[EMAIL PROTECTED] wrote: > We have the same problem with resonance speeds when designing and operating > our large turbine and generator sets in power plants. At certain speed (RPM) > ranges the natural vibration frequency of the shafts and rotating parts comes > > into resonance with the speed of rotation. (The axis of rotation "hunts" > between the physical center and the rotation center and can destroy the > machinery.) > Our solution is when bringing the machinery up to speed or slowing down to > always pass that critical RPM as fast as possible along with safety.
Parson's early turbines were not bolted to the floor but rested on rubber pads. One set actually left the pads and 'walked' down the power station when an inexperienced engineer did not move through the critical speed fast enough. Turbines actually suffered less from vibration than their reciprocating counterparts. This was one of their advantages in the days when power stations were actually situated in the local neighbourhood (i.e. a neighbourhood that could afford electric lighting). Naturally the locals did not like the vibrations carrying up through their foundations. This was particularly the case with one station in Paddington London, which used Willans Engines. Every thing was tried to stop the problem. Finally the neighbours went to court to close the station down, the station was only saved when it replaced the engines with Parsons Turbines. Parsons tried to ameliorate the fundamental frequency issue by providing floating bearings at each end of the shaft. I had the privilege of looking after the Parsons original turbine of 1884 for a time. Sam E _______________________________________________ SSLiveSteam mailing list Send messages: [email protected] Cancel subscription: http://postfix.45mm.com/mailman/listinfo/sslivesteam Rules: http://www.45mm.com/sslivesteam_guide.html
