Abstract: A generator/motor system comprises a generator/motor having a primary winding and a secondary winding installed on the motor rotor coupled to a prime mover/load, a main circuit interposed between a power system and the primary winding of the generator/motor, an excitation circuit including a frequency converter inserted between a part of the main circuit and the secondary winding of the generator/motor, a frequency difference detector for determining the difference between the frequency of the power system and a frequency dependent on the rotational speed of the load, and a phase-shift control device for controlling the firing phase of the frequency converter in the excitation circuit by use of a signal from the frequency difference detector as a reference signal.

Abstract: A method and apparatus for diagnosing an overheating of a gas-cooled type electric machine having at least some components coated with an organic insulating material which decomposes into, for example, particles when subjected to high temperatures. The apparatus includes an extracting arrangement for enabling an extraction of gas from any region in an interior space of the electric machine. A device is provided for detecting a density of the particles contained in the gas and an arrangement is provided for analyzing a composition of the decomposed organic insulating material in the coolant gas so that, at first, an overheat region may be found and, secondly, an overheat position in the overheat region can be determined on the basis of the organic composition of the decomposed organic insulating material contained in the coolant gas.

Abstract: In a gas cooled rotary electric machine using insulating coating material which is subjected to thermal-decomposition when the insulating coating material is exposed to high temperatures thereby generating submicron particles, the concentration in the cooling gas of submicron particles generated through thermal-decomposition of the insulating coating material and distributed in the cooling gas is detected and an alarm signal is issued when the time-integration of a signal representing the concentration of the submicron particles exceeds a predetermined reference integration value.