# The turn-on time of a SCR with inductive load is 20 s. The pulse frequency is 2.5 kHz with a mark/space ratio of 1/10, then the SCR will

1.  turn on

2.  not turn on

3.  turn on if inductance is removed

4.   turn on if pulse frequency is increased to two times.

4

turn on

Explanation :
No Explanation available for this question

# The maximum di/dtin a SCR is

1.  directly proportional to Vm of supply voltage

2.  inversely proportional to Vm of supply voltage

3.  inversely proportional to L in the circuit

4.   directly proportional to L in the circuit

4

inversely proportional to L in the circuit

Explanation :
No Explanation available for this question

# A SCR fires at a minimum current of 80 mA and - 65oC. The minimum current required to fire at 25oC is

1.  > 80 mA

2.  equal to 80 mA

3.

4.  half of 80 mA

4

half of 80 mA

Explanation :
No Explanation available for this question

# A thyristor is triggered by a pulse train of 5 kHZ. The duty ratio if 0.4. If allowable average power is 100 W, then maximum allowable gate drive power is

1.

2.  50 W

3.  150 W

4.   250 W

4

250 W

Explanation :
No Explanation available for this question

# For an UJT employed for the triggering of an SCR, stand-off ratio h = 0.64 and dc source voltage VBB is 20 V. The UJT would trigger when the emitter voltage is

1.  12.8 V

2.  13.1 V

3.  10 V

4.  5 V

4

13.1 V

Explanation :
No Explanation available for this question

# An SCR can withstand a maximum junction temperature of 120oC with an ambient temperature of 75oC. If the SCR has thermal resistance from junction to ambient as 1.5oC/W, the maximum internal power dissipation allowed is

1.  30 W

2.  60 W

3.  80 W

4.   50 W

4

30 W

Explanation :
No Explanation available for this question

# In the figure, suppose capacitor C is charged to 50 V with lower plate positive. Switch S is closed at t = 0. Current through the diode at t = 0 and final voltage across C are respectively

1.  25 A, 250 V

2.  25 A, 200 V

3.  20 A, 200 V

4.  15 A, 150 V

4

25 A, 200 V

Explanation :
No Explanation available for this question

# In the figure, switch S is closed at t = o with iL (0) and VC (0) = 0. In steady state VC equals

1.  200 V

2.  100 V

3.  zero

4.   -100 V

4

zero

Explanation :
No Explanation available for this question

# The average on-state current for an SCR is 20 A for a conduction angle of 120o. The average on-state current for 60o conduction angle will be

1.  20 A

2.  10 A

3.  less than 20 A

4.  40 A

4

20 A

Explanation :
No Explanation available for this question

# The average on-state current for an SCR is 20 A for a resistive load. If an inductance at 5 mH is included in the load, then average on-state current would be

1.  more than 20 A

2.  less than 20 A

3.  15 A

4.  20 A

4