1. In the industrial use site, the distance between the inverter and the motor can be roughly divided into three situations: long distance, medium distance and short distance. Within 20m is short distance, 20-100m is medium distance, and above 100m is long distance.

Since the voltage waveform output by the inverter is not sinusoidal, the waveform contains a large number of harmonic components, among which the higher harmonics will increase the output current of the inverter, cause the motor winding to heat up, generate vibration and noise, accelerate the aging of the insulation, and may damage it. At the same time, the harmonics of various frequencies will transmit radio interference of different programs to the space, and may also cause other equipment to malfunction. Therefore, it is desirable to place the inverter near the controlled motor. However, due to the limitation of production site space, there is often a certain distance between the inverter and the motor. If the distance between the inverter and the motor is within 20m, it can be directly connected to the inverter; for the medium distance connection between the inverter and the motor is 20m to 100m, the carrier frequency of the inverter needs to be adjusted to reduce harmonics and interference. ; For the long-distance connection of more than 100m between the inverter and the motor, not only should the carrier frequency be appropriately reduced, but also an output AC reactor should be installed.

2. In a highly automated factory, all control equipment can be monitored in the central control room, and the signal of the inverter system should also be sent to the central control room. If the position of the inverter is in the central control, between the main console and the inverter, It can be directly connected and controlled by 0-5/10V voltage signal and some switching signals. However, the electromagnetic radiation of the high-frequency switching signal of the inverter will cause some interference to the weak current control signal, so it is not necessary to be beautiful and neat, and the inverter should be placed in the central control room. If the distance between the inverter and the central control room is a little farther, you can use 4-20mA current signal and some switches for control connection; if the distance is longer, you can use RS485 serial communication to connect; if you want to increase the distance, you can use The communication intermediate relay can reach a distance of 1km; if an optical fiber connector is used, it can reach a distance of 23km. With communication cable connection, it is very convenient to form a multi-drive control system, so as to realize the requirements of master/slave and synchronous control. Connecting with the current popular field bus system will greatly increase the data conversion rate. The extension of the distance between the central control room and the inverter cabinet is beneficial to shorten the distance between the inverter and the motor, so as to improve the system performance with a more reasonable layout.

In short, when installing the inverter, it is necessary to comprehensively consider the distance between the central control room, the inverter and the motor to minimize the influence of harmonics and improve the stability of the control.