Mahmood,

I remember a device called a Gate Turn Off Thyristor (GTO) which has the feature of being able to terminate the conduction cycle by pulsing the gate pin to the opposite polarity of turning it on. I found a company in the UK called DynexSemi (www.dynexsemi.com) which manufactures GTOs. I didn't read much about them, but did find a cross reference file (pdf) which showed ABB, Siemens, Toshiba and others which build the device. In addition to listing the devices by manifacturer and part number, a couple of specifications were shown. I don't know what the parameters mean, but they values were impressive - 2500 Volts, 1500 amps.

From a previous opportunity, I remember a locomotive refurbished by Marathon Electric which used GTOs in lieu of standard switchgear.

Good Luck,

Bruce