In recent years the development of the SCR has made possible the control of the power system. It is one example that the speed control of the induction motor can be done by changing the frequency with the S.C.R. This paper is devoted primarily to a study of the running characteristics of the single phase induction motor through the experimental and theoretical methods when the speed of the motor is controlled by varying the conduction period in current with S.C.R. under the constant frequency. We conclude from the experiments that the adjustment of the phase angle in current is equivalent to the change of the supply voltage to the motor. Therefore, the speed control of the motor such as a fan duty motor is possibly by this methods.

Up to the present time, laminated insulators have been used for the insulation of electrical apparatus. The reason to use laminated insulators is based on the fact that electrical break-down voltage depends on the weak spot theory. If thin insulators are laminated, the weak spot existence probability across the electrodes decreases according to the number of lamination. In this test, the effect of the number of lamination and the thickness of each lamination sheets on their break-down voltage are discussed. The results taken as a whole indicate; (1) The break-down voltage of laminated insulators composed of thin sheets are higher than those of thick sheets, however, the voltage may become the same beyond any definite thickness of laminated insulators. (2) When the lamination sheets becomes thinner, the variation of break-down voltage is great according to the number of lamination sheets. (3) It may by effective to use laminated insulators even when the insulators are aparted from the electrodes.

Analysis of the transient stability of power systems following disturbances involves many sets of non-linear differential equations. This paper attempts to analyze the transient stability of multi-machine power systems by the step by step method, using the electronic digital computer. The critical switching times and phase angles for the main 154KV transmission system in Korea, are given from the swing curves of the probable conditions. It is concluded that the system is, in general, stable if the relay is cut off within 12 cycles after the fault. However the fault of DAEGU-SANGJU branch, accompanying much real power, makes the system unstable when the raly is cut off within 4 cycles after fault or automatic voltage regulators are equipped in this branch.

본 철탑설계이서 느끼는 점은, 장차 우리나라에서 건설할 345KV 송전용철탑도 국내에서 설계가능함은 물론, 조합부재방식을 활용하면 소요강재도 대부분국산품을 충당할 수 있을 것이다. 그리고, 국내기술의 향상을 위해서는 기술자에게 연구하고, 설계할 수 있는 시간적여유등 여건향상이 절대로 필요하다는 것이다. 국내에서 사용하는 기기는 우리나라 기술자가 국산자재를 이용하는 방침하에서 설계하고 설계가 끝난다음 이것을 국내에서 가공 또는 제작해야 많은 와화도 절약할 수 있고, 생산비도 절하할 수 있고 국내산업의 유기적발전을 기대할 수 있는 것이다.