Many multi-occupancy buildings contain ageing rising and lateral mains (RLMs) found in high rise and multi-tenanted buildings that are due for replacement. Network Operators have a responsibility to maintain these circuits in buildings to reduce the risk of electrical failures that can lead to fires due to the age and condition of wiring. These ageing assets pose a serious health and safety risk to the residents and the public. Many DNOs mentioned the issues faced with RLM in their ED2 submissions and requested funding to address the challenge.
Scottish and Southern Electricity Networks stated, “Given the location of RLM assets within the buildings that our customers live, ensuring the condition and most importantly the safety of these assets is highly critical.”
Electricity North West Limited stated “Our RLM programme addresses safety concerns in multi-occupancy buildings by minimising the risk of fire due to inadequate or poor condition electrical apparatus.”
How can DNOs monitor and assess the condition of RLMs across thousands of buildings with the aim prioritising those that need modernised or replaced?
DNOs have also committed to the deployment of large numbers of LV monitoring products in their ED2 plans. Many of these are basic load monitoring devices only, some claim to perform fault capture and fault location. Could these monitoring devices help solve the RLM problem? In most cases, the answer is unfortunately, no. Where fault capture capability is included, in most devices they are only able to determine late stage developing faults in underground cables. The behaviour of faults likely to cause fires or damage in RLM installations is different and occurs at a much lower current level than an underground fault, often exhibiting behaviour drawing less current than the load current supplied on the cables. Devices that only have the capabilities to detect high level underground fault currents will at best only identify developing RLM issues extremely late in the fault’s development, and in most cases, it will be too late to provide any safety improvements.
Addressing the challenge
Kelvatek had some simple guiding principles when developing their low voltage monitor, PRESense. Key amongst these was that we would deliver a platform that continued to evolve and add value over its 20-year expected operational lifetime. PRESense was designed so that its signal capturing and processing capabilities could be simply re-programmed over the air to improve upon existing functionality, or to add completely new functionality to the platform – safeguarding Network Operators investment in the technology.
The first major new feature set has now been released in the shape of the RLM monitoring functionality. PRESense is already equipped with a series of triggers, which identify a “normal” underground fault, very early in its development - often more than 10 years before the fault will impact any connected customer. The RLM monitoring capability augments these capabilities by implementing a series of proprietary high sensitivity triggers to identify the perturbations and patterns associated with insulation breakdown and developing fire risk.
When a breakdown is identified, Kelvatek’s powerful Sapient data management platform will issue an alarm to Network Operators advising manual inspection or isolation of power is required, thus avoiding fire or other hazardous situations that may present a risk to residents.
The RLM monitoring technology is an extension of Kelvatek’s Wattsguard systems. Deployed in hundreds of buildings across the UK, Wattsguard combines Kelvatek’s field-proven Weezap LV vacuum circuit breaker with our software and services. PRESense is used to monitor the electrical characteristics and behaviour of RLM installations across the network estate and highlight those installations that are most at risk so they can be targeted for refurbishment and recommend a set of Weezap LV circuit breakers to be installed in the meantime to provide remote protection. The Weezap solution ultimately allows for a remote disconnection of power from RLM circuits to prevent fire and is the ideal solution where there is an identified high risk of this occurrence.
DNOs are faced with the prospect of high operational costs associated with visiting RLM installations and examining cables – and even then, many of the cables are inaccessible, leaving a significant risk of unobserved damage, leading to potential health and safety issues. Cable risk reports provided by PRESense will not only highlight those cables where a risk has been identified but can also pinpoint a single fault or short section of the network for investigation, allowing true condition-based maintenance, and targeted replacement of cable sections, rather than a wholesale RLM replacement.
