Despite the emergence of alternative light sources, the DRL lamp is still one of the most popular solutions used to illuminate production facilities and streets. This is not surprising, given the advantages of this lighting device:
Long service life, especially with continuous operation (inherent in all gas-discharge lamps) ;
- High efficiency and significant luminous flux;
- Sufficient reliability of all nodes.
It was believed that with the advent of sodium alternatives, the DRL lamp would lose its position, but this did not happen. If only because its white spectrum of light is more natural for the human eye than the orange shade of the luminous flux of sodium solutions.
What is a DRL lamp?
The abbreviation "DRL" stands for very simply - an arc mercury lamp. Sometimes the explanatory terms "luminescent" and "high pressure" are added. All of them reflect one of the features of this solution. In principle, when speaking of "DRL", one can not especially worry that an error in the interpretation can be made. This abbreviation has long become the nominal, in fact, the second name. By the way, sometimes you can see the expression "lamp DRL 250". Here, the number 250 means consumed electrical power. It is quite convenient, since it is possible to choose a model for
Principle of operation and device
The lamp of the DRL is not something fundamentally new. The principle of generation of the ultraviolet radiation invisible to the eye in a gaseous medium during electrical breakdown is known for a long time and is successfully used in luminescent tubular flasks (we recall the "housekeepers" in our apartments). Inside the lamp in an inert gas environment with the addition of mercury is a tube made of quartz glass that can withstand high temperatures. When the voltage is applied, an arc arises between two closely located electrodes (working and incendiary). This starts the ionization process, the conductivity of the gap increases and when a certain value is reached, the arc is switched to the main electrode located on the opposite side of the quartz tube. The ignition contact leaves the process, because it is connected through the resistance, and, therefore, the current on it is limited.
Thus, the difference from the classical fluorescent lamp in a special way of kindling the arc. The point is that an initial breakdown of the gas is necessary to initiate ionization. Previously, pulsed electronic devices capable of creating a sufficiently high voltage for the breakdown of the entire gap in the quartz tube did not have sufficient reliability, so the developers in 1970 made a compromise - they placed additional electrodes in the design, which were fired between them during mains voltage. Anticipating the counter question about why in tube tubes the discharge, after all, is created with the help of a choke coil, we will answer - it's all about power. The consumption of tubular solutions does not exceed 80 watts, and the DRL is not less than 125 W (reaching 400). The difference is palpable.
The connection scheme for the LRL lamp is very similar to the solution used to ignite tubular fluorescent lighting fixtures. It includes a series-connected choke (limiting the electric current), a parallel-connected capacitor (eliminating interference in the network), and a fuse.