If you have had the opportunity to participate in the test of motors, you may have a deeper understanding of frequency conversion technology. Especially those who have experienced old test equipment can better feel the advantages of frequency conversion technology.

Whether it is a motor inspection test or a type test, the motor will go through the motor starting process. Especially for the case of large motor power and small grid capacity, it will be very difficult to start the motor without load. The test process is like this, and the process of putting the motor into operation can also be imagined.

The stall test is to ensure that the motor rotor is in a stationary state. It is a test of the motor's starting characteristics and overload characteristics. For industrial frequency motors, starting is always a very critical factor, especially in some special occasions. Due to factors such as working conditions or equipment performance constraints, there is often only industrial frequency power supply, and of course industrial frequency motors will be selected.

Many motor factories, especially those that have newly purchased or improved test equipment, have also adopted variable frequency power supplies, which completely solved the problem of motor starting. However, there are also disadvantages, that is, the motor's performance weaknesses cannot be fully discovered. There was once a batch of dual-speed motors that did not find any abnormalities during the manufacturer's test, but the user failed to start at a certain speed. Further inspection revealed that the motor was tested only at one speed, and the motor's starting performance at another speed was not found to be insufficient. However, the motor was actually started at the corresponding speed with relatively poor starting performance during actual use. In fact, it is very easy to start the motor with variable frequency, which is why it can start during the test but may have problems under power frequency operation conditions.

High-efficiency motors are the product of national policy guidance. The high-efficiency requirements of the basic series of motors force different manufacturers to make design improvements through technical means, which of course may involve an increase in material investment.

When the industrial frequency motor is started at full voltage, the starting current is 5-7 times the rated current due to the starting torque required by the motor, which wastes electricity and causes great damage to the power grid. If variable frequency starting is adopted, the impact of the starting current on the power grid is reduced, saving electricity bills, and the impact of the starting inertia on the speed of the large inertia of the equipment is reduced, extending the service life of the equipment. It is beneficial to the power grid, the motor and the towed equipment.

The effect of frequency conversion technology on motor starting is very obvious, but there are also some unfavorable factors in the use of frequency conversion motors. For example, the non-sinusoidal waves generated by the inverter have a great impact on the reliability of the motor and are also prone to generate shaft current. This problem is particularly serious for motors with higher power and higher rated voltage. In order to avoid the shaft current problem, the selection of motor winding materials and necessary shaft current prevention measures are very necessary.