Serial arc-fault circuit interrupter and serial arc-fault protection method thereof

Abstract

The invention discloses a serial arc-fault circuit interrupter, comprising a power circuit, a current sensor, a current sensing circuit, an amplifying and filtering circuit, a voltage zero-crossing comparison circuit, a microcontroller, a trip trigger circuit. A current transformer collects current signals in a circuit; the current signals are converted into voltage signals through the current sensing circuit, and are input into the microcontroller through the amplifying and filtering circuit; the voltage zero-crossing comparison circuit inputs a voltage zero-crossing pulse signal into the microcontroller; the microcontroller judges arc emergence through arc characteristics analysis and is disconnected with a load circuit by the trip trigger circuit. The protection method transforms a one-dimensional time signal into a two-dimensional time signal by utilizing short-time Fourier transform, analyzes changes of fundamental component, even-order harmonic and odd harmonic component of eachcyclic wave, extracts and judges the serial arc-fault characteristics. The method has the advantages that multiple characteristics are extracted to realize comprehensive judgment of fault arc, missedtrip and balk generated in serial arc detection in small load are prevented, and the reliability of judgment is improved effectively.

Description

technical field [0001] The invention relates to the technical field of power supply protection, in particular to a series arc fault circuit breaker and a method for protecting the series arc fault. Background technique [0002] Residential electrical lines or equipment, due to the aging or damage of the wire insulation layer, or poor electrical connection, etc., may cause fault arcs in the electrical lines or equipment, resulting in electrical fires. In low-voltage power supply and distribution lines, there are three types of arc faults: series, line-to-line, and line-to-ground. The series arc is more dangerous because the current is smaller than the other two types of arc when the arc fault occurs, and the characteristics of the fault arc are more difficult to detect due to the influence of the load type and load size. [0003] As a kind of circuit protection technology, AFCI technology has been studied abroad, especially in European and American countries. In recent year...

AI Technical Summary

Problems solved by technology

[0004] 1. Arc voltage and current contain high-frequency noise components;

[0005] 2. The voltage drops when the arc occurs;

[0007] 4. There is a sudden change in the current;

[0009] 6. Randomness of arc current

However, since the characteristics of the series arc fault current are related to the type of circuit load, the complexity of the circuit load, the change of the load size, the fluctuation of the load opening and other factors, coupled with the harmonic interference of the power grid, etc., will affect the extraction of the characteristics of the series arc fault. accuracy, resulting in false tripping or refusal of the protection device

[0014] Under the condition of series arc and small load fault current (0.2A-20A), if the method of arc fault detection technology cannot be improved, including series arc detection under small load and dealing with false trips under various disturbance loads, the reliability of the protection device will be improved. Improving cannot be achieved

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