Online Partial Discharge (OLPD) testing provides valuable information for condition-based asset management. Over 80% of power equipment failures and losses are attributed to insulation failures. Conventional tan delta, infrared, and DGA testing is very effective at discovering a portion of the problems which lead to failures. The remaining unexpected failures are the result of localized insulation defects which are not detected by tan delta measurements, they do not produce significant heat, and they do not produce dissolved gasses unless the defect is in oil. OLPD testing is the methodology of detecting and locating these common insulation problems. It can conveniently be performed online while the power system is energized and in service. OLPD testing time varies depending on the type of asset under inspection. OLPD tests can be  conducted on Transformers, both internally and externally, including the bushings, utilizing all types of sensors use by our equipment.  Additionally, every insulator and insulating material in any power apparatus, in the entire substation can quickly and conveniently be screened for PD. Every switch, lightning arrestor, PT, CT, SF6 breaker, cable termination and splice can all be tested in a short time. OLPD is the future of power testing and PMDT is the company dedicated to the manufacture of powerful, efficient test and diagnostic instruments, providing expert PD test services, and engineering support.  

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In-Service Substation Testing and Inspection Solutions

PD          IR           1st Trip

•PD Partial Discharge inspections identify insulation defects in solid or fluid dielectrics, surface tracking, corona, arcing, internal PD, voids, and floating electrodes. Partial discharges are very short and confined electrical discharges which give produce electromagnetic signals, induced electrical signals and, acoustic emissions which can be detected non-invasively. PD also causes thermal, physical and chemical changes in the insulating material. PD can also occur on a conductor such as a bus bar, or at the interface between insulation, semi-conductor, and conductors.  

 

•IR Infrared Thermography find many defects in conductors which cause abnormal release of thermal energy. 

• 1st Trip: Circuit breaker mechanism issues can be identified by measuring coil currents and operation times.