Regarding the issue of cable length between the inverter and the motor
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There are usually requirements regarding the length of the cable between the inverter and the motor; the shorter, the better, as a general rule. Reputable frequency converter manufacturers will list in the manual the length of the motor cable required for each model of frequency converter. Taking ABB as an example, for the ACS510-01-012A-4 5.5KW inverter, the maximum length of the motor cable is 100 meters; with the use of an output reactor, this length can be increased to 150 meters. For the ACS510-01-017A-4 7.5KW inverter, the maximum length of the motor cable is 200 meters; with the use of an output reactor, this length can be increased to 250 meters. The question now is: when using a 7.5KW inverter with a 5.5KW motor, what is the maximum cable length, 100 meters or 200 meters? How many meters after using the output reactor?
7.5kW inverter with a 5.5kW motor – it depends on the power rating of the cable you choose; if it’s rated for 7.5kW, then 200 meters are needed, while if it’s rated for 5.5kW, 150 meters will suffice~
If it is a motor cable for a 7.5kw motor, the model should be the same as that for a 5.5kw motor. However, in the situation you described, 200 meters should be sufficient; the addition of an output reactor is also intended to prevent voltage drops caused by an excessively long cable length. It’s not very meaningful to consider this issue; it depends on the actual situation on site. .
This post was last edited by h20090630 on 2020-9-12 at 23:13. The question now is: why is it necessary to limit the length of the cable? Since a capacitor is formed between the cable and the ground, which consumes some power, it is necessary to choose an inverter or use an output reactor for this purpose. Since the problem is caused by the excessive length of the cable, using cables with good insulating properties, such as armored cables, and ensuring proper grounding and equipotential bonding can help minimize losses, allowing the cable length to be increased to some extent. The criterion for judgment is that the voltage drop of the cable is not significant, and the frequency converter does not experience overcurrent. There is another unsuggested method, which is to increase the output voltage of the inverter. The maximum voltage that an inverter can provide is 400V, while standard motors operate at 380V; therefore, it is possible to increase the inverter’s output voltage slightly, to around 390V, as long as the motor terminals are rated for 380V. I’ve used it many times and it works very well. ,