In the industrial field, the installation distance between the variable-frequency drive (VFD) and the motor can be roughly divided into three situations: long distance, medium distance and short distance. The short distance is within 20m, the middle distance is 20-100m, and the long distance is above 100m.
Since the voltage waveform output by the VFD is not sinusoidal, the waveform contains a large number of harmonic components, among which high-order harmonics will increase the output current, cause heating, vibration and noise of the motor winding, accelerate insulation aging, and may damage the motor; at the same time, harmonics of various frequencies will emit radio interference of different programs into the space, and may also cause misoperation of other equipment. Therefore, it is best to place the VFD close to the controlled motor.
However, due to space constraints on the production site, there is often a certain distance between the VFD and the motor. If the distance to the motor is within 20m, it can be directly connected with VFD; for the medium-distance connection between VFD and 20m to 100m motor, the carrier frequency needs to be adjusted to reduce harmonics and interference; for the long-distance connection between VFD and motor greater than 100m, not only the carrier frequency should be moderately reduced, but also an output AC reactor should be installed.
In a highly automated factory, all control equipment can be monitored in the central control room, and the output signal of the VFD is also sent to the central control room. If the position of the VFD is controlled in the central control room, the main console and the VFD can be directly connected, but the electromagnetic radiation of the high-frequency switching signal of the VFD will cause certain interference to the weak current control signal, so it does not have to be beautiful and tidy. Put the VFD in the central control room.
If the VFD is far away from the central control room, 4-20mA current signal and some switches can be used for control connection; if the distance is long, RS485 serial communication can be used for connection. If you want to extend the distance, you can use a communication intermediate relay to reach a distance of 1km; if you use a fiber optic connector, the distance can reach 23 kilometers. Using communication cables to connect, it is convenient to build 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 improve the data conversion rate. The extension of the distance between the central control room and the VFD cabinet is conducive to shortening the distance between the VFD and the motor, and improving system performance with a more reasonable layout.
When installing VFD, it is necessary to comprehensively consider the distance between the central control room, VFD and the motor, minimize the influence of harmonics, and improve the stability of control. If you want to know more about VFD, you are welcome to read other contents of this website.
In the industrial field, the installation distance between the variable-frequency drive (VFD) and the motor can be roughly divided into three situations: long distance, medium distance and short distance. The short distance is within 20m, the middle distance is 20-100m, and the long distance is above 100m.
Since the voltage waveform output by the VFD is not sinusoidal, the waveform contains a large number of harmonic components, among which high-order harmonics will increase the output current, cause heating, vibration and noise of the motor winding, accelerate insulation aging, and may damage the motor; at the same time, harmonics of various frequencies will emit radio interference of different programs into the space, and may also cause misoperation of other equipment. Therefore, it is best to place the VFD close to the controlled motor.
However, due to space constraints on the production site, there is often a certain distance between the VFD and the motor. If the distance to the motor is within 20m, it can be directly connected with VFD; for the medium-distance connection between VFD and 20m to 100m motor, the carrier frequency needs to be adjusted to reduce harmonics and interference; for the long-distance connection between VFD and motor greater than 100m, not only the carrier frequency should be moderately reduced, but also an output AC reactor should be installed.
In a highly automated factory, all control equipment can be monitored in the central control room, and the output signal of the VFD is also sent to the central control room. If the position of the VFD is controlled in the central control room, the main console and the VFD can be directly connected, but the electromagnetic radiation of the high-frequency switching signal of the VFD will cause certain interference to the weak current control signal, so it does not have to be beautiful and tidy. Put the VFD in the central control room.
If the VFD is far away from the central control room, 4-20mA current signal and some switches can be used for control connection; if the distance is long, RS485 serial communication can be used for connection. If you want to extend the distance, you can use a communication intermediate relay to reach a distance of 1km; if you use a fiber optic connector, the distance can reach 23 kilometers. Using communication cables to connect, it is convenient to build 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 improve the data conversion rate. The extension of the distance between the central control room and the VFD cabinet is conducive to shortening the distance between the VFD and the motor, and improving system performance with a more reasonable layout.
When installing VFD, it is necessary to comprehensively consider the distance between the central control room, VFD and the motor, minimize the influence of harmonics, and improve the stability of control. If you want to know more about VFD, you are welcome to read other contents of this website.
continue reading
Related Posts
Variable Frequency Drives (VFDs) and motors are integral components in industrial automation, each serving distinct yet interconnected roles in controlling […]
Variable frequency motors (VFMs) are crucial in modern industrial applications due to their efficiency and precise control over motor speed […]
Variable Frequency Technology (VFT) is increasingly being recognized as a game-changer in the industrial automation sector, particularly in applications involving […]