Today I will explain use of fiber optic cable in power electronics at high voltage. Optical cable application in power electronics. Here I have shown, few thyristors connected in series, at high voltage 100KV or 220 KV. Our purpose is to trigger all thyristors at a time, using signal available at earth voltage. Here we convert electrical signal in to optical signal. Transmit this optical signal, using separate optical fiber cable. This circuit, converts optical signal in to electrical signal, amplify this and trigger the thyristor. Similarly this circuit, converts optical signal in to electrical signal, and trigger the thyristor. If there are 3 thyristor, there will be 3 circuits. This circuit does not require any external power. It draws the power from here itself. Similarly, suppose we have to send some monitoring signal, from here to here We need another cable in reverse diretion. Here electrical is converted in to optical signal, This is fiber optic cable. Here again we convert optical into electrical signal. So for this thyristor, We use 2 cables, one for transmitting data. One for receiving data. If there are 3 thyristor, then there will be 3 cable forward direction, 3 for reverse direction. Here we have 220KV. One CT is connected. There is a circuit here. This is connected to 220KV. This is electronic circuit. This measure the current, or any other parameter whatever we want. And then convert electrical signal to optical signal, This is fiber optic cable. We receive here optical signal, convert it in to electrical signal. And use it for monitoring or protection. This circuit would again, draw power from this 220KV line itself. No separate power is given. We also use optical cabes, in very high electrical noise area. Distance may be less, high voltage may not be there. But because electrical noise is more, so we have to use optical cable. In locos connected in the train, use optical cable for normal signal transmission also, for triggering also or for any other application. Today this much only.