By Mark McCartney
It's no secret that technology has advanced rapidly in the automation and control field over the past few decades. The world of pump control has not been immune to these advances. The advent of the PLC, the evolution of communication protocols and the introduction of modems and radios for data transfer all played significant roles in the capabilities we're familiar with today. Now, Ethernet and Web-page functionality have found their ways into control panels, further advancing the industry.
As semiconductors evolved, ever-smaller devices became capable of collecting and storing more data. It wasn't long until this type of "intelligence" appeared in motor starters, drives, soft starters and PLCs. These devices generated more data than the traditional on/off signals, gathering actual motor current, voltage, flow, level and other numerical data. This information can be useful for diagnostics or regulatory compliance purposes. At first, this technology mostly appeared in large-scale control systems, but not in stand-alone pump panels. There was a misconception that users could apply this higher functionality only in advanced custom control panels.
Our company has been building custom control solutions and predesigned configurable pump panels for more than 35 years. The custom panels often offer advanced benefits. Configurable or "rapid release" panels offer price and speed-of-delivery benefits. We believed there had to be a way to use the superior features of this technology in our custom panels and allow the control to be configurable in a manner similar to the traditional rapid release concept.
We partnered with Schneider Electric's OEM Technology and Solutions Center to develop the design. The result is our Intelligent Station Controller (ISC), which provides run status, amperage (average, phase and ground fault), fault codes (including jam protection), motor thermal limit, alarms and other diagnostic information to help provide enhanced maintenance ability for customers. The advance diagnostics and maintenance data can help a utility predict anomalies and failures and increase the reliability of the pump station.
The data gathered using the ISC is displayed on an operator screen and logged and trended in an internal Web page. Stacon's customers decide whether the Web pages are accessible through the Internet, through a dedicated Ethernet network that is not connected to the Internet or at the panel via a hardwired connection. Regardless of the level of access, a standard browser is all that's needed to display these pages, eliminating specialized software and training. Additionally, the system stores user manuals for the panels. This allows access to all needed information with no risk of losing paper copies.
The ISC consists of motor starters, a Web server and an integrated HMI/PLC—all configured for serial Modbus and Modbus TCP Ethernet. This configuration allows each device to connect to each other through preassembled Cat. 5 cables. The plug-and-go technology reduces wiring time.
There are fewer components in the ISC than there are in a traditional pump panel. One example of this is the operator panel, which replaces all pilot lights and selector switches. In addition, this unit combines the PLC and HMI into one unit, further reducing panel space. Programming is simplified through one software package for the entire system. The combination of communication cables, Web server and HMI removes any remaining interposing relays, timers, counters, chart recorders, loop controllers and other devices.
Panel real estate is decreased with the use of space-saving devices such as self-protected, combination NEMA starters rather than traditional NEMA starters. This lets us use a smaller enclosure compared to a traditional pump panel. Furthermore, the combo starter generates less heat than melting-alloy-based NEMA starters, which can contribute to longer component life and greater panel reliability. Heat is a constant concern when working with control panels. Our ISC test panel is a NEMA 3R stainless steel panel installed in the central Florida sun with only filtered ventilation. Since its installation in April 2008, the panel has not suffered any heat-related failures.
Mark McCartney is president of Stacon (www.stacon.com) in Apopka, Fla.
