll with the minimized superposition error (< ±40 µm) of engraved registration marks and implementing the R2R doping process for tailoring the V th using polymer-based p- and n- doping inks. Through those two methods, the R2R printed the p,n- SWCNT-TFTs was tailored to shift V th to near ±2.7 V and reduce V th variation to ±1.6 V while the noise margin was improved by 24% so that a large number of R2R printed logic gates could be integrated with clear logic levels at ±10 V of operation voltage. Based on the tailored p,n- SWCNT-TFTs, a fully R2R printed 4-bit arithmetic and logic unit was successfully demonstrated by integrating 156 p,n- SWCNT-TFTs.