Range Settings for Relay Elements

Have you looked at the data sheet for the relay, this information should be listed in there. As far actually choosing an under and over voltage setpoint, it depends a little on the application (and to some extent the standards you are working to).

The normal relay votage is 150V (Is the right?)

No, for standard applications the voltage monitored is the standard phase to ground voltage and/or phase to phase (eg-120/208V, 230V/400V, 240V/415V, etc). For higher voltages a step-down transformer is used (again down to a standard voltage). Not sure where 150V came from.

This Relay which we are designing is for the power protection of feeder

Are you actually designing and building a protection relay or trying to program settings into an existing product? If so you need to design in a settable range for the set points, not an individual value (see one of the many example relay products on the market below).

http://www.abb.co.nz/product/db0003db004281/c12573e700330419c1257110004f5938.aspx?tabKey=7

Can you please provide more information on your application.

Dear sir

Over and under voltage limits depends up on your equipment to be protected.It also depends on the consumer to whome you feed.

normaly the higher and lower range is set near + or - 5%

for 150V secondary 27 around 142.5V

and 59 around 157.5V

best regards

raju