Frequency converters, also known as variable frequency drives (VFDs), are widely used in various industries for speed control of electric motors. Before putting an inverter into operation, it is important to conduct thorough inspections and tests to ensure its proper functionality and avoid potential safety hazards. In this article, we will provide a step-by-step guide for conducting a no-load power-on inspection and test runs with and without load, highlighting key considerations and settings for single-phase to three-phase VFDs. Following these guidelines can help ensure the safe and efficient operation of your VFD and motor system.
No-load power-on inspection of the inverter
1) Connect the ground terminal of the inverter to ground.
2) Connect the power input terminal of the inverter to the power supply through the leakage protection switch.
3) Check whether the factory display of the inverter display window is normal, if it is not correct, it should be reset, otherwise it is required to return.
4) Be familiar with the operation keys of the inverter. General frequency converters have 6 keys such as run (RUN), stop (STOP), programming (PROG), data P confirmation (DATAPENTER), increase (UP,), decrease (DOWN, “), etc. The definitions are basically the same. In addition, some inverters also have function keys such as monitor (MONITORP DISPLAY), reset (RESET), jog (JOG), and shift (SHIFT).
The frequency converter runs without load with the motor
1) When setting the power and number of poles of the motor, the operating current of the inverter should be considered comprehensively.
2) Set the inverter’s maximum output frequency, base frequency, and torque characteristics. General-purpose inverters offer various VP curves for users to choose based on load nature. For fan and pump loads, select the appropriate VP curve and set the torque running code to variable torque or reduced torque characteristics. Adjust the starting torque to ensure the motor meets production load requirements for improved low-speed performance during startup. In asynchronous motor frequency conversion speed regulation systems, torque control is more complex. In the low-frequency band, resistance and leakage reactance influence magnetic flux, reducing motor output torque if VP pseudo-constant is maintained. Compensate for voltage in the low-frequency band to increase torque. Users typically manually set and compensate for the inverter.
3) Set the frequency converter to its own keyboard operation mode, press the run key and stop key, and observe whether the motor can start and stop normally.
4) Familiarize yourself with the protection code when the inverter fails, observe the factory value of the thermal protection relay, observe the set value of the overload protection, and modify it if necessary. The user of the frequency converter can set the electronic thermal relay function of the frequency converter according to the instruction manual of the frequency converter. When the output current of the inverter exceeds its allowable current, the overcurrent protection of the inverter will cut off the output of the inverter. Therefore, the maximum value of the threshold of the electronic thermal relay of the inverter shall not exceed the maximum allowable output current of the inverter.
Test run with load
1) Manually operate the running stop key on the panel of the inverter, observe the process of the motor running and stopping and the display window of the inverter to see if there is any abnormal phenomenon.
If the inverter triggers overcurrent protection during motor start and stop, reset the acceleration and deceleration time. Motor acceleration and deceleration rely on acceleration torque, while the frequency converter’s frequency change rate is user-set. Changes in motor or load inertia may lead to insufficient acceleration torque, causing motor stall—mismatched motor speed and inverter output frequency, resulting in excess current or overvoltage. Set acceleration and deceleration times based on motor and load inertia for coordinated frequency and speed changes.
More: Installation And Wiring Requirements For Variable Frequency Drive
Frequency converters, also known as variable frequency drives (VFDs), are widely used in various industries for speed control of electric motors. Before putting an inverter into operation, it is important to conduct thorough inspections and tests to ensure its proper functionality and avoid potential safety hazards. In this article, we will provide a step-by-step guide for conducting a no-load power-on inspection and test runs with and without load, highlighting key considerations and settings for single-phase to three-phase VFDs. Following these guidelines can help ensure the safe and efficient operation of your VFD and motor system.
No-load power-on inspection of the inverter
1) Connect the ground terminal of the inverter to ground.
2) Connect the power input terminal of the inverter to the power supply through the leakage protection switch.
3) Check whether the factory display of the inverter display window is normal, if it is not correct, it should be reset, otherwise it is required to return.
4) Be familiar with the operation keys of the inverter. General frequency converters have 6 keys such as run (RUN), stop (STOP), programming (PROG), data P confirmation (DATAPENTER), increase (UP,), decrease (DOWN, “), etc. The definitions are basically the same. In addition, some inverters also have function keys such as monitor (MONITORP DISPLAY), reset (RESET), jog (JOG), and shift (SHIFT).
The frequency converter runs without load with the motor
1) When setting the power and number of poles of the motor, the operating current of the inverter should be considered comprehensively.
2) Set the inverter’s maximum output frequency, base frequency, and torque characteristics. General-purpose inverters offer various VP curves for users to choose based on load nature. For fan and pump loads, select the appropriate VP curve and set the torque running code to variable torque or reduced torque characteristics. Adjust the starting torque to ensure the motor meets production load requirements for improved low-speed performance during startup. In asynchronous motor frequency conversion speed regulation systems, torque control is more complex. In the low-frequency band, resistance and leakage reactance influence magnetic flux, reducing motor output torque if VP pseudo-constant is maintained. Compensate for voltage in the low-frequency band to increase torque. Users typically manually set and compensate for the inverter.
3) Set the frequency converter to its own keyboard operation mode, press the run key and stop key, and observe whether the motor can start and stop normally.
4) Familiarize yourself with the protection code when the inverter fails, observe the factory value of the thermal protection relay, observe the set value of the overload protection, and modify it if necessary. The user of the frequency converter can set the electronic thermal relay function of the frequency converter according to the instruction manual of the frequency converter. When the output current of the inverter exceeds its allowable current, the overcurrent protection of the inverter will cut off the output of the inverter. Therefore, the maximum value of the threshold of the electronic thermal relay of the inverter shall not exceed the maximum allowable output current of the inverter.
Test run with load
1) Manually operate the running stop key on the panel of the inverter, observe the process of the motor running and stopping and the display window of the inverter to see if there is any abnormal phenomenon.
If the inverter triggers overcurrent protection during motor start and stop, reset the acceleration and deceleration time. Motor acceleration and deceleration rely on acceleration torque, while the frequency converter’s frequency change rate is user-set. Changes in motor or load inertia may lead to insufficient acceleration torque, causing motor stall—mismatched motor speed and inverter output frequency, resulting in excess current or overvoltage. Set acceleration and deceleration times based on motor and load inertia for coordinated frequency and speed changes.
More: Installation And Wiring Requirements For Variable Frequency Drive
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