2．1 Motor is applied for intermittent periodical load.There are for types of operating system,namely S2、S3、S4、S5 dependent on different load characteristics. Reference operating system is; if iperating system is S3,for single-speed it is 40%，and for it is 25%；at high-speed and 15% at low-speed（That is to say,if operating system is S3 ,duration ratio of load is 40%、25%、15% respectively and operating period is 10min）。
2．2 Main technical data。
2．2．1 With reference operating system for motor ,corresponding relation of its rated power,moment of inertia of rotor （Jam）、static brake moment（YBZ & YBZS motor is nothing with static brake moment.）with its base frame number is compatible with Table 2。

2．2．2 With rated voltage and reference operating system,ratio between maximum torque & stall torque with rated torque is no less than value regulated on Table 3-1（single-speed）and Table 3-2（two-speed）。