Hitachi, Ltd.

Akinori Watanabe

Nobuo Mitsui

Sadao Hokari

Katsu Komuro

Katsuya Teranishi

Yasuyuki Maeda

Tadao Kameyama

Takeshi Oohira

Takeshi Ohira

Shoichi Nakao

Kazuhiko Kawauchi

In a three phase load controlling system two bilateral switching circuits control the current in the first and the third phases; the first phase is later than the third. The second phase is uncontrolled. The gating signals applied to the bilateral switching arrangement connected in the first phase are advanced by a constant degree with respect to the voltage of the first phase. The gating signals applied to the bilateral switching arrangement connected in the third phase are synchronized with the voltage of the third phase.

Three phase controlling system

A driving system for moving paths or escalators which use an endles chain adapted to be circulated between a path for transporting passengers, comprising a first and a second sprocket disposed at one end portion and substantially middle portion of the path, respectively, a first and a second induction motor coupled respectively to the first and second sprockets and each having the same rating output the sum of which is selected to be substantially equal to a maximum capacity of the system, an induction coupling interposed between the second sprocket and the second induction motor, means for detecting a current flow through the first induction motor, means for setting a reference value, and a thyristor amplifier for exciting the induction coupling in response to an excess developed when an output of the detecting means exceeds the reference value.

Driving system for moving paths or escalators

In an AC elevator which is provided with a multi-speed induction motor unit connected to an AC power source and including a high-speed motor and a low-speed motor and in which an elevator car is started and accelerated by the high-speed motor, a control system comprising regenerative braking means connecting the low-speed motor to the AC power source through one set of thyristors connected in parallel in opposite polarity, DC braking means for supplying direct current to the high-speed motor from a controlled reactifier circuit, means for controlling the regenerative braking means to reduce the speed of the elevator car, means for detecting the reduction of the speed of the elevator car to a level at which the regenerative braking means is no more effective in producing the regenerative braking torque, and means for deenergizing the regenerative braking means and energizing the DC braking means in response to the output of the detecting means.

AC Elevator control system

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Katsuta, Japan

Akinori Watanabe