1. Improper Inverter Parameter Settings If the rated voltage, current, capacity, acceleration/deceleration time, and power factor of the load motor are set improperly, it can lead to a mismatch between the inverter and the motor, causing the motor to overload or overheat, and preventing the inverter from working properly. Example: The No. 6 homogenization trolley is driven by a Siemens MMV300/3kW inverter. After installation on September 30, 2003, a test run was conducted. The trolley motor failed to run, only vibrating continuously and emitting a "humming" sound. Inspection revealed that the mechanical transmission and electrical circuits were normal. The initial diagnosis was that the inverter's function parameters were improperly set, leading to a mismatch between the inverter and the motor, causing motor overload. Further investigation revealed that the acceleration time PO02 "rampuptime" was set too short, resulting in excessive torque boost, causing motor flux saturation, high current, and motor overload, preventing it from starting. The carrier frequency was also set to the factory default value (maximum), increasing the inverter's rated output current. After measures such as extending the acceleration time, reducing the torque increase, and reasonably setting the carrier frequency were taken, the inverter was restarted, and the cloth-laying trolley motor worked normally. [b]2 Inverter Frequency Cannot Reach Higher Frequency[/b] The inverter frequency could not reach higher frequencies due to increased load, lower input voltage, or problems with the control circuit. Example 1: In October 2002, the inverter (Yaskawa 616G5/22kW, control method: panel input) used in the No. 6 cement mill classifier was set to 32Hz. After starting the inverter, the frequency rose to 16Hz and then stopped rising, with no other fault indications. On-site inspection revealed that the motor rotated slowly, had slight vibrations, and a "humming" sound. After disconnecting the load, the inverter frequency rose normally. Inspection of the classifier's vertical shaft revealed a damaged bearing. After repairing the bearing, the inverter worked normally. Example 2: In August 2003, the frequency converter was set to 35Hz. After starting the converter, the frequency rose to 12Hz and then stopped increasing, and the converter did not display any fault information. Initially, it was suspected that there was a problem with the vertical shaft of the air classifier, but this was found to be normal. After reconnecting power, the DC bus voltage of the frequency converter was tested, and the displayed value was only 440V, while the normal value is between 560 and 600V. Testing the input terminal revealed that one phase of the dedicated contactor supplying power to the frequency converter had poor contact, resulting in a phase loss at the frequency converter input terminal. Cause analysis: The frequency converter could still operate at low frequencies without any fault display even with a phase loss at the input terminal because most general-purpose frequency converters only issue fault alarms when the bus voltage drops below 400V. With only two phases of voltage input, the DC bus voltage of the frequency converter can reach 1.2 times the line voltage (i.e., 380V x 1.2 = 456V), which is greater than the lower limit of 400V. When operating at low frequencies, the DC voltage of a frequency converter can reach normal values ​​due to the effect of the smoothing capacitor. General-purpose frequency converters, employing PWM control technology, perform voltage and frequency regulation at the inverter stage, allowing them to continue operating normally even with a phase loss at low frequencies. However, due to the low input voltage, the output voltage is correspondingly low, preventing the frequency converter from reaching its maximum output frequency. [b][align=center]For more details, please click: Common Frequency Converter Fault Classification Analysis and Handling[/align][/b]