Thermal switch of electric motor
What are the types of thermal switches for electric motors and their correct selection?
The overheating protection system of electronic motors generally consists of a control system and a thermal switch. In terms of control methods, direct control using thermal switches is a relatively simple and convenient control method, and small-volume mechanical thermal switches are also relatively inexpensive. There are many types of thermal switches for motors. Choosing the right one is also a very important step. So what types of thermal switches are there? What should be paid attention to when choosing?
The types of thermal switches of motors can be classified as follows:
1. According to the principle of action: Temperature type (acts only when sensitive to temperature), Current temperature type (sensitive to temperature and current and action protection);
2. According to the mode of action: quick action, slow action;
3. According to the state of the contact: normally open, normally closed;
4. According to the structure of the contact: single-ended, double-ended;
5. According to the heating method of the bimetallic strip: self-powered heating type, reheating type, and indirect heating type;
6. According to the shape of the bimetallic strip: dish shape and strip shape;
7. According to the adjustment temperature, it can be divided into: adjustable and fixed temperature;
8. According to the sealing form: open type and sealed type;
9. According to the potential of the shell: live and uncharged.
The above are the general classifications of thermal switches. Different types of thermal switches have different application methods. Temperature control and temperature adjustment of electric heating devices; Control and protect the over-temperature operation of the motor; The overheating protection of the windings caused by the motor's long-term locked-rotor or overload.
The thermal switch of the motor should be selected according to the product type and application method. Reasonable selection of matching protective components and proper selection can play a good role in protection. If the temperature of the thermal switch is selected too low, it will cause frequent overheating protection when the motor is in normal use. Selecting too high will cause the motor windings to run at too high a temperature. After the winding limit temperature is exceeded, the overheating protection will shorten the winding life and cause the motor to burn out.
How to choose the right thermal switch correctly?
Through testing and combining the actual working conditions and environment of the motor, the overheating protection temperature of the thermal switch can be correctly selected. If the thermal switch has other special uses, it can also perform such as: Extreme short circuit test, thermal shock, corrosion resistance and other tests, so as to select the best overheating protection temperature point. The correct overheating temperature point makes the thermal switch of the motor work in the most perfect state and exert its due function.