01․ A 3 – φ delta connected symmetrical load consumes P Watts of power from a balanced supply. If the same load is connected in star to the same supply then what is the power consumption?

P

_{Δ}= 3P_{Y}02․ Condition for a balanced 3 - phase load is that, each phase has the same value of __________________.

The condition of a 3 - phase balanced are that each phase has the same value of impedance, resistance and power factor.

03․ A 3 wire, 3 - φ supply feeds a load consisting of three equal resistors. By how much is the load reduced if one of the resistors be removed when the load is in star?

If one resistor is removed from a 3 - φ circuit, then the circuit is no longer 3 - φ but converted into single phase circuit, having two resistor, each of R Ω connected in series across the supply of V

_{L}Volts.04․ Phase voltages of a star connected alternator are E

_{R}= 240∠0^{o}V, E_{Y}= 240∠-120^{o}V and E_{B}= 240∠ + 120^{o}V. What is the phase sequence of the system?Here E

_{R}is reference voltage E_{Y}lags behind it by 120^{o}, E_{B}lags behind E_{R}by 240^{o}and E_{Y}by 120^{o}. So phase sequence is RYB.05․ A balanced three Phase Y-connected load has one phase voltage V

_{B}= 277∠45^{o}V. The phase sequence is RYB. The line to line voltage V_{RY}is06․ In delta connected circuit when one resistor is open, then power will be

Power consumed in case of balanced delta connection P = V

_{ph}2/R_{eq}. R_{eq}= 2R/3. So, P = 3V_{ph}2/2R. If one resistor is removed from a 3 - phase delta connected circuit, then the circuit will be converted into single phase circuit having two resistors in series. P’ = V_{ph}2/R_{eq}. R_{eq}= 2R. So, P’ = V_{ph}2/2R. P’ = P/307․ For balanced star load, if unbalanced line current are I

_{R}, I_{Y}, I_{B}equal to - j10, - j10 and - j20 respectively, the neutral current will be equal toAll three current will be separated by 120

_{o}in space.08․ V

_{RN}, V_{YN}and V_{BN}are three phase voltage of a balanced three phase system. If V_{RN}= 200∠30^{o}V and V_{BN}= 200∠- 90^{o}V, then phase sequence of the system isPhase Y lags phase R by (30 + 90)

^{o}= 120^{o}so the phase sequence RBY.09․ Three identical inductors are connected in delta with a 220 V, 50 Hz, 3 - φ, supply. If the phase current is 24 A, then what is the value of each of the inductance?

10․ A balanced 3 - φ star connected load is fed from a 208 V, 3 - φ supply. Each load has resistance of 35 Ω. The total power is

<<<5556575859>>>