The difference between thermal relay and motor protector - Solutions - Huaqiang electronic network

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The difference between the bimetal thermal relay and motor protector, according to statistics, the occurrence of burnout of the motor 100 per event, thermal relay 30 can not function. The reasons are many, mainly due to the presence of defects can not be overcome thermal relay. For example, a bimetal is prone to thermal fatigue, and it is difficult to recover from the initial after several times of overheating. Therefore, many electromechanical devices do not use thermal relays at the beginning of the design.
Motor protectors have been in the land of China for more than 30 years, still can not stop the burning of the motor. The reasons are mainly the following three aspects: 1. There is no correct product function positioning during design, which are essential functions? What are the auxiliary? (Not as many functions as possible) 2. There is no ideal current sensor at the moment, and the motor protector produced cannot meet the following requirements: block the occurrence of malfunction; have good interchangeability with the thermal relay; To adapt to a variety of harsh environments and extend its service life. 3, failed to bring immediate benefits to users.
More than 97% of low-voltage motors are destroyed due to over-current, resulting in over-current reasons such as overload (blocking), start-up timeout, phase loss, overvoltage, undervoltage, and poor contact of three-phase lines. The overcurrent caused by overload (blocking), starting timeout, overvoltage, undervoltage, etc. is the three-phase current equalization increase; and the overcurrent caused by phase loss, poor contact, voltage imbalance, etc. is one or two phase current increase. Therefore, high precision and sinusoidal current sampling are the key to motor protectors.
The destruction of an electric motor is not only costly to repair it: sometimes it takes time for the mechanic to take time to dismantle the damaged electric motor from the mechanical device, which is time consuming and delays production; once the factory critical equipment motor is destroyed, the indirect loss will be even greater. Increased expenses and increased processing costs of products. The repaired motor is not as good as the original, which accelerates the depreciation of the whole machine. Today, when copper prices are so high, it is especially important to protect and maintain the motor from burning.
A small motor with hundreds of thousands of tens of thousands of yuan is not worthy of being protected by a thermal relay that is not very reliable. Light and white consumes less energy (20 is equivalent to about 60W, 60 equivalent) about 80W, 150-type equivalent to about 100W), does not give protection to provide the most personal of the motor. In the past, when energy and resources were abundant, energy conservation and resource conservation were not taken seriously by the society. Today, the situation that the government is so concerned about is very different. Therefore, the birth of an ideal motor protector is an inevitable choice in today's society.