Wired for gains
Cable suppliers are basking in the gains of rising eRTG popularity, finds Alex Hughes
The cables industry has received something of a boost in recent years as more effort has been made to convert noisy diesel-fueled equipment into something quieter and more fuel efficient.
The main focus of this has been on the RTG, where Cavotec has been one of the major players.
Cavotec offers terminal operators a solution for converting diesel RTGs into electrically powered ones. However, the company stresses that the only additional cabling required is that relating to the cable reel, plus a few others sections for the system control and interface.
“The existing quantity of cables from the diesel generator to the electrical housing remains the same, but runs from the transformer or switching panel to the electrical housing. Therefore the impact of new fixed cables on board an electric RTG is kept to a minimum,” says Diego Sanchez, product manager of Cavotec's eRTG Group.
Yann Duclot, group manager, marketing & sales, adds, “Cavotec has been working closely with cable manufacturers in order to engineer a complete eRTG solution encompassing not only the cable, but also a solution capable of withstanding the specific application requirements. Parameters such as the speed, acceleration and mechanical strength on the cables have been taken into consideration in order to meet the specificity of the application.”
Both men note that the types of cables used in a retrofitted RTG are exactly the same as would be found in a brand new electric RTG.
“They would be the same or similar cables, because the overall construction is the same,” says Mr Sanchez, pointing out that cable selection is made taking into account the electrical consumption of the RTG (basically hoist, trolley motors and auxiliary power). The new eRTGs are normally lighter than the old RTGs therefore less power is required, but this is not a hard and fast rule as it much depends on the different OEM designs.
Retrofit eRTGs require customised solutions and a stronger engineering component as Cavotec needs to adapt the system to a crane that has not been primarily designed for electrical power. For brand new eRTGs, Cavotec is involved at the earliest stage of the project with the crane OEMs, thereby reducing the overall complexity.
According to Mr Duclot: “eRTGs can be powered with medium voltage cables, which consequently requires Cavotec to not only provide the suitable technical solution, but also carefully consider the safety aspects related to MV electrical connections,” he says.
While the eRTG is a niche market, it is one that has kept on growing and has proven to be an attractive market for cable manufacturers and cable reel manufacturers alike. The cable reel solution for electrifying eRTG is a proven technology that ports not only appreciate due to the limited infrastructure requirements, but also for the high level of reliability and safety of the full system.
There are, argues Mr Duclot, substantial economic benefits to be had from operating electric RTGs. “They need less maintenance than diesel RTGs, whose diesel generator costs more money and isn’t as easy as simply cleaning and changing the oil of the cable reel. However, it is important to make a proper installation of the cable in order to guarantee perfect functionality of the system.
“To ensure this is done correctly, Cavotec has developed the DACO turnover anchor system, ensuring a proper fixing/anchoring of the cable in the yard and offering complete protection of the cable,” he says.
As for what percentage of a converted RTG cost is the result of cabling depends on whether low or medium votage is being discussed. The cross section of the cable (copper figure/pricing) also has to be taken into account.
Asked whether it is Cavotec or customer that specifies which cable supplier is used, Mr Sanchez says it tends to be a mix of both. “Sometimes the end customer identifies and selects the cable brand, while in other cases the cable reel manufacturer can select the cable. There is no fixed rule regarding this.”
Nevertheless, when selecting a cable, Cavotec also takes into consideration other aspects. These include the integration of the cable into the system, as the company can also warrant the entire engineered solution (requiring a technical analysis regarding the suitability of the cable) for the specific application, and the correct integration of the cable with the cable reel and other eRTG components.
But there is no cutting corners.
The type of cable used on the cable reel eRTGs cannot, by definition, be a cheap cable, says Mr Duclot. As eRTGs run around 145m/min with five to eight second acceleration time, the cable needs to be suitable for these types of installations, and needs to be managed in a proper way.
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