Slot Partial Discharge

Slot discharges are known to have a distinct phase resolved partial discharge pattern for power frequency (50/60 Hz) excitation. These distinct patterns are useful in identifying the presence of slot discharge activity in rotating machines.

  1. Slot Partial Discharge Definition
  2. Slot Partial Discharge Meaning
  3. Slot Partial Discharge Symptoms

Source

  1. In electrical engineering, partial discharge (PD) is a localized dielectric breakdown (DB) (which does not completely bridge the space between the two conductors) of a small portion of a solid or fluid electrical insulation (EI) system under high voltage (HV) stress.
  2. Partial Discharge Monitoring Iris Power Stator Slot Couplers (SSCs) are by far the most sensitive partial discharge sensor in the world since they are installed directly underneath the wedges in high voltage stator slots.
Partial

IEEE Transactions on Dielectrics and Electrical Insulation>2010>17>5>1428 - 1440

Abstract

To improve our understanding of slot partial discharge (PD) mechanisms, an accelerated aging test was initiated two years ago. This long-term experiment is being performed on six stator bars subjected to slot PDs under electrical, thermal and mechanical stresses. It is well known that slot PD activity in air-cooled generators is harmful to the stator winding ground insulation. The degradation induced by slot PDs will modify the physical properties of the surfaces of the cavity where PDs take place and this in turn will influence the slot PD process. To understand the evolution of slot PD activity and the changes in its PRPD (Phased Resolved Partial Discharge) pattern, it is therefore essential to recognize and understand the interdependence between surface modifications and PD signals. This paper presents results of visual observations of stator bar surface degradation, changes in surface conductivity and the effect on the evolution of PD signals in the presence of slot PD activity under conditions of electrical, thermal and mechanical stresses.

Identifiers

journal ISSN : 1070-9878
DOI 10.1109/TDEI.2010.5595544

Authors

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Lévesque, M.

  • Ecole de Technol. Super., Montréal, QC, Canada

Slot Partial Discharge Definition

David, E.

  • Ecole de Technol. Super., Montréal, QC, Canada

Hudon, C.

  • Inst. de Rech. d'Hydro-Quebec IREQ, Varennes, QC, Canada

Bélec, M.

  • Inst. de Rech. d'Hydro-Quebec IREQ, Varennes, QC, Canada

Keywords

Slot Partial Discharge Meaning

statorsageingelectric generatorslife testingmachine insulationmachine testingpartial dischargessurface conductivityslot partial discharge activityaccelerated aging teststator barsair-cooled generatorsstator winding ground insulationphased resolved partial dischargesurface modificationsstator bar surface degradationSurface treatmentBarsInsulationAgingDegradationSurface dischargessemi-conductive coating, temperature, vibration, conductivitySlot partial discharges, generator, stator bars, insulation

statorsageingelectric generatorslife testingmachine insulationmachine testingpartial dischargessurface conductivityslot partial discharge activityaccelerated aging teststator barsair-cooled generatorsstator winding ground insulationphased resolved partial dischargesurface modificationsstator bar surface degradationSurface treatmentBarsInsulationAgingDegradationSurface dischargessemi-conductive coating, temperature, vibration, conductivitySlot partial discharges, generator, stator bars, insulation

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Contribution of Electrical-Thermal Aging to Slot Partial Discharge Properties of HV Motor Windings

Abstract

During the operation of HV motor, the abrasion of stator windings because of vibration caused by electromagnetic force will lead to slot partial discharge (PD). Furthermore, the superheat induced by overcurrent or poor heat dissipation will aggravate the slot PD. To understand the developing process of slot PD and comprehend the influences of aging factors on slot PD properties, two discharge bar models were made under electrical-thermal aging. At triple the rated line-to-earth voltage of 6 kV, two stator bars were aged for 37 days under different temperatures. The slot PD was measured during different aging stages, and visual observations of the insulation and stator core surface were made at the beginning and the end of aging. The experiment results indicate that electrical-thermal aging has a significant impact on the slot PD activities. The slot PD was intense under higher thermal stress, and the surfaces of insulation and stator core were oxidized after the long-time aging. This study can provide a judging basis for fault diagnosis of HV motors.


Publication:
Journal of Electrical Engineering & Technology
Pub Date:
May 2019
DOI:
Slot
10.1007/s42835-018-00076-8
Bibcode:
2019JEET...14.1287K
Keywords:

Slot Partial Discharge Symptoms

  • Electrical-thermal aging;
  • Slot partial discharge properties;
  • HV motor windings