I have seen some induction motors have information on their nameplate listed for 50hz and 60hz. While I've read a requirement that the Voltage/Frequency ratio be consistent, using these nameplate numbers you can come up with examples like 380V/50Hz = 7.6, and 440V/60Hz = 7.33. These are not the same. Are they close enough that it doesn't matter? Does this mean all induction motors can be run in either frequency? All 3 phase induction motors can be run at either frequency? Only motors designed used in at both frequencies?
Edit: I see the nameplates. I'd just like to have an idea of why - I'll take any direction you can point me in. Did marketing de-rate these motors so they can run slow enough or cool enough at either frequency? Did accounting let them use better materials? Do I need to take a graduate level FEM course in order to understand, and I'm asking the equivalent of how to measure the current across and the voltage through?