why is the voltage on name plate details of ac machines written as 415V ?

 

Is it three phase AC system? The voltage between 2 hot phases of the 3 phase system is 415V and the voltage between one hot and the neutral is 240V.

Allen

 

It's also written there primarily to remind you not to exceed the rating. Ignore the "warning" [if you like] & suffer the consequences, such as outright damage to the machine or degradation of its expected operating life.