Question

Question 4 For the bridge rectifier shown below, SCR1 SCR4 Trigger circuit Trigger circuit R V Trigger circuit SCR2 SCR3 Trigger circuit V= 170 sin 50 t V, the load is 17 and the firing angle is 720 Find the AC voltage across the load in (V).

Answer 1

Solutions Given that A bridge rectifier . Vs = 17o Sin sot Load (R) = 17h And we know that the output to firing angle 72° Ganeform due will be as- =72° Vs 170 e Wt Vo بیاد 1 T Tz T3 Tu T., Ta Io ht

For first half cycle only I, and Tz (SCR, and SCR₂) will be conclent due to formare and biased and T3, T4 will be in revers biased so non- conducting mode . Further in second half cycle Tz, Tu will come into contuuting mode mode due to forward biased and Ti, Tz will come into non-conducting mode due to reverse biased. Then the output Voltage in R. M.S. =) We know that Ya Tount Vm [II -a) + (Sin2] 27 Where, Vm = 170 V (manimum Peak Valtage) 2 = 72°C firing angle)

Se, Varums) 170 (T- TX 72° 180 + 1 (Sin@x720) 27 2 Since = radian and 72° in degree. And to convert 72 in radian T 180° *729 1 + 1 2 Now, Vorms = 67.82 fag Now, Vorams = 67.82 3a Sinema "]Y = 67.82 [2.18 ou Vorums = Top./35 V And we know that Drums Vm s - So, Vm r Varms

Now, Vom = Jz Vormy Vom = re ( 100. 135) on Vom = 141.61 V In sine form - Vo = Vom Sinut ginven that - wt = Sot So, Vo 141.61 Sin sot