Deck machinery winches for anchoring and mooring are fundamental equipment on all marine vessels, with hydraulic-oil-driven winches traditionally being used. Winching operations are very challenging since a slack mooring or anchor line with almost zero tension at the start has to, in just a few seconds, deal with torque rapidly racing to extreme levels. To properly maneuver and secure high-mass marine vessels moving on the water surface, it is vital to have precise and 100% reliable control of the huge torque forces at work.
Hydraulic oil still dominant, until now
Electrical three-speed winch motors with contactors have existed already for many years, as have electrical VSD (variable speed drive) solutions with basic functionality. Although these first-generation electrically-driven winches offered improved control and positive environmental benefits, they were not widely accepted. The DOL (Direct on Line) motors with 3 motor windings for low-middle-high speeds had limited success, as did the early VSD design which included a PLC with winch application, motors with encoders and tension control via load sensors.
Drawbacks of this first generation included costly motors with three windings, a high starting current, high noise, and the requirement for electrical cabinets with contactors for each set of windings in the motor. In addition, external control via old control cards raised questions about support, maintenance and spare parts. On the early VSD winches, external PLCs, encoders and load sensors made the systems complicated and sometimes unreliable.
The result, until recently, has been that older hydraulic systems have so far been maintained by approximately 70% of the worldwide marine vessels. This is understandable considering the fact that winch builders, and of course shipowners, are extremely careful with their multimillion dollar vessels and cargoes. This clearly is not a place where new things are tested before they are first well-proven with years of experience on both the hardware and software. To create a smart, secure, drives-based solution for deck machinery, ABB decided to take a different approach.