I. Introduction <br> <br> recent years, newly built around a lot of large public buildings, especially large sports, cultural venues, etc. These buildings are highly concentrated populations of open spaces in case of fire and power failure accident, It is extremely important to be prone to evacuation, mutual trampling, causing casualties and improve the reliability of emergency evacuation lighting. However, due to the failure to modify and unify some technical specifications in time, the design is based on different design ideas, which are very different and cannot meet the actual needs and need to be improved. This paper makes a brief analysis of the problems encountered in the practice of emergency lighting technical specifications to attract sufficient attention from practitioners.
Second, the relevant technical specifications
(1) "Code for Design of Civil Building Electrical Appliances" JGJl6-2008 Section 3.1.9.1: "The primary load shall be supplied by two power sources. When one power supply fails, the other power supply shall not be damaged at the same time. Primary load capacity When there is a large or high-voltage power equipment, two high-voltage power supplies should be used. If the primary load capacity is not large, the second low-voltage power supply from the power system or the adjacent unit should be used preferentially, or the emergency generator set, such as the primary load. When only for lighting or telephone station load, battery pack should be used as backup power supply."
(2) "Code for Fire Protection of Building Design" GBJ 16-87 Article 10.1.2: "Fire accident lighting and evacuation lighting signs can be used as backup power supply, but the continuous power supply time should not be less than 20min."
(3) "Code for Fire Protection of Building Design" GBJ 16-87 Article 10.1.3: "Fire-fighting electrical equipment shall adopt a separate power supply circuit, and when a fire cuts off production and domestic electricity, it shall be able to ensure fire-fighting electricity. Its power distribution equipment should have obvious signs."
(4) Article 10.2.8 of the Code for Fire Protection of Building Design GBJ 16-87: “...the evacuation walkway and evacuation door shall be provided with a light evacuation indication signâ€.
(5) "Code for Design of Automatic Fire Alarm System" GB 501 16-98 Article 6.3.1.8: "After confirming the fire, the fire control room should be able to cut off the non-fire power supply of the relevant part, and turn on the alarm device and the fire emergency light. And evacuation sign lights."
(6) "Fire Protection Code for High-rise Civil Building Design" GB 50045-95 (revised edition 200l) Article 9.2.6: "Emergency lighting and evacuation indication signs, battery can be used as backup power supply, and continuous power supply time should not be less than 20min ".
Third, the fire emergency lighting power supply damage analysis <br> <br> with too amplitude country's economic strength increased, large public buildings in general by high regulatory requirements, according to a load of fire control power supply design. At present, most of the diesel generators are used as fire emergency power sources. The generator start signal is taken from the upper end of the mains breaker. Once the mains power is lost, the generator will automatically start within 30 seconds to supply power to the fire equipment.
In the fire, due to the first damage to the power supply line and the electrical appliances, causing short-circuit, overload, etc., in general, a partial breakdown will occur in a short period of time, including emergency circuits. In addition, in practice, when a large public building fires, water is often used as a fire extinguishing medium. In order to prevent the electric shock of the disaster relief personnel and other personnel on the site, it is also necessary to manually cut off the power supply (including the fire power supply) and then extinguish the fire; Switching lines can also cause short circuits and leakage, causing tripping and power failure. These have certain practical contradictions with the power supply requirements of fire-fighting equipment.
In the event of a fire, even if the backup generator can be started in time, it will not be able to restore the on-site lighting power supply due to faults such as line damage or equipment short-circuit overload. At this time, the dual-circuit power supply emergency lighting that is usually used cannot function to restore power. of. Therefore, the backup generator can only supply power to the fire-fighting water pump and the high-power fire-fighting equipment that are generally designed to be safely concealed. It is obviously unreliable for the evacuation lighting of the fire site to be powered by the generator.
Therefore, the power supply for emergency lighting is extremely important. The national "Fire Emergency Lights" clearly stipulates the power supply for such emergency lighting fixtures. These lamps should be powered by the battery as a backup power source, and the power supply time is not less than 30 minutes. However, the "Regulations on Fire Safety Management of Public Entertainment Places" stipulates that it is 20 minutes, and there is a situation of non-uniformity.
Fourth, problems in practice
In practice, many design units are still powered by dual-circuit mains in accordance with the primary load when designing large public buildings, with automatic mutual investment. Generators are used as emergency power sources. When both mains power supply loses power, the generator will automatically start, and the power supply will be provided to each of the emergency evacuation lighting, evacuation signs, fire pumps, smoke exhaust fans and other fire protection devices through mutual investment of the mother cabinet. In the selection of related equipment, only the safety exit signage and evacuation signage use the self-contained battery. The emergency lighting fixtures of the evacuation channel are still ordinary lamps, but only the double-loop emergency circuit with automatic switching at the end is used. This design idea is basically in line with relevant technical specifications. It has been used for decades.
It can also be seen from the technical specifications extracted from the above that the state does not mandate emergency lighting to use emergency lights with self-contained batteries, but it is “acceptableâ€. From the textual expression, it seems that the battery as the backup power source is lower than the generator as the backup power source.
Some local government construction supervisors also hold the same view as the guiding ideology when building some large public buildings: in the event of a power outage or fire accident. If the mains power is cut off, you can pass the mutual joint parent cabinet. The power supply is automatically restored by another city power supply; when the two mains power sources are cut off, the generator will automatically start, and the power supply to the emergency lighting line will be restored through the mutual investment of the parent cabinet. To meet the needs of personnel escape and disaster relief, it is completely foolproof. Moreover, it is also considered that the emergency lighting power supply method using the generator as the backup power source is higher than the emergency light with the battery itself, and is reliable.
However, it is known from the above analysis that in the event of a fire, this traditional design can no longer meet the needs of emergency lighting. "Emergency lighting", also known as "accident lighting", is essentially "accident lighting", taking into account the specific circumstances of the fire, not just the case of a sudden power outage. Moreover, from the large number of actual fire cases, the number of deaths and injuries caused by the pedaling of the emergency lighting is enough to cause us to re-recognize the importance of emergency lighting in the fire.
In practice, some large-scale public buildings completed in recent years have repeatedly appeared such things: when building fire protection is built, it is designed according to the traditional dual-circuit emergency power supply design specification, and the generator set is used as emergency power supply. The drawings can pass the government fire department. The audit can also pass the building fire inspection and acceptance; however, when it is put into use, the government regional fire management unit responsible for the daily fire supervision and management has raised objections to the emergency lighting, requiring important safety exits, evacuation passages, fire equipment rooms, etc. In the area, the installation of self-contained battery-powered double-head emergency lighting or downlights meets the actual needs, and disregards the so-called dual-loop power supply to ensure emergency lighting.
The reason for this is mainly because some design units did not fully consider the actual needs, lack of practical experience, and some construction units also believe that emergency lighting affects the aesthetics and cannot be adapted to the increasingly high-end decoration standards. In addition, the state stipulates that the scope of use of emergency lighting fixtures is also small. The relevant technical specifications do not clearly state the level difference between the use of self-contained battery mode and standby generator mode for emergency lighting. There are unclear situations, and designers do not know. Deep, unable to meet the fire safety needs of large public buildings.