Engineers from Control Corp. of America (Richmond, Virginia) completed the first large-scale automation of an U.S. Navy aircraft carrier using commercial-off-the-shelf (COTS) automation equipment. Automation provides state-of-the-art control for the management of jet fuel on the carrier. Using commercial equipment reduces the cost of construction, personnel requirements to operate the ship, and repair time, while improving system fault detection time, and providing enhanced logistics support.
The primary function of a Nimitz class nuclear-powered aircraft carrier, Harry S. Truman (CVN75), is to launch and recover warplanes, as part of its assigned defense missions. Fuel must be available at the flight deck service tanks at all times. Despite the crucial nature and complexity of systems on its advanced ships, the Navy wanted to move away from proprietary, one-of-a-kind control systems in favor of COTS products. Behind the automation effort was a five-year journey of discussion, design reports, product selection testing, application software development testing, hardware construction, ship installation testing, and sea trials.
A conservative approach was used to automate the Trumanís two fuel management systems, located forward and aft. The aft configuration was completed first, with installation and testing performed at anchor, followed by testing at sea during flight operations. Those associated with the project selected Siemens Energy & Automationís S7-416 PLCs, primarily for their capability in networking, performance, redundancy options, and open protocols. These controllers operate in a "warm-backup" mode, reading and writing the I/O points simultaneously through Siemensí redundant ET200M I/O interface modules.
Communication between the controllers and the I/O points is Profibus-DP at 1.5 Mb/sec. Profibus was chosen for its speed, large assortment of available products, and status as an international standard. The CNV75 project mainly uses Siemens I/O devices, but other applications on these ships have I/O products from several other vendors. Tests and trials show that COTS equipment can meet operational needs of many military applications.