Coupling of discharge currents between conductors of electrical machines owing to laminated steel core

Tavner, Peter; Jackson, R.J.

doi:10.1049/ip-b.1988.0032

Cited by 27 publications

(12 citation statements)

References 2 publications

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“…Along with the work of Cheng et al, Pemen et al [40] modified the experiment by drilling a small hole in the insulation to directly feed signals to conductors. They verified the two propagation modes of PD signal in stator windings, and showed experimentally that the absence of end-windings prevents the fast mode, and thus denied the result derived from Tarver's experiment on micro-rotating machine in [36]. In addition, they presented the attenuation of two modes and the cross-coupling phenomenon caused by end-winding coupling quantitatively, as shown in Figure 4.…”

Section: Cross-couplingmentioning

confidence: 79%

“…In [34], the fast mode is thought to be capacitive coupling, while in [35] the authors wondered whether it is in fact due to displacement currents. It must be pointed out that the authors used a micro-rotating machine in [36], therefore it is still unknown whether the result is true for large generators or not. The critical boundary frequency between fast and slow modes is in the region of 1 MHz, whereas it is seen differently by different groups, and in some cases only the slow component is observed.…”

Section: Propagation Modesmentioning

confidence: 99%

“…However, the nature of the fast mode is contested anyway. It is said to be due to end-winding coupling in [33], but in [36] inductive coupling between bars of adjacent slots is expected, for frequencies even up to 20 MHz. In [34], the fast mode is thought to be capacitive coupling, while in [35] the authors wondered whether it is in fact due to displacement currents.…”

Section: Propagation Modesmentioning

confidence: 99%

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A Review of Online Partial Discharge Measurement of Large Generators

Luo

Wang³

2017

Energies

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Abstract:Online partial discharge (PD) measurements have long been used as an effective means to assess the condition of the stator windings of large generators. An increase in the use of PD online measurement systems during the last decade is evident. Improvements in the detection capabilities are partly the reason for the increased popularity. Another reason has been the development of digital signal processing techniques. In addition, rapid progress is being made in automated single PD source classification. However, there are still some factors hindering wider application of the system, such as the complex PD mechanism and PD pulse propagation in stator windings, the presence of detrimental noise and disturbances on-site, and multiple PD sources occurring simultaneously. To avoid repetition of past work and to provide an overview for fresh researchers in this area, this paper presents a comprehensive survey of the state-of-the-art knowledge on PD mechanism, PD pulse propagation in stator windings, PD signal detection methods and signal processing techniques. Areas for further research are also presented.

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Section: Cross-couplingmentioning

confidence: 79%

Section: Propagation Modesmentioning

confidence: 99%

Section: Propagation Modesmentioning

confidence: 99%

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A Review of Online Partial Discharge Measurement of Large Generators

Luo

Wang³

2017

Energies

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“…There has been a considerable interest in the transient response of conventional rotating electric machines, especially electric motors subjected to steep fronted switching surges [1][2][3][4][5][6][7][8][9][10][11][12]. The propagation of impulses along a machine winding is also of interest for other reasons.…”

Section: Introductionmentioning

confidence: 98%

Coupled FEM and lumped circuit model of the electromagnetic response of coaxially insulated windings in two slot cores

Holmberg

Leijon

2007

Int Trans Elec Energy Syst

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SUMMARYThis paper presents a coupled FEM and lumped circuit modelling approach that is primarily intended for high-frequency and overvoltage simulations of rotating electric machines with coaxially insulated windings, such as Powerformer and Motorformer. The magnetic fields and their interaction with the conductors of the winding are simulated with the aid of a FEM-program. The displacement current and its losses are modelled with an external lumped circuit. To consider eddy current losses, the stranded conductors and the laminated steel cores are replaced by homogeneous bodies with similar losses over a wide frequency range. The approach is illustrated and experimentally verified for a set-up with a cable wound around two slot cores. The model agrees well with measurements up to 1 MHz.

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“…Apparently, the contribution of the magnetic field in the skin layer may not be ignored due to the large relative permeability of the iron , as can be seen from the relatively low velocity of the fast mode. The penetration of the magnetic field into a laminated core is analyzed by Tavner [16]. He concludes that the iron laminations themselves can carry the PD current.…”

Section: A Analysis Of the "Slow Mode" And The "Fast Mode"mentioning

confidence: 99%

Propagation of Partial Discharge Signals in Stator Windings of Turbine Generators

Pemen

Laan

Leeuw

2006

IEEE Trans. On Energy Conversion

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Abstract-We studied the propagation of partial discharge pulses in a stator winding by means of measurements on a dismantled 35-MW generator and found that a stator winding acts as a transmission line. Therefore, a partial-discharge (PD) signal manifests itself at the generator terminals after a transit time that depends on the location of the discharge. Due to capacitive and inductive couplings in the end-winding region, a second propagation mode is present for higher frequencies. This "fast mode" manifests itself at the terminals without appreciable time delay. The capacitive and inductive couplings also cause crosstalk between the phases. As a consequence, a signal measured in one phase does not necessarily originate from a discharge in that phase. The amplitudes of the fast mode and, to a lesser extent, the slow mode (or transmission-line mode) are heavily damped when the discharge occurs further away from the measuring terminal. The consequence is that only discharges close to the measuring terminal can be observed. The propagation of a PD signal is not only influenced by the construction of the generator but also by its external connections.

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Coupling of discharge currents between conductors of electrical machines owing to laminated steel core

Cited by 27 publications

References 2 publications

A Review of Online Partial Discharge Measurement of Large Generators

A Review of Online Partial Discharge Measurement of Large Generators

Coupled FEM and lumped circuit model of the electromagnetic response of coaxially insulated windings in two slot cores

Propagation of Partial Discharge Signals in Stator Windings of Turbine Generators

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