Motor protection tips


Release time:

2018-07-26

Why is it easier for electric motors to burn out now than in the past? Due to the continuous development of insulation technology, the design of electric motors requires both increased output and reduced volume, resulting in a decreasing thermal capacity and weakened overload capacity of new motors; Due to the improvement of production automation, it is required that the motor frequently operates in various ways such as frequent starting, braking, forward and reverse rotation, and variable load, which puts higher requirements on the motor protection device. In addition, motors have a wider range of applications and are often used in extremely harsh environments, such as damp, high temperature, dusty, and corrosive environments. In addition, non-standard motor repair and equipment

Why is it easier for electric motors to burn out now than in the past? Due to the continuous development of insulation technology, the design of electric motors requires both increased output and reduced volume, resulting in a decreasing thermal capacity and weakened overload capacity of new motors; Due to the improvement of production automation, it is required that the motor frequently operates in various ways such as frequent starting, braking, forward and reverse rotation, and variable load, which puts higher requirements on the motor protection device. In addition, motors have a wider range of applications and are often used in extremely harsh environments, such as damp, high temperature, dusty, and corrosive environments. In addition, non-standard motor repair and equipment

新闻资讯

Why is it easier for electric motors to burn out now than in the past? Due to the continuous development of insulation technology, the design of electric motors requires both increased output and reduced volume, resulting in a decreasing thermal capacity and weakened overload capacity of new motors; Due to the improvement of production automation, it is required that the motor frequently operates in various ways such as frequent starting, braking, forward and reverse rotation, and variable load, which puts higher requirements on the motor protection device. In addition, motors have a wider range of applications and are often used in extremely harsh environments, such as damp, high temperature, dusty, and corrosive environments. In addition, there are non-standard motor repair and equipment management omissions. All of these have resulted in the current motor being more prone to damage than in the past. 2. Why are traditional protective devices not ideal in terms of protection effectiveness? Traditional motor protection devices mainly rely on fuses and thermal relays. Fuses are the earliest and simplest protective devices used. In fact, fuses are mainly used to protect power supply lines and reduce the expansion of fault range in case of short circuit faults. It is unscientific to believe that fuses can protect motors from short circuits or overloads, and to choose fuses based on the rated current rather than the starting current of the motor. Don't you know, this is more likely to cause damage to the motor due to phase failure during operation. Thermal relays are the most widely used motor overload protection devices. However, the thermal relay has a single function, low sensitivity, large error, and poor stability, which has been recognized by many electrical workers. All these defects cause unreliable motor protection. The fact is exactly the same; Although many devices are equipped with thermal relays, the phenomenon of motor damage affecting normal production is still common. 3. Principles for selecting protectors? The purpose of selecting a motor protection device is not only to fully utilize the overload capacity of the motor, but also to avoid damage, and to improve the reliability and production continuity of the electric drive system. When selecting protective devices at the same time, several contradictory factors must be considered, such as reliability, economy, simple structure, convenient operation and maintenance, etc. When the protection requirements can be met, the simplest protection device should be considered first. Only when simple protection devices cannot meet the requirements or when higher requirements are put forward for protection characteristics, complex protection devices should be considered for application. 4. Ideal motor protector? The ideal motor protector is not the most functional or advanced, but should be the most practical. So what is practicality? Practicality should meet the elements of reliability, economy, convenience, and have a high cost performance ratio. So what is reliability? Reliability should first meet the reliability of functions, such as overcurrent and phase failure functions, which must be able to reliably act on various occasions, processes, and modes of overcurrent and phase failure. Secondly, its own reliability (since the protector is designed to protect others, it should have high reliability) must have adaptability, stability, and durability to various harsh environments. Economy: Adopting advanced design, reasonable structure, specialized and large-scale production, reducing product costs, and bringing extremely high economic benefits to users. Convenience: It must be at least similar to thermal relays in terms of installation, use, adjustment, wiring, etc., making it as simple and convenient as possible. Because of this, relevant experts have long predicted that in order to simplify electronic motor protection devices, a design scheme without a power supply transformer (passive) should be designed and adopted, and semiconductors (such as thyristors) should be used to replace electromagnetic actuators with contacts. In this way, it is possible to manufacture a protective device composed of the minimum number of components. We know that active power will inevitably bring unreliability. When one needs a working power supply for normal operation and the other loses phase, it will inevitably lose the working power supply, which is a fundamental contradiction that cannot be overcome. In addition, long-term power supply is required, which is easily affected by voltage fluctuations and high current surges in the power grid. The fault rate of the system will greatly increase, while increasing its volume and cost. It is necessary to consider the power supply voltage level, which makes it inconvenient to use. So the motor protection industry regards active and passive as milestones in technological progress. As a user, passive products should also be considered first when choosing. 5. What are the characteristics of the Julong UL series protectors? The UL series protector has the protection function for symmetrical faults (such as overload, locked rotor, overvoltage, undervoltage, etc.) and asymmetric faults (such as phase failure, current imbalance, phase to phase short circuit, turn to turn short circuit, etc.). When used in conjunction with AC contactors, it can provide fast and reliable protection for any type of three-phase motor. This protector adopts current detection technology without the need for external power supply. The output interface adopts the design scheme of an intelligent zero crossing and cut-off AC solid-state relay. The entire series adopts a core piercing and fully enclosed structure. This protector not only has a simple structure, reliable operation, convenient use, and low price, but also has no power consumption, sparks, maintenance free, long service life, and small size. It is currently the only electronic motor protector in China that can truly replace thermal relays. Especially suitable for situations with harsh working environments and poor power grid quality, achieving immediate results. Why is the "Dragon" protector the preferred brand in China? Due to Julong's penetration of the concept of "user first" into every employee, and its implementation in every link of scientific research, manufacturing, and service, our products have truly achieved high-quality and affordable, and our services reflect sincerity and trustworthiness everywhere. High quality: With three internationally leading technologies: passive, core piercing, and intelligent. Having six outstanding advantages that stand out from peers: complete protection functions, ideal protection characteristics, intuitive indication functions, simple wiring, precise settings, and easy installation. Affordable: Specialized and large-scale production provides unparalleled performance price ratio for the giant dragon protector. Advanced design, reasonable structure, exquisite craftsmanship, and a constantly improving work attitude ensure the high reliability of the product. Only then can we dare to promise the society a system of free trial, unconditional return and exchange, and lifelong warranty.