Single motor protection device for dragging double motor through single frequency conversion

Abstract

The invention provides a single motor protection device for dragging double motor through single frequency conversion and relates to a protection device for dragging double motor through single frequency conversion. The device comprises a detecting unit and a control unit, wherein the detecting unit is used for detecting the current strength of each phase circuit of each motor; the control unit comprises an analog value input module and a data processing module; and the control unit is a PLC controller for receiving a current detecting signal from the detecting unit, analyzing the current detecting signal and controlling the work state of a frequency converter connected to the motor according to a signal processing result so as to protect the motor. In the single motor protection device for dragging double motor through single frequency conversion of the invention, a current transformer is used for collecting motor current at real time, timely detecting the fault of one motor or the faults of two motors at the same time and cutting off the output of the frequency converter in time so as to effectively and timely protect each motor dragged by the frequency converter.

Description

technical field [0001] The invention relates to a motor protection technology, in particular to a protection device with double motors driven by a single frequency converter. Background technique [0002] With the rapid development of the national economy, electric motors have become commonly used power machinery in all walks of life. Generally, there are two electric motors installed in the fan in mine operation, and the usual usage is to use a frequency converter to drive the two electric motors. However, the working conditions of each motor are different. In most cases, the output power of the two motors sometimes differs greatly, that is, the output of the two motors is unbalanced, so that one motor is overloaded and the other is overloaded. If one motor is working at a very low current, the frequency converter cannot effectively protect the motor at this time; if one motor fails, it is not found in time that one motor has failed, so continue to let the other motor conti...

AI Technical Summary

Problems solved by technology

However, the working conditions of each motor are different. In most cases, the output power of the two motors sometimes differs greatly, that is, the output of the two motors is unbalanced, so that one motor is overloaded and the other is overloaded. If one motor is working at a very low current, the frequency converter cannot effectively protect the motor at this time; if one motor fails, it is not found in time that one motor has failed, so continue to let the other motor continue to work. It is possible to burn out another normal motor, which will also cause irreparable losses, so it is required to implement protection control for each motor

[0003] Most of the motors in the prior art are installed with thermal relays as overload protection. When the current is too large, the bimetal strip is used to generate heat, the main circuit is disconnected, and the motor is stopped. However, the actual temperature rise caused by the excessive current varies greatly. The equipment is installed in an explosion-proof box, and it is inconvenient to reset the thermal relay, so it cannot effectively protect the motor from heat, and the thermal relay cannot effectively protect the faults such as phase loss and three-phase imbalance.

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