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You Are On Multi Choice Question Bank SET 1289

64451. In an SCR, the anode current consists of





64452. In the below figure, the average value of load current is 15 A. The load is highly inductive. The peak value of thyristor current is




64453. A 3 phase semiconverter when supplying a certain load has a rectification efficiency of 0.6 and transformer utilisation factor of 0.35. When a 3 phase full converter is supplying the same load





64454. Assertion (A): A high dv/dt may cause triggering of a thyristor.Reason (R): A high dv/dt results in charging current in the thyristor.





64455. Assertion (A): When an SCR is conducting, the voltage drop across is about 1 V. Reason (R): When an SCR is conducting, the junction temperature is about 200°C.





64456. When the core of a saturable reactor is saturated, the inductance is high.



64457. In controlled heating circuits, thyristors act as





64458. In a fully controlled bridge converter feeding a resistive load the waveshapes of output voltage and output current





64459. A chopper cannot be line commutated.



64460. Natural commutation can be used in :





64461. In a thyristor the gate lead is connected to the n layer near the p layer to which anode is connected.



64462. A single phase half wave rectifier circuit has a free wheeling diode. The free wheeling diode will conduct only if





64463. McMurray Bedford full bridge inverter uses





64464. Which converter is used in HVDC transmission?





64465. Assertion (A): The turn on time of SCR is about 1 to 4 ms.Reason (R): The turn off time of SCR is about 10 to 300 ms.





64466. Calcium carbonate is the chemical name of?





64467. Which chopper circuit operates in all the 4 quadrants?





64468. A single phase cycloconverter feeds a resistance heating load. The heating power is provided by





64469. The vast resources of unutilised natural gas can be used in the production of?





64470. Which of these commutation methods uses an external pulse for commutation?





64471. In a single phase full wave regulator feeding an R-L load, the power factor angle of load is θ. The range of control of firing angle a is





64472. A separately excited dc motor is run from a dc source through a chopper. At 600 rpm and rated torque, the duty cycle of chopper is 0.8. At 600 rpm and half the rated torque, the duty cycle is likely to be





64473. A relaxation oscillator uses





64474. In a 3 phase bridge inverter with 180° mode of operation the numbers of thyristors conducting at one time are





64475. A single phase full converter can operate in





64476. In a 3 phase semiconverter, the freewheeling diode comes into operation only if firing angle





64477. In the circuit of figure, the load current when thyristor is off





64478. A full bridge inverter is fed by a battery of 30 V. The rms value of output voltage is





64479. In brushless excitation system of modern alternators, the main exciter is





64480. The two-transistor model of a thyristor consists of two transistors :





64481. In a thyristor, the forward breakover voltage





64482. The gate lead, in a thyristor is welded to :





64483. In a 3 phase full converter, the firing angle is less than 60°. The instantaneous output voltage





64484. In a stud mounted SCR, the stud is





64485. In pulse width modulation of chopper





64486. In a full bridge inverter, the waveshape of load current depends on





64487. The characteristics of which device has peak point and valley point





64488. In a class of 100 students, 50 students passed in Mathematics and 70 passed in English, 5 students failed in both Mathematics and English. How many students passed in both the subjects?





64489. In a thyristors are i = kva. The value of a is





64490. In an ordinary thyristor





64491. Thyristors connected in series need :





64492. Convert from CFC12 to HFC 134 appliance,the compressor displacement will be:





64493. If 4 quadrant operation is required we need





64494. A single phase half wave converter is feeding a resistive load. Output dc power is Pdc and total power delivered to load is Pac then





64495. Which of the following devices exhibit negative resistance characteristics?





64496. In integral cycle control of ac regulators, the period of integral cycle control, i.e., (m + n) T should be





64497. All other parameters remaining the same, a 3 phase bridge inverter with 180° mode of operation





64498. As compared to BJT, MOSFET has





64499. If a step down chopper is fed by a dc voltage V with Ton and Toff are on and off periods then is





64500. A voltage VBB is applied across the terminals of a UJT. The emitter voltage at peak point is





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