11. If a resistor ZR is connected between R and N, ZBR between R and B, ZRY between R and Y, and ZBY between B and Y form a delta connection, then after transformation to star, the impedance at R is?
A. (ZBRZBY)/(ZRY + ZBY + ZBR)
B. (ZRYZBR)/(ZRY + ZBY + ZBR)
C. (ZRYZBY)/(ZRY + ZBY + ZBR)
D. (ZRY)/(ZRY + ZBY + ZBR)
12. If a resistor ZR is connected between R and N, ZBR between R and B, ZRY between R and Y, and ZBY between B and Y form a delta connection, then after transformation to star, the impedance at Y is?
A. (ZRY)/(ZRY + ZBY + ZBR)
B. (ZBY)/(ZRY + ZBY + ZBR)
C. (ZRYZBY)/(ZRY + ZBY + ZBR)
D. (ZRYZBR)/(ZRY + ZBY + ZBR)
13. If a resistor ZR is connected between R and N, ZBR between R and B, ZRY between R and Y, and ZBY between B and Y form a delta connection, then after transformation to star, the impedance at B is?
A. (ZBRZBY)/(ZRY + ZBY + ZBR)
B. (ZRYZBY)/(ZRY + ZBY + ZBR)
C. (ZBY)/(ZRY + ZBY + ZBR)
D. (ZBR)/(ZRY + ZBY + ZBR)
14. If the resistors of star connected system are ZR, ZY, ZB then the impedance ZRY in delta connected system will be?
A. (ZRZY + ZYZB + ZBZR)/ZB
B. (ZRZY + ZYZB + ZBZR)/ZY
C. (ZRZY + ZYZB + ZBZR)/ZR
D. (ZRZY + ZYZB + ZBZR)/(ZR + ZY)
15. If the resistors of star connected system are ZR, ZY, ZB then the impedance ZBY in delta connected system will be?
A. (ZRZY + ZYZB + ZBZR)/(ZB + ZY)
B. (ZRZY + ZYZB + ZBZR)/ZB
C. (ZRZY + ZYZB + ZBZR)/ZY
D. (ZRZY + ZYZB + ZBZR)/ZR
16. If the resistors of star connected system are ZR, ZY, ZB then the impedance ZBR in delta connected system will be?
A. (ZRZY + ZYZB + ZBZR)/ZY
B. (ZRZY + ZYZB + ZBZR)/R
C. (ZRZY + ZYZB + ZBZR)/ZB
D. (ZRZY + ZYZB + ZBZR)/(ZB + ZR)
17. Asymmetrical three-phase, three-wire 440V supply is connected to star-connected load. The impedances in each branch are ZR = (2 + j3) Ω, ZY = (1 − j2) Ω, ZB = (3 + j4) Ω. Find ZRY.
A. (5.22 − j0.82) Ω
B. ( − 3.02 + j8) Ω
C. (3.8 − j0.38) Ω
D. ( − 5.22 + j0.82) Ω
18. A symmetrical three-phase, three-wire 440V supply is connected to star − connected load. The impedances in each branch are ZR = (2 + j3) Ω, ZY = (1 − j2) Ω, ZB = (3 + j4) Ω. Find ZBY.
A. ( − 5.22 + j0.82) Ω
B. (5.22 − j0.82) Ω
C. (3.8 − j0.38) Ω
D. ( − 3.02 + j8) Ω
19. A symmetrical three-phase, three-wire 440V supply is connected to star − connected load. The impedances in each branch are ZR = (2 + j3) Ω, ZY = (1 − j2) Ω, ZB = (3 + j4) Ω. Find ZBR.
A. (5.22 − j0.82) Ω
B. ( − 3.02 + j8) Ω
C. ( − 5.22 + j0.82) Ω
D. (3.8 − j0.38) Ω
20. If a star-connected system has equal impedances Z1, then after converting into delta connected system having equal impedances Z2, then?
A. Z2 = Z1
B. Z2 = 2Z1
C. Z2 = 3Z1
D. Z2 = 4Z1