An inverter is an electrical device that uses the switching action of power semiconductor devices to convert industrial frequency power into another frequency, serving as a control device capable of soft starting, variable frequency speed regulation, improving operational accuracy, altering power factor, and providing overcurrent/overvoltage/overload protection for AC induction motors. After installation and wiring, inverters require commissioning, which starts with system inspection, followed by debugging according to the principle of "no-load first, then light load, and finally heavy load".

I. Inspection
Before trial operation of the variable frequency speed control system, it's necessary to inspect the system. The inspection includes both power-off and power-on checks.
1. Power-off Inspection
The main contents of power-off inspection include:
a. Appearance and structural inspection
Mainly check whether the model and installation environment of the inverter meet requirements, whether there is any damage or detachment, whether cable size and type are appropriate, whether electrical connections are loose or incorrect, and whether grounding is reliable.
b. Insulation resistance measurement
When measuring the insulation resistance of the inverter’s main circuit, connect terminals R, S, T and U, V, W together, then use a 500V megohmmeter to measure the insulation resistance between these terminals and ground. The normal value should be above 10MΩ. When measuring the control circuit insulation resistance, use a multimeter on the R×10kΩ range to measure the insulation resistance between each terminal and ground. Do not use a megohmmeter or other high-voltage instruments to avoid damaging the control circuit.
Product1.jpg Inverter
c. Power supply voltage check
Check whether the main circuit power supply voltage is within the allowable range to prevent the inverter from operating outside its rated voltage.
2. Power-on Inspection
The main contents of power-on inspection include:
a. Check if the display works normally
After powering on, the inverter display will show information; different inverters may display different content. Refer to the operation manual to verify if the display is normal.
b. Check whether the internal fan operates properly
After power-on, the internal fan of the inverter will start running. Use your hand near the air outlet to feel if the airflow is normal.
II. Familiarize Yourself with the Inverter Operation Panel
Different brands have different operation panels. Before commissioning the variable frequency speed control system, familiarize yourself with the inverter panel. During operation, refer to the operation manual to perform basic operations such as testing each key function and setting parameters.
III. No-Load Test
During the no-load test, disconnect the motor load first, connect the inverter output to the motor, and proceed with the power test. The steps are as follows:
1. Start-up Test: Set the frequency to 0Hz first, then gradually increase to 50Hz, and observe the motor acceleration.
2. Motor Parameter Detection: Inverters with vector control functions need to automatically detect motor parameters during no-load operation, including static parameters such as resistance and reactance, and dynamic parameters such as no-load current.
3. Basic Operation: Perform basic operations such as starting, jogging, accelerating, and decelerating.
4. Stop Test: Run the inverter at the set frequency for 10 minutes, then quickly adjust the frequency to 0Hz and observe the motor braking condition. If normal, the no-load test is completed.
IV. Load Test
After the no-load test is completed, reconnect the motor load for testing. The load test mainly includes startup tests, stop tests, and load capacity tests.
1. Startup Test
The main contents of the startup test include:
a. Gradually increase the working frequency of the inverter from 0Hz, observe the system startup performance, and monitor the motor load operation. Record the frequency at which the system starts. If the motor cannot run when the frequency is low, it indicates difficulty in starting, and torque compensation settings should be adjusted.
b. Switch the display to current mode, set the frequency to maximum, and let the motor accelerate to high speed within the set acceleration time. Observe the current changes during this period. If the inverter trips due to overcurrent protection during acceleration, it means the acceleration time is too short and needs to be extended.
c. Observe whether the system accelerates smoothly. For large inertia loads, acceleration/deceleration at the preset rate may result in insufficient torque, causing the motor speed to be out of sync with the inverter output frequency. Consider setting a pause-acceleration function at low speeds.
d. For fan-type loads, observe whether the blades reverse after shutdown due to natural wind. If reversal occurs, consider setting DC braking before startup.
2. Stop Test
The main contents of the stop test include:
a. Set the inverter working frequency to the maximum, press the stop button, and observe whether overcurrent or overvoltage causes tripping. If so, extend the deceleration time.
b. When the frequency drops to 0Hz, observe whether the motor exhibits “creeping” (failure to stop completely). If present, consider setting DC braking.
3. Load Capacity Test
The main contents of the load capacity test include:
a. At the required low speed under load, operate the motor under rated load for a long time and observe heating. If overheating occurs, take cooling measures.
b. At the required high speed under load, the inverter frequency exceeds the rated frequency. Observe whether the motor can drive the load at this speed.
Changsha Sunye Electric Co., Ltd. (established in 2010) and Shenzhen Sunye Electric Co., Ltd. (established in 2002) are national high-tech enterprises integrating R&D, manufacturing, and sales of inverters, industry-specific integrated machines, servo drives, and new energy products.
Sunye Electric owns independent intellectual property rights. Its products have passed inspections and certifications by national authoritative institutions and have obtained multiple software copyrights and IP certificates. Each year, significant investment is made in researching new technologies and developing new products, resulting in numerous patents and software copyrights. The company possesses core platform technologies such as construction hoist drivers, high-performance vector inverters, servos, and permanent magnet synchronous motor controls. Medium- and low-voltage inverters and servo drives are widely used in industries such as lifting, stone processing, HVAC, machine tools, metal products, wire and cable, plastics, printing and packaging, textile and chemical fibers, building materials, metallurgy, coal mining, municipal services, and automotive manufacturing. Guided by the philosophy of “Innovation, Technology, Strength,” driven by the corporate spirit of “Unity, Progress, Pragmatism, Innovation,” and adhering to the business principle of “Sincerity and Excellence, Mutual Benefit and Coexistence,” the company aims to provide industry-leading products through comprehensive quality management, continuous improvement, and pursuit of zero defects.
Address: Sunye Electric Industrial Park, No. 669 Xinsheng Road, High-Tech Zone, Changsha City
Tel/Fax: 0731-89932666 0731-89932688
Business Phone: 400-0755-731
Technical Support: 400-0755-731