Non-invasive tool for online PD measurements in MV and HV substations
- Large colour touch-screen for easy operation
- Dual channel system for direct comparison between two sensors
- Synchronises with power frequency via internal, mains or external sensor for PRPD pattern recognition
Component failure in a substation has serious repercussions. It has the potential to cause injury, damage and unplanned outages, which result in significant disruption and cost. Predictive condition assessment aims to identify faults developing in electrical equipment so that they can be addressed before failure.
The UHF PD Detector is the ideal tool for quick, non-invasive surveys in MV and HV substations and should be part of the toolkit for all maintenance and service teams. Due to its high measurement bandwidth, the UHF method provides accurate local online partial discharge (PD) measurements on HV components such as cable end-terminations, surge arrestors, voltage transformers and isolators.
Dual measurement channels allow two phases or two types of UHF sensors to be compared, which further increases the scope of use of the UHF Detector. MV switchgear surveys can also be carried out using the radio frequencies in combination with the wide selection of TEV and HFCT sensors. The phase resolved PD pattern (PRPD) display helps to identify type of defect and, importantly, differentiate the noise from the PD signal. Noise can affect PD readings, leading to a false interpretation of the results and unnecessary component replacement. The noise handling capability of the Megger UFH PDD ensures a true reading of PD, eliminating false positives, so only failing component are identified for replacement.
The handheld unit can either be operated using a keypad or using the large 6” colour touch-screen. It has a battery life of over 10 hours. Its mix of features and performance make the UHF detector the most cost effective unit of its kind.
APPLICATION NOTE - UHF PD diagnosis at high voltage cable terminations
D. Gotz, H.T. Putter; Megger, Germany
Introduction: High voltage terminations are essential components in high voltage cable systems. Great reliability is provided by high manufacturing quality and company type testing. However onsite installations represent a considerable uncertainty for successful service of the system. Commissioning testing of cable systems according to IEC60840 and IEC62067 should allow a safe, undisputed service. The cable can be put into service after successfully passing a commissioning test, which is increasingly accompanied by partial discharge measurement. While acable is in service, periodically performed offline testing and diagnostic measurements rarely take place due to the significant effort of switching off the cable system. Online diagnostic methods, which could be used whilst a cable is in service, are valuable sources for information and represent a reasonable compromise between costs and benefit. UHF PD Diagnosis has proven to be a valuable and effective method for measuring high voltage assets (cables, GIS, transformer), because this online measurement is performed at frequencies which are not affected by environmental noise.