A noticeable problem in the design of the hottest

A noticeable problem in the design of emergency lighting

when designing the power supply of emergency lighting, designers follow the provisions of the jgj/t code for electrical design of civil buildings on the design of emergency lighting power supply (11.8, 7.2, 11.8.7.4, 11.8.9, etc.). The above provisions point out that emergency lighting should be powered by two-way power supply. When there are no two power supplies or two-way lines in important places or power supply conditions, The emergency lighting with battery shall also be set or powered by battery pack: the emergency lighting with battery can be connected from the special circuit of the distribution board on this floor (in this area) or the special distribution board for disaster prevention. However, in the process of practice, the author found that one-sided emphasis on the application of the above provisions is not very appropriate, and may even cause adverse consequences. This paper presents a view on the power supply mode of emergency lighting with storage battery for discussion by designers and relevant standard makers

brief introduction:

the so-called emergency lighting refers to the lighting facilities used only under abnormal conditions, including standby lighting, evacuation lighting, and safety lighting. The power supply time and illumination requirements for different types of emergency lighting are clearly specified in the specification

the power supply design of emergency lighting is designed by the designer according to the power supply and distribution conditions of the project itself and in line with the requirements of the specification. There are generally two forms of emergency lighting control: one is that the light source is normally closed at ordinary times, and it will be automatically lit only when the normal lighting returns to failure and loses power; The second is to use it as a part of the normal lighting at the same time. When the normal lighting loses power for some reason, no matter what state the control switch of the emergency lighting is in (on, off), it should be automatically lit

for example,

when a designer designs the emergency lighting of an important shopping mall, he should follow the electrical state (open and closed) of civil buildings and light it automatically

examples

when designing the emergency lighting of an important shopping mall, a designer completely followed the relevant provisions of the code for electrical design of civil buildings jgj/t, selected the emergency lighting with battery as the main device of emergency lighting, and adopted two ways of power mains from two transformers in the substation According to the experimental environment, it can be divided into: room temperature fatigue test, low temperature fatigue test, high temperature fatigue test, thermal fatigue test, corrosion fatigue test, contact fatigue test, fretting wear fatigue test and other power supplies. The emergency lighting lamp is powered by the local dual power supply automatic switching control box. As shown in the following figure:

the control mode of emergency lighting is: normally, the light source is normally closed, and the lighting is in the floating charge state: when the normal lighting loses power for some reason, it will automatically light up

it seems that there is nothing wrong with the above design, which has been approved after review. However, problems occurred when the project was put into operation after completion. One night, the normal lighting power circuit of the mall suddenly lost power for some reason, and the emergency lighting did not automatically light up at this time, which was suddenly dark and chaotic

reason

because the selected emergency lighting lamp with battery has its own functional structure, that is, when the external power is loaded, it is in the floating charge state, loses the external power, and the battery in the lamp discharges and automatically lights up. Since the emergency lighting power supply is provided through the dual power automatic switching control box, when the normal power supply loses power, the standby power supply will be automatically switched into operation. Therefore, the external power actually loaded on the emergency lighting still exists, but another power supply is changed, and the emergency lighting cannot be automatically lit

evaluation:

the dual power automatic switching control box is used to supply power to the emergency lighting. However, today's emergency lighting products with batteries only have one power input, so it is impossible to identify the power supply. At present, it is impossible to count the exact number of changes. As long as there is external power loading, it is always in the floating charge state. Only when the external power is lost, it will be automatically lit by the discharge of the battery in the lamp. The purpose of using dual power automatic switching control box to supply power to emergency lighting is to improve its power supply reliability, but the result is counterproductive. In addition, it is assumed that the power supply of the above design is not through the dual power automatic switching control box, but directly from the normal lighting power supply, or through the dual power automatic switching control box without selecting the emergency lighting with battery, and the control form is changed to: the emergency lighting is used as a part of the normal lighting at the same time, then the above accident may not occur

conclusion:

the emergency lighting has its own battery, for example, the micro generator has been set inside the lighting, and in the case of loss of external power, it will automatically impose a tariff of 20% for discharge work, while the external power supply line only plays a role in maintaining the internal energy of the battery, but it will hardly play a role in abnormal conditions. Therefore, in daily operation, it is necessary to regularly check the working condition of emergency lighting (generally, emergency lighting products with batteries have the function of condition indicator), but it is not necessary to emphasize that its power supply must come from the dual power automatic switching control box

in the design of emergency lighting power supply, emergency lighting can be used as a part of normal lighting at the same time, with separate control switches and distribution lines, and it is not necessary to choose lighting fixtures with batteries for all emergency lights. In smaller places, if the emergency lighting lamp with battery is selected, its power supply line is simply directly connected to the normal lighting circuit in the same place. Of course, this is against the requirements of the current specifications, but the author believes that due to current emergency lighting products and other reasons, this is appropriate

suggestions:

it is recommended that all relevant manufacturers step up the development of a new type of emergency lighting products and related dual power automatic switching control box products that can not only meet the requirements of the current specifications, but also meet the design requirements. The above is just a view on a certain issue. The purpose is to raise the issue for everyone to discuss. Because of this, it is inevitable that there are some inappropriate and fallacious remarks. Please comment and correct them

References:

code for electrical design of civil buildings jgj/t