The Leaky Insulator Detector with Video Partial Discharge (LID RTS) is hand-held non-destructive inspection system which utilises AC/ DC Current sensor and Ultrasonic technology for predictive maintenance. The (LID RTS) has a Flexible clamp sensor and Ultrasound Imager. The Flexible AC/DC Clamp meter is specially designed sensor to measure the AC/DC leakage current in HVAC/ HVDC Towers leg (caused due to the leaky insulator). Ultrasound Imager is based on Ultrasound Technology which picks
Partial Discharge Ultrasound from a distance upto 100 meters and converts Ultrasound into visual video digital image. After leakage current measurement, Ultrasound Imager is used to scan the insulator strings of leaky tower and pinpoint the phase and position of the leaky insulator.
Electrical Arching, Tracking, Partial Discharge, IR & Current Leakage
Overhead insulators provides mechanical support to high voltage cables and electrically isolate them from ground structure. In contaminated condition, uneven resistance exist. The surface of contaminated insulator leads to formation of conductive layer causing leakage current to flow. As quoted from IEC 60270 PD does not cause immediate breakdown of the insulation, the appearance of PD indicates the presence of fault which causes energy dissipation and further leads to insulation degradation.
Procedure
The Leakage current is measured in pole leg to get the total Leakage Current. If the total Leakage Current is more than prescribed limit, the tower & insulator is declared to be leaky. Then the Ultrasound Imager discharge detector is used to scan every insulator string and pinpoint the leaky insulator string by identifying the Partial Discharge arcing in the insulator causing the leak. The graphical evidence of arcing is then recorded for future reference. In the final stage of partial discharge, the breakdown of the insulator causes a reduction in internal resistance, leading to an increase in heat.
Increase of temperature is the sign of failure. LID RTS can be used to capture thermal images of the assets simultaneously. This inbuilt feature of the equipment helps the maintenance team to make quick decisions. High resolution photos and video combined with PD IR impressions, will help to spot the exact problematic area.
