Hitachi, Ltd.

Yuuzi Yamasawa

Setsuo Arita

Tetsuo Ito

Mitsuru Kudo

Yukiharu Ohga

Hideyuki Sato

Fumio Murata

Yuichi Higashikawa

Satoshi Ibori

Nobuyoshi Mutoh

Akiteru Ueda

Kenji Nandoh

Motonobu Hattori

Hideyuki Shimonabe

In an apparatus for operating and monitoring a plant, a manipulating device provides the plant with manipulation signals for operating the plant. In response to information supplied from the plant and a manipulating signal of the manipulating device, a first display data producing device produces first display data needed for the operation of the plant changing every moment. On the basis of data supplied from the first display data producing device, a first display device displays information relating to the operation of the plant. In response to information supplied from the plant and a manipulating signal of the manipulating device, a second display data producing device produces data needed for monitoring the plant. On the basis of data supplied from the second display data producing device, a second display device displays information relating to the monitoring of the plant on a larger display screen than that of the first display device. Information displayed by the first display device and information displayed by the second display device complement each other and make it possible to accurately operate and monitor the plant.

Plant operating and monitoring apparatus

A method and apparatus are disclosed for controlling a pulse width modulated (PWM) inverter controlled for ignition by a (PWM) pulse produced with a carrier wave and a modulation wave. The method comprises sampling an amplitude of the modulation wave at a cycle rate related to the frequency of the carrier wave. The modulation wave and the carrier wave are synchronized when the sample modulation wave amplitude has a peak value greater than an amplitude of the carrier wave. The modulation wave and the carrier wave are asynchronized when the sampled modulation wave has a peak value less than the amplitude of the carrier wave.

Method and apparatus for selectively controlling an operation mode of a

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Hitachiota, Japan

Yuuzi Yamasawa