# For an SCR with turn-on time of 5 microsecond, an ideal trigger pulse should have

8 views
For an SCR with turn-on time of 5 microsecond, an ideal trigger pulse should have

(a) short rise time with pulse width = 3 µsec (b) long rise time with pulse width = 6 µsec (c) short rise time with pulse width = 6 µsec (d) None of the above

## Related questions

Turn-on time of an SCR in series with RL circuit can be reduced by   (a) Increasing circuit resistance R (b) Decreasing R (c) Increasing circuit inductance L (d) Decreasing L

Output of an op-amp is a square wave of 4 V peak to peak with a rise time of 5 microsecond and fall time of 4 microsecond.Maximum frequency (in kHz)of undistorted sine wave output of 2 V peak to peak is about  A) 100 B) 150 C) 200 D) 250

Turn on time of an SCR can be reduced by using a:

Circuit turn-off time of an SCR is defined as the time  (A) taken by the SCR turn to be off (B) required for the SCR current to become zero (C) for which the SCR is reverse biased by the commutation circuit (D) for which the SCR is reverse biased to reduce its current below the holding current

In a 3-phase converter circuit during commutation when one SCR in one phase is turned on to turn-off an SCR in another phase, results in (A) voltage notching (B) harmonic distortion (C) voltage sag (D) voltage swell

An ideal voltage source should have?

Turn-on of a thyristor (SCR) takes place when  A) Anode to cathode voltage is positive B) Anode to cathode voltage is negative C) Positive current is applied to gate D) Anode to cathode voltage is positive and positive current pulse is applied to gate

A digital board has a unipolar square clock of 250MHz. If the clock on the board at all places should have all the harmonic components which have more than 10 % of DC value, the board has to be designed for at least —  A) 250MHz B) 750MHz C) 1250 MHz D) 2500 MHz

For a pulse transformer, the material used for its core and the possible turn ration from primary to secondary are respectively   (A) ferrite : 20 : 1 (B) laminated iron : 1 :1 (C) ferrite : 1 : 1 (D) powered iron : 1: 1

The clock frequency of an 8085 microprocessor based system is 3 MHz. What should be the minimum pulse width of the INTR signal so that it is recognized successfully? A) 5.6 µs B) 5.7 µs C) 5.8 µs D) 5.9 µs

To turn a UJT ON, the forward bias on emitter diode should be:  1. more than the peak point voltage 2. less than the peak point voltage 3. Equal to the peak point voltage 4. Equal to the stand - off voltage

Each time you turn on your computer, it will check on the control file  (1) Command.com, io.sys (2) Command.com, date.com, dir.com (3) Command.com, io.sys, msdos.sys (4) Chkdsk.exe

Each time you turn the power switch on which control files the computer will check  (1) command.com, io.sys (2) command.com, date.com, time.com (3) command.com, io.sys, msdos.sys (4) chkdsk.exe

When cathode is positive with respect to anode in an SCR, the number of blocked p-n junctions is   (a) 1 (b) 2 (c) 3 (d) 4

The turn-off time of a thyristor is 30 is at 50°C. What is its turn-off time at 100°C ?

The materials used for permanent magnets should have

A material for good magnetic memory should have?

A pulse waveform has a high time of 8 ms and a pulse width of 32 ms. The duty - cycle is equal to: A. 25% B. 50% C. 1% D. 100%

For an SCR, dV/dt protection is achieved by the use of   (a) RL in series with SCR (b) L in series with SCR (c) RC in series with SCR (d) RC across SCR

A Lissajous pattern on an oscilloscope has 5 horizontal tangencies and 2 vertical tangencies. The frequency of the horizontal input is 1000 Hz. What is the frequency of the vertical input?  (A) 400 Hz (B) 5000 Hz (C) 4000 Hz (D) 2500 Hz

A commutator with a diameter of 50 cm rotates at 1000 r.p.m. If brush width is 1.5 cm, the time of commutation will be (a) 0.168 m sec (b) 0.374 m sec (c) 0.481 m sec (d) 0.573 m sec

The hysteresis loop of magnetic material has an area of 5 cm2 with the scales given as 1 cm=2AT and 1 cm=50 mWb, at 50 Hz, the total hysteresis loss is  (A) 15 W (B) 20 W (C) 25 W (D) 50 W

Consider the following statements : Any element connected in  1. Series with an ideal current source is redundant. 2. Parallel with an ideal current source is redundant. 3. Series with an ideal voltage source is redundant. . 4. Parallel with an ideal voltage source is redundant.  Which of the above statements is/are correct ?

Which one of the following does not have an effect on corona ?  (a) Spacing between conductors (b) Conductor size (c) Line voltage (d) Length of conductor

Give broad classification of maintenance with meaning of each type. State the factors on which ideal maintenance of electric rolling stock is judged. Give any two means to improve any one factor of these.

For a traction transformer circuit breaker state: 1) Rated current and rupturing capacity 2) Any two tests it should be capable of withstanding 3) Overall tripping time and relay time.

A dc shunt motor runs at 500 r.p.m at 220 V. A resistance of 4.5 Ω is added in series with the armature for speed control. The armature resistance is 0.5 ohms. The current to stall the motor will be (1) 44 A (2) 50 A (3) 44.4 A (4) 60 A

A resistor with the color coded value of 1000 ohms and ± 10% tolerance can have an actual resistance between ________. A. 990 ohm and 1010 ohm B. 900 ohm and 1100 ohm C. 1000 ohm and 1100 ohm D. 900 ohm and 1000 ohm.

What is the clock cycle time for a system that uses a clock with frequency of 150 kHz?  (A) 55 µ sec (B) 5.5 µ sec (C) 202 sec (D) 6.6 µ sec

The time/div and voltage/div axes of an oscilloscope have been erased. When a 1 kHz, 5V p-p square wave calibration pulse is connected to channel 1 ofthe scope the waveform observed on the screen is as shown in the upper trace of the figure. An unknown signal is connected to channel 2 (lower trace) ofthe scope. If the time/div and V/div on both channels are the same, the amplitude (pp) and period of the unknown signal are respectively.

What is the charge on each capacitor when a 150 V is applied across two capacitors with values 5 μF and 10 μF, connected in series? A) 500 μC B) 0.5 μC C) 0.5 C D) None of these

A coherent QPSK demodulator is required on ground for receiving data from a LEO satellite. What should be optimum order of PLL in the carrier phase tracking loop?  A) 1st order B) 2nd order C) 3rd order D) None of the above

To enable dc series motor work satisfactory with an AC supply, the following modifications should be done (1) The yoke and poles should be completely laminated (2) The poles should be made of laminated steel (3) The air gap between stator and rotor be reduced (4) Compensating poles should be introduced

Consider the following statements with regard to a GTO : 1. The turn-off gain of the GTO is large. 2. Large negative gate current pulses are required to turn off the GTO. 3. GTO has large reverse blocking capability. Which of the above statements is/are correct ? (a) 1 only (b) 2 only (c) 3 only (d) 1, 2 and 3

What is the power factor when a single phase watt meter operating on 200 V and 5 A for 5 hours makes 2016 revolutions and the meter constant in revolution is 420? A) 0.04 B) 1.04 C) 0.96 D) None of these

One single-phase energy meter operating on 230 V and 5 A for 5 hours makes 1940 revolutions. Meter constant is 400 rev/kWh. The power factor of the load is