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www.us-tech.com Production
Retrofitting Legacy RTUs, Without Lifting a Wire
By Stephen Armstrong
wired sensors, or to control breakers, tap changers and capacitor banks. These remote, real-time data enabled operators to perform supervisory control and data acquisition functions. However, with the earliest RTU implementations dating back to
F
the late 1970s, many legacy systems are no longer supported by the original manufacturers and spare parts can be difficult to acquire. In addition, continued advancements in the processing power and con- trol capabilities of modern RTUs mean these units can often elimi- nate additional boxes. As a result, transmission
and distribution substations that rely heavily on legacy RTUs are ripe for upgrade. Un- fortunately, the task tradition- ally meant not only replacing the RTUs, but also disconnect- ing and reconnecting hundreds of wires to monitored and con- trolled devices. “Even medium-sized distri-
The material matters in material handling
...leading substation automation manufacturers have developed retrofit solutions that allow the replacement of legacy RTUs used in SCADA and other applications with modern alternatives -- without the need for rewiring.
bution substations can have 200 to 300 I/O points that need to be monitored by RTUs,” says Ray Wright, VP of product management at NovaTech, a provider of substation au- tomation solutions. “The larger transmission substations can have well over 1,000.” In response, leading substation automation manufacturers have
developed retrofit solutions that allow the replacement of legacy RTUs with modern alternatives without the need for rewiring. One innovative solution from NovaTech allows for the replace-
ment of legacy RTUs — including D20, Telegy, ACS, Systems North- west and Telvent — with adaptor boards in the place of the legacy I/O. These adapter boards are connected to the company’s Orion I/O unit through pre-designed wire harnesses. The adaptor boards are de- signed so the pre-existing wire connectors from the legacy system can be removed and installed while keeping all the wiring intact. In situations where field wiring cannot be removed, a “top hat”
approach can be used. The top hat is a NovaTech board that is placed on top of the legacy I/O card, connecting to the I/O signal pins. These pins would normally be connected to the legacy RTU, but in retrofits is connected to the Orion RTU. With a modern RTU like the Orion I/O, one of the primary ben-
efits of an upgrade is significantly enhanced automation and visuali- zation functionality. Math and Logic can now be executed on the RTU to add needed local real-time control in the substation, including con- trolling tie breakers, minimizing circulating VARs, forcing settings group changes, adding complex interlocking to reclosing schemes, and executing “distribution automation” schemes. All this can be put into the “Smart RTU” without adding logic to
protective relays or adding a separate controller. In addition, pre-con- figured math and logic for alarm grouping, filtering and intelligent blocking can make reported alarms more meaningful, so that they are reported only when pertinent. Security is significantly enhanced with today’s modern RTUs as
well. “Legacy RTUs only support elementary passwords, include no security event logging, and can’t tell you when someone is logged in,” said Wright. “All that is standard fare in modern RTUs, along with secure protocols based upon public key infrastructure.” Eliminating rewiring from the scope of a retrofit can save signif-
icant time and cost for the utility thereby ensuring that their RTUs will continue to provide critical remote control and management functions.
Contact: NovaTech, LLC, 1720 Molasses Way, Quakertown, PA 18951 % 484-812-6000 Web:
www.novatechweb.com r
or decades, Remote Terminal Units (RTUs) have been utilized in substations to monitor circuit breaker positions, alarms, voltage/current, temperature, and other data from a variety of
June, 2021
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