What is SCR ?
It is Silicon Controlled Rectifier , use in power electronic device. It use as a switching devices in many high voltages area and high temperature .
figure shows physical diagram and symbol of SCR.
SCR is well known member of thyristor family, although there are many different members are available in thyristor family but SCR are so widely used that as if thyristor and SCR become synonymous.
If we see from the constructional and operation point of view , it is a four layer (PNPN) three terminals (anode,cathode, gate) semiconductor device. This device has two states ON and OFF. We can turn it ON by sending gate current signal between second P layer and cathode. But we cannot turn OFF by control signal. That means we have control upon its turn ON, once it goes to conduction mode , we lose control over it.
It can block both forward and reverse voltage but can conduct only in one direction.It use in high power application like AC -DC converter etc.
SCR V-I Characteristic
Different circuit of SCR in application
DC supply
DC thyristor switching circuit
Half Phase Control
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