hiii my question is how can we calculate power factor in 3 phase system if only power(kva) and voltage (kv) is given?
http://www.elec-toolbox.com/Formulas/Useful/formulas.htm E x I x 1.732 Since you have kva, just multiply by 1.732 I guess. Wait for confirmation from someone smarter than I.
I don't see how you can. It's like asking how can you figure your car's mileage knowing how fast you were going and what yours car's horsepower rating is. Vital information is missing. Are you sure you were given voltage (kV) and not real power (kW)?
The 1.732, which is sqrt(3), merely takes you from knowing I and E for a single phase and figuring out the total for all three phases (assuming a balanced load). You can use this to find the phase current, but that tells you nothing about whether that current is in phase and, if not, by how much it is out of phase.