Electronic frequency conversion 50Hz to 60Hz

What are they turning, and what is the consequence of running at 83% of the 60Hz speed?

Try these guys, they rent:

http://www.50hz.com/?gad=CPrE7IADEgjW8jDVVjEo1hih7Y__AyDS1dMp&OVRAW=frequency%20converters&OVKEY=frequency%20converter&OVMTC=standard&OVADID=962945021&OVKWID=6020317521

You can just buy VFDs for those motors that need to run a specific speeds and/or power levels. VFDs don't care what the input frequency is and can be set to give you any output frequency. The advantage over a single frequency converter for the entire plant is that electronic frequency converters that are NOT designed as motor drives, are typically not very good at supplying motors. The starting inrush can damage the frequency converter, or the converter may limit current, which will interfere with the motor starting. A VFD is made for motor controls, already has built in motor protection and allows for other often beneficial control capabilities.

What is the Voltage to which they were connected in US and what u propose to use?

most of these machines have a multi tap autotransformer so you can set the voltage tap to match the voltage of you plant, the 50 HZ will run on 60 Hz Perry

Yes ! A lot in the name "Drives" or "VFDs" ie Variable Frequency Drive.

You have to look for your requirements i.e. for 60 Hz output