Hitachi Industrial Equipment Systems Co., Ltd.

Norio Aoyagi

Akihiro Yamamoto

Hiroaki Saito

Fuminori Kato

Daichi Oka

Yoshiyuki Kanemoto

There are provided an operation number control device and a method for controlling the same that can level the operation times of the fluid machines, which are connected to the operation number control device. A fluid machine system comprises a plurality of fluid machines, and an operation number control device capable of individually controlling start and stop of the fluid machines. The operation number control device sets a continuous operation time for each of the fluid machines based on total operation times of the fluid machine and other fluid machines. When among fluid machines in operation, there is a fluid machine for which the continuous operation time set for the fluid machine has elapsed and there is a fluid machine at stop, the operation number control device causes the fluid machine at stop to start and causes the fluid machine to stop.

Fluid machine system and method for controlling same

A gas compressor includes inverters, a plurality of compressor units and a control device for controlling each of the inverters. The control device increases the number of compressor bodies to be operated after confirming that the rotational speed of the operational motors will reach a steady value immediately after causing the number of the compressor bodies to be operated to increase.

Gas compressor and method for controlling same

The purpose of the present invention is to provide a gas compressor capable of reducing variation in discharge pressure through control of the number of compressor bodies and a control method for the gas compressor. In order to solve the problem, this gas compressor includes a plurality of compressor units each having a compressor body, a motor for driving the compressor body, and an inverter for controlling a rotational speed of the motor, and a control device for controlling the inverters. Discharge pipes of the compressor bodies converge on one main discharge pipe. A drive frequency of the motor of each compressor body is controlled by the corresponding inverter, whereby a pressure of each discharge pipe is controlled and a discharge pressure of the main discharge pipe is controlled. When the discharge pressure of the main discharge pipe has increased in a period of reduction in the drive frequency of the motor of the compressor body before the drive frequency reaches a lower-limit frequency, the control device calculates a prediction time for reaching a stopping pressure. The control device stops one of the compressor bodies when the prediction time is less than a threshold value.

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Tokyo, Japan

Norio Aoyagi