Microprocessor-based protection units, such as ABB’s REF542plus, add intelligence to “dumb” medium-voltage substations. The REF542plus combines measurement, monitoring, protection, control and self-diagnostics in one package.
By Editorial services
The latest release features web-based remote monitoring and SMS alert messaging. New GPS-based time synchronization also makes fault identification more accurate – helping to reduce the fault frequency in distribution networks.
The main task of a medium-voltage substation is to switch down the voltage of distributed power to levels that are useful to power utilities and heavy industries such as steel works, paper mills and petrochemical plants. As vital parts of any distribution network, these electrical workhorses are all around us – although they’re no longer as conspicuous as they used to be thanks to increasingly smaller footprints.
Substations are also equipped with circuit breakers that interrupt power, either automatically in case of electrical failure, or manually to allow for maintenance work. “These breakers are like the electrical switches in our homes,” says Marco Tellarini, global product manager at ABB Medium-Voltage Products in Switzerland. “Only in a medium-voltage system, they protect large equipment such as electrical motors, transformers and distribution lines instead of household devices.”
But these circuit breakers need help to detect a fault before cutting power – which is literally a matter of milliseconds. This is exactly what the REF542plus does. It identifies the fault, trips the breaker and alerts the operator of the status.
Web-based monitoring liberates service technicians
Conventionally, operators analyze the status of switchgear on site or from a control room using a full-scale monitoring and control system such as SCADA. With the release of REF542plus version 2, this can be done remotely using a standard web browser.
“Operators simply log on to the device from wherever they might be,” says Tellarini. “The next step will be to make it possible to access data using mobile technologies.”
The new REF542plus release also features SMS support to further liberate service technicians. Any event registered by the REF542plus can be sent as a regular text message (SMS) to the technician’s cell phone. The technician can then connect to the switchgear via the web, access the REF542plus and analyze the data needed to correct the problem.
“We’re alone to be offering this kind of mobile support. It helps customers plan the work of their service personnel more efficiently,” says Tellarini.
Time synchronization analyzes faults more accurately
Identifying faults more precisely is key to reducing the fault frequency in a power distribution network. A bit surprisingly, the new generation REF542plus uses GPS – the Global Positioning System – for this purpose. But it’s not the navigation capabilities of GPS that are crucial to REF542plus, rather its accurate time data sent via a satellite-based GPS-clock.
REF542plus uses the GPS time data to continuously synchronize its own embedded clock. This clock time-tags events occurring in the switchgear with an extremely high precision, way beyond milliseconds. The time-tagged event is then sent to a remote computer, which analyzes the cause of the fault.
“The higher the accuracy of the time data, the easier it is to reconstruct the fault by cross comparing data from all pieces of equipment detecting the fault,” says Tellarini. “The GPS-based time synchronization will help us gradually reduce the fault frequency in substations around the world,” concludes Tellarini.