Partial Discharge (PD), as its name would suggest, is an electrical discharge that occurs across a portion of the insulation between two conducting electrodes, without completely bridging the gap. PD’s are caused when there is a discontinuity in the insulation system and as a general ‘rule-of-thumb’ PD will occur in systems operating at voltages of 3000V and above (although it should be noted that PD can occur at lower voltages than this). Partial discharges can occur in voids in solid insulation (paper, polymer etc), along the interfaces of multi-layer solid insulation systems, in gas bubbles in liquid insulation or around an electrode in a gas (corona discharge). Partial Discharge activity can initiate under normal working conditions in high voltage equipment where the insulation condition has deteriorated with age, has been aged prematurely by thermal or electrical over-stressing or due to improper installation (this leads to ‘infant mortality’).
PD can often be observed with the commissioning of new equipment due to improper installation, poor design and/or workmanship (this is seen particularly in cable joints and terminations which are made-up on site). It is known that poor workmanship can lead to ‘infant mortality’ of MV/HV networks with a disproportionate percentage of insulation failures being observed within the first 1-3 years of service compared to the rest of the service life of the cables/plant.
PURPOSE
1. To understand the basics of stator winding insulation systems and
why they deteriorate
2. To understand basic Corona and Partial Discharge theory
3. To understand how Partial Discharge detection devices work
4. To interpret the test data collected and relate the data to
specific failure mechanisms, to enable you to plan maintenance
WHO SHOULD ATTEND
1. Engineers working in HV department, in transmission and
distribution
2. Maintenance engineers working in HV equipments
3. Senior technicians working in HV equipments
OUTLINE MATERI
1. Introduction to Corona and Partial Discharge
2. Diagnostics Corona and Partial Discharge for High Voltage Equipment
3. Equipment failure mechanisms
4. Conventional and unconventional test techniques
5. On-line and Off-line methods
6. How to test different items of plant
7. Deployment of Corona and Partial Discharge Testing in Asset Management Programs
8. Ageing population problem
9. Focus plant replacements/avoid unplanned outage
10. Increasing failure rate or problem with a particular plant type
11. Troubleshooting and failure investigations
12. Safety (mostly with cable terminations and sealing ends/outdoor HV plant)
13. Quality Assurance
14. Corona and Partial Discharge Testing, and Diagnostics for MV and HV Cables
15. Introduction to test methodologies
16. PD Location methods
17. Assessing criticality
18. PD Testing and Diagnostics for MV Switchgear
19. Partial Discharge Testing and Diagnostics for Motors and Generators
20. Introduction to Online PD Testing of HV Motors and Generators
21. Recognizing Phase-Resolved PD (PRPD) Patterns
22. Assessing criticality
23. Case studies
METHOD
Presentation
Discussion
Case Study
Evaluation
