Riccardo Giussani and Simon Bates, HVPD, Daniel Roberts and James Dalton, Breedon Group, explain how online partial discharge (PD) measurements help avoid electrical faults on high voltage systems to minimise downtimes and safety risks in the cement industry.
Partial Discharge (PD) is a degenerative phenomenon that affects the electrical insulation of medium and high voltage (MV/HV, 3.3 kV and above) equipment including: motors, cables, generators, transformers, etc. If undetected, with time, the degeneration of the insulation due to PD will lead to a disruptive discharge that may be very harmful to people and assets and will also result in long downtimes and financial losses. Figure 1 shows an example of what PD activity can do to such MV/HV assets.
The financial and safety incentives
The deployment of any type of condition monitoring (CM) technologies, be they electrical, mechanical, and so on, are to increase the safety on and around the site and to minimise financial losses caused by the downtime related to safety or maintenance issues. This article looks at what has been done at the Breedon Hope Cement Works since 2017 to deploy online PD measurements and how these have helped to prevent deleterious impacts on production processes. The same financial and safety benefits can be achieved within any HV plant where CM technologies are deployed.
OLPD technology: from spot testing to continuous monitoring
A number of options for performing online PD measurements in HV networks are available. From the use of portable screening technology (to make periodic online PD spot test measurements) through to the use of continuous online PD monitoring technology for the most important/critical assets. Having the ability to scale and phase out the measurement campaigns helps to deal with the many challenges that may come with restricted budgets, resistance to utilise new technologies (unfortunately industry may sometimes be reluctant to change), or simply just time constraints in a demanding production schedule.
A typical and very efficient approach is to perform an initial test campaign to assess the overall health of the site and then focus the effort and resources on the most critical assets (from the business and safety point of view). This was the approach used at Breedon Hope Cement Works; the site has been operating since 1929 now standing as the largest cement plant in the UK.
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