Andritz was recently commissioned for three different pulp and paper projects which would include the supply and installation of a total of six portal cranes. Each project required the supply and installation of two portal cranes which would be used for unloading logs from logging trucks and transporting the materials to an onsite woodyard.
Altogether there are seven radios fitted to the two crane systems. One set of radios is dedicated on each crane to allow them to communicate their GPS positions to one another. A second set of radios connects each crane’s gantry control system to its trolley control system
With sophisticated processes involving multi-million dollar portal cranes operating at rapid speeds while carrying several US tons of materials, crane collision is a clear concern.
In these cases, a real-time wireless ethernet network was the only way to facilitate the conditions needed for a high-performance anti-collision system.
Andritz placed a satellite GPS system on each crane to accurately determine their respective locations on the rail. For this to be an effective solution, each crane would need to know the position of the other crane
The cranes would need the ability to operate independently and simultaneously while sharing a common set of two perpendicular rail tracks. This system would enable the two cranes to travel from the log truck unloading area to the woodyard infeed equipment or to the log storage area located in between the two rails.
Robert Dunlop, senior electrical and automation project engineer at Andritz, who was responsible for the control systems on the cranes, said: “Andritz portal cranes are capable of lifting an entire load of tree-length logs from a logging truck with a single bite of the grapple.”
Many of these portal crane grapples can lift up to 44 US tons of logs in a single bite and transport them along rail runways sometimes up to a mile in length. Cranes can safely operate up to 750ft/min.
Many of these portal crane grapples can lift up to 44 US tons of logs in a single bite and transport them along rail runways sometimes up to a mile in length
Dunlop added: “A typical portal crane unloading and delivery cycle is about 2.5 minutes per crane, translating into hundreds of [US] tons of wood per hour being processed.”
Given the high performance demands of modern crane applications, the old practice of using 300-400ft long bus bars or festooning cables to communicate between the gantry and trolley was not an option.
“Festooning cables and bus bars are costly and are a frequent source of operational problems. It can cost around $10,000 for materials alone, plus installation and maintenance costs. Then when the equipment fails, downtime is a serious problem to a customer and can sometimes take a day to repair,” said Dunlop.
The bus bar systems operate on a serial communication network so data rates are slow and during poor weather, particularly precipitation, the signal is often degraded. Even if the serial communication system was faster, bus bars can only communicate from gantry-to-trolley and not from crane-to-crane which is needed for anti-collision systems.
Andritz needed the ability to monitor the real-time locations of each crane on the rails and to automatically slow down and stop each crane should they enter a potential collision situation. Until the advent of wireless devices, safe and reliable anti-collision systems were just wishful thinking.
Andritz placed a satellite GPS system on each crane to accurately determine their respective locations on the rail. For this to be an effective solution, each crane would need to know the position of the other crane. Andritz selected ProSoft Technology RadioLinx Industrial HotspotTM Ethernet radios (RLX-IH) as its wireless solution.
ProSoft Technology’s radios provide the speed needed to transfer data between the cranes and the operators in real time. They are certified for harsh environments, making them a dependable solution despite poor weather conditions.
“I use ProSoft’s radios all the time for this type of application,” said Dunlop. “The main advantage of using high-speed ethernet radio systems is that they help the cranes avoid collisions on both the network and on the track. Plus, operating wirelessly creates a significant cost saving by eliminating additional communication bus bars and festooning cables.”
Altogether there are seven radios fitted to the two crane systems. One set of radios is dedicated on each crane to allow them to communicate their GPS positions to one another. A second set of radios connects each crane’s gantry control system to its trolley control system.
“The high-speed Ethernet communications are very effective, so that when the crane operator moves the joysticks inside the operator cab, the gantry and trolley controls respond seamlessly, without any noticeable delays,” Dunlop added.
Finally, a seventh radio was implemented to connect the control systems of both cranes to a woodyard ground station. This ground station radio allows for remote troubleshooting, programming and operational data acquisition of the cranes. It also allows Andritz to provide remote crane diagnostics and programming support through internet connections.
So far, two of the Andritz projects are live as of October 2006 and January 2007 respectively, while the third project is scheduled to go live in November 2008. In application, the three wireless systems not only created a more efficient, cost-effective network than bus bars and festooning cables, but are far more reliable in diverse weather conditions. The wireless networks are self-healing, with significantly less risk of signal degradation than the alternative, and they operate in real-time which is key to a successful anti-collision system.
Altogether there are seven radios fitted to the two crane systems. One set of radios is dedicated on each crane to allow them to communicate their GPS positions to one another. A second set of radios connects each crane’s gantry control system to its trlogs 4 Andritz placed a satellite GPS system on each crane to accurately determine their respective locations on the rail. For this to be an effective solution, each crane would need to know the position of the other crane logs 3 Many of these portal crane grapples can lift up to 44 US tons of logs in a single bite and transport them along rail runways sometimes up to a mile in length logs 2 Andritz is an international provider of services and equipment for pulp, paper and tissue and provides equipment for the processing of tree length logs logs 1
