Hi Dear Vikram

A AVR (Automatic Voltage Regulator) is designed to automatically maintain a constant voltage level in any frequency.

Hi Dear Vikram

A AVR (Automatic Voltage Regulator) is designed to automatically maintain a constant voltage level in any frequency.

Whether the frequency is 50 or 60 Hz the line to line voltage to design for or to test depends on the standards of the country you are specifying the product for use in.  It also depends on whether the product is to be supplied from single phase, split phase, 3 phase or single phase derived from 3 phase.  It depends on whether the product is a low power device or something that needs high current supply.

See

http://en.wikipedia.org/wiki/Mains_electricity_by_country

I don't find any relation between the two. The L-L voltage or for that matter any voltage for a given transmission/distribution system shall be taken constant. It depends on the country and the level of transmission/distribution (Primary/ secondary and so on). After all one cannot change the system voltage or frequency at ones will.

Line voltage(Vline=squrt3 Vphase), and Vphase= Induced EMF in primary multiplied turn ratio, at no load. Hence Vline=squrt3(4.44fOmaxN1) multiplied the turn ratio(N2/N1), where Omax the maximum flux density produced by magnetizing current, N1 the primary turns and f the supply frequency(changed to 50 Hz) . Though primary winding inductive reactance Xl=2paifL, will increased, yet the magnetizing current will not changed much at power frequency variation of 10Hz, as all other factors for inductive circuit has not changed(L=do/di, variation of flux with respect to variation of current).