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Selection of motor detection devices and accessories

The commonly used detection devices for motors are: stator temperature measuring device, bearing temperature measuring device, water leakage detection device, stator winding grounding differential protection, etc. Some large motors are equipped with shaft vibration detection probes, but due to the small necessity and high cost, the selection is small.


? In the stator winding temperature monitoring and overtemperature protection: some low-voltage motors use PTC thermistor, the protection temperature is 135℃ or 145℃. Six Pt100 platinum thermal resistors (three wire) are embedded in the stator windings of the hV motor, two for each phase, three for working and three for standby.

? Bearing temperature monitoring and overtemperature protection: each bearing of the motor is equipped with a Pt100 double platinum thermal resistance (three wire system), a total of 2, some motors only need on-site temperature display. The motor bearing bush temperature should not exceed 80℃, alarm temperature 80℃, stop temperature 85℃. Motor bearing temperature should not exceed 95℃.

? The motor is equipped with anti-leakage measures: for the water-cooled motor with upper water cooling, it is generally equipped with a leakage detection switch. When the cooler leaks or a certain amount of leakage, the control system will give an alarm.

? stator windings grounding differential protection: according to relevant national standards, when the motor power is greater than 2000KW, the stator windings should be equipped with grounding differential protection devices.


How are motor parts classified?

Motor stator

Motor stator is an important part of motor such as generator and starter. The stator is an important part of a motor. The stator consists of stator core, stator winding and frame. The main function of the stator is to generate a rotating magnetic field, while the main function of the rotor is to be cut by magnetic lines in the rotating magnetic field to generate (output) electric current.

The motor rotor

The motor rotor is also a rotating part of the motor. The motor is composed of rotor and stator, which is used to realize the conversion device of electrical energy and mechanical energy and mechanical energy. Motor rotor is divided into motor rotor and generator rotor.

The stator winding

Stator windings can be divided into centralized and distributed types according to the shape of coil winding and wiring mode of embedding. The winding and embedding of centralized winding are relatively simple, but the efficiency is lower and the operation performance is poor. At present, most of the stator of AC motor are distributed windings. According to different machine types, models and process conditions of coil embedding, motors are designed with different winding types and specifications, so the technical parameters of their windings are also different

The motor shell

Motor housing generally refers to the external housing of all electrical motor equipment. The motor shell is the protection device of the motor, made of silicon steel sheet and other materials by stamping and drawing process. Plus the surface of the rust and spray and other processes can be very good protection of the motor internal equipment. Main function: dust – proof, noise – proof, waterproof.

End cover

End cover is a rear cover installed behind the motor and other chassis, commonly known as “end cover”, mainly composed of cover body, bearing, brush plate. Whether the end cover is good or bad directly affects the quality of the motor. A good end cover, mainly from its heart – brush, its role is to drive the rotation of the rotor, this part is the key part.

Motor blades

The motor blade is generally located at the tail of the motor, used for ventilation and cooling of the motor, mainly acting on the tail of the AC motor, or placed in the special ventilation pipe of DC and high voltage motor. The blades of explosion-proof motors are generally made of plastic.

According to the material classification: motor blades can be divided into three types, and plastic blades, cast aluminum blades, cast iron blades.


Bearing is an important part of modern mechanical equipment. Its main function is to support the mechanical rotating body, reduce its friction coefficient in the process of motion, and ensure its rotation accuracy.

Rolling bearings are generally composed of outer ring, inner ring, rolling body and cage. Strictly speaking, they are composed of outer ring, inner ring, rolling body, cage, seal and lubricating oil. Mainly with outer ring, inner ring, rolling body can be defined as rolling bearings. According to the shape of the rolling body, rolling bearings are divided into ball bearings and roller bearings.