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P a g e
When the commutating current Ic is
higher than the load current, the SCR will automatically turn OFF
and the capacitor charges with original polarity.
In the above process, the SCR is turned ON for some time and then automatically turned OFF for some
time. This is a continuous process and the desired frequency of ON/OFF depends on the values of L and
C. This type of commutation is mostly used in chopper circuits.
Class C Commutation
In this commutation method, the main SCR is to be commutated is connected in series with the load and
an additional or complementary SCR is connected in parallel with main SCR. This method is also called
as complementary commutation.
In this , SCR turns OFF with a reverse voltage of a charged capacitor. The figure below shows the
complementary commutation with appropriate waveforms
.
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