Partial discharge

About: Partial discharge is a research topic. Over the lifetime, 13997 publications have been published within this topic receiving 102058 citations. The topic is also known as: PD.

Silent discharge type pulse laser device

Abstract: A silent discharge type pulse laser device having a pair of opposing electrodes, at least one of which is an electrode covered by a dielectric, which is mounted opposite to a metallic electrode with a silent discharge space in between, a laser resonator consisting of a total reflection mirror and a partial reflection mirror mounted opposite to each other with the silent discharge section in between, a source of high frequency voltage for supplying to the pair of electrodes a high frequency voltage having a predetermined period for silent discharge, and a controller for controlling the high frequency voltage from the source with respect to a first interval and a second interval that form a period longer than the period for silent discharge. The high frequency voltage is supplied to the silent discharge section at a first peak voltage value during the first interval and at a second peak voltage value during the second interval, wherein the second peak voltage value is sufficient to cause a discharge but insufficient to excite laser oscillation.

Novel frequency domain based technique to detect incipient stator inter-turn faults in induction machines

Abstract: Traditionally, for medium and high voltage motors and generators, condition based monitoring (CBM) of stator faults are performed by measuring partial discharge (PD) activities. For low voltage machines, negative sequence impedance or currents are measured for the same. Such prognosis schemes should be carefully implemented as supply voltage unbalance, manufacturing related asymmetry, etc. also produce negative sequence voltages. A few motor current signature analysis (MCSA) based approaches have already been proposed to detect stator inter-turn faults. However little or no physical insight was provided to explain the occurrence of certain harmonics in the line current or the influence of voltage unbalance on these harmonics. Also, in at least one of the papers, a large portion of the stator winding was shorted to emulate the faults. The method proposed in this paper monitors certain rotor slot related harmonics at the terminal voltage of the machine once it is switched off. In the absence of supply voltage, issues such as voltage unbalance and time harmonics do not influence the measurements except as initial conditions; a very desirable feature when the machine is fed from an adjustable speed drive. Satisfactory simulation and experimental results have been obtained with only about 1.5% (5/324) of the total number of turns shorted.

DC corona discharge ozone production enhanced by magnetic field

Abstract: We have studied the effect of a stationary magnetic field on the production of ozone from air at atmospheric pressure by a negative corona discharge in a cylindrical electrode configuration. We used a stainless steel hollow needle placed at the axis of the cylindrical discharge chamber as a cathode. The outer wall of the cylinder was used as an anode. The vector of magnetic induction was perpendicular to the vector of current density. We found that: (a) the magnetic field extends the current voltage range of the discharge; (b) for the discharge in the Trichel pulses regime and in the pulseless glow regime, the magnetic field has no substantial effect on the discharge voltage or on the concentration of ozone that is produced; (c) for the discharge in the filamentary streamer regime for a particular current, the magnetic field increases the discharge voltage and consequently an approximately 30% higher ozone concentration can be obtained; (d) the magnetic field does not substantially increase the maximum ozone production yield. A major advantage of using a magnetic field is that the increase in ozone concentration produced by the discharge can be obtained without additional energy requirements.

Understanding Partial Discharge Behavior from the Memory Effect Induced by Residual Charges: A Review

Abstract: Residual charges produced in previous partial discharges (PDs) are considered as one aspect of memory effects that affect subsequent discharge behavior. In this paper, we review past studies about memory effects induced by residual charges during successive PDs. At first, surface charge dynamics for cavity and needle-to-dielectric discharges are presented. Subsequently, three methods used to unravel the memory effects are described, e.g. conditional distribution, pulse sequence analysis (PSA) and chopped PD (CPD). Then effects of residual charges on PD inception, discharge propagation and collective behavior are summarized. In addition, contributions of residual charges to the transitions between discharge modes and discharge patterns are presented. At last, some problems relevant to the memory effects are discussed, followed by suggestions for future work.

Pattern formation and boundary effect in dielectric barrier glow discharge.

Abstract: In this paper, we report the experimental results on the characteristics of plasma patterns with different planar electrode shapes in dielectric barrier glow discharge. The formation and the evolution of the discharge patterns at different voltages were investigated. The results show that the plasma patterns in this glow-barrier system form at the beginning of the discharge pulse. The limited size of planar electrodes and the electric field distribution are important factors for the pattern formation.