Because of voltage instability, phase failure, overcurrent and other reasons, the motor is damaged, resulting in abnormal work, so it is necessary to protect the motor, so there is a motor protector.
There are many kinds of protectors, such as open-phase protection, over-current and under-current protection, time protection, temperature protection, leakage protection and overheating protection. Protector is divided into mechanical protection and electronic protection. The principle is to protect the motor under the above circumstances, minimize losses and even protect people's lives.
Extended data
First, the significance of motor protector in national economy and energy saving.
Motor protector (motor protector) is an important device in power generation, power supply and power consumption system. It is a cross-industry, large-scale and wide-ranging energy-saving electromechanical product with remarkable energy-saving effect.
It permeates almost all fields of electricity consumption; It is an important guarantee for industry, agriculture and national defense construction, as well as people's life, normal production and safety work, and plays an irreplaceable role in national economy and energy conservation.
Second, the common types of motor protectors
1, thermal relay: ordinary small-capacity AC motor, in good working condition, without frequent starting and other bad working conditions. Due to poor accuracy, reliability cannot be guaranteed, so it is not recommended.
2. Electronic: detect the three-phase current value, which is set by the potentiometer knob or the pull code switch. The circuit generally adopts analog type, which adopts the working characteristics of inverse time limit or fixed time limit. Protection functions include overload, phase failure, locked rotor and other fault protection, fault types are displayed by indicator lights, and running power is displayed by digital tubes.
Baidu encyclopedia-motor protector