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Crane power systems on a surge

The cable chain is now well-established in the container crane market but other alternatives to conventional festoons are coming on, too. ZPMC advocates its own driven cable belt system for delivering power to crane trolleys and has had some further success. This system is similar to a cable tender and features a rubber belt conveyer-type arrangement to support the cables and a small electric motor to drive the belt when the crane trolley moves.

The market for mobile electrification systems is diversifying considerably and more operators are willing to try new systems and some are preparing to electrify more equipment

ZPMC says the system has many advantages: only 50% of the cable required for a festoon system is needed, there is no large loop that needs to be accommodated and, therefore, less space is required than with a plastic cable chain and the system is not affected by wind.The belt is always under the correct tension, it continues, so the cable is subject to a constant working condition and the system can support crane speeds up to 350 m/min.

Auckland installation

Ports of Auckland Ltd (POAL) in New Zealand recently took delivery of three ZPMC cranes with this system and operations engineer John Miller says that although it is too early to make any comment about long term reliability, "so far the ZPMC system looks very good." The cranes have an outreach of 50m and a trolley speed of 240 m/min. POAL's first two ZPMC cranes (delivered in 2002) have ZPMC's own conventional nondriven festoons. Miller says the port had a lot of maintenance issues with them, including broken bungee cords, although connecting the middle festoon roller to the landside catenary trolley has been an improvement. For its new cranes, POAL considered alternative festoon suppliers, motorised festoons and other cable chain systems. "After looking at the ZPMC `energy chain,' we thought it was better and more simple than other systems on the market," Miller added. Another option for crane trolley power is the unipole conductor bar and slotted microwave guide (SMG) system being offered by Paul Vahle GmbH. The installation on a crane at HIT in Hong Kong has now operated for two years without problems and without any required maintenance, says Vahle. That crane is now being relocated from HIT to Hui Zhou. Meanwhile, last month Vahle installed another system at a different HPH terminal, Shanghai Pudong International Container Terminal at Waigaoqiao Phase I. The girder length is 101m (52m outreach) and Vahle has installed its Vahle U35/230AE Unipole Conductor Bar (3 poles + earth) and SMG for profibus with 1.5 Mbit/sec and emergency stop. Conductix motorised trolley system at Intership, San Juan, Puerto Rico. cation for its "U plus SMG" system. It says several prototype installations for these applications "show a positive picture concerning speed and reliability" and is confident about getting orders in the short term. This is also an application Wampfler is targeting with its frequency controlled cable reels. Daniel Dörflinger, head of cranes and heavy machinery at Wampfler, says the application requires the highest availability and reliability and is not comparable to any other reeling application. Selecting and then thoroughly testing all the system components for the application was one reason why Wampfler decided to build the test track at its facility in Rhein-amWeil, completed last year. One obvious synergy is to combine Conductix Mag Drive reels with Wampfler festoons and frequency controlled spreader reels. Conductix says it has seen some increase in crane gantry speeds, from 45 to 55 m/min, but this is still well within the capability of a magnetic coupler. The new relationship also has ramifications for the cable industry as Wampfler generally uses Pr ysmian and Draka cables whereas Delachaux tends to source more cables from Nexans.

Monitoring power

There is now no doubt that the crane market has accepted energy chains as an alternative to festoons for the trolley power and communication on ship-to-shore cranes. However an energy chain is not maintenance-free and, just as with festoons, there are maintenance items and terminal operators benefit greatly if these are predictable. Predictability is improved through systems that monitor the condition of the chain to give notice that something needs attention before any failure that takes a crane out of service. Igus' product manager Theo Diehl says that chain maintenance is really about checking to see that nothing is loose, there is no debris is in the guiding trough and, if a moving arm is fitted, greasing certain components. If something is wrong it will not only be visible, but detectable in the force needed to push and pull the chain along the guiding trough.

In confidence

Test results are confidential, although Dörflinger says they will probably be used on projects Wampfler has won recently. Wampfler is delivering the reels for the Gottwald ASCs at Antwerp Gateway and they must support a long travel speed of 240 m/min. The test track is a crucial part of Wampfler's R&D programme and it has been put to first use on cable reels. Wampfler is also conducting tests on energy guiding chains, festoon systems and conductor rails "of various kinds" but again no results are public. Dörflinger points out that the track is not just for testing components; it can also be used "for terminal operators that are looking for a solution on a specific problem they encounter in their terminal. We can easily simulate most situations on container cranes and help them find solutions for problems without partly having to block the terminal."

Ground hogs

Igus launched its Push Pull Detection System (PPDS) two years ago and one of the first customers was PSA Singapore where Igus chains were installed in a former bus bar trench to carry the main power and data cables to quay cranes. In this application dust, dirt and debris in the chain guide trough are more of a risk than high up on the crane boom. PPDS measures the push pull forces on the chain; that is, the amount of force on each section of the chain that is moving. Depending on the application a maximum force is set, above which an alarm is activated to in-

RMG systems

Vahle has identified high-speed RMGs and ASCs as a good appli-

Synergies?

Some months after Delachaux Group announced that its Conductix division was buying Wampfler, there has been no decision on whether and to what extent the product lines will be offered together. Working groups of Conductix and Wampfler people have been established and tasked with making recommendations on these and other issues."

Siemens cable recall

Siemens has issued a statement saying it has identified a "potential issue involving Siemens power supply cables typically used in connection with industrial applications of variable-speed drives. "With these cables, there is a possibility that the plastic insulation of the individual conductors can age prematurely causing the cables to no longer meet all specified functional and protection specifications. Should this situation arise, there is the possibility for serious personal injury in addition to property damage." The affected cables are the Protoflex EMV 4 Plus UV 2YSLCYK-J 600/1000V and Protoflex EMV 2YSLCY-J 600/ 50 1000V, manufactured by another supplier for Siemens between 1996 and July 1999, but may have been delivered from stock as late as 2001.The cables were used in a variety of applications with variable speed drives including conveying and hoisting gear systems. Because the cables were sold through the wholesale trade Siemens has not been able to identify all end users and is now publicly seeking to inform and contact any unknown users. Any user of the affected cables is asked to contact Siemens at: PTD Customer Support Centre, [email protected], phone: +49 180 524 7000, and use the reference "Protoflex." May 2007

CARGO HANDLING

The 4040HD has a reduced interior height, so takes less space on the crane and less material to construct.Another significant order has been received from SPMP, which will fit 4040RHD chains to 20 cranes it is building for the Tianjin Port Authority. Igus is also building up its reference list in retrofit projects and has installed chains on Paceco Portainers and cranes from Mitsubishi, Konecranes and Morris cranes among others. possible failures and the system is continually being refined. Incidentally, Wampfler has decided against developing a chain monitoring system similar to the one that Igus offers. Conductix is looking to increase its presence in the festoon market with its recently developed motorised festoon system. The first one was installed on a crane at GPA Savannah in December 2005 with 113m of travel and a trolley speed of 180 m/min. The system has 19 loops with a depth of 5m carrying 236kg of cable per trolley, three are motorized. A second identical system was installed on another crane at Savannah in July 2006 and this year Conductix delivered another system to Intership at its San Juan One terminal in Puerto Rico.This system has 92m of active travel and maximum speed is 170 m/min. There are 15 cable loops with a 5m depth carrying 448kg of cable per trolley; again, three are motorised. While other motorised festoons (including Wampfler's) drive the carrier rollers either directly or through a belt drive, Conductix has chosen a direct drive system with the drive wheel running on the on the underside of the beam. In this position the drive wheel is unaffected by debris on the top flange of the beam. A spring system ensures there is consistent drive wheel alignment and pressure on the beam surface. The system can run on most existing beam surfaces; the two systems at SavanThe "pull & store" system from Cavotec (Specimas) is an industry "classic" and is still in strong demand

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Cable core breakage during testing by Prysmian dicate the chain needs immediate attention. However, Diehl says the real value of the system is not as a tool to prevent a catastrophic failure, but in its ability to indicate problems that if not addressed will accelerate wear. PPDS generates a data log that can track the chain's operating condition and indicate areas where there is any unusual variance. In one case, an end user identified an anomaly in the data and an inspection found a dead bird in the guide trough.

Festoon monitoring

One reason some operators prefer festoons is that all the moving components can be inspected from the festoon platform, but monitoring systems are also available. Wampfler says its standard software has a data logging system that also offers feedback functions on the specific

"Easy PPDS"

Igus has now launched a simplified version of PPDS called "Easy PPDS" that does not have the data logging functionality of the full PPDS system (but can still store up to 40,000 entries) and measures the maximum push and pull power on the chain. If a pre-set threshold is reached and alarm is sounded and the system can be set for an emergency shutdown. Both systems are aimed mainly at operators concerned about an undetected event such as a component breakage or damage to the guide trough causing a major failure. PPDS adds under 10% to the price of the chain and that, Diehl says, is a small price to pay for the added safety. Igus is supplying energy chains for the 14 cranes that Liebherr is building for South African port operator SAPO. This is an important reference as Liebherr is known for requiring well-proven technology and for a long time stayed away from cable chains. Four years ago it fitted an Igus chain to a crane in Dublin where site constraints meant the cable loops of a festoon in the backreach would have been in the way of a yard crane. For the SAPO cranes Igus will supply its 4040HD chain, the newer version of the heavy duty 5050HD chain used on the grab unloaders at EMO in Rotterdam - a full machinery trolley application where the high cable weight required two chains running to the trolley.

Tratos at 40

Italy-based cables specialist Tratos Cavi SpA celebrates its 40th anniversary this year. It began life as a steel wire cable manufacturer - Tratos is an amalgam of Trafileria Toscana (Tuscan Wire) - but soon diversified into copper cables. Over the years it has steadily built up a major presence in the power and energy sectors, mining and tunnelling, telecoms, anti-flammables, and so on, with a full range of cables and a wide choice of insulation materials largely developed in-house.The company has always been in private hands. Affiliated companies include Smaltos (braids, copper wire drawing and enamels), Tratos Ltd in England (formerly Hamilton Cables Ltd) and Tramet (Tratos/Metozzi), which specialises in rubber compounds and FCC (Fabbrica Cavi Catania). Tratos started supplying optical fibre cables originally for telecommunications (Telecom Italia) in the early 1990s and shortly afterwards produced its first medium voltage cables in XLPE. It began production and worldwide marketing of special cables for mobile applications in 2002 and is today present in more than 35 countries around the world in this field. Recent investments include a new plant for manufacturing HV/MV cables, new stranding lines for anti-torsion conductors, faster production lines for elastomeric materials and new vulcanisation lines. Production capacity of cables for mobile applications has also been increased. The company works closely with crane OEMs and electrical contractors, and leading cable reel manufacturers and electrical integrators such as Cavotec. May 2007 51

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nah run on a metric beam (IPN 240) in an `I' configuration with flanges sloped at 7 deg whereas the Intership system runs on an S8 x 18.4 beam, similar to the IPN 240, but sized to US standards. Conductix held off developing a motorised festoon for a long time and it continues to supply non-motorised systems for high speed applications. Recently is has supplied heavy duty festoons for 14 cranes supplied by ZPMC for DP World and Patrick Stevedores. Most of these cranes are now in service and range in speeds from 210 to 240 m/min, with high acceleration and high wind speeds. All systems feature interchangeable parts to facilitate ease of maintenance and unique protective socks to maximize the life of shock cords and tow ropes.The systems were designed by Conductix in close cooperation with ZPMC to achieve some physical elements that were requested to fit within the crane's geometry, said Conductix's director of marketing Rod Griffith. ZPMC has noted that an increase in crane travel requirements mean it has had to fit large level winding reels in some cases, but easy to maintain. The basic principle of `pull & store' from Cavotec (Specimas) has stood the test of time, while Conductix claims that its Mag Drive (magnetic coupler) system, when operated within its capabilities, is the most cost-effective solution. Variable frequency drives are not needed for crane speeds under 120 m/min. Conversely, the Mag Drive system is not well suitable for speeds over 200 m/min. Another issue is the increasing power requirements of today's cranes and how that affects cable size. Some twin hoist cranes have as much as 2 kW of hoist power alone. Larger cables are of course heavier and the reel drive must overcome this inertia as well as avoid over-tension in the acceleration and braking stages. For the more demanding applications Conductix offers its "SmartDrive" system that uses a real-time calculator to regulate the torque based on actual reeling parameters and reduce cable fatigue. Within the Smart Drive series there are three levels of control, as Conductix explains: `VF' (level 1) is basic control for low dynamic applications; `PR' (level 2) is a Wampfler frequency controlled cable reel on high speed Gottwald ASC more sophisticated pull regulation system for medium-level dynamics. `Dynamix" is the most advanced control level, used for high speed systems, large/heavy cables and applications that need the maximum accuracy of control. The Dynamix system takes into account, on a real-time basis, cable wrap diameters, sustained cable weight, and system inertia during acceleration/deceleration. Conductix stresses that correct cable control is important to an optimised system and enables the cable and reel to be properly matched. If the reel generates the exact tension required, it is smaller to use smaller, lower cost cable. For the fibre optic connection Conductix has introduced a new `TFO' (fibre optic transmitter) with increased range and capabilities. "The TFO is a reliable and cost effective device that transmits fibre optic data through the cable reel system, said Griffiths. "Unlike fibre optic rotary joints, the TFO introduces no signal loss into the system and is considerably more reliable.The device

CARGO HANDLING

Igus' new condition monitoring tool "Easy PPDS" in operation this would not appear to be the start of an enduring trend. Berths have to be longer to accommodate the larger post-Panamax ships, but crane density also needs to increase to maintain productivity on these vessels. The trend is perhaps more towards cranes with a shorter long travel distance?

Tried and tested

Many users still prefer the tried and tested solutions from companies such as Cavotec and Conductix for long travel application because they are simple and

is available with either 50 or 120 turns, and can handle six, 12, 18, or 24 optical fibers." While they require two spreader reels, twin hoist cranes seem to present no difficulty for spreader reel suppliers."Due to the basic design of these reels," says Dörflinger, "they do not need any synchronisation with the hoist. This makes life for crane manufacturers and customers a lot easier. Both reels can be used independently from each other and also in parallel without having to change anything."Vahle also notes that there is no need for the two spreader reels to be synchronised and it is able to provide the necessary solution "out of its standardized toolbox."

Electric RTGs

There are two terminals (in Oslo and Shenzhen) known to be operating RTGs with cable reels to receive mains power.With the environmental pressure that US ports, in particular, are under to cut diesel PM emissions, they may become more common. PSA International is understood to be considering mains power for its terminal in Incheon, Korea, where diesel prices are particularly high. Diesel fuel is also expensive relative to electricity in China and ZPMC says the operating costs of the electric RTG in Shenzhen are 80% lower than those of a diesel-electric unit. One consideration with electric RTGs is vehicles driving over the power trench and cable but solutions for this already exist. Cavotec Specimas offers "Super Panzerbelt" for applications where heavy industrial vehicles need to cross the cable trench. Super Panzerbelt offers more protection than the standard Panzerbelt and has been applied at the landside rail for quay crane power applications where there is heavy vehicle traffic. Of course, with an RTG another concern is that the crane itself will drive over the cable but this could be solved by `zoning off ' the cable trench in an autosteering system."

ficult job of producing cable that meets the demands of an application they do not have control over. Poorly engineered components and systems will damage cable and cable manufacturers say that mistakes are being made that are costing crane operators money. Draka has observed that there are still instances where reeling systems are designed with S-bends and this has a dramatic affect on the life of the cable. On other cranes one less roller is being used in the cable turnover guide. This has a minuscule impact on the price of the overall cable system but reduces the life of the cable. Prysmian Kabel & Systeme GmbH is asking crane owners to consider the reeling power cable's proper role as one of the most important components on a crane. Given that the entire crane depends on a component that costs less than 1% of the total crane price, Prysmian says, it makes absolute sense to invest in a cable that is properly tested and can be shown to have a financial return through a reduction in risk and downtime incidents. To verify quality, Prysmian tests cables for separating torsion, bending properties, cold flexing and how they are affected by tension. Prysmian has recently also tested other cables and found that the best cable performed 60% better than the worst. Nexans also has a test centre (in Lyon) set up to demonstrate its cables' performance against other brands and help end users make informed decisions about "equivalency." The problem for cable manufacturers is that cable decisions are often made by the OEMs with freedom to select an "equivalent" cable. Over the last few years they have been driven to look for cheaper cables by steep price increases as the rising cost of copper has been passed on. Although it has come back somewhat, copper averaged US$8000/t over the last three years compared to US$1500/t over the past decade, and about 30% of cable content is copper.

More on mobiles

Liebherr-Werk Nenzing reports a slight increase in inquiries for harbour mobile cranes equipped with cable reels to use shore power. Today 10% of its harbour mobile cranes are equipped with cable reels. Keeping the cable clear of the travel gear is relatively straightforward compared to an RTG application and the motor driven cable reel is manually operated with a local push button control station. A cable trench is preferable but not required. The more demanding cable reeling application on a harbour mobile crane is the control cable reeled at the tip of the boom. Liebherr uses a Hartmann and König reel combined with what it calls a "Liebherr Special Trailing Cable" - a multicore cable for power and control designed for heavy duty vertical cable reel application with a breaking load of more than 20kN and a service life of over 15,000 hours.

Integrated couplers

Mine Cable Services Corporation of Canada (MCS) has recently developed a coupler that enables container crane cables with both power (up to 25kV) and integral fibre optic elements to be connected through a single, sealed coupler system. MCS calls the system "Integrated Fibre Optics Technology" (IFOT) and president John Parkes says it has good advantages in container crane applications. Having a coupler with IFOT at both ends of the crane main power cable makes cable replacement much simpler as the conductor and fibre optic components do not have to be terminated separately. It also makes it easier to test the whole cable end to end. The coupler itself is a sealed waterproof unit to protect from ingress of salt, spray and other debris. Parkes adds that MCS has put together a demonstration unit and is willing to take it to interested ports. MCS also offers cable repair services using Prysmian repair technology which includes fibre optic splicing. May 2007

Cable quality

Cable manufacturers face the dif52

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