The commonly used detection devices for electric motors include: 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 low necessity and high cost, the selection is small.
• In terms of stator winding temperature monitoring and over-temperature protection: some low-voltage motors use PTC thermistors, and the protection temperature is 135°C or 145°C. The stator winding of the high-voltage motor is embedded with 6 Pt100 platinum thermal resistors (three-wire system), 2 per phase, 3 working and 3 standby.
• In terms of bearing temperature monitoring and over-temperature protection: each bearing of the motor is provided with a Pt100 double platinum thermal resistance (three-wire system), a total of 2, and some motors only need on-site temperature display. The temperature of the motor bearing shell should not exceed 80°C, the alarm temperature is 80°C, and the shutdown temperature is 85°C. The motor bearing temperature should not exceed 95°C.
• The motor is provided with water leakage prevention measures: for the water-cooled motor with upper water cooling, a water leakage detection switch is generally installed. When the cooler leaks or a certain amount of leakage occurs, the control system will issue an alarm.
• Grounding differential protection of stator windings: 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 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 three parts: stator core, stator winding and frame. The main function of the stator is to generate a rotating magnetic field, and the main function of the rotor is to be cut by magnetic lines of force in the rotating magnetic field to generate (output) current.
motor rotor
The motor rotor is also the rotating part in the motor. The motor consists of two parts, the rotor and the stator. It is used to realize the conversion device between electrical energy and mechanical energy and mechanical energy and electrical energy. The motor rotor is divided into the motor rotor and the generator rotor.
stator winding
The stator winding can be divided into two types: centralized and distributed according to the shape of coil winding and the way of embedded wiring. The winding and embedding of the centralized winding is relatively simple, but the efficiency is low and the running performance is also poor. At present, most of the stators of AC motors use distributed windings. According to different models, models and process conditions of coil winding, the motors are designed with different winding types and specifications, so the technical parameters of the windings are also different.
motor housing
The motor casing generally refers to the external casing of all electrical and electrical equipment. The motor casing is the protection device of the motor, which is made of silicon steel sheet and other materials by stamping and deep drawing process. In addition, the surface anti-rust and spraying and other process treatments can well protect the internal equipment of the motor. Main functions: dustproof, anti-noise, waterproof.
end cap
The end cover is a back cover installed behind the casing of the motor, commonly known as the “end cover”, which is mainly composed of a cover body, a bearing, and an electric brush. Whether the end cover is good or bad directly affects the quality of the motor. A good end cover mainly comes from its heart – the brush, its function is to drive the rotation of the rotor, and this part is the key part.
Motor fan blades
The fan blades of the motor are generally located at the tail of the motor and are used for ventilation and cooling of the motor. They are mainly used at the tail of the AC motor, or are placed in the special ventilation ducts of the DC and high-voltage motors. The fan blades of explosion-proof motors are generally made of plastic.
According to the material classification: motor fan blades can be divided into three types, and plastic fan blades, cast aluminum fan blades, cast iron fan blades.
bearing
Bearings are an important component in contemporary machinery and equipment. Its main function is to support the mechanical rotating body, reduce the friction coefficient during its movement, and ensure its rotation accuracy.
Rolling bearings are generally composed of four parts: outer ring, inner ring, rolling body and cage. Strictly speaking, it is composed of six parts: outer ring, inner ring, rolling body, cage, seal and lubricating oil. Mainly with outer ring, inner ring and rolling elements, it can be defined as rolling bearing. According to the shape of the rolling elements, rolling bearings are divided into two categories: ball bearings and roller bearings.
Post time: May-10-2022