PURPOSE: To make superconducting turbine generator compact, by placing a normal conducting limit resistor at rotary side, and providing a superconducting generator to be used exclusively for feeding power to the limit resistor upon interruption of load and a superconducting switch for opening/closing the circuit thereof.

CONSTITUTION: A power generating system employs a water turbine 8 as a prime mover and a superconducting turbine generator 1 as a driven machine. In the generator 1, a rotor coil and a stator coil consist of a superconducting coil and these superconducting coils are coreless structure. And these coils are magnetically shielded with superconducting member. A field coil 2 and a power generating coil 3 constitute a superconducting generator having a disc rotor coil arrangement for supplying power to a brake resistor 7 only when the load is interrupted. Superconducting members are employed entirely except the brake resistor 7 employing normal conducting resistor. Excessive energy of turbine is converted through the brake resistor 7 into thermal energy so as to suppress over speed and over pressure.