【 Weak current College 】 electric fire main precautions

1. actively promote application with leakage protection function of the circuit breaker
To prevent short circuit arc resistance of earthing should vigorously promote the use of belt leakage protection of circuit breakers, general building, apart from the end of the installation of 30mA circuit leakage current protective device (RCD), into the line should be installed with leakage protection function of three-phase circuit breakers, earth leakage current optional 300mA or 500mA, belt 0.15-0.3 seconds delay. With leakage protection function of the circuit breaker for the delay feature and 30mA RCD at the second level, implementation of selective protection and 500mA following ARC energy not yet sufficient to ignite the fire, which can effectively remove the current outbreak of the arc of the grounding caused fire hazard.

2. prevent higher harmonic fire hazards caused by

Current harmonic to residential customers in more than a small number of public buildings, now only take increasing line section, especially increasing the neutral section to reduce circuit impedance, which reduce the harmonic current in the circuit impedance on the harmonic voltage, reduced lines of harmonic content. For public buildings, preventing harm, in addition to harmonic reducing line impedance, can also be fitted with source (or passive) harmonic filters, harmonic cancellation to filter out or offset the harmonic components.

3. reconstruction of the old line, eliminate electrical fire hazard

For old age should use copper wire transmission line (cable) to update, eliminate fire hazards. Aluminum wiring and copper terminal connection terminals should be lined aluminium Tin, copper and aluminum wire connection should be used copper and aluminium transition joints. The new building project should be strictly in accordance with the domestic design code GB50096-1999 requirements for design, "electrical lines should be in compliance with security and fire safety requirements of laying wires, conductors should be copper, each residential gas line section should not be less than 10mm2, branch circuit section should not be less than 2.5mm2".

4, with small resistance grounding of 10KV power grid, substation should equipotential connection or set apart for the grounding network

To prevent the small resistance grounding of 10KV power supply network grounding failure is too high for transient overvoltage conduction to low user devices, you can set the substation power system protection earthing and grounding of the low voltage system separation settings, and they should have a certain distance, making the transient overvoltage cannot be performed by the original common grounding grid transmission to low user. Alternatively, you can significantly reduce the grounding resistance value of substation work, and adjust the 10KV via low resistance grounding system of small resistor to ground of power supply control 10KV short-circuit current in a certain range, so that the transient overvoltage not reached dangerous values. If substation located in high-rise building, the transformer protective grounding and the low voltage side of the Earth through the equipotential connection and share a grounding, the buildings of steel, metal pipes, cables, metal jacketing and so do the equipotential connection occurs when substation 10KV ground fault, the buildings all metal parts together in the same potentials, not likely to cause an electric shock accident. Therefore equipotential connection of high-rise building with low-voltage system grounding the transformers, high-voltage Cabinet protection earthing common grounding device.

5. appropriate increase design standards to ensure the quality of construction

With the economic development of the future will have more electrical equipment into the home and office buildings, electrical design should be based on the development of vision select wire cross section, it is necessary to meet the future needs. It also should take full account of the relatively large flow of conductors, strictly control line length does not exceed the allowable range, eliminate risk. In construction should be strictly according to norms, do line connection, high-power lamps of fire, protect line insulation, preventing neutral line breaking, eliminating unnecessary risk. In addition, China's national standards for building fire safety design specification, electrical construction and acceptance, and IEC standards have a gap, some electrical fire hazard prevention in these specifications without specific provisions should therefore be to improve national standards and norms of electrical safety level, and to develop national standards for conductors flow, in order to facilitate the implementation of the measures.

6. perfect fire-fighting equipment configuration

On this point, should the practical implementation of the national fire protection equipment configuration of wires and intensive Department, cable tunnels sealing zone configuration of fire fighting equipment. Many thanks to the electric fire is implicit, it happens not always quick to let people discover, therefore more suitable equipped with automatic fire-fighting equipment, and set the automatic alarm function for the first time make firefighting response. Electric fire cannot be used to extinguish the fire, more suitable for use in aerosol and heptafluoro, belong to cold aerosol extinguishing an ultrafine powder extinguishing agent relative heptafluoro, more efficient, more environmentally-friendly, on the protection of the cable circuit no corrosive effect, heptafluoro need network-fire, such costs are relatively high, ultra-fine powder extinguishing agent has its matching suspended the automatic fire fighting equipment appropriate to the cable tunnel and circuit density.

Electrical fires caused by circuit fire, compared to other liquid and solid fuel fire let people feel terrible, it can be lethal, fire will cause the entire circuit crash, combustion, electric fire danger we must have a clear understanding and comprehensive understanding of, and do adequate precautions, after all, in order to own shuihuowuqing lives and property, but also for the national economy development, we must always guard against the open or secret fire hazard.