Current going to the gate terminal controls breakover voltage, the point at which conduction starts. Turn-off occurs as current is reduced below a holding value. Drawbacks include relatively slow switching speed and large size of the resulting drive. GTOs and SCRs are mature power devices. Very rapid switching results, since no junction effect exists at the input.
Power consumption is small due to the insulated gate.
Standard IGBTs have voltage-switching limits and need to be connected in series for MV drive usage. This eases the need to gang standard devices. The integrated diode and gate unit lowers the parts count, resulting in increased reliability. SGCTs block voltage in both directions while allowing only one-directional current to flow. However, SGCTs do not need a series diode or anti-parallel diode, as IGCTs do.