When the Terminal de Contenedores de Yucatán – TCY – container and cargo-handling terminal in Mexico’s Yucatán peninsula began operation in 2005, the two Panamax Starporter ship-to-shore cranes, manufactured by Star Iron & Steel of Tacoma, Washington State, USA, were already nearly thirty years old. During the next seven years, however, keeping the cranes operational was becoming difficult – despite being mechanically sound, they were in a poor electrical condition. Furthermore, finding replacement parts for the old DC drives was nearly impossible.
To overcome the issue, Emerson Control Techniques proposed a new fully integrated drive and control system featuring its Mentor MP DC drive. David Asensio, project manager for Grub TCB of Spain, which owns the terminal, explained that being rugged and easy to maintain, this drive solution proved to be the best for the application.
The control system encompasses all the electrical equipment including low-voltage auxiliaries, DC drives, PLC, I/O, crane management system and MCC; plus new remote I/O and control stations, RF Ethernet-based remote diagnostics, and a modern rotating operator’s chair and consoles.
A 120 amp Mentor MP was selected for the hoist, which uses a 373kW motor rated at 50 tons and has a speed of 45/min. The 55kW trolley, with a speed of up to 120m/min and the 55kW boom with a maximum speed of 6m/min, share a 210 amp Mentor MP, which is switched between the two. The eight 14kW, 45m/min gantry motors have their duty shared between four 105 amp Mentor MP DC drives.
Increasing reliability
Described as a reliable, flexible and powerful digital DC drive, the Mentor MP is designed to maximize motor performance, enhance system reliability and interface digitally with the latest control equipment using Ethernet and a wide range of industrial networks – making it suitable for modernising port cranes and equipment.
Additional features of the range include user-configurable functions – including master-slave management, electric shaft function, digital or analogue feedback and torque control – that are arranged logically in different menus and preconfigured with default values to facilitate commissioning. The operational parameters can be selected and modified from the drive keypad or through the Windows-based software CTsoft. The SM-Application module is an easy plug-in second processor, capable of writing application specific programs without needing to use a PLC or stand alone controllers. It is programmed using SyPT, an IEC 1131 compliant programming tool incorporating function blocks programming.
The SM-Application modules of the two drives, which operate the hoisting motors and connect via Control Techniques’ own high-speed network CT-net, use a load balancing function to control container hoisting and calculate the maximum lifting speed as a function of the load hooked to the spreader. With the spreader empty, the SM-Application modules enable movements at the maximum programmed speeds.
Crane productivity is maximized by using a series of bespoke basic, modular and open-ended software packages, developed by Control Techniques specifically for crane control. These are programmed into the PLC and onboard SM-Application modules, and connected via fieldbus, optimising movements in order to relieve the operator of these delicate and repetitive tasks.
In addition, hoisting, trolley, boom and gantry movements are all driven by DC motors that are controlled by means of Mentor MP digital drives connected via a Profibus network to a controlling PLC.
Control Techniques also designed the Crane Management System integrated into its basic software and enhanced with control modules for the maintenance guide and diagnostics. Operational at the various levels of automation, the software automatically signals events as they occur.
