Combating theft and improving the quality of supply in low voltage distribution networks is the way forward for a sustainable utility business, writes Sipho Mthembu, managing director of Izembe Technologies.
As a key asset in any electrical distribution network,prolonging the lifespan and improving the efficiency of low voltage (LV) distribution transformers will be of benefit to the utility and the customer alike.The challenge, however, is around how to achieve this without having to invest in a huge capital outlay.Furthermore, by design, most distribution transformers are not equipped to monitor and report possible power problems they may encounter. This creates operational issues for field service personnel, plant and/or planning personnel as well as revenue personnel, when equipment failure or burnout occurs without reasons for the causes being evident.
Another major challenge is that customers are sensitive to supply outages, disturbances and unreliable supply. Therefore, power utilities need to focus on improving the System Average Interruption Duration Index (SAIDI) and System Average Interruption Frequency Index (SAIFI) in their networks.
In terms of these challenges, which cause utilities and customers considerable frustrations, the use of transformer monitors – commonly known as CVMs (Current and Voltage Monitor Systems) – have paved the way forward to curb theft and improve the quality of electricity supply.
Smart wireless solutions
CVM devices, which measure the currents and voltages of pole mounted transformers and miniature substations on LV networks, host monitoring software that remotely manages the devices using a GPRS network through a web browser.
Thus, recorded events, graphical representations and set reports assist in the effective management of these assets.
The great benefit to both utilitie sand customers is that the CVM:
• Improves the quality of supply to the customer,
• Provides instant reporting to Network Control Centres when an event occurs for quick supply restoration, and
• Provides load profiles for planning purposes as well as energy balancing purposes in terms of revenue.
Quality proves best
A client that Izembe assisted in 2011 had an estimated 36,000 pole mounted transformers installed with a failure rate of between 3 and 5%. The primary cause of the system failure was not successfully identified and was mostlyr ecorded as ‘unknown’. However, lightning, overloading,unbalancing, system faults and temperature control were identified as key factors.
With an estimated cost to replace a pole mounted transformer being in the region of ZAR60,000 ($4,500), fora 5% failure rate per annum, the replacement cost would be estimated at ZAR 108 million ($8.2 million) per annum. With this kind of expenditure in mind and added to the technical performance of the pole mounted transformers, the quality of supply to customers is always a priority for Izembe.
This article first appeared in ESI-Africa Edition 4, 2018.