Generator-motor efficiency 1

[onico]

This is related to synchronous generator-motor units for pump-turbine hydropower plants. Would it be any significant difference of the efficiency in motor mode compared to generator mode?
If yes, how can the motor mode efficiency be calculated if you know the efficiency in generator mode?

 

[ccfowler]

The pump vs. turbine efficiency will be much more significant than the motor vs. generator efficiency which will probably be nearly equal.