Overcurrent protection device for medium-frequency asynchronous motors

Abstract

The invention relates to an overcurrent protection device for medium-frequency asynchronous motors. Input ends of two relays are connected into two phases of a three-phase power source AC together, and output ends of the two relays are connected into a motor M and opposite to each other. Another phase in the three-phase power source AC is connected into the motor M through a sampling end of a current transformer L, a sensing end of the current transformer L is connected with a sampling resistor R and a positive electrode of a voltage comparator S after passing a rectifying diode P, sources of N-channel MOS (metal oxide semiconductor) transistors are connected with the power source, drains are respectively connected with the two relays, and grids are respectively connected with a control wire of the motor M and an anode of a thyristor J. A gate of the thyristor J is connected with an output end of the voltage comparator S. The overcurrent protection device for medium-frequency asynchronous motors realizes the overcurrent protection function for medium-frequency asynchronous motors, and is applicable to various medium-frequency asynchronous motors different in specifications and operating environments by adjusting parameters of components, low in operating limits and long in service life.

Description

technical field [0001] The invention relates to an overcurrent protection device, in particular to an overcurrent protection device for an intermediate frequency asynchronous motor. Background technique [0002] The function of the intermediate frequency asynchronous motor is generally to drive the load device to rotate or drive the load to move through the transmission mechanism. When the external load is too large or the transmission mechanism is stuck, the current of the motor will greatly exceed the normal working current, and a large amount of heat will be generated to burn out the motor windings, resulting in damage to the motor. In the past, in order to avoid overcurrent damage to the motor, a fuse was generally connected in series in the input circuit to realize the protection function. When the current was too large, the fuse would blow and cut off the power to avoid damage to the motor. [0003] The basic principle of the fuse is a conductor with a high resistivit...

AI Technical Summary

Problems solved by technology

[0003] The basic principle of the fuse is a conductor with a high resistivity and a low melting point, which is greatly affected by the conditions of use and generally has a short service life and a high possibility of misuse

At the same time, the fuse is a one-time use device. Once the fuse is unrecoverable, even if the external fault is eliminated, the motor still cannot be used, and the fuse needs to be disassembled and replaced.

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