What is the distance between the control room, the frequency converter, and the motor?

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1. In industrial applications, the distance between the frequency converter and the motor can be roughly divided into three categories: long distance, medium distance, and short distance. Less than 20m is short range, 20 – 100m is medium range, and over 100m is long range. Since the voltage waveform output by the inverter is not sinusoidal, it contains a large amount of harmonic components. The higher-order harmonics cause the current output by the inverter to increase, leading to heating of the motor windings, as well as vibration and noise. This accelerates the aging of the insulation and can also damage the motor ； At the same time, harmonics of various frequencies emit different types of radio interference into space, which can also cause other devices to malfunction. Therefore, it is desirable to place the inverter near the motor being controlled. However, due to space constraints at the production site, there is often a certain distance between the frequency converter and the motor. If the distance between the inverter and the motor is within 20 meters, it can be connected directly to the inverter ； For medium-distance connections between the inverter and the motor ranging from 20 m to 100 m, it is necessary to adjust the inverter’s carrier frequency in order to reduce harmonics and interference ； For long-distance connections of over 100m between the inverter and the motor, it is necessary not only to appropriately reduce the carrier frequency but also to install an output AC reactor. 2. In highly automated factories, all control devices can be monitored from a central control room; the signals from the frequency converter systems also need to be sent to this control room. If the frequency converters are located in the central control area, a direct connection can be established between the main control panel and the frequency converters, with control being carried out through 0 – 5/10V voltage signals as well as some digital signals. However, the electromagnetic radiation from the high-frequency switching signals of the inverter can cause interference with weak control signals; therefore, it is not necessary to place the inverter in the central control room just for aesthetic reasons. If the frequency converter is located at a distance from the central control room, a 4-20mA current signal along with some digital signals can be used for control purposes ； If the distance is greater, RS485 serial communication can be used for connection ； If a longer distance is needed, communication relay stations can be used to achieve a distance of 1 km ； If fiber optic connectors are used, a distance of 23 km can be achieved. By using communication cables for connection, it is possible to easily create multi-drive control systems, thereby meeting requirements such as master/slave and synchronous control. Connecting to currently popular fieldbus systems will **increase** the data conversion rate. Increasing the distance between the central control room and the inverter cabinets helps to reduce the distance from the inverter to the motor, thereby enabling an improved system performance through a more rational layout. In short, when installing an inverter, it is necessary to take into account the distance between the central control room, the inverter, and the motor, in order to minimize the impact of harmonics and improve the stability of control.