Despite the emergence of alternative light sources, the DRL lamp is still one of the most popular solutions used to illuminate industrial premises and streets. This is not surprising, given the advantages of this lighting fixture:
-
drl lamp long service life, especially with continuous operation (inherent in all gas discharge lamps);
- high efficiency and high 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 light spectrum is more natural to the human eye than the orange tint of the light flux of sodium solutions.
What is a DRL lamp?
The abbreviation "DRL" stands for very simply - an arc mercury lamp. The explanatory terms "luminescent" and "high pressure" are sometimes added. All of them reflect one of the features of this solution. In principle, when saying “DRL”, you don’t have to worry too much that a mistake in interpretation can be made. This abbreviation has long become a household name,in fact, the second name. By the way, sometimes you can see the expression "DRL 250 lamp". Here the number 250 means the consumed electric power. Quite convenient, as you can choose a model under
existing launch equipment.
Working principle and device
The DRL lamp is not something fundamentally new. The principle of generating ultraviolet radiation invisible to the eye in a gaseous medium during electrical breakdown has long been known and has been successfully used in luminescent tubular flasks (remember the "housekeepers" in our apartments). Inside the lamp, in an inert gas atmosphere with the addition of mercury, there is a quartz glass tube that can withstand high temperatures. When voltage is applied, an arc first appears between two closely spaced electrodes (working and incendiary). At the same time, the ionization process begins, the conductivity of the gap increases, and when a certain value is reached, the arc switches to the main electrode located on the opposite side of the quartz tube. In this case, the ignition contact exits the process, as it is connected through a resistance, which means that the current on it is limited.
The main radiation of the arc falls on the ultraviolet range, which is converted into visible light by a layer of phosphor deposited on the inner surface of the bulb.
Thus, the difference from the classic fluorescent lamp is in a special way of starting the arc. The fact is that an initial breakdown of the gas is necessary to start ionization. Previously, pulsed electronic devices capable of creating a sufficiently high voltage to breakdown the entire gap in a quartz tube did not have sufficient reliability, so the developers in the 1970s made a compromise - they placed additional electrodes in the design, ignition between which occurred at mains voltage. Anticipating a counter question about why a discharge in tube lamps is nevertheless created using a choke coil, we will answer - it's all about power. The consumption of tubular solutions does not exceed 80 watts, and DRL does not happen less than 125 watts (reaching 400). The difference is palpable.
The DRL lamp connection diagram is very similar to the solution used to ignite tubular fluorescent lighting fixtures. It includes a choke connected in series (limiting electric current), a capacitor connected in parallel (eliminating network noise) and a fuse.
