Latching Current and Holding Current in Thyristor
What is Latching Current?
Latching current is the minimum value of current flowing through the anode that keeps turning on the thyristor or keeps in a conducting state even after removing the gate pulse. So at the turning-on time of the thyristor, the current flowing through it must meet the value of latching current.
What is Holding Current?
Holding current is the minimum value of current flowing through the anode below which the thyristor cannot keep turning on or maintaining the current flow and it will get turned off.
Example
The concept of holding current and latching current we can understand with an example. For example, The latching current of a thyristor is 3A, and the holding current of a thyristor is 1A. Now when the thyristor conducting 3A or more than 3A current we can remove the gate pulse. After removing the gate pulse the thyristor will be able to conduct current. Now if we reduce the current below 1A the thyristor will not be able to maintain the current flow and it will stop conducting current. You also may notice we have taken the value of the latching current more than the holding current this is because the latching is always greater than the holding current.
Difference between Latching Current and Holding Current
1. The concept of latching current is associated with Turning On of the thyristor whereas the concept of holding current is associated with turning off the thyristor.
2. Latching current is the minimum current that must be attended by the anode current to turn on the thyristor. On the other hand, holding current is the minimum current the thyristor should continuously conduct to keep turning on itself.
3. The thyristor will not turn on if the current flowing through the thyristor does not meet the minimum value of the latching current. On the other hand, the thyristor will turn off immediately once the current flowing through the thyristor goes below the value of the holding current.
4. The value of the holding current of a thyristor is generally less than the latching current. On the other hand, the latching current is generally 2 to 3 times greater than the holding current.
Now, the question is why the concept of latching current and holding current is very important. When a thyristor is used in rectifier or inverter circuits the concept of holding current and latching current is helpful to control the waveforms, and angles of output signals.
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Latching Current and Holding Current in Thyristor
Reviewed by Author
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January 31, 2022
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Reviewed by Author
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January 31, 2022
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