After firing an SCR, the gate pulse is removed. The current in the SCR willa)rise up.b)remain the same.c)rise a little and then fall to zero.d)immediately fall to zero.Correct answer is option 'B'. Can you explain this answer?

Question

Answer

Once the thyristor (SCR) is turned-on, and the anode current is above latching current level, there is no need of gate current, hence, gate signal can be withdrawn i.e. gate looses control over the anode current.

Answer

When the gate pulse is given to the SCR the SCR enters to the conduction mode and it will start conducting i.e the current will flow through SCR till the voltage across SCR is reversed or commutation is given across the SCR . As the SCR starts the conduction there will be no effect of removal of gate pulse to the SCR, because SCR is already in the conduction mode .

Answer

Explanation:

When an SCR (Silicon Controlled Rectifier) is fired, it turns on and allows current to flow through it. The SCR remains in the on state until the current through it drops below a certain level called the holding current.

After firing an SCR, when the gate pulse is removed, the current in the SCR will remain the same (option B). This is because once the SCR is turned on, it latches itself into the conducting state and continues to conduct until the current through it drops below the holding current.

Reasoning:

When the SCR is fired, a gate pulse is applied to the gate terminal of the SCR. This gate pulse triggers the SCR and turns it on, allowing current to flow through it. Once the SCR is turned on, it remains in the on state even if the gate pulse is removed.

The SCR is a latching device, which means that once it is triggered into conduction, it continues to conduct until the current through it drops below the holding current. The holding current is the minimum current required to keep the SCR in the on state.

Even if the gate pulse is removed, the SCR will continue to conduct as long as the current through it remains above the holding current. This is because the SCR has a regenerative feedback mechanism that sustains conduction until the current drops below the holding current.

Conclusion:

After firing an SCR, when the gate pulse is removed, the current in the SCR will remain the same. The SCR will continue to conduct as long as the current through it remains above the holding current. It will only turn off when the current drops below the holding current.

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