Conduction Angle in SCR Single Phase Rectifiers

  • #1
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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  • #2
meBigGuy
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considering a single period to be 0 to 360 degrees, the scr turns on at the conduction angle.
 
  • #3
I thought the SCR is turned on at the firing angle (α).
 
  • #4
Below are the formulas that I am referring to:
 

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  • #5
meBigGuy
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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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