Cable distance between inverter and motor

Since the voltage waveform output by the inverter is similar to a sine wave, its waveform contains a large number of harmonic components, especially high-order harmonics, which will increase the output current of the inverter, cause heating of the motor winding, generate vibration and noise, accelerate insulation aging, and even damage the motor; at the same time, harmonics of various frequencies will emit radio interference of different programs into space, so it may cause malfunction of other electromechanical equipment.

Therefore, 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 impact of harmonics and improve the stability of control.

(I) Definition of distance:

1. Short distance: The distance between the inverter and the motor is ≤20m;

2. Medium distance: The distance between the inverter and the motor is >20m and ≤100m; the distance between the SOWAKAM inverter and the motor is 50m.

3. Long distance: The distance between the inverter and the motor is >100m;

(II) Occasions for industrial use:

1. Short distance: The inverter and the motor can be directly connected;

2. Medium distance: The inverter and the motor can be directly connected, but the inverter carrier frequency needs to be adjusted to reduce harmonics and interference;

3. Long distance: The inverter and the motor can be directly connected, not only does it need to adjust the inverter carrier frequency to reduce harmonics and interference, but it also needs to install an output AC reactor.

(III)  highly automated factories:

In highly automated factories, all equipment needs to be monitored and controlled in the central control room. Therefore, the inverter system signal must also be sent to the central control room.

1. Short distance: if the inverter is installed in the central control room. The console and the inverter can be directly connected and controlled by 0-5/10V voltage signals and some switch signals. However, the electromagnetic radiation of the high-frequency switch signal of the inverter will cause some interference to the weak current control signal.

2. Medium distance: if the inverter is farther away from the central control room, 4-20mA current signal and some switch signals can be used for control connection; if the distance is farther, RS485 serial communication can be used for connection;

3. Long distance: if the distance between the inverter and the central control room is greater than 100m. At this time, the communication intermediate relay can be used to reach a distance of 1km; if it is further, a fiber optic connector is required, which can reach up to 23km. Using communication cable connection, it is very convenient to form a multi-level drive control system, thereby realizing the requirements of master/slave and synchronous control. The extension of the distance between the central control room and the inverter cabinet is conducive to shortening the distance between the inverter and the motor, so as to improve the system performance with a more reasonable layout.