Today We are Discuss About Line-Commutated converter. In converter input is AC supply, the current will flow through the zero mossing lines while going from a positive peak to negative peak. Thus, a reverse voltage can seem across the device at the same time, which can shut down the thyristor at once. This process is called natural commutation or line commutation as thyristor is turned off naturally without using any external components or circuit or supply for commutation purpose’
There are two aspects of line commutation. First, line commutation is possible only in converters that are connected to an AC voltage bus, because the presence of an alternating voltage is necessary to serve as the commutating voltage. Second, to with success succeed put off switch by means that of line commutation, it’s essential that the associated line voltage, that is the commutating voltage, should have the polarity which will verse-bias the outgoing thyristor.