Question

Three identical coils each resistance 15 ohm inductance 100 mH connected in delta to 415 V,3-phase supply determine impedance

Answer 1

Note: Considering that Inductance as 0.05 H , because unit of inductive reactance is ohm, not henry.]

Per phase impedance ,

Z = √[(R^2)+((2πfL)^2)] ohm

Z = √[(20^2)+((2*π*50*0.05)^2)] ohm

Z = 25.43 ohm

Per Phase Voltage, V = 415 volt

So, per phase current = 415/25.43 = 16.32 amp.

So, line current = √3 x 16.32 = 28.27 amp.

And, total power consumption,

P = 3 x ((per phase current)^2) x (per phase resistance) = 3 x (16.32^2) x 20 watt

P = 15980.544 watt = 15.98 kw