| 摘要 |
PURPOSE:To readily detect a malfunction by connecting light emitting elements having different wavelengths with a plurality of thyristors connected in series with a high voltage circuit, combining the outputs, and transmitting it through an optical fiber at a low potential side to divide to waves. CONSTITUTION:A plurality (3 as shown) of thyristors 11A-11C are connected in series with a high voltage circuit. Resistors 12A-12C and diodes 13A-13C are connected in series with the thyristors 11A-11C, and the first - third light emitting diodes 21-23 which output lights of different wavelengths are connected in parallel with the diodes 13A-13C. The light of diodes are led by light guides 24A-24C to a light composite nit 25 to combine them, and transmitted by a transmitter 36. It is photoelectrically converted by photodiodes 31-33 through light filters 27, compared by comparators 17A-17C, and input to a controller 18. Thus, less light guides are used to detect the malfunction of the thyristor by a circuit insulated from a high voltage circuit. |
