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 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

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

A balanced delta-connected load of (2+j3) Ω per phase is connected to a balanced three-phase 440V supply. The phase current is 10A. Find the total active power.

A

7.26W

B

726W

C

7260W

D

72.6W

A balanced delta-connected load of (2+j3) Ω per phase is connected to a balanced three-phase 440V supply. The phase current is 10A. Find the apparent power.

A

10955.67 VAR

B

10.95567 VAR

C

109.5567 VAR

D

1.095567 VAR

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

A single wattmeter is connected to measure the reactive power of a three-phase, three-wire balanced load. The line current is 17A and the line voltage is 440V. Calculate the power factor of the load if the reading of the wattmeter is 4488 VAR.

A

0.6

B

0.8

C

1

D

1.2

Find branch current IR2.
Branch, Loop and Node Analyses mcq question image

A

5.4 mA

B

-5.4 mA

C

113.0 mA

D

119.6 mA

Using the mesh current method, find the branch current, IR1, in the above figure.
Branch, Loop and Node Analyses mcq question image

A

115 mA

B

12.5 mA

C

12.5 A

D

135 mA

A 3 phase star connected winding is fed from symmetrical 3 phase supply with their neutrals connected together. If one of the 3 supply lines gets disconnected, then the revolving MMF wave will have a ___________

A

Constant amplitude but sub synchronous speed

B

Varying amplitude but synchronous speed

C

Constant amplitude but super synchronous speed

D

Varying speed and a speed fluctuating around the synchronous speed

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)

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.

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