b'WATER-COOLING CONVERSIONWater-cooled multi-motor drive for a complete paper machineBy Michael Herold, Sales Manager, Fibre, Siemens Gas and PowerENTIRE MULTI-MOTOR DRIVE REPLACED INcores were fitted to the outputs of both NINE DAYSthe inverters and converters to protect In April 2018 Siemens put a water- the motors against bearing currents. cooled multi-motor drive into operation for Progroup, one of the leadingAt PM2, its sister paper mill in manufacturers of containerboard andEisenhttenstadt, Progroup has had corrugated board in Europe. Whilevery good experience with the proven their paper mill PM1 in Burg nearSiemens SINAMICS S120 CM (Cabinet Magdeburg, Germany, was down for tenModule) converter series, since the days for the installation, the opportunityhigh levels of dynamism and control was taken to migrate and combine whataccuracy of this series make it possible had been separate operating areas intoto achieve the drive parameters needed the PCS 7 SIPAPER process controlfor the paper machine. Progroup system at the same time.also decided to utilise this innovative drive solution for PM1, and take full The drive system used in the multi- advantage of the benefits of the water-motor drive at PM1 had been runningcooled frequency converters at the same reliably for more than 15 years. To bothtime. The presence of a cooling plant improve machine speed and enable thefor the raw water connection on-site mill to maintain its very high availabilitymade it easier to set up the converter level into the future, Progroup replacedplant with energy-efficient water cooling. the multi-motor drive of the air-cooledThe entire water-cooling system is Masterdrive converter with efficient,configured with redundancy: In the innovative water-cooled converters.event of failure or when required for This forward planning means PM1 ismaintenance purposes, the redundant already prepared for future performancesystem automatically takes over. The enhancements.new, space-saving cabinet arrangement and direct heat dissipation via the water MULTI-MOTOR DRIVE WITH 13 MW INSTALLEDcircuit substantially reduced heat losseslower drive power than fans would DRIVE POWER in the switchgear room. otherwise require.With about 41 drive circuits, the new multi-motor drive includes both theWHY WATER-COOLING? Greater efficiency is the result.variable drives in the paper machineWater is much denser than air, andUnlike and the pump drives. Systemtherefore has a more favorable heatWater-cooling substantially reduces theair-cooling, compatibility ensured the feed-in points,transfer coefficient. Heat is directlyamount of air-conditioning required,water-cooling motors, and most of the cabling coulddrawn off to the cooling fluid rather thanwhich also removes the need torequires be reused, although selected drivesthe environment. Unlike air-cooling,change air filters every year. Additionalmuch lower were replaced as a preventive measurewater-cooling requires much lowersavings can be obtained from targetedcirculation of or to improve performance. As acirculation of the cooling agent, whichheat recovery for process or heatingthe cooling precaution, nanocrystalline toroidal tapealso means the pumps need muchpurposes. This can also reduceagent52 WORLD PULP&PAPER'