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 starting process will be experienced. Especially for the case of large motor power and small grid capacity, the motor no-load starting will be very difficult. 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 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 only tested for starting performance 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 increased material investment.
When the industrial frequency motor is started at full voltage, due to the starting torque requirement of the motor, the starting current is 5-7 times the rated current, 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, electricity bills are saved, and the impact of the starting inertia on the speed of the large inertia of the equipment is reduced, which prolongs the service life of the equipment. It is beneficial to the power grid, the motor and the towed equipment. The effect of variable frequency technology on motor starting is very obvious, but there are also some unfavorable factors in the use of variable frequency motors. For example, the non-sinusoidal waves generated by the inverter have a greater impact on the reliability of the motor and are also prone to generate shaft currents. Especially for motors with larger power and higher rated voltage, the problem is more serious. In order to avoid the shaft current problem, the selection of motor winding materials and necessary shaft current prevention measures are very necessary.
low voltage electric motor, Ex motor, Motor manufacturers in China, three phase induction motor, SIMO motor