Preface:
For electrical fire accidents, the phenomenon of "light and heat" eventually appears. "Arc" is the phenomenon of "light" to show "from arc to combustion", such as short circuit, poor contact, leakage, fault arc caused by fire. Therefore, the detection of fault arc belongs to a judgment of the essence of the dangerous signal causing the electrical fire accident.
1. Causes of Arc Fault
(1) Arc is caused by aging and breakage of wire.
(2) Arc generated by wire joints
A. Wire service environment is relatively bad, insulating layer is affected by high temperature, humidity or corrosion, insulation performance is reduced.
B. Overvoltage occurs in the power supply, which breaks down the insulation of the wire.
C. Installation is not standardized and the connection points of conductors are loose.
D. There are impurities in the connection of the conductor, such as oxide layer, clay, oil pollution, etc.
(3) Arc Fault Formed by Fault of Household Appliances
A. Electrical appliances exceed their service life and are seriously ageing
B. There are many dust and impurities in the electrical appliances, and the insulation performance is reduced, which causes the arc.
C. The internal insulation layer of electrical appliances is bitten by rats and other animals, and other reasons lead to wire breakage and poor insulation.
2. The Role of Arc Fault Circuit Breaker
The traditional MCB or RCD technology cannot detect parallel arc and series arc. At present, the residual current electric fire monitoring detectors on the market cannot detect the leakage current and high frequency components of residual current between the phase line and the earth, so it is particularly important to prevent this kind of electric fire caused by arc fault.
Arc Fault circuit breaker (AFCI) is the latest Arc fault Detection device. Its main function is to detect and identify dangerous grounding arc fault, parallel arc fault and series arc fault, and promptly drive the device to disconnect the current to avoid electric fire. The digital circuit control of embedded system and the original arc feature recognition algorithm are adopted, which are small in size, powerful in function and integrated with leakage current protection function. The automatic monitoring and protection of fault arc and leakage current are realized, and the safety of low-voltage distribution lines, electrical equipment and human body is effectively guaranteed.
3. Functional characteristics of arc fault circuit breaker:
In order to locate fault arc simultaneously in time domain and frequency domain, a comprehensive arc fault detection method based on line current time domain typical feature detection and frequency domain FFT is adopted.
Its functional characteristics are as follows:
(1) It has the functions of automatic control and manual control.
(2) It has the functions of detecting and distinguishing dangerous ground arc faults, parallel arc faults and series arc faults.
(3) The utility model has the function of promptly driving the device action which causes the current to be disconnected to avoid the occurrence of electric fire;
(4) It has many functions such as detecting leakage, over-current, short circuit, over-voltage, etc.
(5) It has the function of fault memory, which is convenient for fault inquiry and analysis.
(6) It has the function of indicator lamp alarm.
(7) Functions with multiple rated currents and voltages
(8) Unipolar rated switching-on and breaking function
(9) It has the function of displaying fault results.
(10) Free release function
(11) It has the functions of rust-proof, moisture-proof and electric shock protection.
4. Technical parameter
5. Application
AFCI (Arc Fault circuit breaker) can be installed in the distribution box of power transmission system. It can also be installed in families, offices, various large supermarkets, Department stores, hospitals, airports, textile factories, warehouses, oil depots, refineries, oil pipelines and other control points. It can be installed and used in all places where electricity is used, and widely used in electrical fire prevention.