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Partial Discharge Testing

Partial Discharge Testing | FamilyImage
Partial Discharge Testing | FeatureInfographics

When an electrical failure happens, the results can be catastrophic. Most electrical failures occur because of insulation breakdown due to small electrical sparks known as partial discharge. Vertiv’s partial discharge (PD) testing and monitoring provide early warning of impending failure. Through data collection and analysis you are able to make strategic decisions about repairing or replacing your electrical equipment.


  • Site visit and pre-screening services evaluate your electrical infrastructure to indentify and prioritize equipment for PD testing
  • Online PD testing provides a non-destructive, inexpensive testing option that can be performed while your equipment is energized at normal operating voltages
  • Permanently mounted sensors in hard-to-access equipment and areas facilitate safer, more efficient PD detection
  • Periodic PD testing uses a portable monitor to conduct continuous monitoring ranging from one hour up to three months
  • Continuous online monitoring delivers continuous and accurate information on the condition and capability of the most critical assets in your system
  • Ultrasonics are used in conjunction with other PD testing technologies to increase the reliability of detection by identifying sound waves that are produced when problems occur in electrical equipment
  • Offline PD testing measures a system’s response to a specific stress level, predicts its future performance without causing a fault, and can pinpoint the exact defect location on field-aged equipment
  • Tan-delta testing is a powerful offline test that measures the deterioration of insulation, detects water trees, and predicts the life expectancy of assets by comparing periodic readings
  • Very low frequency (VLF) testing is a go/no-got test that checks the AC integrity of an electrical asset


  • Fewer catastrophic failures or unplanned outages are due to early identification of PD
  • Increased electrical system availability occurs when failure-causing PD is remedied
  • Improved operating efficiency is achieved when electrical systems are free of PD that causes insulation breakdown
  • Reduced maintenance costs are possible as PD testing helps prioritize equipment requiring maintenance or repair
  • Improved risk management happens when PD is regularly monitored and addressed prior to probable failure

Brochures and Data Sheets