A star connected capacitor bank is connected to the induction motor having capacitance C and VA rating as VAs. If the capacitor bank is replaced by a delta bank then?

A 400 V, 50 Hz three phase balanced source ripples to a star connected load whose rating is S(=300+j400) kVA. The rating of the delta connected capacitor bank needed to bring p.f. to 0.9 lagging is _______ KVAR.

A

254.7

B

25.4

C

84.9

D

284.5

Two capacitors having capacitance value 4F, three capacitors having capacitance value 2F and 5 capacitors having capacitance value 1F are connected in parallel, calculate the equivalent capacitance.

A

20F

B

19F

C

18F

D

17F

Apart from connection which of the following is different in star/delta or delta/star compare to delta/delta?

A

Flux is flat-topped

B

Impedance offered to third-harmonic currents in delta is less

C

Impedance offered to third-harmonic currents in delta is constant

D

Impedance offered to third-harmonic currents in delta is more

A 400 V, 50 Hz three phase balanced source ripples to a star connected load whose rating is S(=300+j400) kVA. A delta connected capacitor bank needed to bring p.f. to 0.9 lagging. The operating power factor of the system is

A

0.8

B

4/3

C

3/4

D

0.6

Seven people A, B, C, D, E, F and G live on separate floors of a 7-floor building. Ground floor is numbered 1, first floor is numbered. 2 and so on until the topmost floor is numbered 7. Each one of these having a different cars-Cadillac, Ambassador, Fiat, Maruti, Mercedes, Bedford and Fargo but not necessarily in the same order. Only three people live above the floor on which A lives. Only one person lives between A and the one having a car Cadillac. F lives immediately below the one having a car Bedford. The one having a car Bedford lives on an even-numbered floor. Only three people live between the ones having a car Cadillac and Maruti. E lives immediately above C. E is not having a car Maruti. Only two people live between B and the one having a car Fargo. The one having a car Fargo lives below the floor on which B lives. The one having a car Fiat does not live immediately above D or immediately below B. D does not live immediately above or immediately below A. G does not have a car Ambassador. Question : How many people live between the floors on which D and the one having a car Bedford ?

A

One

B

Two

C

Three

D

Four

At a 33kV 50 Hz to a bus a load of 35 MW is connected. To improve the power factor to unity a synchronous phase modifier is connected taking 5 MW. If the SPM is represented as delta connected impedance, where in each phase we have capacitor connected parallel to resistance forming RC parallel network, then the value of this capacitance is __________

A

25.57 μF

B

76.2 μF

C

32.2 μF

D

24 μF

A set of 6 flower vases of different sizes cost Manik Tk. 825. Each vas costs Tk. 25 more than the next one below it in size. What was the cost of the largest vas?

A

Tk. 175

B

Tk. 185

C

Tk. 200

D

Tk. 215

A 3-phase, 400 V, 50 Hz delta connected induction motor has power factor of 0.35 when delivering 30% of its load. If it is star connected, then its?

A

p.f. increased and the stator current decreases

B

p.f. worsened and the stator current decreases

C

p.f. increased,and the stator current increases

D

p.f. does not change,and the stator current increase

A delta connected capacitance bank is preferred over a star connected bank. This is done to ensure _________

A

lesser capacitance

B

easy calculation

C

easier connection

D

all of the mentioned

Two monochromatic waves having frequencies $$\omega $$ and $$\omega + \Delta \omega \left( {\Delta \omega \ll \omega } \right)$$ and corresponding wavelengths $$\lambda $$ and $$\lambda - \Delta \lambda \left( {\Delta \lambda \ll \lambda } \right)$$ of same polarization, travelling along X-axis are superimposed on each other. The phase velocity and group velocity of the resultant wave are respectively given by

A

$$\frac{{\omega \lambda }}{{2\pi }},\,\frac{{\Delta \omega {\lambda ^2}}}{{2\pi \Delta \lambda }}$$

B

$$\omega \lambda ,\,\frac{{\Delta \omega {\lambda ^2}}}{{\Delta \lambda }}$$

C

$$\frac{{\omega \Delta \lambda }}{{2\pi }},\,\frac{{\Delta \omega \Delta \lambda }}{{2\pi }}$$

D

$$\omega \Delta \lambda ,\,\omega \Delta \lambda $$

A star connected capacitor bank is connected to the induction motor having capacitance C and VA rating as VAs. If the capacitor bank is replaced by a delta bank then?

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