30 + Mcqs in Star Delta Transformation Page 1 McqOptions

1.	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
Answer» D. Z2 = 4Z1

Discussion

2.	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
Answer» C. (-5.22+j0.82) Ω

Discussion

3.	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
Answer» C. (3.8-j0.38) Ω

Discussion

4.	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 ZRY.
A.	(5.22-j0.82) Ω
B.	(-3.02+j8) Ω
C.	(3.8-j0.38) Ω
D.	(-5.22+j0.82) Ω
Answer» D. (-5.22+j0.82) Ω

Discussion

5.	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)
Answer» B. (ZRZY + ZYZB + ZBZR)/R

Discussion

6.	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
Answer» E.

Discussion

7.	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)
Answer» B. (ZRZY + ZYZB + ZBZR)/ZY

Discussion

8.	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)
Answer» B. (ZRYZBY)/(ZRY+ZBY+ZBR)

Discussion

9.	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)
Answer» D. (ZRYZBR)/(ZRY+ZBY+ZBR)

Discussion

10.	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)
Answer» C. (ZRYZBY)/(ZRY+ZBY+ZBR)

Discussion

11.	Find the equivalent resistance between A and B.
A.	32ohm
B.	31ohm
C.	30ohm
D.	29ohm
Answer» E.

Discussion

12.	If an 8/9ohm, 4/3ohm and 2/3ohm resistor is connected in star, find its delta equivalent.
A.	4ohm, 3ohm, 2ohm
B.	1ohm, 3ohm, 2ohm
C.	4ohm, 1ohm, 2ohm
D.	4ohm, 3ohm, 1ohm
Answer» B. 1ohm, 3ohm, 2ohm

Discussion

13.	If a 1ohm 2ohm and 32/3ohm resistor is connected in star, find the equivalent delta connection.
A.	34 ohm, 18.67 ohm, 3.19 ohm
B.	33 ohm, 18.67 ohm, 3.19 ohm
C.	33 ohm, 19.67 ohm, 3.19 ohm
D.	34 ohm, 19.67 ohm, 3.19 ohm
Answer» B. 33 ohm, 18.67 ohm, 3.19 ohm

Discussion

14.	Ra is resistance at A, Rb is resistance at B, Rc is resistance at C in star connection. After transforming to delta, what is resistance between A and B?
A.	Rc+Rb+Ra*Rb/Rc
B.	Ra+Rb+Ra*Rc/Rb
C.	Ra+Rb+Ra*Rb/Rc
D.	Ra+Rc+Ra*Rc/Rb
Answer» D. Ra+Rc+Ra*Rc/Rb

Discussion

15.	Ra is resistance at A, Rb is resistance at B, Rc is resistance at C in star connection. After transforming to delta, what is resistance between A and C?
A.	Ra+Rb+Ra*Rb/Rc
B.	Ra+Rc+Ra*Rc/Rb
C.	Ra+Rb+Ra*Rc/Ra
D.	Ra+Rc+Ra*Rb/Rc
Answer» C. Ra+Rb+Ra*Rc/Ra

Discussion

16.	Ra is resistance at A, Rb is resistance at B, Rc is resistance at C in star connection. After transforming to delta, what is resistance between B and C?
A.	Rc+Rb+Rc*Rb/Ra
B.	Rc+Rb+Ra*Rb/Rc
C.	Ra+Rb+Ra*Rc/Rb
D.	Rc+Rb+Rc*Ra/Rb
Answer» B. Rc+Rb+Ra*Rb/Rc

Discussion

17.	Find the equivalent resistance between X and Y.
A.	3.33 ohm
B.	4.34 ohm
C.	5.65 ohm
D.	2.38 ohm
Answer» E.

Discussion

18.	Find the equivalent delta circuit.
A.	9.69 ohm, 35.71 ohm, 6.59 ohm
B.	10.69 ohm, 35.71 ohm, 6.59 ohm
C.	9.69 ohm, 34.71 ohm, 6.59 ohm
D.	10.69 ohm, 35.71 ohm, 7.59 ohm
Answer» B. 10.69 ohm, 35.71 ohm, 6.59 ohm

Discussion

19.	FIND_ZBR.?$
A.	(5.22-j0.82) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ
B.	(-3.02+j8) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ
C.	(-5.22+j0.82) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ
D.	(3.8-j0.38) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ
Answer» C. (-5.22+j0.82) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ

Discussion

20.	IF_AN_8/9OHM,_4/3OHM_AND_2/3OHM_RESISTOR_IS_CONNECTED_IN_STAR,_FIND_ITS_DELTA_EQUIVALENT.?$
A.	4ohm, 3ohm, 2ohm
B.	1ohm, 3ohm, 2ohm
C.	4ohm, 1ohm, 2ohm
D.	4ohm, 3ohm, 1ohm
Answer» B. 1ohm, 3ohm, 2ohm

Discussion

21.	If_a_star_connected_system_has_equal_impedances_Z1,_then_after_converting_into_delta_connected_system_having_equal_impedances_Z2,_then?$
A.	Z<sub>2</sub> = Z<sub>1</sub>
B.	Z<sub>2</sub> = 2Z<sub>1</sub>
C.	Z<sub>2</sub> = 3Z<sub>1</sub>
D.	Z<sub>2</sub> = 4Z<sub>1</sub>
Answer» D. Z<sub>2</sub> = 4Z<sub>1</sub>

Discussion

22.	Find ZBY in the question 7?
A.	(-5.22+j0.82) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ
B.	(5.22-j0.82) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ
C.	(3.8-j0.38) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ
D.	(-3.02+j8) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ
Answer» C. (3.8-j0.38) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ

Discussion

23.	If a 1ohm 2ohm and 32/3ohm resistor is connected in star, find the equivalent delta connection?
A.	1ohm, 3ohm, 2ohm
B.	4ohm, 3ohm, 5ohm
C.	4ohm, 5ohm, 2ohm
D.	5ohm, 3ohm, 2ohm
Answer» B. 4ohm, 3ohm, 5ohm

Discussion

24.	A symmetrical three-phase, three-wire 440V supply is connected to star-connected load. The impedances in each branch are ZR = (2+j3) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ, ZY = (1-j2) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ, ZB = (3+j4) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ. Find ZRY.$
A.	(5.22-j0.82) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ
B.	(-3.02+j8) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ
C.	(3.8-j0.38) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ
D.	(-5.22+j0.82) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ
Answer» D. (-5.22+j0.82) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ

Discussion

25.	Rab is the resistance between the terminals A and B, Rbc between B and C and Rca between C and A. These 3 resistors are connected in star connection. After transforming to delta, the resistance at A will be?
A.	Rc+Rb+Rc*Rb/Ra
B.	Rc+Rb+Ra*Rb/Rc
C.	Ra+Rb+Ra*Rc/Rb
D.	Rc+Rb+Rc*Ra/Rb
Answer» B. Rc+Rb+Ra*Rb/Rc

Discussion

26.	If the resistors of star connected system are ZR, ZY, ZB then the impedance ZRY in delta connected system will be?
A.	(Z<sub>R</sub>Z<sub>Y</sub>+ Z<sub>Y</sub>Z<sub>B</sub>+ Z<sub>B</sub>Z<sub>R</sub>)/Z<sub>B</sub>
B.	(Z<sub>R</sub>Z<sub>Y</sub>+ Z<sub>Y</sub>Z<sub>B</sub>+ Z<sub>B</sub>Z<sub>R</sub>)/Z<sub>Y</sub>
C.	(Z<sub>R</sub>Z<sub>Y</sub>+ Z<sub>Y</sub>Z<sub>B</sub>+ Z<sub>B</sub>Z<sub>R</sub>)/Z<sub>R</sub>
D.	(Z<sub>R</sub>Z<sub>Y</sub>+ Z<sub>Y</sub>Z<sub>B</sub>+ Z<sub>B</sub>Z<sub>R</sub>)/(Z<sub>R</sub>+Z<sub>Y</sub> )
Answer» B. (Z<sub>R</sub>Z<sub>Y</sub>+ Z<sub>Y</sub>Z<sub>B</sub>+ Z<sub>B</sub>Z<sub>R</sub>)/Z<sub>Y</sub>

Discussion

27.	Delta connection is also known as____________
A.	Y-connection
B.	Mesh connection
C.	Either Y-connection or mesh connection
D.	Neither Y-connection nor mesh connection
Answer» C. Either Y-connection or mesh connection

Discussion

28.	Which, among the following is the correct expression for star-delta conversion?
A.	R1=RaRb/(Ra+Rb+Rc), R2=RbRc/(Ra+Rb+Rc), R3=Rc*Ra/(Ra+Rb+Rc)b)
B.	R1=Ra/(Ra+Rb+Rc), R2=Rb/(Ra+Rb+Rc), Rc=/(Ra+Rb+Rc)
C.	R1=Ra+Rb+RaRb/Rc, R2=Rc+Rb+RcRb/Ra, R3=Ra+Rc+Ra*Rc/Rb
D.	R1=RaRb/Rc, R2=RcRb/Ra, R3=Ra*Rc/Rb
Answer» D. R1=RaRb/Rc, R2=RcRb/Ra, R3=Ra*Rc/Rb

Discussion

29.	In the question above the impedance at Y is?
A.	(Z<sub>RY</sub>)/(Z<sub>RY</sub>+Z<sub>BY</sub>+Z<sub>BR</sub>)
B.	(Z<sub>BY</sub>)/(Z<sub>RY</sub>+Z<sub>BY</sub>+Z<sub>BR</sub>)
C.	(Z<sub>RY</sub>Z<sub>BY</sub>)/(Z<sub>RY</sub>+Z<sub>BY</sub>+Z<sub>BR</sub>)
D.	(Z<sub>RY</sub>Z<sub>BR</sub>)/(Z<sub>RY</sub>+Z<sub>BY</sub>+Z<sub>BR</sub>)
Answer» D. (Z<sub>RY</sub>Z<sub>BR</sub>)/(Z<sub>RY</sub>+Z<sub>BY</sub>+Z<sub>BR</sub>)

Discussion

30.	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.	(Z<sub>BR</sub>Z<sub>BY</sub>)/(Z<sub>RY</sub>+Z<sub>BY</sub>+Z<sub>BR</sub>)
B.	(Z<sub>RY</sub>Z<sub>BR</sub>)/(Z<sub>RY</sub>+Z<sub>BY</sub>+Z<sub>BR</sub>)
C.	(Z<sub>RY</sub>Z<sub>BY</sub>)/(Z<sub>RY</sub>+Z<sub>BY</sub>+Z<sub>BR</sub>)
D.	(Z<sub>RY</sub>)/(Z<sub>RY</sub>+Z<sub>BY</sub>+Z<sub>BR</sub>)
Answer» C. (Z<sub>RY</sub>Z<sub>BY</sub>)/(Z<sub>RY</sub>+Z<sub>BY</sub>+Z<sub>BR</sub>)

Discussion

Explore topic-wise MCQs in Network Theory.

If a star connected system has equal impedances Z1, then after converting into delta connected system having equal impedances Z2, then?

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 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 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 ZRY.

If the resistors of star connected system are ZR, ZY, ZB then the impedance ZBR in delta connected system will be?

If the resistors of star connected system are ZR, ZY, ZB then the impedance ZBY in delta connected system will be?

If the resistors of star connected system are ZR, ZY, ZB then the impedance ZRY in delta connected system will be?

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?

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?

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?

Find the equivalent resistance between A and B.

If an 8/9ohm, 4/3ohm and 2/3ohm resistor is connected in star, find its delta equivalent.

If a 1ohm 2ohm and 32/3ohm resistor is connected in star, find the equivalent delta connection.

Ra is resistance at A, Rb is resistance at B, Rc is resistance at C in star connection. After transforming to delta, what is resistance between A and B?

Ra is resistance at A, Rb is resistance at B, Rc is resistance at C in star connection. After transforming to delta, what is resistance between A and C?

Ra is resistance at A, Rb is resistance at B, Rc is resistance at C in star connection. After transforming to delta, what is resistance between B and C?

Find the equivalent resistance between X and Y.

Find the equivalent delta circuit.

FIND_ZBR.?$

IF_AN_8/9OHM,_4/3OHM_AND_2/3OHM_RESISTOR_IS_CONNECTED_IN_STAR,_FIND_ITS_DELTA_EQUIVALENT.?$

If_a_star_connected_system_has_equal_impedances_Z1,_then_after_converting_into_delta_connected_system_having_equal_impedances_Z2,_then?$

Find ZBY in the question 7?

If a 1ohm 2ohm and 32/3ohm resistor is connected in star, find the equivalent delta connection?

A symmetrical three-phase, three-wire 440V supply is connected to star-connected load. The impedances in each branch are ZR = (2+j3) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ, ZY = (1-j2) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ, ZB = (3+j4) ‚Äö√Ñ√∂‚àö√´¬¨‚àÇ. Find ZRY.$

Rab is the resistance between the terminals A and B, Rbc between B and C and Rca between C and A. These 3 resistors are connected in star connection. After transforming to delta, the resistance at A will be?

If the resistors of star connected system are ZR, ZY, ZB then the impedance ZRY in delta connected system will be?

Delta connection is also known as____________

Which, among the following is the correct expression for star-delta conversion?

In the question above the impedance at Y is?

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?