Use of soft starters and motor protectors
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I hope an expert can explain in what situations soft starters and motor protectors are used, and what the advantages of using them are Currently, enterprises use thermal relays. The motors range from a few watts to 55 watts, while the transformer has a capacity of 400 KVA
Should I ask a question? What are you studying?
Reduce such posts and share more of your own opinions
1. The purpose of soft starting is to reduce the current during the motor’s start-up; in fact, soft starting is essentially voltage reduction starting. For example: normal startup requires an instantaneous current of 500A, but with reduced-voltage startup only 200A is needed, which serves as a form of protection for the circuit. 2. The function of a motor protector is to provide overcurrent protection when the motor is operating normally and smoothly; for instance, if a motor’s rated current is 10A, the setting value for a thermal relay is usually 1.3 times the rated current, That is, 13 A. When the motor is overloaded and the current reaches 13A for a certain period of time, the thermal relay will disconnect, thereby breaking the entire motor circuit and thus protecting the motor
This post was last edited by Brett on 2016-6-20 at 12:10. Is a soft start still necessary for motors with power ratings ranging from a few watts to 55 watts? ? This current is very small, so soft starting is not even necessary ； Soft starting involves starting the motor with a reduced voltage. Large motors require a current that is 4 to 7 times their rated current when starting, which can cause stress on the power grid and affect the lifespan of the equipment; this is where soft starting comes in handy ； A thermal relay serves to protect the motor when it is overloaded
If the transformer’s load factor is high, it is advisable to use soft start for the 55KW motor, considering that the transformer’s capacity is only 400KVA
The inverter currently in use for model 55 has a transformer load rate of around 85%
Thermal relays are used for small motors, while soft starters or frequency converters are used for larger motors
I’m quite conflicted about motor protectors; many of the protections are unnecessary. Protectors are indeed more effective in protecting motors, but in industrial production, continuous operation is sometimes more important, especially in cases of emergency fans – the operation cannot be stopped even if the motor burns out