The use of electric motors, market conditions and comprehensive protection

A motor is a device that converts electrical energy into mechanical energy. It uses an energized coil to generate a rotating magnetic field, which acts on the rotor to form a magnetoelectric rotating torque. Motors are divided into DC motors and AC motors according to different power sources. Most of the motors in the power system are AC motors, which can be synchronous motors or asynchronous motors. The motor is mainly composed of a stator and a rotor. The direction of the forced movement of the wire in the magnetic field is related to the direction of the magnetic induction line and the direction of the current. The force applied by the magnetic field to the current is the working principle of the motor, which makes the motor rotate.
Motor use: AC asynchronous motor is relatively widely used in various motors. It is easy to use, reliable in operation, low in price, and sturdy in structure, but it has low power factor and difficulty in speed regulation. Synchronous motors are often used in large-capacity and low-speed power machinery. Synchronous motors not only have a high power factor, but also the speed has nothing to do with the load and only depends on the grid frequency. DC motors are widely used in occasions requiring wide speed regulation. But it has a commutator, complex structure, expensive, difficult to maintain, and is not suitable for harsh environments. After the 1970s, with the development of power electronics technology, AC motor speed regulation technology has gradually matured, and the price of equipment has been decreasing day by day, and has been applied. The maximum output mechanical power that a motor can withstand under the specified working mode without causing the motor to overheat is called its rated power. When using it, pay attention to the regulations on the nameplate. When running the motor, pay attention to match the load characteristics with the load characteristics of the motor to avoid loss of control or stall. The electric motor can provide various powers from milliwatts to 10,000 kilowatts. The motor is very convenient to use and control, with the ability to start, accelerate, brake, change direction, and brake. Generally speaking, the output power of the motor will change with the change of speed.
Motor market situation: In the past ten years, all walks of life have adopted motor speed control to a certain extent, and the country is also committed to promoting motor speed control technology. According to the sample survey results of enterprises in the steel, chemical, building materials, papermaking, non-ferrous metals, petroleum, coal, electric power, textile and other sectors, motor speed regulation is well applied in the building materials, petroleum, chemical and other industries.
Motor protection: Motor protection is a comprehensive protection for the motor, that is, when the motor is three-phase unbalanced, bearing wear, axial movement, leakage, overheating, undervoltage, short circuit, locked rotor, overload, out-of-phase, overvoltage, stator and rotor eccentricity , Alarm or protection is issued when radial beating; the protection device of the motor is a motor protector, including electronic protectors, thermal relays and intelligent protectors. Large and important motors generally use intelligent protection devices.