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# IEE Proceedings - Science, Measurement and Technology

Includes the top 50 most frequently accessed documents for this publication according to the usage statistics for the month of

• ### Circulating-current loss in transformer windings

Publication Year: 1998, Page(s):136 - 140
Cited by:  Papers (5)
| | PDF (448 KB)

Circulating-current loss in stranded windings of transformers has always attracted the attention of transformer designers. Analytical formulae based on the axial leakage field have long been used by designers for the calculation of circulating-current loss. The authors discuss these analytical formulae and compares them with 2-D finite element method (FEM) analysis, highlighting the errors involve... View full abstract»

• ### Method for RMS and power measurements based on the wavelet packet transform

Publication Year: 2002, Page(s):60 - 66
Cited by:  Papers (26)
| | PDF (659 KB)

The study provides the theoretical basis for the use of the wavelet packet transform (WPT) method for RMS and power/energy measurements. The proposed method can simultaneously measure the distribution of RMS quantities and power with respect to individual frequency bands directly from the wavelet transform coefficients associated with the concurrent voltage-current pair. Their dependent quantities... View full abstract»

• ### Degradation of cellulosic insulation in power transformers. Part 3: effects of oxygen and water on ageing in oil

Publication Year: 2000, Page(s):115 - 119
Cited by:  Papers (69)
| | PDF (336 KB)

Heat, water and oxygen accelerate the degradation of cellulose insulation in electrical transformers. Their effects on insulation have been studied over a number of years using degree of polymerisation (DP) of the paper as a measure of ageing. Results are reported of a systemic study to measure the relative effectiveness of each component individually and in combination, on ageing in oil in a thre... View full abstract»

• ### Circulating current and hysteresis losses in screens, sheaths and armour of electric power cables-mathematical models and comparison with IEC Standard 287

Publication Year: 1997, Page(s):101 - 110
Cited by:  Papers (4)
| | PDF (1004 KB)

Computation of the current carrying capacity of a cable involves evaluation of electrical and thermal parameters of the circuit. Formulas for the calculation of these parameters are summarised in Standard No. 287 published by the International Electrotechnical Commission (IEC). The first edition of this Standard was issued in 1969 and the latest revision in 1994/5. The formulas for the computation... View full abstract»

• ### Optimal battery energy storage system (BESS) charge scheduling with dynamic programming

Publication Year: 1995, Page(s):453 - 458
Cited by:  Papers (32)  |  Patents (7)
| | PDF (628 KB)

A dynamic programming algorithm for the optimal charge/discharge scheduling of BESS energy storage is presented. It ensures the minimisation of the electricity bill for a given battery capacity, while reducing stress on the battery and prolonging battery life. Optimal scheduling of the battery charge state is in itself unique; the methods of multipass dynamic programming are used to accomplish thi... View full abstract»

• ### Low measurement uncertainties in the frequency range 30 MHz to 1 GHz using a calculable standard dipole antenna and national reference ground plane

Publication Year: 1996, Page(s):221 - 228
Cited by:  Papers (14)
| | PDF (776 KB)

Using a pair of calculable standard dipole antennas above a large specially constructed ground plane it is demonstrated over the frequency range of 30-500 MHz that the antenna factor can be attributed to the standard antenna with an uncertainty as low as ±0.1 dB. The uncertainty is derived from a comparison of measured and predicted insertion loss between two antennas. The insertion loss an... View full abstract»

• ### Design theory of thermoelectric modules for electrical power generation

Publication Year: 1996, Page(s):351 - 356
Cited by:  Papers (14)
| | PDF (580 KB)

One of the main requirements in the design of a thermoelectric module is to determine the optimum module geometry, based upon available thermoelectric material and manufacturing technology, which meets the given application specifications. In order to assist in determining the appropriate module geometry for thermoelectric generation, its relationship to the power output and conversion efficiency ... View full abstract»

• ### European intercomparison of antenna factors in the frequency range 30 MHz to 1 GHz

Publication Year: 1996, Page(s):229 - 240
Cited by:  Papers (7)
| | PDF (964 KB)

In January 1993 an intercomparison exercise began in which 15 laboratories from nine European countries participated in the measurement of six antennas. The antenna factor and reflection coefficient were measured at a selection of frequencies in the range 30 MHz to 1 GHz. The project was sponsored by the European Commission under its BCR programme, with NPL as the pilot laboratory. The main purpos... View full abstract»

• ### Review of radio frequency microelectromechanical systems technology

Publication Year: 2004, Page(s):93 - 103
Cited by:  Papers (29)  |  Patents (15)
| | PDF (498 KB)

A review of radio frequency microelectromechanical systems (RF MEMS) technology, from the perspective of its enabling technologies (e.g. fabrication, RF micromachined components and actuation mechanisms) is presented. A unique roadmap is given that shows how enabling technologies, RF MEMS components, RF MEMS circuits and RF microsystems packaging are linked together; leading towards enhanced integ... View full abstract»

• ### Review of chemical indicators of degradation of cellulosic electrical paper insulation in oil-filled transformers

Publication Year: 1994, Page(s):324 - 334
Cited by:  Papers (109)  |  Patents (1)
| | PDF (840 KB)

Chemical and thermal degradation of electrical insulation in oil-filled transformers, mechanisms of failure and methods of condition monitoring and of life prediction are reviewed. An insulation life prediction model is developed and estimates of insulation life are presented under a variety of oil/paper conditions. Systematic measurements of the concentration of chemical indicators in transformer... View full abstract»

• ### Phenomenon of sympathetic interaction between transformers caused by inrush transients

Publication Year: 1995, Page(s):323 - 329
Cited by:  Papers (21)
| | PDF (524 KB)

In power systems with appreciable resistance, the transformers already connected to the supply system can experience unexpected saturation during the inrush transient of an incoming transformer. This saturation, which is established by the asymmetrical voltage drop across the system resistance caused by the inrush current, demands offset magnetising currents of high magnitude in the already connec... View full abstract»

• ### Impact of technology on the defeat of the U-boat September 1939-May 1943

Publication Year: 1994, Page(s):343 - 355
Cited by:  Papers (1)
| | PDF (1384 KB)

From the 3rd September 1939 to 31st May 1943 the Allies lost 11576000 tonnes of shipping. Although the great destructive power of U-boats had been demonstrated during the First World War the essential lesson to be learnt (the need for huge air and sea escort forces) was incapable of being implemented at the outbreak of the Second World War. The expectation that ASDIC (a submarine location system d... View full abstract»

• ### Short-time Fourier and wavelet transforms for fault detection in power transformers during impulse tests

Publication Year: 1998, Page(s):77 - 84
Cited by:  Papers (26)
| | PDF (1568 KB)

A novel approach using the short-time Fourier transform and wavelet transform (time frequency analysis tools) for fault detection during impulse testing of power transformers is described. The neutral and/or capacitively transferred currents which are recorded during an impulse test can be directly analysed with this approach. These currents are considered to be evolving in time, i.e. as nonstatio... View full abstract»

• ### Arc erosion behaviour of silver electric contacts in a single arc discharge across a static gap

Publication Year: 2001, Page(s):8 - 14
Cited by:  Papers (17)
| | PDF (1220 KB)

Static-gap electrical erosion experiments are conducted using an iron needle cathode and silver anode, where the gap distance can be adjusted with high precision and high accuracy. The effects of supply voltage and gap distance on the arc erosion behaviour are investigated in a single arc discharge. Results show that the air breakdown occurs at 70 V/μm up to 175 V, at 330 V at 10 μm, and 500... View full abstract»

• ### Computational algorithms for linear variable differential transformers (LVDTs)

Publication Year: 1997, Page(s):189 - 192
Cited by:  Papers (7)
| | PDF (336 KB)

The authors present an equivalent magnetic circuit for a solenoid linear variable differential transformer. Using magnetic circuit theory, the calculations for its magnetic circuit reluctance, mutual inductance, output voltage and sensitivity are provided. Experimental tests are used to verify the calculations View full abstract»

• ### Manufacturing variation of the measuring tube in a Coriolis flowmeter

Publication Year: 2004, Page(s):201 - 204
| | PDF (1337 KB)

To achieve an increase in robust design for Coriolis flowmeters a numerical model is developed. This uses finite-element (FE) methods and starts from direct-coupled fluid-tube equations of motion using a Timoshenko beam element with two nodes and six degrees of freedom for each node. It is solved using ANSYS MATRIX27 elements. The FE solution is compared with analytical solutions and found to be i... View full abstract»

• ### Inductance and resistance calculations for isolated conductors

Publication Year: 2005, Page(s):7 - 14
Cited by:  Papers (1)
| | PDF (673 KB)

Various analytical and numerical calculation methods for computing the high-frequency and low-frequency inductance and resistance of isolated conductors are reviewed. The high-frequency estimates are obtained using conformal mapping theory. In both cases, a uniformly distributed return current at an arbitrary radius is assumed. Formulae are presented for the inductance of a strip conductor of zero... View full abstract»

• ### Partial discharge detection: theoretical and practical aspects

Publication Year: 1995, Page(s):29 - 36
Cited by:  Papers (26)
| | PDF (592 KB)

The phenomenon of electricification by electrostatic induction is introduced. This fundamental approach allows the concepts of Poissonian and Laplacian induced charge to be clearly developed. These concepts form the necessary basis for partial discharge detection analysis. Thereafter a quantitative theory is developed. This field-theoretical approach furnishes the correct input parameters for the ... View full abstract»

• ### Comparison of analytic, numerical and approximate models for shielding effectiveness with measurement

Publication Year: 1998, Page(s):61 - 66
Cited by:  Papers (21)
| | PDF (496 KB)

The authors present a comparison between different estimates of the shielding effectiveness (SE) of cavities containing apertures and predictions made using a rigorous variational solution. Although the rigorous solution is computationally intensive, the method can be used as a standard against which more practical approximations, numerical methods and laboratory measurements can be compared. SE p... View full abstract»

• ### Degradation of cellulosic insulation in power transformers .4. Effects of ageing on the tensile strength of paper

Publication Year: 2000, Page(s):285 - 290
Cited by:  Papers (47)
| | PDF (500 KB)

For pt.3 see ibid., vol.147, no.3, p.115-19, 2000. Evidence for transformer failures related to insulation failure indicates that the primary cause is normally mechanical failure/loss of integrity due to loss of mechanical strength as a result of degradation. The paper investigates the primary causes of loss of strength of paper during ageing under accelerated conditions in insulating oil. The lat... View full abstract»

• ### Electric field breakdown at micrometre separations in air and nitrogen at atmospheric pressure

Publication Year: 2000, Page(s):261 - 265
Cited by:  Papers (14)
| | PDF (812 KB)

For efficient operation, micromotors and microactuators, such as those employed in microsystems, are required to operate with high electric fields at electrode separations of the order of micrometres. An apparatus was built to accurately measure the breakdown voltage for electrode spacings as low as 0.5 μm. Breakdown voltage measurements in air and nitrogen are presented and discussed for the g... View full abstract»

• ### Soil ionisation under lightning impulse voltages

Publication Year: 2004, Page(s):343 - 346
Cited by:  Papers (5)
| | PDF (275 KB)

Experiments have been carried out to study soil ionisation and the variation of the critical ionisation gradient against the soil resistivity. Compared with relevant experimental results of other researchers a satisfactory convergence has been proved. An accurate estimation of the critical ionisation gradient has been achieved, of the order of 200 kV/m, following the finding that the critical volt... View full abstract»

• ### Capacitance and charge distribution of two cylindrical conductors of finite length

Publication Year: 1997, Page(s):280 - 286
Cited by:  Papers (5)
| | PDF (516 KB)

The authors present a method of finding the effect of fringing on capacitance and charge distribution of conducting structures consisting of coaxial cylinders or of parallel cylinders of identical diameter, each of finite and equal length. The moment method, employing pulse and delta functions as the basis and testing functions, respectively, is used for the analysis. Numerical data on charge dist... View full abstract»

• ### Degradation of epoxy resin by partial discharges

Publication Year: 2000, Page(s):97 - 104
Cited by:  Papers (19)
| | PDF (608 KB)

Epoxy resins are used in the production of high-voltage insulation components. Partial discharges, inherent in high-voltage installations, degenerate the resinous material and cause degradation of the insulation thus reducing the working life of the component, An understanding of the nature of the chemical changes taking place under partial discharge stressing should allow the production of improv... View full abstract»

• ### Pulse-sequence analysis: a new method for investigating the physics of PD-induced ageing

Publication Year: 1995, Page(s):95 - 101
Cited by:  Papers (31)
| | PDF (448 KB)

A new method is presented of partial discharge data analysis for the investigation of space charge and degradation phenomena in high-voltage insulation systems. The basic principles of the pulse-sequence-analysis (PSA) are illustrated and the characteristic differences with regard to standard procedures that have been established during the past few years are outlined. A description is given of an... View full abstract»

• ### Electrostatic separation of metals and plastics from granular industrial wastes

Publication Year: 2001, Page(s):47 - 54
Cited by:  Papers (40)
| | PDF (1284 KB)

Recycling of metals and plastics from wastes is one of the major applications of the electrostatic separation technologies. The paper analyses the multitude of factors that affect the efficiency of this technique, to establish design principles and formulate operation recommendations. The theoretical analysis of corona and induction charging of, respectively, insulating and conducting particles al... View full abstract»

• ### Towards a piezoelectric vibration-powered microgenerator

Publication Year: 2001, Page(s):68 - 72
Cited by:  Papers (44)  |  Patents (10)
| | PDF (500 KB)

As MEMS and Smart Material technologies advance, embedded and remote applications are becoming more widespread. Powering these systems can be a significant engineering problem, as traditional solutions such as batteries are not always appropriate. An inertial generator is developed that uses thick-film piezoelectric technologies to produce electrical power from vibrations in the environment of the... View full abstract»

• ### Acoustic fields from PVDF interdigital transducers

Publication Year: 1998, Page(s):250 - 259
Cited by:  Papers (5)  |  Patents (3)
| | PDF (1076 KB)

Interdigital transducers (IDTs) made from the piezoelectric polymer PVDF have been built; they transmit ultrasonic Lamb waves into 1-2 mm thick steel and aluminium plates and receive signals reflected from features in the structure. The IDTs are designed to be permanently bonded to the structure under inspection. Such IDTs have considerable potential for use in smart-structure monitoring applicati... View full abstract»

• ### Classification of partial discharge events in gas-insulated substations using wavelet packet transform and neural network approaches

Publication Year: 2006, Page(s):55 - 63
Cited by:  Papers (4)
| | PDF (469 KB)

To ensure the safe and reliable operation of a gas-insulated substation (GIS), it is crucial to quickly identify partial discharge (PD) sources to prevent the occurrence of breakdowns. A method based on wavelet packet transform techniques is developed to meet this requirement. The proposed method extracts is able to extract features from ultra-high frequency resonance signals measured from a test ... View full abstract»

• ### Partial discharge plant-monitoring technology: present and future developments

Publication Year: 1995, Page(s):4 - 10
Cited by:  Papers (39)
| | PDF (680 KB)

The paper discusses the role of partial discharge measurement in the conditioning monitoring of power plant. Following a discussion of recent developments in partial discharge detection and measurement technologies, the problems and challenges for the future in the different technologies are analysed and discussed. For those unfamiliar with partial discharge detection as a condition monitoring too... View full abstract»

• ### Measurement of the wet-mass, moisture content, volume and density of single wheat grain kernels

Publication Year: 2004, Page(s):384 - 388
Cited by:  Papers (1)
| | PDF (333 KB)

The development of microwave techniques and a separate gas displacement method to measure the wet-mass, moisture content, volume and hence density of single wheat grain kernels are described. The perturbation of the circularly symmetric TM010 mode inside a cylindrical cavity is used with a linear model to determine the single grain moisture content and wet-mass. A bellows loading mechan... View full abstract»

• ### Huygens' principle in electromagnetics

Publication Year: 1996, Page(s):103 - 105
Cited by:  Papers (2)
| | PDF (296 KB)

A simple way of deriving Huygens' principle in electromagnetic and transmission-line theory is given without recourse to Green's functions and Green's formulas. Huygens' principle is derived for the electromagnetic fields simply by truncating Maxwell's equations. The same is done for the voltage and current in a transmission line by truncating the telegrapher's equations. Some simple consequences ... View full abstract»

• ### Review of claimed enhanced lightning protection of buildings by early streamer emission air terminals

Publication Year: 1997, Page(s):1 - 10
Cited by:  Papers (4)
| | PDF (1160 KB)

Simple air terminals are earthed conducting objects able to launch a connecting streamer or leader discharge that intercepts a downward lightning leader discharge and diverts to itself the lightning strike. Early streamer emission (ESE) air terminals are claimed to initiate the connecting streamer earlier in time than would a simple air terminal in the same position, and are therefore claimed to b... View full abstract»

• ### Generalised TLM switch model for power electronics applications

Publication Year: 1998, Page(s):101 - 104
Cited by:  Papers (3)
| | PDF (340 KB)

A generalised model of a switch suitable for power electronic circuits simulation, based on the transmission-line modelling or matrix (TLM) method, is presented. It consists of an inductive stub model terminated by a resistance having a small or large value depending on whether the switch is on or off, respectively. In the previous TLM switch model, a series resistance is always required to be add... View full abstract»

• ### Phase-variable model of PM synchronous machines for integrated motor drives

Publication Year: 2004, Page(s):423 - 429
Cited by:  Papers (21)
| | PDF (617 KB)

In a phase-variable model of PM synchronous motors and its implementation in integrated motor drive simulations the stator winding inductances and the three-phase flux linkages contributed by permanent magnets are considered as rotor-position dependent. The first-mentioned is calculated by an energy perturbation method using FE solutions, the second is obtained through FE analysis without applying... View full abstract»

• ### Tests of the early streamer emission' principle for protection against lightning

Publication Year: 1998, Page(s):200 - 206
Cited by:  Papers (4)
| | PDF (676 KB)

Experiments are described which are designed to test two devices based on the early streamer emission' (ESE) principle, for lightning protection, against the traditional Franklin rod. In all three cases, the device was subjected to a steady negative electric field from a sphere, simulating the field beneath a thundercloud, prior to application of a superimposed negative impulse field, simulating ... View full abstract»

• ### Prior-online iteration for image reconstruction with electrical capacitance tomography

Publication Year: 2004, Page(s):195 - 200
Cited by:  Papers (19)  |  Patents (1)
| | PDF (1880 KB)

Electrical capacitance tomography (ECT) has been developed for imaging dielectric material distributions. While iterative image reconstruction algorithms may produce high-quality images, they are regarded as being time-consuming and currently can only be used offline. This paper describes a new image reconstruction algorithm for ECT. First, a coefficient matrix is generated through an offline iter... View full abstract»

• ### Signal-to-noise ratios in recorded patterned media

Publication Year: 2003, Page(s):232 - 236
| | PDF (328 KB)

The replay flux from isolated and sequences of recorded patterned elements was analysed and analytical expressions for the replay spectra were derived. The noise arising from bit size variations and bit position jitter has been modelled analytically allowing expressions for the signal-to-noise ratio for patterned media to be presented. View full abstract»

• ### UHF couplers for gas-insulated substations: a calibration technique

Publication Year: 1997, Page(s):117 - 122
Cited by:  Papers (10)
| | PDF (596 KB)

Methods that have been used to evaluate the performance of UHF couplers for partial discharge monitoring of gas-insulated substations are briefly reviewed, illustrating the need for a standard test procedure. A measurement scheme is proposed in which the coupler is mounted beneath an aperture in a ground plane and subjected to an incident electric field of known intensity. A TEM line is used to ev... View full abstract»

• ### New AC-based capacitance tomography system

Publication Year: 1999, Page(s):47 - 53
Cited by:  Papers (66)  |  Patents (1)
| | PDF (512 KB)

Electrical capacitance tomography (ECT) is a new technology that is used to visualise the internal behaviour of industrial processes comprising dielectric components. A particular difficulty with capacitance measurement for tomography is that the stray capacitance to earth of an ECT sensor is large (~150 pF) compared with the interelectrode capacitance to be measured (usually <0.5 pF), and the ... View full abstract»

• ### Modelling losses in electrical steel laminations

Publication Year: 2002, Page(s):218 - 221
Cited by:  Papers (7)
| | PDF (356 KB)

The possibility of obtaining a voltage-driven solution of the diffusion equation by using a history-dependent hysteresis model based on the transplantation principle and a model for excess loss simulation derived from the Landau-Lifshitz-Gilbert equation for magnetic viscosity is presented. The proposed solver appears to be more versatile than existing models and can predict the total losses under... View full abstract»

• ### Review of arcing phenomena in low voltage current limiting circuit breakers

Publication Year: 2001, Page(s):1 - 7
Cited by:  Papers (20)
| | PDF (744 KB)

Low voltage current limiting circuit breakers referred to as miniature circuit breakers (MCBs) are widely used for electrical fault protection in domestic and light industrial installations. Modern designs employ current limiting technology where the arc is forced rapidly away from the contacts through an arc chamber and into a set of splitter plates. The motion of the arc is dependent on a comple... View full abstract»

• ### Vector measurement of modulated RF signals by an in-phase and quadrature referencing technique

Publication Year: 2006, Page(s):210 - 215
Cited by:  Papers (8)
| | PDF (680 KB)

Vector measurements of modulated RF signals are demonstrated using a sampling oscilloscope with in-phase and quadrature referencing. Certain sampling oscilloscope designs exhibit sub-picosecond time-correlation between channels. This correlation allows independent referencing of the carrier frequency and the modulation signals. This measurement technique, which can be implemented using simple RF c... View full abstract»

• ### Electromagnetic compatibility in the automotive environment

Publication Year: 1994, Page(s):252 - 258
Cited by:  Papers (9)
| | PDF (536 KB)

Modern automotive vehicles depend increasingly on sophisticated electronic control systems to enhance driver comfort and vehicle safety. Radiated immunity testing of cars to field strength levels of the order of 50 V m-1 has been an important part of the vehicle development process for the last decade because of the harsh environment encountered and the safety-related nature of the cont... View full abstract»

• ### Analysis of neural and fuzzy-power electronic control

Publication Year: 1997, Page(s):25 - 33
Cited by:  Papers (17)
| | PDF (864 KB)

Current-controlled voltage-source inverters offer substantial advantages in improving motor-system dynamics for high-performance AC-drive systems. The controller switches follow a set of reference current waveforms. Fixed-band hysteresis and sinusoidal-band hysteresis controllers have been studied. Neural network and fuzzy-logic-based current-controlled voltage-source inverters are developed. The ... View full abstract»

• ### Degradation of cellulosic insulation in power transformers. Part 2: formation of furan products in insulating oil

Publication Year: 2000, Page(s):110 - 114
Cited by:  Papers (50)
| | PDF (372 KB)

The analysis of furan degradation products in transformer oil provides a complementary technique to dissolved gas analysis for monitoring transformer condition. The main products of the ageing are 2-furfuryl alcohol, 2-furaldehyde (furfural), 2-acetylfuran and 5-methylfurfural and are formed from wood-based paper (containing lignin and hemicellulose), cotton-based paper and pure cotton linters in ... View full abstract»

• ### Modelling partial discharge inception and extinction voltages of sheet samples of solid insulating materials using an artificial neural network

Publication Year: 2002, Page(s):73 - 78
Cited by:  Papers (5)
| | PDF (657 KB)

This work attempts an estimation of partial discharge inception and extinction voltages (PDIV and PDEV) of sheet samples of solid dielectrics due to void inclusions of different sizes using an ANN. The effect of void dimensions and also the dielectric thickness of three common insulating materials, namely, Leatherite paper, polyethylene film and Perspex sheets on PDIVs and PDEVs are examined. Furt... View full abstract»

• ### Optimisation of a switched reluctance motor using experimental design method and diffuse elements response surface

Publication Year: 2004, Page(s):411 - 413
Cited by:  Papers (3)
| | PDF (714 KB)

The experimental design method is applied to the construction of a response surface based on diffuse elements as preliminary steps in the optimisation process of the magnetic torque of a switched reluctance motor. The experimental design method is used to find and choose the most significant parameters related to the magnetic torque of the motor, reducing the number of parameters to be optimised. ... View full abstract»

• ### Measuring voltage response: a non-destructive diagnostic test method of HV insulation

Publication Year: 1999, Page(s):249 - 252
Cited by:  Papers (30)
| | PDF (392 KB)

In insulation materials several chemical and physical deterioration processes arise, such as thermal and electrical ageing, and moistening, due to operational and environmental stresses. As well as electrical strength, these deterioration processes influence the dielectric processes, the conduction and the polarisation of the insulation. The dielectric strength of insulation cannot be determined w... View full abstract»

• ### An approach to partial-discharge investigation by height-distribution analysis

Publication Year: 1995, Page(s):102 - 108
Cited by:  Papers (16)
| | PDF (480 KB)

Results of partial-discharge measurements, performed on insulation systems of rotating machines, are processed referring to the Weibull statistics. It is shown that the partial-discharge height distribution fit the two-parameter Weibull function when partial discharges having the same origin occur, whereas deviations from the Weibull plot are detected in the presence of various simultaneous partia... View full abstract»