433 IS LILNE TO LINE VALUE OF 250

415 IS NOT DIVISIBLE BY 1.732

Appliances rated voltage is 415V. If Trasformer is specied 
at 415V, it will further drop down at receving end and 
appliances may not work

To compensate Voltage drop at receiving end

Appliances rated voltage is 415V. If Trasformer is specied 
at 415V, it will further drop down at receving end and 
appliances may not work

Power distribution network is supposed to have a voltage 
drop of around 4%.  As the utility provider has to assure a 
three phase voltage of 415 V at consumer's metering point, 
the secondary phase to phase voltage of the distribution 
transformer is specifed at 4% higher than standard three 
phase-phase to voltage of 415 V, which works out to 433 V.