SEW-EURODRIVE’s MACC series two-stage gear units for air cooled condensers have recently been installed in a power station for a highly specialised application. The condensers are being used to ensure adequate air movement to cool circulating water so that power generation can continue.

The company had installed its MACC units over the past few years, and says their reliable operation has led to a request to supply several additional units. SEW-EURODRIVE business development representative Quintin Bianchina says the design is specific to this demanding application.

“Comprising a gearbox and long output shaft that attaches to a fan via a hub, these MACC units also boast a thicker, more rigid cast iron housing than a standard gearbox,” explains Bianchina. “The radial and axial loads transmitted by the fan are substantial, requiring a suitable design that will withstand these forces.”

With the fan in operation, there is both upward and downward thrust as well as forces to the left and right and the gearbox, bearings and shaft must be designed and manufactured to accommodate these forces while continuing to operate reliably. The flat topography and climatic conditions around the power station also exacerbate the situation, especially on hot days when air moves rapidly up the cooling towers.

In addition, the MACC units are designed to be quieter which helps ensure that noise levels do not exceed maximum limits. Heat build-up in the gearbox must also be dissipated, so the design includes cooling ribs to increase the surface area, which enhances the cooling significantly on the gear units. SEW-EURODRIVE also offers a low noise axial cooling fan as an option, for enhanced thermal improvements.

The units features a maintenance safety brake on the high speed input section of the gearbox, which can be applied to bring the fan safely and easily to a standstill under wind milling conditions when maintenance is required.

SEW-EURODRIVE has recently built a new and expanded facility at Aeroton in Gauteng, allowing for the local assembly and reduced turnaround time for the MACC units.

“Rather than the usual 30+ weeks to import this equipment, we expect to assemble and deliver these in batches within 8 to 12 weeks,” says Bianchina. The MACC series is designed and tested in Finland.