Don Genutis and Neil Davies, No-Outage Electrical Testing, Inc.
There is an ongoing requirement to improve operational reliability of large power distribution systems and frequently, the pressure to extend operations between scheduled maintenance periods for mediumvoltage (MV) switchgear. As insulation breakdown and flashover represents a high percentage of metalclad switchgear faults, early detection of insulation degradation is critical. In service assessment by the application of diagnostic techniques can provide confidence in the continuing safety and reliability of switchgear.
Use of detection, location, and monitoring of partial discharge activity provides very valuable information to effectively identify equipment at risk of failure. Equipment failures result not only in the loss of supply and consequent disruption to production but also represent a danger to operational staff in the area.
The process of non-intrusively surveying switchgear for partial discharge activity using electromagnetic and ultrasonic principles detects both continuous and intermittent discharge activity from both 'visible' surface sites and 'invisible' sources internal to insulation components.
Hand-held nonintrusive equipment enables regular use by staff entering substations and continuous monitoring systems utilizing state of the art signal processing and analysis enable permanent monitoring of critical MV switchboards.
The presentation discusses the techniques and equipment together with examples of findings from switchgear installations throughout the US.