Can anyone tell me why are Thyristors(SCRs) used in power electronic circuits? How are they more adept at handling power as opposed to other active or passive electronic components?

UPDATE: As per the request made by jippie i am uploading the circuit diagram for a simple full wave rectifier to add a context.

 Full wave rectifier using scrs
(source: circuitstoday.com)

why should some one use SCRs in this circuit when the same action can be achieved using diodes?

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    \$\begingroup\$ In an AC stage an SCR can be used to regulate phase angle, in DC stages they are commonly used for crowbarring on voltage surges. In other words, it entirely depends on the circuit. Do you have an example circuit diagram? \$\endgroup\$ – jippie Apr 14 '13 at 7:39
  • \$\begingroup\$ what do you mean by "crowbarring on voltage surges"? \$\endgroup\$ – Infusion of Wormwood n Asfodel Apr 14 '13 at 8:34
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    \$\begingroup\$ A crowbar circuit triggers when the output voltage of a power supply rises above a configured maximum. The SCR shorts instantanuously shorts the power supply output to protect the connected electronics. Usually a fuse will blow as a result of the short. \$\endgroup\$ – jippie Apr 14 '13 at 8:55

Using Silicon Controlled Rectifiers it becomes very easy to control the output voltage by changing the phase angle for firing the SCR's. With the phase angle the average voltage and power can be controlled without dissipating energy in series resistors. Before SCR's became common, huge series resistors were used to control output power.

Using diodes does not allow for controlling the output voltage.

enter image description here

Image found on Wikipedia

| improve this answer | |
  • \$\begingroup\$ Nice animation! \$\endgroup\$ – Brian Drummond Apr 14 '13 at 9:26

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