Bolzano (South Tyrol) is home to the headquarters of Etschwerke Netz AG, the largest utility company in the area. The company's network spans 33 communities, including the most densely populated towns (Bolzano, Merano, Laives), covering a total area of around 1,077 km². Over 1,000 million kilowatt hours of electricity are safely and reliably distributed to 140,000 customers every year thanks to 15 substations, 20 main transformer stations, 24 main distributor stations, 1,688 local network stations, and in excess of 3,000 km of cables and overhead lines.
The company aims to efficiently supply customers with quality electricity without any interruptions – and customer surveys show that Etschwerke Netz AG is doing this very well. The use of new and innovative technologies has enabled the company to get to where it is. It's no surprise then that Etschwerke Netz AG is one of the first companies in Europe to use the new TESSA® fleet management system from Maschinenfabrik Reinhausen (MR). "Our goal is to design the network as intelligently as possible. We want to be able to make the greatest use of the information in the network in order to make it even more stable, efficient, economical and reliable. However, we naturally test new technology thoroughly before deciding to use it. Safety is paramount and benefits are decisive," says Andreas Bordonetti, General Director of Etschwerke Netz AG.
The average age of power transformers is rising -- 30 years is becoming reality -- and the need for complete status monitoring is therefore also growing. The six transformers used in the Bolzano and Naturns substations come from different manufacturers, are between 5 and 39 years old, and are used at a voltage level of 220/66 kV. In addition to capturing and enriching data, Etschwerke Netz AG also needed the system to provide interpretations and maintenance recommendations based on the data. "Prevention is the key – we want to be able to respond before an alarm sounds or major damage occurs. For this we need all relevant information, processed by intelligent software," sums up Mr. Springhetti, Project Manager at Etschwerke Netz AG. “Based on our long-term partnership with MR we knew that its fleet monitoring would also fulfill our requirements.”
ISM® - the principle
The new ISM® platform from MR forms the basis for monitoring. As a standardized hard-ware and software basis, the flexible-use modules capture and evaluate all of a power transformer's relevant operating data. Whether simply displaying status or generating in-dividual reports, the ISM® features an outstanding variety of function offerings and a particularly high level of operating comfort.
The system enables customer-specific expansion of the basic functions by individually selectable and combinable supplementary modules and function packages that can be considered and added at a later date. Not only standard functions, such as voltage and temperature measurement, but also wide-ranging functions such as gas-in-oil analysis (DGA) and OLTC monitoring are among the function packages.
The visualization and preparation of the measured values also provides a high degree of flexibility. All measured values, events, and binary states can be transmitted by an Ether-net interface to a local PC or, via remote access, to the control center. The system makes operating states transparent, enables analysis of current and historical operating data, and supports the technician in recognizing critical situations at an early stage. At Etschwerke Netz AG, the ISM® components were either fitted in the motor-drive unit directly, attached to the transformer in a separate housing or integrated in a control cabinet in the control room – decoupled from the transformer. This highlights the flexible installation options, which may differ depending on transformer and local circumstances.
It is the job of the monitoring system to make planning of operation, utilization, mainte-nance, and equipment replacement as easy as possible. Of course, the focus is on meet-ing individual customer requirements in a practical system. "The advice offered by MR and the integration into our existing software architecture were key to our decision," says the project manager.
A wealth of data is collected at Etschwerke Netz AG on the transformers equipped with ISM® – including gas-in-oil, moisture-in-oil, active power, apparent power, reactive power, load current, load voltage, ambient temperature and oil level as well as the tap-changer position and the contact wear of the main switching contact and transition contacts. The actions to take and when to take them are defined on the basis of this data. This includes maintenance notices, status information or warning messages.
A complete overview with TESSA® fleet monitoring
ISM® is what is known as a field device, which provides the defined data per transformer. TESSA® ensures a superior and clear visualization of all transformers. The "E" in the product name is especially important – it stands for "Enrichment". In other words, the data is not only collected in a central database, but also enriched and interpreted. This is where the experience and expert knowledge of MR comes into play. The software provides the Asset Manager with reliable results and recommendations for action to reduce mainte-nance costs and minimize risks and failures. The software also makes simple and central-ized service and deployment planning possible. Various depictions in the TESSA® fleet monitoring system permit a quick check or a detailed review of individual equipment or the entire fleet, as required. Should critical events occur, notification is also sent out by e-mail or text message (SMS). The system also includes a substantiated trend analysis and comparisons between equipment as well as a historical review function. "We want to see what has happened to the transformer in the past to be able to trace its life history. This information is very important and useful to us and serves as a basis for future decisions," says General Director Andreas Bordonetti.
But TESSA® offers even more. The management team at Etschwerke Netz AG is already looking into extending the system. The next step will be to integrate the pressure-level measurement of the circuit breaker. Because this value is not directly related to the transformer, the graphic display is being adapted too. The benefits are obvious – one user interface, one installation, one contact person, and just one system, that has to be incorporated into the communication architecture. All values at a glance in one piece of software.
Upgrading of both ISM® and TESSA® is simple. Costs can be saved by directly attaching the ISM® modules to the available sensors. The modules are located in the on-load tap-changer's motor-drive unit, as a separate control cabinet or in existing cabinets in the con-trol room. TESSA® uses existing communication channels such as data lines or existing control systems.
"To date, we have found the handling, efficiency, and intelligence of the system to be impressive. We have carefully implemented the project in an appropriate timeframe and are very happy with how it works," sums up Mr. Springhetti.