Method for restarting electromotor after power failure

Abstract

The invention relates to a method for restarting an electromotor after power failure. The electromotor power failure restarting logic is divided into restarting charge, restarting discharge and restarting action, and the power failure restarting can be carried out only after the charge is finished, wherein the restarting charge has the condition that after the electromotor is in a normal running state for 0.2-1s, charge is finished; the restarting discharge has the condition that after the electromotor is powered down due to a power failure command or an internal faults, the electromotor should not be started, and if the electromotor is restarted, discharge is carried; the restarting action (begins to time) has the condition that after the restarting charge is finished, the device judges that the electromotor trips because a contactor is broken off due to interference or electricity loss, and at the moment, an electricity loss timer begins to time accumulated electricity loss time; and after the voltage recovers to a normal value, the electromotor is automatically started in batches according to preset sequence time. The invention provides a reliable and economical electromotor (group) restarting method on the basis of absorbing the experience of high-voltage line reclosing by combining with the running characteristics of a low-voltage electromotor.

Description

technical field [0001] The invention relates to a method for restarting a motor or a group of motors in the industrial field according to a preset program and a related control device after the system shakes or loses power. Background technique [0002] Power plants, petrochemicals, steel and other industries are continuous production enterprises. Many motors in the low-voltage plant power system are not allowed to trip and shut down in the process flow. Once this part of the key motor trips and shuts down, it will cause unplanned shutdown. Bring great economic loss to production. However, there are many uncertain factors in actual operation, such as lightning strikes, equipment failures, etc., which can easily affect the power grid, causing the power supply voltage of the enterprise's internal distribution network to drop or resume power supply after a short-term interruption (usually called swaying power supply). ), causing the low-voltage motor to trip and shut down, and...

AI Technical Summary

Problems solved by technology

[0004] The solution of using PLC (Programmable logic Controller) as the self-starting cabinet has high hardware cost and complicated wiring

And PLC sampling and operation speed is not very fast

[0005] The existing motor restart relay only judges the power failure by judging the bus voltage of the motor and the auxiliary contact position of the contactor, and the probability of restart failure is high. There are the following situations: 1. After the voltage returns to normal, other motor switches are closed Restarted automatically, and the motor did not respond, nothing happened

2. In the case of a long duration of swaying electricity, stop the car for on-site treatment and prepare to drive. After the emergency stop measures are lifted, the motor starts by mistake

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