By Dan Hebert, PE, Senior Technical Editor
You get a frantic call from a customer on Friday morning. One of your machines is down, and they can't figure out how to get it back up and running, so you book a last-minute and very-expensive flight.
When you arrive at the customer site, you're tired and more than a little peeved with the customer for ruining your weekend. The customer is breathing down your neck, but you need some time and space to diagnose and correct what turns out to be a fairly complex problem.
This is a snapshot of life for many machine control professionals in the bad old days before remote diagnostics. Nowadays, remote connections enabled by the Internet, wireless technologies and other telecommunications advancements allow automation pros to routinely and quickly diagnose and correct problems anywhere in the world from the office. This not only saves time and money. It also allows complex analysis to be done in an ideal off-site environment, free from distractions and omnipresent anxious clients.
Physically separating problem analysis from machine-operating locations confers many advantages. It cuts cost for each machine because complex analysis tools can be staged at one central location instead of at each machine. It reduces travel costs and makes it easier to retain employees. It lessens the number of experts required to maintain machines. Finally, it improves analysis because automation pros can service machines from a comfortable and safe location. Examples abound.
Electromechanical shovels used in open-pit mining operation are huge mobile machines capable of loading 100 tons of ore into a truck per pass. Traditionally, it has been difficult to apply condition monitoring and predictive techniques to these shovels due to inadequate analysis algorithms and equipment, as well as the harsh environment.
Traditional vibration analysis is the main tool for predictive maintenance on rotating machines. It's performed by Fourier transforms that assume constant rotational speed. This doesn't work for mining shovel machines, so a different approach is needed.
A story on the National Instruments' (www.ni.com) web site explains how the University of Concepción in Chile developed a vibration-analysis algorithm suitable for analyzing the vibration signals of electromechanical shovels. Once the algorithm was ready, it was implemented as the core of a continuous remote monitoring system.
The monitoring system consists of onboard equipment, a remote server and wireless network equipment. The onboard NI CompactRIO system acquires simultaneous signals from accelerometers, encoders and strain gages.
Acquired data is stored temporarily on the CompactRIO internal Flash and later downloaded automatically via a wireless link to a remote master server. At the remote location, the data is processed, compared against complex alert and alarm parameters, and stored in a database.
Once the data is processed and stored, it is available for further user visualization, analysis, manual processing and trends management on the server or on any computer with network access to the database. As of April 2008, nine shovels reportedly are continuously and remotely monitored at four different open-pit mining locations in Chile, two of which are among the biggest copper mines in the world.
Siemens' (www.sea.siemens.com) remote response command center is situated in the middle of its mobile mining solutions engineering team. Mines are located in very remote and often inhospitable areas. It's very costly to fly out experts to correct a problem or install new software, both in terms of travel and machine downtime.
The command center enables field service engineers and system design engineers to sit behind a desk and perform problem analysis at a moment's notice using Siemens' remote access system.
"From this secure war-room environment, qualified factory experts can connect to machines all across the world and have access to all of the troubleshooting tools available onboard the machine," says Daniel Robertson, business development manager for mobile mining solutions at Siemens Energy & Automation. "Remote access not only enables access to the diagnostic tools, it also provides access to drive control systems and other hardware. This makes loading new software or adjusting parameters easier, faster and cheaper."
