Following are the disadvantage of a GTO as compared to a conventional thyristor:
- The magnitude of latching and holding current is more than that of a SCR. The value of latching current is around 2 A which is around 100 mA-500 mA for an SCR.
- The ON state voltage drop across the GTO and associated are more.
- Due to multi-layer structure, the value of Gate triggering current is more when compared to that of a conventional thyristor.
- Gate drive circuit losses are more.
- The reverse blocking voltage capability of GTO is less its forward voltage blocking capability.
In spite of the above disadvantage of a GTO, it is having much more advantage than a SCR and hence widely used for various applications like adjustable frequency inverter drives, high performance drive systems such as field-oriented control used in rolling mills, robotics and machine tools etc.
Following are the advantages of the Gate Turn Off Thyristor over the SCR:
- The main advantage of GTO is that it can be turned off using negative gate signal of sufficient amplitude. This eliminates the necessity of bulky and costlier commutation circuit which is required for turning OFF an SCR.
- Its switching speed is more than that of SCR.
- It has more di/dt rating at turn-on.
- GTO circuit configuration has lower size and weight as compared to thyristor circuit unit.
- GTO unit has higher efficiency even though its gate drive power loss and ON state loss is more than an SCR. This is due to the fact that, gate drive loss and ON state loss in GTO is less than that of forced-commutation losses of conventional thyristor.
- Its current surge capability is comparable with an SCR.