Working system of electric motor

The working system of the motor is an explanation of the load condition of the motor. It includes starting, electric braking, no-load, break-energy stop, and the duration and sequence of these stages. The working system of the motor needs to be considered when selecting the rated capacity of the motor. There are S1 ~ S10 motor working system, the following mainly introduces S1 ~ S3.

1.S1-continuous working system

The running time of the motor under constant load is sufficient to achieve thermal stability, that is, to reach a stable value of temperature rise. The production machinery using this working system has water pumps, blowers, machine tool spindles, etc.

2.S2 -- short-time working system

The motor runs for a given time under constant load, which is not enough to achieve thermal stability, and then the motor can be stopped for enough time to cool the motor again to within 2K of the temperature difference with the cooling medium. The production machinery using this working system is the auxiliary motion machinery of the organic bed, some metallurgical auxiliary machinery, etc. The short-term working time stipulated in our standard GB755 is 15min, 30min, 60min and 90min.

3.S3-intermittent cycle work system

The motor operates in a series of identical duty cycles, each cycle consisting of a period of constant load operation and a period of off-energy stalling. In this working system, the working time and the rest time alternate, and both periods are short. During the working period, the temperature rise of the motor is too late to reach the stable value, and during the rest period, the temperature rise is too late to drop to the stable temperature rise after cooling. After a cycle of work and rest, the temperature rise rises, and finally the temperature rise will fluctuate up and down within a certain range. The production machinery using this type of work system includes cranes, elevators, steel rolling auxiliary machinery, etc.

The intermittent cycle work system is similar to the short-term work system. If it is operated continuously, the motor will overheat.

In the intermittent cycle system, the ratio of the load working time to the entire cycle is called the load continuation rate, expressed as a percentage.

There are 4 kinds of load duration rates stipulated in China's standard GB-755: 15%, 25%, 40%, 60%, etc. The total time of a cycle is stipulated as tg t0 ≤ 10 min.