SOLUTIONS - Moeller Electric Parts

SOLUTIONS18Bow thruster BU90F, with a tube diameter of 1600mm and a drive output 700 kW, generates a thrust of96 kN at 1770 rpm.Jastram supplies transverse thrusters fornew ships and conversions for older ships.The sailing school ship of the German Navy,the “Gorch Fock” and the “Bodo Supplier”,which were converted to a cable repairand maintenance ship are examples ofvessels that were retrofitted with Jastramtransverse thruster systems. On mega yachtssuch as “Al Mirqab” (Kusch yacht building),Jastram transverse thrusters are used withnoise reduction. The technology and thedimensioning of transverse thrusters areanything but simple, even the mountinginvolves precision work.Structure of a bow thruster systemA bow thruster system basically integratesa drive and gear unit as well as a propeller.Diesel, hydraulic or electric motors are usedas drives.When mounted, the bevel gears of thecyclo palloid gear and the propellers areexpanded hydraulically and adapted to thegear shaft. For this oil press fit, the contactpattern or contact surface is examinedclosely to ensure a 100 percent fit.Transverse thrusters have either a variableor fixed pitch propeller. Variable pitchpropellers are run at a constant speedand the thrust is controlled by changingthe pitch of the propeller blades. Fixedpropellers are driven with slip ring motorsand rheostats as well as frequencycontrolled systems. The circuit of theresistors in the rotor circuit controls thespeed over three to seven stages, and threestagetransverse thrusters are mostly used.Each bow thruster and all individualcomponents are tested and approvedby classification societies such as Lloyd’sRegister (LR), Germanischer Lloyd (GL), DetNorske Veritas (DNV), Bureau Veritas (BV)and American Bureau of Shipping (ABS) etc.DIL - rugged, reliable and durableJastram drives switch ratings of up to 1650kW, which means that conventional barmountedcontactors or motor-operatedcircuit-breakers and switch-disconnectorswith remote operators are used. Transversethruster systems are designed for anaverage ship lifetime of 25 years, and sothe corresponding switchgear assembliesmust be dimensioned accordingly. With3000 to 4000 switch operations a year,this amounts to around 75,000 to 100,000operations after 25 years. For these kinds ofapplications, a 1600A switch-disconnectoris unsuitable since it is only designed foraround 2000 switch operations in AC-3 applications. On the other hand, theDILM 1600 A contactor with vacuumtechnology in AC-3 operation (starting/stopping, squirrel-cage motors) at 100percent of the rated current Ie has a devicelifetime verified at around 250,000 switchoperations. The vacuum tubes on the DILMare ideal for switching high voltages as arcsare not produced and no escaping gasesoccur during switching. As the switchingof a slip ring motor can only be assigned toutilisation category AC-2, the DILM offerssufficient reserve for zero maintenanceoperation with a ship lifetime of 25 years.The propeller speed can be varied on a3-stage rudder system by shorting theresistors in the rotor circuit in stages of 70,85 and 100 percent of the rated speed.The shorting of the resistors is handledby maintenance-free DILM 400/ 300contactors. The rotation direction of thepropeller and thus the starboard or portthrust is implemented with a reversingcontactor circuit consisting of two DILM1600 contactors.CONCLUSIONTorsten Jensen, responsible at Jastramfor the electrical design of the bowthrusters, had this to say about the useof Moeller components: “We only knowa few other suppliers on the marketwith products that can switch currentsup to 2000 A with the required 4000switch operations per year, and whichalso have all the relevant shippingapprovals. Our suppliers must have aworldwide logistics network so that wecan ensure the procurement of spareparts at any time. A comprehensive,partner-based support is equallyimportant to us. This is why we rely onMoeller technology.”Switchgear for a 700 kW bow thruster system, consisting of two DILM 1600 contactors for controlling thepropeller rotation direction and DILM 400/ 300 for the speed control by bridging the resistors in the rotorcircuit.Quicklink ID:MS1810For Moeller Electric Sales and Support call KMparts.com (866) 595-961611