Commonly used detection devices for electric motors are: stator temperature measurement device, bearing temperature measurement 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 lack of necessity and high cost, the amount of selection is small.
In terms of stator winding temperature monitoring and over-temperature protection: some low-voltage motors are equipped with PTC thermistors, with a protection temperature of 135°C or 145°C. High-voltage motor stator winding buried Pt100 platinum thermistors (three-wire system) 6, 2 per phase, 3 work, 3 standby.
In terms of bearing temperature monitoring and over-temperature protection: each bearing of the motor is set with a Pt100 double-branch platinum RTD (three-wire system), 2 in total, some motors as long as the on-site temperature display. Motor shaft tile temperature should not exceed 80℃, alarm temperature 80℃, stop temperature 85℃. Motor bearing temperature should not exceed 95°C.
The motor is equipped with water leakage prevention measures: for the water-cooled motor with upper water cooling, it should generally be equipped with a water leakage detection switch, when the cooler leaks or a certain amount of leakage, the control system will issue an alarm.
Stator winding grounding differential protection: the relevant national standards stipulate that when the motor power is greater than 2000KW, the stator winding should be set up with grounding differential protection device
How are the motor accessories classified?
Motor stator
The motor stator is an important part of motors such as generators and starters. The stator is an important part of the motor. The stator consists of the stator core, the stator winding and the seat. The main function of the stator is to produce a rotating magnetic field, while the main function of the rotor is to be cut by magnetic lines in the rotating field and thus produce (output) current.
Motor rotor
The motor rotor is also the rotating part of the motor. The motor consists of a rotor and a stator, which are used to convert electrical energy into mechanical energy and mechanical energy into electrical energy. Motor rotors are divided into motor rotors and generator rotors.
Stator winding
The stator winding can be divided into two categories: centralised and distributed, depending on the shape of the winding and the way the wiring is embedded. Centralised windings are simpler to wind and assemble, but are less efficient and have poor operational performance. At present, the majority of AC motor stators are used in distributed windings. Depending on the type and model of the motor and the technological conditions of the coil winding, each motor is designed with different winding types and specifications, so the technical parameters of the windings are different.
Motor housing
The motor housing generally refers to the external housing of all electrical motor equipment. The motor housing is a protective device for the motor and is made of silicon steel and other materials by stamping and deep drawing processes. In addition to the surface of the anti-rust and plastic spraying and other technological processing can be good protection of the motor internal equipment. Main functions: dustproof, noise proof and waterproof.
End caps
The end cover is a back cover installed behind the motor housing, commonly known as the "end cover", mainly composed of the cover body, bearings and brush pieces. The end cap is good or bad and directly affects the quality of the motor. A good end cap comes mainly from its heart - the brush blade, whose role is to drive the rotation of the rotor, and this part is the key part.
Motor airfoil
The motor airfoil is generally at the end of the motor, used for ventilation and cooling of the motor, mainly acting at the end of the AC motor, or placed within the special ventilation duct of DC and high voltage motors. Explosion-proof motors are generally made of plastic.
Bearing
Bearings are an important component in contemporary mechanical equipment. Its main function is to support the mechanical rotating body, reduce the friction coefficient during its movement, and ensure its rotary accuracy.
According to the material classification: motor airfoil can be divided into three kinds, and plastic airfoil, cast aluminium airfoil, cast iron airfoil.
Rolling bearings are generally composed of four parts: outer ring, inner ring, rolling body and cage, strictly speaking, outer ring, inner ring, rolling body, cage, seal and lubricant. Mainly with the 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 two categories: ball bearings and roller bearings.
