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Early warning of failure

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EA Technology has launched a new monitoring system designed to prevent up to 85% of failures in gas insulated switchgear (GIS) sets, which are typically used in strategically important substations.

Called the PD Monitor GIS, the system works by continuously locating, measuring and classifying internal Partial Discharge (PD) using a network of ultra high frequency (UHF) sensors. If PD activity reaches critical levels in any part of the switchgear, it automatically transmits warnings to engineers via text messages and emails.
EA Technology instruments director Neil Davies explained: "We have developed the PD Monitor GIS specifically for situations where failure of extra high voltage gas insulated switchgear would cause unacceptable outages, including loss of power to city centres, regional networks and critical customers."

"Our system is the first on the market to locate, measure and classify PD activity 24/7, providing engineers with automatic, immediate and accurate warnings when critical GIS assets are starting to break down, without anyone having to be present. It also provides continuous assurance when they are working correctly and will significantly reduce the incidence of engineers being called out on false alarms."

EA Technology has identified five areas where PD faults develop on GIS assets: contamination by free moving metallic particles, voids in insulator cast resin, corona activity emanating from sharp points, conducting particles on insulator surface and contact noise from support brackets. All can escalate rapidly to flashover and failure.
The PD Monitor GIS continuously monitors PD activity via external UHF sensors, which can easily be retro-fitted to the switchgear or via existing internal sensors. The sensors are connected to the system's server via measurement nodes, in a daisy chain configuration, to simplify cabling.

More than 100 sensors can be connected simultaneously to the server, which has a web-based Windows interface and uses expert system software to analyse the data and indicate the location, type and severity of PD activity in the form of reports and graphs.
The server is configured to recognise when PD activity reaches a critical level and automatically transmit alerts to engineers via text message and email.
Davies added: "The PD Monitor GIS is a major advance in extra high voltage switchgear reliability, with the added advantage of reducing the costs of human monitoring, false alarm call-outs and intervention."
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