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The gate characteristics of thyristor is a plot of
Answer: b Explanation: It is the gate current versus the gate voltage plot and gives the minimum and maximum values of gate parameters.
Answer: b
See lessExplanation: It is the gate current versus the gate voltage plot and gives the minimum
and maximum values of gate parameters.
To avoid commutation failure
Answer: a Explanation: If the thyristor turn off time is more than the circuit turn off time, the circuit will be turned off and the thyristor will keep conducting, which is not at all desirable.
Answer: a
See lessExplanation: If the thyristor turn off time is more than the circuit turn off time, the circuit
will be turned off and the thyristor will keep conducting, which is not at all desirable.
For effective turning off of the SCR after the anode current has reached zero value, ______________
Answer: b Explanation: To enable the device to regain its reverse blocking capabilities, the stored charges in the junctions of the SCR must be removed.
Answer: b
See lessExplanation: To enable the device to regain its reverse blocking capabilities, the stored
charges in the junctions of the SCR must be removed.
For an SCR the total turn-on time consists of i) Delay time ii) Rise time and the iii) Spread time The spread time interval depends upon
Answer: c Explanation: During the spread time the conduction starts spreading all over the SCR cathode cross-section structure, which depends upon the structure of the gate & cathode. Higher the cathode area more is the time required for the charges to spread all ove
Answer: c
See lessExplanation: During the spread time the conduction starts spreading all over the SCR
cathode cross-section structure, which depends upon the structure of the gate &
cathode. Higher the cathode area more is the time required for the charges to spread all
ove
The latching current is _________ than the holding current
Answer: b Explanation: The latching current is the value of current on which the device will remain in the on state even after removal of the gate signal. Whereas, the holding current is the threshold above which the device will work.
Answer: b
See lessExplanation: The latching current is the value of current on which the device will remain
in the on state even after removal of the gate signal. Whereas, the holding current is the
threshold above which the device will work.
For an SCR the total turn-on time consists of i) Delay time ii) Rise time and iii) Spread time During the rise time the
Answer: c Explanation: The losses are maximum during the rise time because both Ia & Va are high.
Answer: c
See lessExplanation: The losses are maximum during the rise time because both Ia & Va are
high.
The minimum value of anode current below which it must fall to completely turn-off the device is called as the
Answer: a Explanation: The device will remain in the conducting state unless the anode current falls below the holding current value.
Answer: a
See lessExplanation: The device will remain in the conducting state unless the anode current
falls below the holding current value.
In the reverse blocking mode the middle junction (J2) has the characteristics of that of a
Answer: b Explanation: It is like a capacitor, as the dv/dt voltage triggering turns on the device. The charging current is given by, IC = CjdVa/dt.
Answer: b
See lessExplanation: It is like a capacitor, as the dv/dt voltage triggering turns on the device. The
charging current is given by,
IC = CjdVa/dt.
The value of anode current required to maintain the conduction of an SCR even though the gate signal is removed is called as theThe value of anode current required to maintain the conduction of an SCR even though the gate signal is removed is called as the
Answer: b Explanation: It is the minimum anode current value required to maintain the conduction of an SCR even though the gate signal is removed. It is a very important parameter when employing an SCR in any circuit.
See lessAnswer: bExplanation: It is the minimum anode current value required to maintain the conduction
of an SCR even though the gate signal is removed. It is a very important parameter
when employing an SCR in any circuit.
For the SCR to remain in the ON (conducting) state
Answer: b Explanation: Unlike the transistor devices, once the SCR is turned on by the gate terminal, the gate terminal losses its control over the device.
Answer: b
See lessExplanation: Unlike the transistor devices, once the SCR is turned on by the gate
terminal, the gate terminal losses its control over the device.