Crane cables get smart

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On cranes, a spreader cable is connected to the “spreader” which picks up containers. These cables must be synchronized with the steel ropes which move the spreader if excessive force is to be avoided on the cables. By measuring cable tension, this cable allows drum control to be optimized. 

A time saver

This power and/or control cable is one of the first to deliver information about the status of the cable, itself. Whereas monitoring temperature or humidity in the vicinity of a cable is already normal, measuring tensile performance is quite new and will allow operators to work faster and avoid breakdowns.

The big squeeze

The project is being done in close cooperation with a Swiss Research Institute and a Technical University in Germany. The idea is to use two stranded insulated copper wires in the middle of the cable as a sensor element. Due to stranding, when there is a tensile load on the cable, the two cores are pressed together and the mutual capacitance is measured (which increases with decreasing distance).

Further developments

Current lab tests are being done on a drum used for ship-to-shore cranes. Next, a field test will be done on an actual crane in a German harbor. This project is a starting point for many other applications where information about mechanical performance could be useful: for example in mining, wind turbines and automation. There is also a medium-voltage cable under development which uses the same sensor solution to supply power to the whole crane. Two new patents have already been filed.