IEEE 841-2021: For ultra-high-efficiency, heavy-duty, fully enclosed, low-voltage squirrel-cage induction motors for the petrochemical industry, with a power range of 0.75 kW to 370 kW (1 hp to 500 hp).

SPM, or surface permanent magnet synchronous motor, is characterized by its permanent magnets being directly attached to the rotor surface. In contrast, IPM, or internal permanent magnet synchronous motor, is designed and placed inside the rotor.

The reasons for the reduction of motor insulation performance include environmental factors, material aging, mechanical damage, electrical problems, etc. The following methods can be used to deal with them.

When a NEMA motor has special mounting dimensions, flanges, or special shaft features, this is indicated by adding a suffix letter to its frame number.

The protection level is also called the IP level. The larger the number, the better the protection performance, and of course the higher the price. The IP (INGRESS PROTECTION) protection level system was drafted by IEC (INTERNATIONAL ELECTROTECHNICAL COMMISSION) to classify electrical appliances according to their dust and moisture resistance characteristics.

When the motor is running, copper loss, iron loss and mechanical loss are all manifested in the form of heat. Part of this heat is absorbed by the motor and part is transmitted to the air. The heat ab