Digital DC drives from Control Techniques have been chosen for the latest phase in the upgrading of cranes in La Spezia Container Terminal (LSCT) in northern Italy. One of the last cranes to be refurbished is a ship-to-shore (STS) gantry crane manufactured by Italian crane company MGM OMG. For this project, Emerson Control Techniques Italy was responsible for replacing all medium voltage electrical equipment, low-voltage auxiliaries, drives, the controlling PLC and the crane management system. They also replaced the DC hoist motors with new ones from sister company Leroy Somer.
The customer’s list of requirements for the latest STS gantry crane was demanding. They needed rapid container handling, fast and precise crane positioning to provide the required productivity, maximum crane availability and reliability, as well as excellent technical support and effective preventative maintenance utilising an improved faults analysis facility.
Hoisting, trolley, boom and gantry movements are now driven by DC motors, controlled by Mentor MP digital drives from Control Techniques that are connected via a Profibus network to an S7-300 PLC.
The completed OMG crane features:
• Two 1200 A Mentor MP drives controlling 290 kW DC LSK Leroy Somer hoist motors
• A 60 tonne lifting capacity under the spreader
• A lift rating of 70 tonnes
• Lift speeds of 90 m/min (rated load) and 150 m/min (unloaded).
Each hoist drive is fitted with a plug-in SM-Applications module: a second processor, connected by CTNet and using a load-balancing function to control container hoisting. With the spreader empty, the SM-Applications modules enable movements at the maximum programmed speeds. Crane productivity is achieved 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 SM-Applications modules and optimise movements, trajectories, position location and load swaying, in order to relieve the operator of these delicate and repetitive tasks.
Four 470 A Mentor MP drives control the four 30 kW DC trolley motors to give a dockside speed of up to 160 m/min. One 470 A Mentor MP controls the 120 kW DC boom motor and two 470 A Mentor MP drives control the sixteen 15 kW DC gantry motors, which have a travel speed of 60 m/min.
Control Techniques’ Crane Management System (CMS), is integrated into its basic software and includes control modules for diagnostics and maintenance. These software packages automatically signal events as they occur, guiding the operator in manoeuvres and assisting technicians with repair and preventative maintenance operations.
Mentor MP is designed to withstand extremely harsh conditions. The drive is reversible, giving maximum speed control during acceleration and deceleration, and also saves energy by using regeneration during braking. The Mentor MP range of digital DC drives spans output currents from 25 A to 7400 A, with all sizes sharing the same control, monitoring and communications features. A comprehensive self-tuning algorithm gives improved current loop performance for a faster and more uniform response at all speeds. Drive performance is also enhanced with full PID digital speed control.
Mentor MP drives feature a series of user-configurable functions (reference-follower management, electric shaft function, digital or analogue feedback, torque control, etc.) that are arranged logically in different menus and preconfigured with default values to facilitate commissioning.
During the last eight years, Emerson Control Techniques has been responsible for the electrical refurbishment of ten STS cranes, eight rail-mounted gantry cranes (RMGs), four rubber-tyred gantry cranes (RTGs) and one mobile harbour crane (MHC) at La Spezia.
La Spezia Container Terminal (LSCT), owned by Contship Italia Group, is Italy’s most important cargo-handling and container terminal and is the country’s most advanced port in terms of high technology logistics.
The terminal is capable of handling 1,200,000 TEUs (standard 20 foot equivalent container units), is equipped with 11 STS cranes, eight RMG cranes for park stacking, 10 RTG cranes and two MHCs.