# Conduction Angle in SCR Single Phase Rectifiers

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?

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

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

Below are the formulas that I am referring to:

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meBigGuy
Gold Member
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.

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