Suppliers of frequency converter supporting equipment remind you that the voltage waveform output by the frequency converter is similar to a sine wave, rather than a true sine wave. The waveform contains a large number of harmonic components, especially high-order harmonics, which can increase the output current of the frequency converter, cause the motor winding to heat up, generate vibration and noise, accelerate insulation aging, and even potentially damage the motor; At the same time, harmonics of various frequencies can emit radio interference of different programs into space, which may cause misoperation of other electromechanical equipment.
Therefore, when installing a frequency converter, it is necessary to comprehensively consider the distance between the central control room, frequency converter, and motor in order to minimize the impact of harmonics and improve the stability of control.
（1） Definition of Distance:
1. Close range: The distance between the frequency converter and the motor is ≤ 20m;
2. Medium distance: The distance between the frequency converter and the motor is>20m and ≤ 100m;
3. Distance: The distance between the frequency converter and the motor is greater than 100m;
（2） In industrial settings:
1. Close range: The frequency converter and motor can be directly connected;
2. Medium distance: The frequency converter and motor can be directly connected, but the carrier frequency of the frequency converter needs to be adjusted to reduce harmonics and interference;
3. Long distance: The frequency converter and motor can be directly connected, which not only requires adjusting the carrier frequency of the frequency converter to reduce harmonics and interference, but also requires installing an output AC reactor.
（3） In highly automated factories:
In highly automated factories, all equipment needs to be monitored and controlled in the central control room. So, the signal of the frequency converter system also needs to be sent to the central control room.
1. Close range: If the frequency converter is installed in the central control room. The console can be directly connected to the frequency converter and controlled through 0-5/10V voltage signals and some switch signals. However, the electromagnetic radiation of the high-frequency switch signal of the frequency converter may cause some interference to the weak current control signal, so it is not necessary to have a neat and tidy appearance. Therefore, the frequency converter should be placed in the central control room.
2. Medium distance: refers to the distance between the frequency converter and the central control room, which can be controlled and connected using a 4-20mA current signal and some switch values; If the distance is further, RS485 serial communication can be used for connection;
3. Long distance: that is, the distance between the frequency converter and the central control room is greater than 100m. At this time, communication intermediate relays can be used to achieve a distance of 1km; If it is further away, fiber optic connectors are needed, which can reach up to 23km.
By using communication cables for connection, it is easy to form a multi-level drive control system, thereby achieving requirements such as master/slave and synchronous control. Connecting with the currently popular fieldbus system will greatly increase the data conversion rate. The extension of the distance between the central control room and the inverter cabinet is beneficial for shortening the distance between the inverter and the motor, in order to improve system performance with a more reasonable layout.