What is the starting performance of the electric motor?

For variable frequency motors, starting is a very easy task, while for asynchronous motors, starting is always a crucial performance indicator. In the performance parameter indicators of asynchronous motors, starting torque and starting current are important indicators reflecting the starting performance of the motor. They are usually expressed as a multiple of the starting torque to the rated torque and the starting current to the rated current.

From the perspective of marine motor applications, we prefer a larger starting torque to ensure that marine motors can be easily started in a short period of time, especially for marine motors that start and stop frequently. The magnitude of the starting torque directly affects the overall operating efficiency of the equipment; For the starting current, it is hoped to be as small as possible to avoid the adverse effects of high current on the marine motor body and power grid.

The effective method to solve this contradiction is to increase the rotor resistance, which is very beneficial for improving the starting performance, but not conducive to meeting or improving other performance indicators of marine motors. It is very effective and necessary to write an article on how to balance the start-up and operation indicators in the rotor part of marine motors.

In a wound rotor asynchronous motor, as long as an external resistor is connected in series in the rotor circuit, the rotor resistance can be increased, which is very effective and relatively easy to achieve. When the marine motor starts and enters normal operation, the series external resistor is cut off, which can achieve the dual guarantee effect of starting performance and operating performance.

According to the idea of improving the starting performance of wound asynchronous motors, for cage rotor asynchronous motors, deep slot rotors and double cage rotors are used, and the "skin effect" is dynamically utilized to ensure the starting and operating performance.

For special working conditions that require high starting performance, there is a high slip marine motor. The guide rod of the cage rotor is made of a material with high electrical resistivity, and the starting torque of the marine motor is increased by increasing the rotor resistance.

In order to solve the contradiction between the starting torque and starting current of asynchronous motors, and to balance the performance relationship between starting performance and other operating indicators, auxiliary starting measures such as voltage reduction starting and frequency conversion starting have also been derived.