The thyristor turn-off requires that the anode currenta)falls below th...
For effective turn-off of the SCR the anode current must fall below the holding current value.
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The thyristor turn-off requires that the anode currenta)falls below th...
Anode current in a thyristor is the current flowing from the anode to the cathode terminal. The thyristor is a four-layer, three-junction semiconductor device that can be turned on by applying a positive voltage between the anode and cathode terminals. Once turned on, the thyristor remains conducting even if the triggering voltage is removed, until the anode current drops below a certain threshold.
In order to turn off a thyristor, the anode current must fall below the holding current. This is because the thyristor has a latching characteristic, meaning that once it is turned on, it will remain conducting until the anode current drops below a certain level. The holding current is the minimum current required to keep the thyristor in the on state.
The turn-off process involves reducing the anode current below the holding current. This can be achieved by either reducing the applied voltage or by interrupting the current flow through external means. Once the anode current falls below the holding current, the thyristor will turn off and stop conducting.
If the anode current falls below the latching current, it does not necessarily mean that the thyristor will turn off. The latching current is the minimum current required to turn on the thyristor in the first place. It is a higher value than the holding current and is used during the turn-on process.
Therefore, the correct answer is option 'A' - the anode current falls below the holding current for the thyristor to turn off. This is because the holding current is the minimum current required to keep the thyristor conducting, and once the anode current drops below this threshold, the thyristor will naturally turn off.
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