10-25: Recent Developments in Motor Technology Allow Direct Drive of Low

This paper is a follow-up to a paper presented in 2009 concerning the use of permanent magnet motors for direct drive of cooling tower fans. In the previous paper, the authors presented a case study where an existing tower was retrofitted with a motor of this type. After a year in operation, the motor was removed from service, completely disassembled and inspected to determine how it performed in the harsh environment inside the cooling tower. Both the electrical integrity of the windings and mechanical attributes such as grease contamination are investigated. Data is supplied on subsequent field installations and the feasibility of larger horsepower machines is considered.