1) When choosing an inverter, consider the load characteristics. If the load is a constant torque type, go for Siemens MM420 or MM440 inverters. For fan or pump loads, choose the MM430 model instead. 2) Always base your inverter selection on the actual current value rather than just the motor's rated power. Keep in mind that inverters produce high-order harmonics, which can reduce the motor’s power factor and efficiency. As a result, motor current may increase by about 10%, and temperature rise could go up by 20%. Make sure to account for this when selecting both the motor and inverter, and leave some extra margin to avoid overheating and extend the motor’s lifespan. 3) If you're using long cables with the inverter, take steps to suppress the effects of ground coupling capacitance. This might involve adding one or two gear stages or an output reactor at the inverter’s output to prevent underperformance. 4) In special environments like high temperatures, high switching frequencies, or high altitudes, the inverter may need to be derated. In such cases, it's recommended to use a higher-rated inverter to ensure reliable operation. 5) When controlling multiple motors in parallel, check the total cable length from the inverter to each motor. If it exceeds the inverter's limits, consider upgrading to a larger model. Also, note that in this configuration, only V/F control mode is available, and the inverter cannot provide overcurrent or overload protection. To protect individual motors, fuses should be installed on each motor side. 6) High-speed motors generate more high-order harmonics due to their lower reactance. This increases the inverter’s output current, so it’s advisable to choose an inverter slightly larger than what would be used for a standard motor. 7) When using an inverter with a pole-changing motor, pay attention to its capacity. Ensure the maximum rated current is below the inverter’s output limit. Also, stop the motor before changing the pole number during operation, as running while switching poles can damage the inverter. 8) For explosion-proof motors, the inverter itself isn’t explosion-proof. Therefore, it should be placed outside the hazardous area to ensure safety. 9) When driving a geared motor, the speed range is limited by the lubrication method of the gears. At low speeds, there are no restrictions, but at high speeds beyond the rated speed, there’s a risk of oil being thrown out. Avoid exceeding the maximum speed rating. 10) When using an inverter with a wound rotor motor, note that these motors typically have lower winding impedance compared to squirrel cage motors. This can lead to overcurrent trips due to ripple current. It’s better to select an inverter with a slightly higher capacity. These motors are often used in applications with high flywheel torque, so pay extra attention to acceleration and deceleration settings. 11) When driving a synchronous motor, the inverter’s output capacity may drop by 10% to 20% compared to a standard power supply. The continuous output current of the inverter must be greater than the product of the motor’s rated current and the standard pull-in current. 12) For loads with large torque ripples, such as compressors or vibrating machines, or peak loads like hydraulic pumps, selecting an inverter based on the motor’s rated current or power may trigger overcurrent protection due to peak currents. Choose an inverter with a higher rated output current than the motor’s maximum current. 13) Submersible pump motors usually have a higher rated current than standard motors. So, make sure the inverter’s rated current is sufficient to handle this. 14) When driving a Roots blower or a special blower, remember that these are volumetric blowers with high pressure output. They exhibit nearly constant torque characteristics and have very high starting currents. Be sure the inverter has enough capacity to handle this. 15) Always verify that the inverter’s protection level matches the site conditions. Dust and moisture can negatively impact long-term performance if not properly addressed. 16) Single-phase motors are generally not suitable for inverter-driven applications. 17) Even if the motor load current is within the inverter’s rated current, don’t use an inverter that is significantly smaller than the motor’s capacity. This is because motor reactance varies with size, and larger motors can produce higher ripple currents, potentially exceeding the inverter’s current tolerance. 18) If the inverter has its own power supply, it’s best to add a line reactor to improve stability and performance.
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