In mechanical equipment with electric motors, when starting, the current of the motor will be 5-6 times higher than the rated value, which not only affects the service life of the motor but also consumes more electricity. The system will leave a certain margin in motor selection during design, and the speed of the motor is fixed and unchanged. However, in actual use, it is sometimes necessary to run at a lower or higher speed, so frequency conversion transformation is very necessary. The frequency converter can achieve soft start of the motor, compensate for power factors, achieve energy-saving speed regulation by changing the input voltage frequency of the equipment, and provide protection functions such as overcurrent, overvoltage, and overload for the equipment.

The lifespan of an electric motor is related to various factors such as insulation degradation, friction in the sliding part, and functional impairments caused by bearing degradation, most of which depend on the condition of the bearings. The lifespan of bearings can be divided into two types: mechanism lifespan and lubricating oil lifespan.

Service life of electric motors and bearings

1. The lifespan of lubricating oil due to thermal degradation

2. Mechanical life caused by operational fatigue

In most cases, electric motors have a greater impact on the lifespan of lubricating oil due to heating than the weight of the load applied to the bearings on the mechanical lifespan. Therefore, calculating the lifespan of electric motors based on the lifespan of lubricating oil has the greatest impact on the lifespan of lubricating oil due to temperature, which greatly affects the lifespan time.

Electric motor - Starting method

The starting methods of the electric motor include: full voltage direct starting, self coupling decompression starting, and y- δ Starting, soft starter, frequency converter.

Full voltage direct start:

When both the power grid capacity and load allow full voltage direct starting, full voltage direct starting can be considered. The advantages are convenient operation and control, simple maintenance, and relatively economical. Mainly used for starting small power motors, from the perspective of energy conservation, motors larger than 11kW should not use this method.

Autocouple decompression start:

Utilizing the multi tap voltage reduction of an autotransformer can not only meet the needs of different load starting, but also obtain a larger starting torque. It is a commonly used voltage reduction starting method for starting larger capacity motors. Its biggest advantage is that the starting torque is relatively high. When the winding tap is at 80%, the starting torque can reach 64% of that of direct starting. And the starting torque can be adjusted by tapping. It is still widely used today.