Class F: AC Line Commutated
1) If the supply can be an alternating voltage, load present will flow through the period that is half is good. The present may remain continuous for a while till the power caught in the load inductance is dissipated having a load that is very inductive.
2) Through the half that is negative, therefore, the SCR will turn off when the load becomes that are present 'naturally'. The polarity that is negative of voltage showing up on the SCR that is outbound turns well if the voltage continues for the rated turn-off period from the unit.
3) The duration of the half period must certanly be truly much longer compared to the turn-off period of the SCR.The rectifier in Fig.1.7 comes from an duration that is supply that is solitary. The commutation procedure included the following is representative of that in a three duration converter.
4) The converter comes with an input inductance Ls arising manly out of the leakage reactance linked to the supply transformer.
5) Initially, SCRs Th1 and Th1' are believed to be performing. The angle that is triggering the converter is mostly about 600. The converter is running in the conduction that is constant along with the load that is highly-inductive.
6) As soon as the inbound SCRs, Th2 and Th2' are triggered, the existing through the inbound products cannot rise instantaneously towards the strain level that is current. A circulating Isc that is present develops inside the path that is short-circuited the supply voltage, Vs-Ls-Th1'- Th2 and Vs- Ls-Th2'-Th1 paths.