The sum of all phase current in a star connected primary winding with no neutral connection is equal to___________?

Related Mcqs:

1. For commutation in three phase PAC, normally balanced three phase voltages VR, VY and VB are connected to the three legs of the converter via______________?

   A. Three inductances
   B. Three capacitances
   C. Three resistance
   D. Three transistors

2. The output current in PWM DC – DC converters is equal to___________?

   A. Average value of the output inductor current
   B. Product of an average inductor current and a function of duty ratio
   C. Either A. or B.
   D. None of these

3. The function of snubber circuit connected across the SCR is to___________?

   A. Suppress dV / dt.
   B. Increase dV / dt.
   C. Decrease dV / dt.
   D. Decrease di / dt.

4. A thyristor string is made of a no. of SCR connected in series and parallel. The string have volume and current of 11 KV and 4 KA. The voltage and current rating of available SCRs are 1800 V and 1000 A. For a string efficiency of 90 % let the number of SCRs in series and parallel are a and b respectively. Then the value of a and b will be_____________?

   A. 5, 7
   B. 4, 6
   C. 7, 5
   D. 6, 4

5. In a 3 phase CSI, if the required line output voltages are balanced and 120 degree out of phase, then the chopping angles are used to eliminate only the harmonics at frequencies

   A. 5
   B. 7
   C. 11
   D. All of these

6. n a phase controlled 3 phase ac voltage controller, the harmonic present is__________?

   A. 2nd
   B. 3rd
   C. 5th
   D. 7th

7. If a shunt motor is started with its field winding open then?

   A. It will rotate at the same speed as that with its field winding closed
   B. It will rotate at less speed as that with its field winding closed
   C. It will rotate at dangerously high speed
   D. None of these

8. If a shunt motor is started with its field winding open then___________?

   A. It will rotate at the same speed as that with its field winding closed
   B. It will rotate at less speed as that with its field winding closed
   C. It will rotate at dangerously high speed
   D. None of these

9. Very large values of modulation index (greater than 3.24) lead to___________?

   A. Square AC output voltage
   B. Sine AC output voltage
   C. Triangular AC output voltage
   D. Trapezoidal AC output voltage

10. Practical way of obtaining static voltage equalization in series connected SCRs is by the use of____________?

    A. One resistor across the string
    B. Resistors of the same value across each SCR
    C. Resistors of different values across each SCR
    D. One resistor in series with each SCR