[in Japanese]

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Parasitic oscillations have been experienced in a voltage and speed control circuits using a rotating amplifier of simple rototrol type, whose control winding is energized by a high gain direct current electronic amplifier. The oscillation has persisted even when the rotor of the rotating amplifier has stopped.
The reverse reaction which have been found in the unit response oscillogram of the open loop transfer function is analyzed, and the cause of the parasitic oscillation is clarified to be attributable to the parasitic coupling of electromagnetic nature between the control and the series compensating winding of the rotating amplifiers, which operates on positive feedback in the control circuit. The analytical expression of the open loop transfer function reveals that the control circuit is a non-minimum phase shift one, whose zero exists in the right half plane.
One of the most efficient and logical method of suppressing the oscillation is presented, that is, to transfer all zeros of the transfer function to the left half plane by neutralizing the effect of the parasitic coupling.
Four examples are given with criteria which may be useful for system design, that is, the first is one using the third winding magnetically coupled to both control and series compensating windings, the second using differentiating transformer, the third using parallel additions and the last using parallel additions with a slight variation to the third.
Control circuits using rotating amplifiers different from the simple rototrol type are also considered to be nearly identical with respect to the parasitic oscillation and the method of suppressing it.

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The dynamic characteristics of steam power plants are studied as a part of automatic frequency control problems in a power system. The dynamic chracteristic of a turbine governer in Sanban Power Plant was reported in Automatic Control Vol.3 No.1.
This paper treates its dynamic chracteristics of the boiler and ACC system examined by test conducted on the steam pressure control system. The ability of fuel response to load variation was examined. Under the present adjustment of the equipment, fuel feed increass due to resonance phenomenon of the control system when period of load variation is about two minutes.
If its amplitude grows up to the saturation range of furnace pressure regulation, large variation of furnace pressure due. to insufficient capacity of an induced draft fan was observed. The delay time due to the heat conduction is found to be as short as about 2 secs in boiler pulverized coals.

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As a device exerting high power, the hydraulic servomotor has been known for about one hundred years, and in future it will play an important role in high speed automatic control systems in virtue of its high power amplification.
However, there have been only a few published literatures on the dynamics of the servomotor with loads.
This paper presents the results of the theoretical and experimental investigation on the static and dynamic charateristics of the servomotor controlled with the underlapped pilot valve, under inertia and static friction loads.
In this paper, the dymamic characteristics of the servomotor are expressed in the form of frequency cahracteristics.

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[in Japanese]

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