Conduction Angle in SCR Single Phase Rectifiers

[buildingblocs]

Hi all,

When considering a half wave SCR rectifier (single phase) with an RL load, the term θ (conductive angle) appears in equations relating to the performance of the circuit.

In terms what is physically happening in the circuit, what does θ actually represent?

 

[meBigGuy]

considering a single period to be 0 to 360 degrees, the scr turns on at the conduction angle.

 

[buildingblocs]

I thought the SCR is turned on at the firing angle (α).

 

[buildingblocs]

Below are the formulas that I am referring to:

 

[meBigGuy]

OK, my bad. Firing angle is angle at which it starts conducting, conduction angle is angle over which it conducts.

But theta in the above circuit is the voltage/current phase angle caused by the RL circuit. The SCR is fired at α, but conducts beyond ∏ -α because of the inductor field collapsing, represented by theta. So it continues to conduct until ∏ + theta.