This paper focuses on the inception of partial discharges within insulation system electrical actuators used for More Electrical Aircraft (MEA). Since these machines should operate in absence Partial Discharges (PDs), dependence PD Inception Voltage (PDIV) voltage impulses typical wide bandgap (SiC) devices is investigated at both 1 bar, reduced pressures close to those aircraft cruising altitudes (150 mbar - 200 mbar) or lower (down 5 mbar). Propagation issues are not dealt with here as...

The development of more electrical transportation systems requires rotating machines having higher efficiency and specific power. To date, this is achieved by feeding them with rising supply voltages frequencies. This generalized strategy introducing several challenges in the correct design insulation that necessary for a reliable system. A major issue to be dealt are partial discharges (PDs), an aging mechanism can bring failure short times. solution often proposed manufacturers involves...

In this paper, the results obtained from lab tests on twisted pairs subjected to different voltage waveforms and atmospheric conditions are used propose how modify IEC Std. 60034-18-41. The goal is make standard suitable for More Electrical Aircraft (MEA). show that it initially necessary screen out materials through simple tests. enhancement factors temperature can be modified consider reduced pressures temperatures using a model. aging factor considering sensitivity of partial discharge...

The arrival on the market of new power devices based wide bandgap semiconductors has raised a relevant interest due to their superior properties compared conventional technologies. On other hand, these are inherently characterized by high rates voltage changes over time, which may result in reliability challenges electric drives adopting them. In fact, dangerous overshoots at motor terminals and uneven distributions within machine windings occur. These phenomena can trigger insulation stress...

This review-type article highlights the challenges ahead in aircraft electrification, with goal of stimulating researchers from academia and industry to contribute this complex, fascinating topic. demonstrates role dielectrics reliability transport electrification.

The Schumann inception criterion was used to predict the partial discharge voltage (PDIV) of insulation models representing both wire wound and form (hairpin) low machines. It found that fitting parameter <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}$ </tex-math></inline-formula> (the logarithm critical number electrons define transition from Townsend streamer discharge) is almost independent...

The partial discharge inception voltage (PDIV) of magnet wires depends on ambient temperature and humidity. Thus, both quantities might affect the reliability inverter-fed wire-wound motors. Contradictory results have been reported in literature, so this paper discusses a variety experiments aimed at explaining dependence PDIV For very high humidity levels, are surprising difficult to explain. Temperature influence air density, dielectric permittivity, surface conductivity enamel, making...

Current standards base the evaluation of partial discharge (PD) harmfulness on their amplitude and repetition rate. This work shows how, contrary, non conventional environmental conditions introduced by aerospace applications (i.e. low-pressure atmosphere, higher frequency supplies) lead respectively to lower or unchanged PD apparent charges, which are however characterized different mean energies, hence destructive potential, in a counter intuitive manner.

Impulse voltage waveforms from power converters enhance the stress on turn insulation system of rotating machines. When exceeds a critical level, partial discharges can be incepted leading to premature failure machine insulation. Besides using thicker insulation, hybrid organic/inorganic (Corona Resistant, CR) used. CR systems have proved successful extend lifetime industrial drives. For aerospace applications as More Electrical Aircraft, one should consider challenging conditions posed by...

Fast switching converters cause increased electrical stresses on the insulation of rotating machines. Within this context one roles impregnating varnishes/resins is to guarantee high partial discharge inception voltages (PDIV). Most resins operate in plasto-viscous region (above their glass-transition temperature) where large permittivity values can be expected. Field enhancement air surrunding such materials may expected, possibily reducing PDIV level. Here value resin and its impact...

In an electrical drive, the impulsive waveforms of power inverter can increase stress on insulation system rotating machines to a point where partial discharges are incepted, and failure occurs in very short times. Electrical drives aerospace applications subjected even more challenging operating conditions, due reduced pressures, which highly enhances probability incept Partial Discharges. A solution often proposed by manufacturers involves use so-called Corona Resistant (CR) materials,...

The effect of wide bandgap converter on the partial discharge inception voltage (PDIV) enameled magnet wires was investigated. Tests were carried out using an optical detection system, changing rise time and switching frequency. experiments showed that neither nor frequency influence PDIV. Physically, this finding supports idea permittivity does not change in range impulse spectrum. However, overshoot can affect PDIV measurements as peak dc bus provides accurate evaluation

Qualification according to IEC 60034-18-41 considers the partial discharge inception voltage (PDIV) equivalent under different test waveforms, assumption that can be surveyed. PDIV tests have been performed on unaged and thermally aged impregnated twisted pairs, models of turn-turn insulation. Results revealed SiC impulse voltages seems larger than one achieved using AC sinusoidal voltages, but only for new samples as after aging they drop comparable values, implying a reduction former. In...

The feasibility of detecting PD in inverter-fed machines using acoustic emission sensor realized fiber optics was investigated. sensors, have a frequency response up to 500 kHz and are interrogated fiber-optic interferometric system. Three sensors were attached the stack stator explore possibility both detection localization. Results compared with those achieved electrical provided by an ultrasonic camera. Preliminary tests AC sinusoidal waveforms did show that camera could couple activity...

This paper investigates the behavior of Repetitive Partial Discharge Inception Voltage (RPDIV), which is defined as voltage level at least one PD occurs in two impulses (or five ten - according to Standard use). It has been noted that, increasing by steps value above PDIV level, sporadic bursts occur. During bursts, conditions for RPDIV are met, but activity unstable and may well extinguish. Since definition International Standards does not consider results using different measurement...

This paper investigates the effect of preconditioning on variability results when measuring Repetitive Partial Discharges Inception Voltage (RPDIV) electrical insulation systems subjected to impulsive voltage stresses. The reference International Standard considered in following (IEC 60034-18-41 [1]) defines RPDIV as minimum at which least five (PD) occurs ten impulses applied. Many testing devices have been designed according such definition: they inject and, if them trigger PD events, is...

Electrical converter-cable-machine systems, such as those in renewable source interfaces and transport drives, are operated with increasingly fast high-performance converters. Their effects on the stator insulation and, particular, turn insulation, need be understood detail. A dynamic/FEM model is used to simulate maximum voltages stressing turn-to-turn phase-to-ground insulation. The results show role of rise time generation overshoots uneven voltage distribution. For machine fed...

For inverter-fed induction motors, preventing partial discharge inception at all possible operating voltages might cause suboptimal power densities. In this paper we investigate the possibility of designing insulation systems that tolerate discharges incepted with a low probability. Such result would help more proper and justified application corona-resistant magnet wires. Rather than providing an ultimate solution to complex problem, want indicate approach using theory cumulative damage...

Detection of partial discharges (PD) with conventional techniques in systems fed by wide bandgap converters is difficult due to the interference inverter, which overlaps PD signals. Analysis frequency domain high pass filtering can be performed successfully detect activity, but it's not clear if content signals collected characteristic discharge or sample under test acting as a transmitting antenna. The analysis emission spectra from turn-turn motor models (i.e., twisted pairs) different...

Epoxy (EP) resins find widespread application in power electronics (PE) applications characterized by multi-frequency electrical stresses. Transient thermal overloads are also not uncommon due to, for example, short circuits the external circuit. This article investigates influence of various temperatures on broadband dielectric properties EP insulation, above and below glass transition temperature ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML"...

Partial discharge testing of complete, low-voltage induction machines and dry-type convertor transformers for the More Electric Transportation is discussed. The current standard (i.e. IEC 60034-18-41, 60317-0-1 61378-1) offers very few answers to new challenges posed insulating systems reliability these increasingly electrified electrical machines. Based on tests performed different kind specimens literature, most promising assessment technique ensure a reliable insulation based optical...

This article investigates the evolution of electrical properties polyethylene terephthalate (PET) with thermal aging. Electrical tests are performed within a wide range frequencies in order to simulate application conditions insulating materials inverter-fed machines. In particular, for aging considered, real part permittivity showed be correlated concentration degradation species, investigated through FTIR. On contrary, dielectric breakdown at high independent from corresponding values...