A useful PD result needs context: the asset, measurement arrangement, background interference and the question being investigated. The choice between online and offline assessment starts with that question.
What is online PD testing?
Online measurements are taken while the asset is operating. They can support a survey or monitoring programme when suitable sensors, connections and site access are available. “Online” does not mean every part of the work is possible without an outage; installing sensors can require separate arrangements.
What is offline PD testing?
Offline testing takes place with the asset removed from normal service and connected to an appropriate test arrangement. The test plan defines the applied voltage, measurement configuration and assessment criteria.
What needs to be agreed?
| Planning question | Online | Offline |
|---|---|---|
| Asset condition | Operating during measurement. | Removed from service for testing. |
| Access | Check sensors and connection points. | Plan isolation, connections and test supply. |
| Context | Record load and operating conditions. | Record voltage, configuration and test conditions. |
Which approach should you request?
Describe the decision you need to make before specifying an instrument. Include asset information and outage constraints so the engineering team can assess the options. Methods, standards and criteria must match the asset and project specification.
DigiStano provides partial discharge testing across the UAE, Saudi Arabia, Oman, Qatar and Bahrain. Use our project checklist to prepare your enquiry.