A step up chopper has input voltage 110 V and output voltage 150 V. The value of duty cycle is_____?

Related Mcqs:

1. The average value of the output voltage in a step – down dc chopper is given by__________?

   A. V 0 = V s
   B. V 0 = D V s
   C. V 0 = V s / D
   D. V 0 = V s / ( 1 – D )

2. The ac output voltage waveform of VSI and AC output current waveform of CSI respectively is composed of___________?

   A. High dv / dt, low di / dt
   B. Low dv / dt, low di / dt
   C. Low dv / dt, high di / dt
   D. High dv / dt, high di / dt

3. In a load commutated DC – DC chopper, the capacitor has a_____________?

   A. Symmetric triangular voltage across itself
   B. Symmetric rectangular voltage across itself
   C. Symmetric trapezoidal voltage across itself
   D. Symmetric sinusoidal voltage across itself

4. In EMC signal, the source delivers maximum power to the input of transmission line when the transmission line input impedance

   A. Is equal to the source resistance
   B. Greater than the source resistance
   C. Smaller than the source resistance
   D. None of these

5. The capacitance of reversed bised junction J2 in a thyristor is CJ2 = 20 pF and can be assumed to be independant of the off state voltage. The limiting value of the charging current to turn on the thyristor is 16 mA. What is the critical value of dv/dt?

   A. 600 V/µs
   B. 800 V/µs
   C. 1200 V/µs
   D. 1000 V/µs

6. An SCR has half cycle surge current rating of 3000 A for 50 Hz supply. One cycle surge current will be_____?

   A. 1500 A.
   B. 6000 A.
   C. 2121.32 A.
   D. 4242.64 A.

7. Under over voltage condition impedance offered by the voltage clamping device is__________?

   A. low
   B. High
   C. moderate
   D. infinity

8. In a 3 phase half wave rectifier, when firing angle is less than 90 degree, then the average dc output voltage becomes__________________?

   A. Positive
   B. Negative
   C. Zero
   D. None of these

9. In a full bridge VSI, in order to avoid the short circuit across the DC bus and the undefined AC output voltage condition, the modulating technique should ensure that___________?

   A. Top switch of each leg is on at any instant
   B. Bottom switch of each leg is on at any instant
   C. Either A. or B.
   D. None of these

10. 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